Bericht 336_Leseprobe

International Thermal Spray 

Conference & Exposition2017 

June 7 – 9, 2017, Düsseldorf/Germany 

2017 

DVS-BERICHTE 

Foto: GTV Verschleißschutz GmbH 

Conference Abstracts 

(including proceedings on USB stick) 

Organizers: 

! DVS – German Welding Society 

! ASM International – Thermal Spray Society (TSS) 

! IIW – International Institute of Welding 

Supporting Partners 

Media Sponsors

Lectures 

PENTA: Anovel high spray rate APS gun 

Plasma Spraying I 

T. Schläfer, A. Wank, C.Schmengler and K. Müller-Roden, Luckenbach/DE 

Multi-electrode APS has proven significant advantages with regard to spray rates, deposit efficiency and 

component life time. So far, three-cathode and three-anode spray guns have been established successfully in 

several industrial sectors where high spray rates are mandatory. Based on the successful three-anode plasma 

spray gun DELTA, the five-anode APS gun PENTA was developed to further increase productivity. With its gross 

power of up to 125 kW it allows very high spray rates and thus significantly reduced coating times. This paper 

focusses on the development ofhigh spray rate parameter settings for producing oxide ceramic coatings. All 

coatings will be investigated with regard totheir microstructures. Furthermore, economical benefits ofthe fiveanode 

technology will be highlighted. 

Novel approaches for thermal spray deposition of fully dense ceramic and metal coatings 

with well bonded lamellae 

C. Li, S.Yao, J.Tian, C. Li, G.Yang, X.Luo and Y. Wei, Xi’an/CN 

It has been well accepted that thermal spray coatings present atypical lamellar structure with limited lamellar 

interface bonding. It has been agreat challenge to deposit afully dense coating with fully bonded lamellae. In this 

report, three different novel approaches are introduced to deposit fully dense ceramic coatings and metal alloy 

coatings. With the deposition of aspecific ceramic coating, it was found that there exists an intrinsic bonding 

temperature corresponding to the glass transient temperature ofspray material. Achemical bonding is formed at 

the interface upon splatting of amolten ceramic droplet, as far as the maximum interface temperature between the 

spreading splat and the solid splat reaches over the intrinsic bonding temperature. Moreover, itwill be presented 

that asimple critical bonding temperature in alinear relation with the melting point of coating materials can be 

utilized to deposit fully dense ceramic coatings bycontrolling the deposition temperature. Furthermore, with metal 

alloy coatings, aself-bonding mechanism is proposed utilizing the ultra-high temperature molten droplet for dense 

coating with fully bonded lamellae. Using specially designed core-shell structured powders, it was demonstrated 

that abulk-like metal coating is deposited by creating ultra-high temperature molten droplet. It will be found that 

such coatings present excellent properties and performance comparable to bulk materials. Moreover, itwill be 

shown that, for ductile metal alloys, the solution-impermeable dense metal coatings can be deposited byusing the 

novel in-situ shot-peening assisted cold spraying. 

Porosity characterization and its effect onthermal properties ofAPS sprayed alumina 

coatings 

W. Tillmann, O. Khalil and M. Abdulgader, Dortmund/DE 

In the present work, three different APS alumina coatings were fabricated using three fused and crushed alumina 

powders of different particle size fine, medium and coarse. The influence of the particle size onthermal properties 

and micro-structural features ofthe produced coating were investigated by thermal insulation test and detailed 

image analysis technique, respectively. The analyzed micro-structural features include the total porosity, pore size 

(fine, medium, and large) and cracks. All types of cracks were considered in calculations as voids and were 

evaluated according totheir sizes aspores. All spray parameters except the particle size were fixed throughout the 

spraying process. The results revealed that the fine starting powder has produced the densest coating with the 

lowest total porosity and that the total porosity increases with an increasing particle size. This was expected as 

DVS 336 1

powders ofsmaller particle size will reach ahigher in-flight temperature and velocity than powders of bigger 

particle sizes aslong asthe same spray parameters are applied. However, adetailed image analysis investigation 

on the three produced coatings showed that the fraction of fine pores and cracks versus the total porosity is 

substantially higher in coatings produced by using fine starting powders than those produced using medium and 

coarse powders. In this work, aconnection between the thermal insulation and the porosity fraction, which includes 

fine pores and cracks, was revealed. 

New investigations of the arc instabilities inaone-cathode-one-anode plasma generator 

via special wavelet-analysis 

S. Zimmermann, M.Mudra, O. Bornschlegl, S.Schein, G. Haderer, J. Marques and J. Schein Neubiberg/DE 

Plasma generators are frequently used in awide field ofapplications. These applications include thermal coating, 

plasma-welding, preprocessing ofsurfaces, sterilization and propulsion systems. The industrial use of plasma 

generators demands a high level of accuracy and reproducibility which has to be monitored throughout the 

process. Rather than analyzing results of e.g. acoating process (by electron microscopic) one prefers to have an 

online assessment of the plasma generator. The plasma generated is defined by various parameters (e.g., 

temperature, conductivity…) which can be measured with suitable measuring systems. Determining all plasma 

parameters inone setup isvery costly and requires abig setup. Inindustrial facilities itisoften suitable to measure 

one or two physical quantities and derive the plasma parameters from these measurements. This paper focuses on 

the evaluation of the electric current consumed by the plasma generator and the sound emitted by the whole 

system. Aquick analyzation ofthese signals – that may result in an online assessment –was accomplished by 

using the wavelet transform. Multiple experiments were performed to gain reliable and significant data (behavior of 

the arc/plasma). 

Aviation &Power Generation Industry I 

Practical aspects ofsuspension plasma spray for thermal barrier coating on potential 

gas turbine components 

X. Ma and P. Ruggiero, Charlotte/US 

Suspension Plasma Spraying (SPS) process has attracted extensive efforts and interests to produce finestructured 

and functional coatings. In particular, thermal barrier coating (TBC) applied bySPS process gains 

increasing interest due toits potential for superior thermal protection of gas turbine hot-section components as 

compared to its conventional APS-TBC and even EB-PVD TBC. Unique columnar architecture and nano- and submicron 

sized grains in a SPS-TBC demonstrate some advantages of thermal shock durability, low thermal 

conductivity and high-temperature sintering resistance. This work will look into some practical aspects ofSPS 

process for TBC application before itbecomes areliable industry method. The spray capability and applicability of 

SPS to achieve uniformity thickness and microstructure on curved substrates was evaluated indesigned spray 

trials tosimulate industrial parts with complex configurations. The performances of SPS-TBCs in erosion, free 

falling ballistic impact and indentational loading tests were tested and evaluated to simulate SPS-TBC 

performances in turbine service conditions. The behaviors ofSPS-TBCs in those tests were correlated tokey test 

factors including grit incident angles, impact object sizes, indentation head sharpes and coating surface curvatures. 

Finally, aturbine blade was coated and sectioned toverify SPS sprayability in multiple critical sections. The SPS 

trials and test results demonstrate that SPS is promising for innovative TBCs, but some challenges need to be 

addressed before it becomes aneconomic and reliable industrial process, especially for gas turbine components. 

2 DVS 336

Effect of spray parameters on the microstructure and porosity content of gadolinium 

zirconate TBCs deposited by suspension plasma spray 

S. Mahade, Trollhättan/SE, D. Zhouand R. Vassen, Jülich/DE 

Gadolinium zirconate (GZ) is considered as a promising top coat candidate for high temperature (>1200°C) 

thermal barrier coating (TBC) applications. Suspension plasma spray (SPS) technique has shown the capability to 

generate awide range of microstructures which includes the more desirable columnar microstructure. In this study, 

GZ single layer TBCs were deposited by axial SPS process. The variable parameters include the standoff distance, 

solid load content of the suspension and input power. The cross section and top surface of the as sprayed TBCs 

were analyzed by SEM. The phase content inthe as sprayed TBCs was analyzed by XRD. The porosity content of 

the assprayed TBCs was measured using image analysis. Inthe SEM analysis, it was observed that alower solid 

load content in the suspension favoured the formation of acolumnar microstructure. Additionally, at lower solid 

load content, increase in standoff distance resulted in columnar microstructure with high porosity content in the 

TBC. However,with higher solid content suspension and alteration ofinput power, only adense vertical cracked 

microstructure can be obtained. 

High feed rate plasma spraying of YSZ from various suspensions 

R. Musalek, J. Medricky, J. Kotlan, T. Tesar, F.Lukac, P. Ctibor, K. Illkova and T. Chraska, Prague/CZ 

In this paper, yttria-stabilized zirconia (YSZ) coatings were prepared by plasma spraying of ready-to-spray 

suspensions provided by three different manufacturers. High-enthalpy hybrid water-argon plasma torch WSP- 

H500 was successfully used for deposition of coatings with porous and columnar microstructure consisting of 

tetragonal non-transformable phase. Sensitivity of the deposition process to variation ofdeposition conditions was 

also evaluated by the change ofsuspension injection point position. Slight differences in the microstructures of the 

deposited coatings (in particular character of porosity and mutual bonding of the microsplats) were reflected in 

slight but measurable differences in hardness and wear resistance of the coatings indicating changes in the 

coating cohesion. Tensile adhesion/cohesion strength of the coatings was found to be in the range of 9to15MPa. 

High coating porosity desirable for low thermal conductivity combined with high suspension feed rate (from about 

100 to 120 ml/min in this study) makes the WSP-H coatings promising for further development for example in 

thermal barrier coatings applications. 

Medical Industry I 

Sporicidal efficacy of thermal spray copper alloy coating with varying degrees of 

roughness 

R. Shafaghi, L.Pershin, M. Riguette and J. Mostaghimi, Toronto/CA 

This study was focused onthe biocidal efficacy on spores of copper alloy sheet and copper alloy coating at two 

different surface topographies. Endospores can remain viable in adormant state for centuries. Our work compares 

the effectiveness inkilling endospores of copper alloy coating and sheet metal. Atwin-wire arc spray system was 

used for coating of stainless steel coupons. The feedstock was CuNiZn wire, the coating thickness was 400 µm. 

The copper alloy sheet metal had the same composition and is registered as antimicrobial by Environmental 

Protection Agency (US). Uncoated stainless steel coupons were used ascontrols in all experiments. The surface 

was polished to two roughness levels Ra=3.5 µm, and Ra=0.1 µm. The surface topography was analysed by a 

stylus profilolemeter and 3D image analysis. EDS and FIB were used tocharacterize the elemental composition 

and structure flower-like nanostructures and endospores. The results obtained in this study indicated that changes 

in Ra values of 0.1 and 3.5 μm had no significant impact on the biocidal activity of sheet metal and the coating on 

E. coli, S. epidermidis and B. subtilils. The coating was as effective as the EPA certified sheet metal inthe 

destruction ofvegetative cells within 5minutes. This study indicates that degradation of B. subtilis endospore 

begins within 2hours after exposure to the coating. By day seven, only extensively degraded endospores and 

nanostructures were visible on the both surfaces. Our results show that thermal spray copper alloy coatings were 

as effective ascertified antimicrobial sheet metal in the destruction ofendospores within hours however; the 

coating was more effective in killing after one week of exposure. 


Transpiring thermally sprayed alumina layers with integrated fluid flow tubes 

M. Rodriguez Diaz, K. Möhwald, N.Loftfield, M.Kästner, E. Reithmeier, S. Knigge, B.Glasmacher and H. J. Maier, 

Garbsen/DE 

Osteoarthritis in the hip or knee is one of the most common diseases in industrialized countries. The implantation 

of an endoprosthesis as a joint replacement represents the most effective way to treat serious pathological 

changes in these joints. The lifetime of an endoprosthesis can be shortened by aseptic inflammation and 

osteolysis. The main cause for the aseptic inflammations, osteolysis, and thus, the failure of the endoprostheses 

are abrasion particles ofthe acetabular cup inlays that are caused by the tribological load of the prosthesis. This 

research project aims atdeveloping coatings with enhanced tribological behaviour for endoprostheses byanactive 

hydrodynamic lubrication ofthe joint with synovial fluid. Inaddition, biocompatibility, as well as the increase of the 

strength under static and cyclic loading need be realized. In the current approach, adeterministic fluid flow tube 

structure isformed inathermally sprayed alumina layer bythe introduction of aleachable placeholder. This tube 

structure allows the transverse transport ofthe synovial fluid through the alumina layer. Furthermore the synovial 

fluid can be transported into the lubricating gap of the sliding surfaces by leaving the alumina layer through the 

porous surface. First results will be presented and the ramifications in correlation to applications will be discussed. 

Experimental analysis of impact behavior of ultra-high molecular weight polyethylenenano 

ceramics composite particles by isolated particle deposition method using 

downstream injection cold spray technique 

K. Ravi, Sendai/JP and Lyon/FR, K. Ogawa, Sendai/JP, O.Lame, Lyon/FR, and J.-Y. Cavaillé,Sendai/JP 

Recent advances has made possible to obtain Ultra High Molecular Weight Polyethylene (UHMWPE) coatings by 

cold spray technique with nano-ceramic additives with the feedstock. However, the exact role ofnano particles is 

largely not understood. In this work, isolated depositions of UHMWPE particles with 0%, 2%, 4%, 10% offumed 

nano alumina (FNA) onAlsurface were performed at different gas/particle temperatures. Particle velocities and 

particle temperatures were controlled byvarying the carrier gas pressure and temperature. The impact behavior of 

UHMWPE was analyzed using SEM, FIB and high-speed camera. Increase ingas temperature and percentage of 

FNA showed asignificant variation in the deposition volume. FIB analysis showed that successful depositions were 

influenced by degree ofdeformation of particle. Further, addition ofFNA helped in deposition ofparticles that have 

required alesser degree of deformation. Finally, high speed camera showed that particles are moving atan 

incidence velocity of 180-200m/s and rebound velocity of40-50m/s. This suggests that particles lose asignificant 

amount of their kinetic energy during the impact. 

Process Diagnostics, Sensors &Controls 

The arc movement as asource ofprocess instability for single-cathode-anode systems – 

anew method for direct investigation 

G. Thomas, Technical University of Berlin, Berlin/DE, S. Mihm, Mägenwil/CH, M. Limburg, Berlin/DE, and H. 

Gruner, Mägenwil/CH 

The almost uncontrollable arc movement in a single-cathode-anode system limits the efficiency and process 

stability of this global used DC plasma spraying technique. Asuccessful approach to stabilize the arc anode 

attachment and thus to increase process efficiency was the replacement of the convergent-cylindrical nozzle 

geometry by aconvergent-divergent nozzle geometry with Laval contour. However, the advantages of this nozzle 

design were connected to an increased anode erosion caused by an excessive heat input from the anode 

attachment ofthe arc. Prerequisite for an optimization of the arc movement isits technical measurement and the 

dedicated correlation out of it with the plasma jet and the trajectory of injected powder particles. For this purpose 

Technical University ofBerlin developed anew optical analysis method based on high-speed video recording to 

examine the arc movement, its position and intensity. The software based data together with the simultaneous 

measured voltage of the corresponding DC-arc clearly show for example the dependence ofthe arc movement 

from the position ofthe cathode tip in relation tocenter axis of the anode, impressively demonstrated for anew 

three-zone anode (convergent, conical and divergent). Thus anew tool is given to the developer of new anode 

geometries for increasing process efficiency and the lifetime of the single-cathode-anode system. 


Investigation of the usefulness of particle jet monitoring in aproduction environment 

L. Leblanc, R. Hinckley and C.Spinicci, Malta/US 

In the thermal spray process, particle state at impact is among the key factors influencing the quality, 

characteristics and properties of the deposit formed. Measuring and eventually controlling in-flight particle jet 

characteristics can help ensure the repeatability of desired coating properties. Moreover, monitoring particle jet can 

lead to cost savings by allowing replacement of consumable parts onaneed-basis rather than on apreventivebasis. 

However, successful use of in-flight particle sensors inaproduction environment requires developing an 

implementation strategy that minimizes impact on coating cycle time, limits operator intervention and reduces 

analysis time, while still generating useful data. The usefulness of in-flight particle sensor in ahigh yield production 

environment isinvestigated. Apreliminary study was first conducted todefine astrategy to implement the data 

acquisition process using an ensemble in-flight particle monitoring system that allows real-time measurements of 

average particle temperature and velocity and overall particle jet profile. Data was collected to capture 

representative torch and particle jet behaviors over the life of several consumable hardware sets. Evolution ofthe 

particle jet parameters over time is compared to that of some of the process parameters, as well as to the 

deposition efficiency and one selected characteristic ofthe coating deposited. Some trends are identified, and 

potential benefits and drawbacks of using in-flight particle monitoring inahigh yield production environment are 

highlighted. 

In situ acoustic monitoring of thermal spray process using high-frequency impulse 

measurements 

W. Tillmann, F. Walther, W. Luo, M. Haack, J. Nellesen and M.Knyazeva, Dortmund/DE 

In order to guarantee their protective function, thermal spray coatings must be free from cracks, which expose the 

substrate surface toe.g. corrosive media. Cracks in thermal spray coatings are usually formed because of tensile 

residual stresses. Most commonly, the crack occurrence isdetermined after the thermal spraying process by 

examination of metallographic cross-sections of the coating. Recent efforts focus on in situ monitoring ofcrack 

formation bymeans of acoustic emission analysis. However, the acoustic signals related to crack propagation can 

be absorbed by the noise of the thermal spraying process. In this work, ahigh-frequency impulse measurement 

technique was applied to separate different acoustic sources by visualizing the characteristic signal of crack 

formation via quasi-real-time Fourier analysis. The investigations were carried out on atwin wire arc spraying 

process, utilizing FeCrBSi asacoating material. The impact of the process parameters on the acoustic emission 

spectrum was studied. Acoustic emission analysis enables toobtain global and integral information onthe formed 

cracks. The coating morphology as well as coating defects were inspected using light microscopy on 

metallographic cross-sections. Additionally, the resulting crack patterns were imaged in3Dbymeans ofX-ray 

micro-tomography. 

Ceramic Coatings 

Epitaxial growth during the rapid solidification of plasma-sprayed molten TiO2 splat 

S. Yao, C. Li, G.Yang and C. Li, Xi’an/CN 

Epitaxial grain growth during the rapid solidification of molten TiO2 in plasma spraying was studied. The 

crystallographic structure of the TiO2 splats deposited on rutile and α-Al2O3 substrates at150, 300 and 500 °C was 

characterized by high resolution transmission electron microscopy and electron back scattering diffraction. The 

results reveal that homo-epitaxial and hetero-epitaxial TiO2 splats can be formed atthe deposition temperature of 

500 °C. Epitaxial growth is significantly influenced by the crystal orientation. Itiseasier toform an epitaxial TiO2 

splat with a orientation inthe direction perpendicular tothe substrate surface. Inorder toexplain the 

formation of epitaxial splat during plasma spraying, acompetition mechanism between heterogeneous nucleation 

and epitaxial growth was proposed. It was indicated that the face (001) of rutile crystal exhibits the largest growth 

velocity, which isconducive to form an epitaxial splat for the melt with alargest undercooling degree. In addition, 

the effect of deposition temperature and crystalline orientation on the epitaxy was simulated. The simulation results 

are in agreement with the experimental observations. 


Cold Gas Spraying I 

Broken characteristics of the oxide film in cold spray 

Y. Xie, C.Chen, M.Planche, R.Raoelison, C. Verdy and H. Liao, Belfort/FR 

In cold spraying, oxide-free interface is an important factor for fresh metal bonding between particles and substrate, 

which determines the bonding strength and final coating quality. In this study, awell-designed experiment was 

performed toexamine the deformation behaviour of the oxide film on copper alloy particle surface after deposition. 

The experiment results show that partial oxide film could bedisrupted during the high-speed impact. However, 

most of the oxide films were found to remain intact after particle deposition, which limited the exposure ofoxide 

free interface. The presence of oxide film atthe interfaces between deposited particles and substrate seriously 

affected the metallurgical bonding. Besides, substrate material is found to have a strong influence on the 

deformation behaviour and final state of the oxide film. The study also demonstrated that the bonding mode 

between deposited particle and substrate strongly depends onthe type of substrate. 

Essential factors influencing the bonding strength of cold sprayed aluminum coatings on 

ceramic substrates 

R. Drehmann, T. Grund, T. Lampke, B. Wielage, Chemnitz/DE, C. Wüstefeld, M.Motylenko and D. Rafaja, 

Freiberg/DE 

The present work summarizes the most important results of aresearch project dealing with the comprehensive 

investigation of the bonding mechanisms between cold sprayed Al coatings and various poly- and monocrystalline 

ceramic substrates (Al2O3, AlN, Si3N4, SiC, MgF2). Due to their exceptional combination of properties, metallized 

ceramics are gaining more and more importance for a wide variety of applications, especially in electronic 

engineering. Cold spraying provides aquick, flexible and cost-effective one-step process to apply metallic coatings 

on ceramic surfaces. However, since most of the existing cold spray-related publications focus on metallic 

substrates, only very little is known about the bonding mechanisms acting between cold sprayed metals and 

ceramic substrates. In this paper, the essential factors influencing the bonding strength insuch composites are 

identified. Besides mechanical tensile strength testing, athorough analysis of the coatings and especially the 

metal/ceramic interfaces was conducted by means of HRTEM, FFT, STEM, EDX, EELS, XRD and EBSD. The 

influence of substrate material, substrate temperature and particle size isevaluated with regard to the observed 

bonding behavior. The results suggest that, apart from mechanical interlocking, the adhesion ofcold sprayed 

metallic coatings onceramics is based on acomplex interplay of different mechanisms such as quasi-adiabatic 

shearing, static recrystallization as well as heteroepitaxial growth. 

Metallization of various polymers bycold spray 

H. Che, P. Vo and S.Yue, Montreal/CA 

Previous results at McGill University have shown that metallic coatings can be successfully cold sprayed onto 

polymeric substrates. This paper studies the cold sprayability ofvarious metal powders on different polymeric 

substrates. Five different substrates were used, including carbon fibre reinforced polymer (CFRP), acrylonitrile 

butadiene styrene (ABS), polyether ether ketone (PEEK), polyethylenimine (PEI); mild steel was also used as a 

bench mark substrate. The CFRP used inthis work has athermosetting matrix, and the ABS, PEEK, and PEI are 

all thermoplastic polymers, with different glass transition temperatures aswell as anumber ofdistinct mechanical 

properties. Three metal powders, tin, copper and iron, were cold sprayed with both alow-pressure system and a 

high-pressure system atvarious conditions. Ingeneral, cold spray on the thermoplastic polymers rendered more 

positive results than the thermosetting polymers, due to the local thermal softening mechanism in the 

thermoplastics. Thick copper coatings were successfully deposited on PEEK and PEI. 


Maritim Industry &Off-Shore Technologies 

Acase study of repair work on ship engine valve stems 

P. T. Nielsen, D. B. Bangsgaard, K. G. Soerensen, Brøndby/DK, and P. Pallesen, Hirtshals/DK 

The degradation mechanisms of machine parts are well-known facts, usually resulting in replacement of 

components. However, in some cases, for instance, parts for large ship engines, repair will often seem more 

attractive. Time-wise, the vessel’s down-time will be reduced and the investment will be lower. This paper 

describes repair work performed onvalve stems from a52-year-old ship engine. Due to this long time in operation, 

the stems were damaged by wear and were no longer functional. The requirements for the stems were scarcely 

documented stating only afew specific requirements; therefore ashort study of the possibilities concerning rebuild 

material and application method was initiated. This paper illuminates the manufacturing process used; twin wire arc 

spraying with Monel asthe rebuild material. Monel ischosen to meet the requirements for hardness and the 

subsequent high precision machining. In addition, the mechanical and metallurgical properties of the rebuild 

coating are examined in regard to adhesion, microstructure and hardness to interpret and support the functionality. 

Partial repair of thermally sprayed and sealed corrosion protection – Organic coating 

material or thermal spraying? 

T. Wilhelm, C. Klesen and T. Maghet, Duisburg/DE 

For many decades thermally sprayed corrosion protection systems onthe basis ofZnAl orAlcarry out their service 

for structures in coastal areas, the offshore sector, as CUI (Corrosion Protection under insulation) oranywhere 

where the properties ofthermally sprayed corrosion protection systems bring important advantages interms of 

durability. Athermally sprayed corrosion protection system is about to protect the structure 25 to 30 years against 

corrosion. During this time it may be damaged due to factors like construction work, improper handling or simple 

aging. There are many standards and regulations, which describe the initial design of thermal spray systems, 

however they remain silent regarding repair. In particular, amending of partial regions is hardly described. Specific 

repair instructions are rare and if present, they differ from one another. Overall there isalack of knowledge of the 

proper procedures for partially repairing thermal spray coating systems. This project was concerned with tangible 

corrosion-technical issues of the coating repairs: How does the critical overlap area perform? Have organic 

coatings benefits? To what extent does arenewed damage affect the lifetime? The aim of the study was to develop 

practice-relevant instructions for the repair of thermally sprayed duplex systems. 

Improvements of coating properties and residual stress states in arc sprayed aluminium 

bronze coatings by using an alternative gas mixture 

M. Hauer, Rostock/DE, S. Krebs, Hamburg/DE, W.Krömmer, Unterschleißheim/DE, and K.-M. Henkel, 

Rostock/DE 

The highly cavitation erosion resistant propeller alloys CuAl9Ni5Fe4Mn and CuMn13Al8Fe3Ni2 were arc sprayed 

with different traverse speeds by using amixture of nitrogen and 2%ofhydrogen as atomising gas. Residual 

stresses were measured by the modified hole-drilling method using ESPI. Microstructural, chemical and 

mechanical analyses were realised to examine adhesive and cohesive properties. Additionally, the cavitation 

erosion behaviour was investigated. Incomparison to coatings sprayed with pressurised air, the results ofthe 

study show superior coating qualities with regard tomicrostructure, cavitation erosion resistance and residual 

stresses. 


Power Generation – Fuel Cell 

Experimental and numerical study ofthe effect of gas-shrouded plasma spraying on 

cathode coating ofalkaline electrolysis cells 

T. Liu and A. Ansar, Düsseldorf/DE 

Dual layer electrode coating for alkaline water electrolysis was prepared byplasma spraying. For improving 

performance this work aims at reducing the oxide inelectrode coating. Regarding the necessity of obtaining high 

specific area, atmospheric plasma spray was employed under protection ofargon which was used as shrouding 

gas. Composite cathode was established on Ni-coated perforated steel sheet with crushed and gas atomized 

Nickel-based alloy powders. The dual-layer structure was acomposite of5layers ofNiAl atthe bottom and 10 

layers of NiAlMo as the top layer. Microstructure and morphology were studied byscanning electron microscope 

(SEM). Element content was estimated by energy dispersive spectrometer (EDS). Enthalpy probe was introduced 

for measuring plasma temperature and velocity as well as gas composition. Numerical calculation was carried out 

with same condition for better understanding the shrouding effect. The results showed moderate protection by 

using of arranged gas shrouding. Overall the dual layer region, Oxygen was decreased by 0.3% from 3.46% to 

3.15%. With gas shrouding coating exhibited similar element contents as coating sprayed by VPS. However, no 

obvious difference was observed in microstructure and morphology with or without gas shrouding. 

Thermally sprayed porous copper coatings for capillary transport ofliquids 

C. Feng, S. Yugeswaran and S. Chandra, Toronto/CA 

Porous copper coatings, which act as wicks for liquid transport, were fabricated using aflame spraying process. 

Copper and aluminum powders were fed independently into the spray torch and deposited oncopper substrates to 

form acomposite coating. The aluminum was subsequently removed using chemical leaching leaving aporous 

copper coating behind. Varying the feed rate ofaluminum powder allowed the coating porosity tobecontrolled. 

Channels to enhance liquid flow were made insome of the porous copper coatings byplacing pieces ofaluminum 

wire mesh onthe copper substrate before spraying. During spraying the sprayed powders passed through the 

mesh opening and created pyramid shaped arrays on the substrates. The groove width was controlled byusing 

different wire mesh sizes. Coatings were made with porosity varying from 2to44%,and groove width ranging from 

0.16 to 0.53 mm. The capillary performance of the coatings was evaluated experimentally by measuring the rateof-rise 

of ethanol in the coatings. The rate of rise increased with coating porosity, and decreased with groove width. 

Anew technology for spraying advanced low-temperature (300 ~600 °C) solid oxide fuel 

cells 

K. Yuan, Y. Yu, X. Lu, X. Ji, Beijing/CN, and B. Zhu, Stockholm/SE 

Solid oxide fuel cell (SOFC) has been developed for ahundred year and met agreat challenge on material design 

and marketing. In recent years, new SOFC materials are dug uptoachieve high energy-output performance at 

lower working temperature (300~600 °C), namely low-temperature SOFC (LTSOFC). In this study, Ni-Co-Al-Li 

oxide (NCAL) was used for making dense, thin and uniform coatings ongrooved bipolar electrode substrate for 

LTSOFC. Low-pressure plasma spray (LPPS) technology was applied tomanufacture the NCAL coatings. The 

performance of afuel cell package using the coated bipolars was tested between 350 and 600 °C, showing 6~8 W 

power output with 4single fuel cells (active area of 25 cm2). The LPPS technology is believed to be one ofthe 

ultimate ways for manufacturing the thin film/coatings for SOFC applications in future. 


Medical Industry II 

Microstructure and mechanical properties of cold sprayed titanium coatings 

W. Żórawski, Kielce/PL, J. Madry, Mielec/PL, J. Sienicki, Mielec/PL, M. Makrenek, Kielce/PL, A. Góral, Cracow/PL, 

and S. Kowalski, Kielce/PL 

The work concerns astudy of the properties ofcold sprayed Ti coatings. This material is anattractive choice for 

many applications because itexhibits high strength-to-weight ratios, very good oxidation resistance, corrosion 

resistance and biocompatibility. Cold spraying is applied to deposit Ti coatings and elements as additive 

manufacturing process, however it needs higher critical velocity for deposition than other, more ductile metals. 

Nowadays nitrogen as cheap gas is used as working gas in cold spray process, however application helium as 

accelerating gas allows to obtain elements with higher strength. Itallows to understand the mechanism of cohesion 

between sprayed particles. In carried out experiment Ti powder with angular shape was applied in the cold 

spraying process. The coatings were sprayed by means of Impact Innovations 5/8 system with nitrogen and 

addition of helium onto 7075 Al alloy. The investigations revealed that the cold sprayed Ti coatings with addition of 

helium as working gas exhibit better mechanical properties, lower porosity and roughness. 

The influence of spray parameters onthe characteristics ofhydroxyapatite in-flight 

particles, splats and coatings during micro-plasma spraying 

X. Liu, Y. Wang, Z.Zhou, G.Wang, Z. Tan and D. He, Beijing/CN 

Phase composition and microstructure of hydroxyapatite (HA) significantly affects the biological and mechanical 

properties offinal hydroxyapatite (HA) coating. In the present study, HA coatings were deposited on Ti-6Al-4V by 

micro-plasma spraying (MPS) using different spray parameters. The influence of spray parameters on the 

composition and microstructure of the coatings were investigated. To understand the formation mechanism ofHA 

coatings, the in-flight particles and splats were examined as well. The morphologies of coatings surface, crosssections, 

initial powder, in-flight particles and splats were characterized byscanning electron microscopy (SEM). X- 

ray diffraction (XRD) was employed to analyze the phase composition. Three typical HA coatings were fabricated. 

The results indicated that the coating composition and microstructure were tightly related tothe melting state of inflight 

particles. And this was influenced bythe spraying parameters. The formation mechanisms ofthese coatings 

were discussed. 

Wear Protection I 

The protection against spray wear using pseudoalloys applied with the method of 

spraying 

R. Winkelmann, Senftenberg/DE, and H. Pokhmurska, Chemnitz/DE 

An important parameter that affects the protection from wear and tear, isthe geometric structure ofthe abrasive 

causing the destruction. The equivalent diameter of the particles of the primary influence on protection from wear 

and tear must be greater than the width of the particle of the crushed abrasive. Here also belongs the requirement 

for the distribution of the particles inside the matrix was more uniform and dense. The use of solid materials gives 

this possibility only in the certain circumstances, therefore, itisnecessary to use pseudoalloys. Pseudoalloys can 

be obtained by means ofthermomechanical processing of the conventional layers deposited bymeans of spraying. 

The particles of the solid material charged with kinetic energy are applied to the heated layers, and they penetrate 

into inside. Under the influence of the heat energy inside the layers suitable for this, the additional reaction 

between the substrate and the layer takes place, thus improving the adhesion of the layers. The appropriate 

regulations were developed, and the reproducible stratification appeared caused by spraying, that ispseudoalloys. 

Apositive consequence ofthe inclusion of the particles of asolid ceramic material into the spayed layer is the 

emergence of the current when compressed. The result of the research of the parameters are the optimal 


performance indexes, optimization criterion served as an indicator of the intensity of the wear. Manufactured 

pseudoalloys underwent checking in terms of spray wear. The study of spray wear was carried out at the 

temperatures upto750 ° Cand speed load amounted to 37.5 m/s. The silica sand fractions +150-212 μm was 

used asanabrasive. Asthe covering material the alloys based onaluminum were used. In the places of transition 

to the substrate the multiphase alloys of the system Fe-Al are formed. It is advisable touse layers with ahigh iron 

content toprevent the loose and destruction. 

Cavitation erosion characteristics ofHVOF thermal sprayed WC-cermet coatings 

A. Kanno and K.Takagi, Akashi/JP, and M. Arai, Tokyo/JP 

Cavitation erosion (CE) damage, which occurs in the main parts (made of high chromium cast steel) of 

hydroelectric power generation machine, is one of the serious problems. Itisexpected that life time ofthose parts 

would be prolonged if the suitable CE-resistant coating is applied onthe surface of the cast steel. In this study, 

WC-cermet coatings (WC-CoCr and WC-Cr3C2-Ni), which were fabricated by high-velocity oxygen-fuel (HVOF) 

thermal spraying process, was interested in protecting CE attack to the cast steel. To clarify CE property of the 

WC-cermet coatings, the ultrasonic vibration tests were conducted, and the amount of volume loss characterized 

as CE damage was measured. The microstructure and the fracture toughness, which was evaluated by the 

indentation test method, of the coatings were related with the CE damage. As the results obtained in this study, the 

fragment which was spalled from the surface after CEtest was almost flake-like shape, and its size was from 2μm 

to 50μm. SEM observation indicated that this fragment included both WC particle and metal binder, which means 

that WCparticle and metal binder was still strongly bonded together. It was also confirmed that the amount of 

volume loss could relate directly with the fracture toughness KIC rather than Vickers hardness. Itwas considered 

that CEdamage was progressed into the depth by throwing out the fragment originated from micro crack initiation. 

Thus, it was required that the CE resistance of the developed coatings could belabelled through the fracture 

toughness. 

Suspension Spraying I 

SPS coating microstructure controlled by the surface topography using laser texturing 

R. Kromer, Belfort/FR, P. Sokołowski, Limoges/FR and Wroclaw/PL, R. T. Candidato, Limoges/FR, S. Costil, 

Belfort/FR, and L. Pawłowski, Limoges/FR 

Thermal barrier coatings (TBC’s) being produced at present either by atmospheric plasma spraying (APS) or 

electron beam physical vapor deposition (EB PVD) are widely used in the hot-temperature sections of turbines to 

provide thermal and corrosion protections. An emerging technology of suspension plasma spraying has become 

interesting for the manufacturing of thermal barrier coatings thanks to the useful microstructure including columns 

similarly tothe EB-PVD deposits associated with considerably lower price ofproduction. Anarrow window of 

optimal suspension plasma spraying (SPS) parameters remain an outstanding problem in creating the favorable 

microstructure. The recent studies demonstrated that the substrate roughness may play an important role in 

reaching columnar growth of the coatings. This study presents a follow up by showing how the substrate 

topography obtained by laser surface texturing may becontrolled tocreate regular columnar structure thanks to. 

The laser generated peaks disposed regularly on the surface can promote columnar structure growth. The 

formulated suspensions were sprayed onto superalloy substrates coated with powder plasma sprayed bond coats. 

Optimized previously, plasma spray parameters were selected to generate columnar structures and tofind out the 

influence of the suspension behavior on coating microstructures. The results indicate that columnar SPS coating 

microstructure can be controlled byoptimizing the laser treatment parameters. The control of surface topography 

may be an important factor toimprove the performances of TBC-SPS coatings. 


Characteristics of dense AI2O3coating prepared by suspension plasma spraying 

H. Ibe, T. Masuda, K.Sato and N. Kato, Gifu/JP 

Sintering ceramics have been widely used in industries which require electrical and mechanical properties. 

Thermal sprayed ceramics coatings are also applied for the industries, however the coating which has micron size 

pores are limited their applications due toinferior electrical and mechanical properties compared with sintering 

bulk. To expand thermal sprayed ceramics coating applications, dense coatings prepared bysuspension plasma 

spraying are widely studied. Dense Al2O3 coatings are applicable to fabricating equipment for electronics devices, 

such as ESC. There are no reports regarding electric properties ofplasma sprayed dense Al2O3 coating with 

different spray conditions. Inthis study toachieve aelectric properties of dense Al2O3 coating, spray parameters 

such as plasma power, gas flow rate and spray distance are investigated. Suspension materials prepared with 

three microns Al2O3 powder are sprayed by high power suspension plasma spraying system. Spray conditions, 

plasma power, gas flow rate and stand off affect the coating density, christal phase, mechanical and electric 

properties. Mechanism of coating formation by plasma spraying with fine powder suspensions will bediscussed 

based onthe findings. Al2O3 coatings obtained bythe plasma spraying is applied for application to application 

utilizing the electrical insulation properties of such electronics devise manufacturing equipment components is 

proceeding. 

Equipment /Consumables &Powders, Wires, Suspensions I 

Influence of feedstock powder modification by heat treatments on the properties of APSsprayed 

Al2O3-40%TiO2 coatings 

L.-M. Berger, Dresden/DE, R. Vaßen and Y.J. Sohn, Jülich/DE 

Aluminum titanate (Al2TiO5) is a congruently melting compound in the binary Al2O3-TiO2 system, which 

decomposes below 1200 °C. Its properties (e.g. thermal conductivity, CTE) differ significantly from those of Al2O3 

and TiO2. Thus itisofspecial interest tostudy the stability ofAl2TiO5 in the spray process and its influence on the 

coating properties. A commercial fused and crushed Al2O3-40%TiO2 powder, which was found to be 

substoichiometric, was selected as the feedstock material for the experimental work, asthe composition is close to 

stoichiometric Al2TiO5. Part of that powder was heat-treated inair at 1150° and 1500°C inorder to vary the phase 

composition, while not influencing the particle size distribution and processability. The powders were analyzed by 

thermal analysis, XRD and FESEM including metallographically prepared cross sections. Apowder having Al2TiO5 

as the main phase was not possible to be prepared due to inhomogeneous distribution of Al and Ti in the original 

powder. Plasma spraying was performed with aTriplexPro-210 (Oerlikon Metco) using Ar-H2 and Ar-He plasma 

gas mixtures with 41 and 48 kW plasma power. Coatings were studied by XRD, SEM of metallographically 

prepared cross sections, and microhardness HV1. Moreover, the results show aclear influence of the Al2TiO5 

content in the feedstock powder on the phase composition of the coatings. 

Dry-sliding wear of laser clad nickel aluminide /chromium carbide coatings against cast 

iron 

S. Bengtsson, S.Dizdar, Höganäs/SE, and K. Gong, Göteborg/SE 

The wear of piston rings inlarge marine two-stroke diesel engines isamajor maintenance cost. Applying coatings 

with good oxidation, corrosion resistance and high temperature strength, can lower the total maintenance cost. In 

the past nickel aluminide with chromium carbide have been applied to pistons by thermal spraying. Using laser 

cladding asuitable microstructure can be formed while atthe same time avoiding cracks and bonding issues. In 

this report powders and coatings were manufactured in order to be able to investigate the dry-sliding wear 

behavior. Material with three levels of carbides was atomized. Wear test samples were manufactured bylaser 

cladding. The dry sliding wear-mechanism maps are generated by using block onring test setup where coated 

blocks slide against cast iron rings. All alloys exhibited regions ofplasticity-dominated wear and oxidational wear 

with atransition region in-between. The carbide-containing alloys showed lower friction and wear in comparison to 

the carbide free nickel aluminide alloy. 


Session Young Professionals 

Twin wire arc torch with optimized flow parameters 

A. Farrokhpanah, L.Pershin and J. Mostaghimi, Toronto/CA 

Wire arc is an effective and affordable type of coating process. Detailed understanding ofithelps improving design 

and optimization of currently available guns. In wire arc process, an arc forming between two charged wires 

generates enough heat to melt the metallic wires. Blow of air athigh velocity over this bath ofmolten metal leads to 

atomization. The formed droplets are then accelerated towards the substrate where they impact and solidify during 

the coating process. The current work isafollow uptoour earlier numerical study [1] where numerical simulation of 

wire arc spraying using ANSYS ® FLUENT ® revealed flow circulations inside the gun can affect flow pattern and 

contribute toenergy dissipation. Inthis study, anattempt has been made to validate and measure this matter using 

experimental procedures and to seek potential ways of improvement. 

Lamellar bonding enhanced NiCr-Mo coating with comparable erosion resistance to 

similar bulk by plasma-spraying shell-core-structured powders 

J. Tian, Y.Wang, C.Li, G. Yang and C.Li, Xi'an/CN 

NiCr-Mo composite coating was prepared by plasma spraying of shell-core-structured NiCr-Mo powders. The 

morphologies of the NiCr-Mo powders and microstructure of the corresponding NiCr-Mo coating were 

characterized by SEM. Furthermore, the erosion behavior of the NiCr-Mo coating at impact angles of both 30o and 

90o was investigated, and was further compared with that ofthe Ni20Cr coating and the In-738 alloy bulk. Results 

showed that fully-dense and homogenous NiCr-Mo coating with excellent interface bonding and no pure Mo 

inclusions was obtained. Furthermore, the erosion test results showed that the erosion rate of the optimized NiCr- 

Mo coating is lower than that ofNiCr coating at both impact angles. Moreover, the NiCr-Mo coating presented 

excellent erosion resistance which was comparable as that of In-738 alloy bulk, attributing tothe fully-dense 

microstructure and metallurgical interface bonding within coating. 

Development ofwear-resistant high-entropy alloy coatings produced bythermal spray 

technology 

M. Löbel, T. Lindner, T. Lampke, Chemnitz/DE, and C. Kohrt, Rheinberg/DE 

The alloying concept of High-Entropy Alloys (HEA) has attracted much scientific interest due to an interesting 

combination of properties. Previous investigations have shown that high hardness and strength, comparable to 

bulk metallic glasses, can be achieved. Furthermore, HEAs show distinct ductility and good high-temperature 

resistance. First investigations on tribological properties are indicating high wear resistance. Previous 

investigations ofthe alloy system AlCoCrFeNiTi in bulk state have shown promising properties. Therefore, the alloy 

AlCoCrFeNiTi with equimolar composition was selected for transferring bulk properties to thermally sprayed 

coatings. The focus of this contribution is on studying tribological properties of thermally sprayed HEA coatings to 

enlarge the field of possible applications. Feedstock material production was carried out by high-energy ball milling 

(HEM) and inert gas atomization. Subsequently, coatings were deposited by Atmospheric Plasma Spray (APS). 

Tribological properties of the coatings under different wear regimes were investigated inball-on-disk wear tests, 

oscillating wear tests and scratch tests. The tribological properties are compared with aconventional hard chrome 

plating and correlated with microstructure. 


Thermal spraying of thin metallic coatings 

F. Trenkle, R.Koehler, M. Winkelmann, F. Wuest, J.Luth and S. Hartmann, Bad Krozingen/DE 

Metallic coatings can be produced with thermal and cold gas spraying processes very easy. But are required, for 

economical or technological reasons, coating thicknesses below 50µmthe tasks become more challenging for 

those well established spray processes. obz innovation has developed specific spray processes, which even 

allows producing metallic coatings below 20 µm. Such coatings are very interesting for example for cold gas 

sprayed silver coatings, which have ahigh purity and agood electrical conductivity. Thinner coatings with such 

valuable materials directly gain economical advantages, often also compared with commonly used thin film 

processes. 

Cold gas spraying of lead-free bearing bronzes 

S. Theimer, P. Brethack, F. Gärtner and T. Klassen, Hamburg/DE 

In current process techniques tomanufacture sliding bearings, bronze components are soldered to the respective 

parts, which is cost and energy intensive. Apart from that, so far most bearing materials still contain lead, which in 

new applications is omitted by EU law to avoid associated health risks. The present study aims to offer solutions for 

both by using cold gas spraying as additive manufacturing technique for processing bearings directly onto steel 

parts and by applying that to new lead-free bronze alloys. Alead-free bronze alloy was processed as powders by 

gas atomization and classified to optimum sizes for cold spraying. During cold spraying, the process gas pressures 

and temperatures aswell asthe substrate temperature were varied with the aim to study influences by impact 

conditions and effective surface temperature on particle deformation and bonding. Respective coatings show low 

porosity, high hardness and high electrical conductivities. With properties similar to that ofbulk cast material 

respectively manufactured parts should meet the requirements for new bearing applications. 

Nozzle-internal particle velocity measurements and loading effect onparticle 

acceleration inside acold spray nozzle 

M. Meyer, F.Caruso and R. Lupoi, Dublin/IE 

The advantages of the solid state deposition process Cold Spray (CS) over conventional spray technologies go 

hand in hand with the requirement of high and well-predictable particle velocities. The acceleration of particles 

primarily takes place within the CS-nozzle while measurements of their velocity are conducted downstream of its 

exit. Despite their essential value, these observations are limited, inthat only the result of the acceleration can be 

evaluated, not the actual driving mechanisms themselves. Previous work has indicated that there is no conclusive 

understanding of these mechanisms, especially in cases of increasing particle loading. This study therefore 

presents atransparent rectangular CS-nozzle design (made out of quartz) for alow stagnation pressure regime. A 

novelty tothe field of thermal spray is the first report of particle in-flight measurements within the CS-nozzle using 

Particle Tracking Velocimetry (PTV) at varying particle loadings and pressure levels. It is found that particle 

velocities in the jet decrease with increasing particulate loading as the momentum exchange of the gas is 

enhanced, while in the subsonic flow region, the average velocity level increases due to particle-particle 

interactions with shallower axial velocity profiles. This effect is aggravated for higher working pressures, as 

energetic collisions cause increasing losses, depending on the number density of particles. This study forms the 

basis for acomprehensive nozzle-internal analysis. 


Automotive Industry 

New mechanical roughening processes as surface preparation of engine cylinder bores 

before thermal spraying 

A. Roffe, M.Morgan-Hague, Belton/UK, M. Waiblinger, Ostfildern/DE, G. Sanuk, M.Joschko, Albstadt/DE, 

M. Kesting, Salching/DE, T. Birkner, Eislingen/DE, K.Over, M. Silk, C. Verpoort, Aachen/DE, and R. Wilton, 

Köln/DE 

Several surface preparation techniques are being used like grit blasting, HP water jet roughening as well as 

mechanical roughening for the preparation of Aluminum cylinder bore surfaces before athermal spray coating can 

be applied. However, incase of spray-repaired CI cast iron engine blocks the conventional mechanical roughening 

processes - using cutting inserts with small dovetail-undercut geometry – are not applicable due to the high 

hardness and high material toughness. Therefore such CI engine blocks are bored oversize in order to remove the 

bore wear damage and subsequently this rough-machined surface is coated by aNiAl-bond coating material in 

order toprovide sufficient bond strength for the functional top coating material. Inthis paper it will be demonstrated 

that the 2-step spray-repair process can be replaced by asingle-step process byusing anew diamond-rollroughening 

method. This process leads to significant higher bond strength values than the conventional process, 

including the bond coating material. PAT Adhesion test results as well as microstructural cross sections of coated 

cylinder bores will bepresented. The principle ofthe roll-roughening process isoutlined. In addition it will be shown 

that different mechanical roughening methods can be combined to obtain high bond strength values for sprayrepaired 

aluminum blocks which require ahigher coating thickness to compensate for the depth of the original 

mechanical bore activation. 

Development ofnovel fe-based coating systems for internal combustion engines 

K. Bobzin, M.Öte, T. Königstein, Aachen/DE, K. Dröder, H.W.Hoffmeister, G. Mahlfeld, Braunschweig/DE, and 

T. Schläfer, Luckenbach/DE 

Nowadays combustion engines are the most common way to impel vehicles. Thereby losses occur, due to cooling, 

exhaust gas and friction. Modern engines roughly dissipate 8% of the chemical energy stored in the fuel because 

of friction in different tribological systems. The highest potentials for optimisation can be found in the tribological 

system ofinner surface of combustion chamber and piston ring. Besides friction, corrosive stress of inner surface 

of combustion chamber increases e.g. due to the utilization of auxiliary systems such as Exhaust-Gas-Recovery. In 

order to save energy, reduce emissions and enhance the lifetime of combustion engines innovative coating 

material systems need to be developed, especially for inner surface of combustion chamber. This study focuses on 

the development of innovative iron based materials for combustion chamber application using Plasma Transferred 

Wire Arc (PTWA) and Rotating Single Wire Arc (RSW) technologies. In order toimprove the wear and corrosion 

resistance boron and chromium are added into the feedstock material. After deposition, different honing 

topographies are manufactured in order to evaluate their influence on the tribological behavior. Furthermore, 

electro-chemical corrosion tests are conducted by using an electrolyte simulating the exhaust gas concentrate. In 

conclusion an optimised coating material deposited byPTWA and RSW and improved surface topographies can 

be combined. 

Effects ofcarbon contents and gas type onhardness and wear resistance of ferrous 

coating fabricated by twin wire arc spray process 

J. Lee, J. Kim and C. Lee, Seoul/KR 

In automotive industry, thermal spray process isused to reduce engine weight by replacing cast iron liners inserted 

in cylinder bores. Especially, twin wire arc spray isone of widely used thermal spray processes with inexpensive 

cost and high deposition rate. Inthis study, two kinds ofwire materials, low carbon steel (0.07 wt.%C) and high 

carbon steel (0.80 wt.%C) were deposited bytwin wire arc spray process using two kinds ofprocess gas (i.e., 

compressed air and nitrogen) in order to elucidate effects ofcarbon contents of ferrous coating and process gas 

type on the hardness and wear resistance ofcoating. Incase of hardness, low carbon steel coatings had higher

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