December 2nd, 2005 - Materials Engineering - University of British ...

MERC 2005
Materials Engineering Research Colloquium
December 2, 2005
Department of Materials Engineering
University of British Columbia
Vancouver BC CANADA

Materials Engineering Research Colloquium
Schedule
December 2, 2005
Presenter
Title
Session I: (10:00 am – 11:00 am)
Y. Zhang Metals Processing Continuous scrap melting in an oxy-fuel-fired rotary furnace
M. Tsui Ceramics Electrochemical deposition of calcium phosphate coating on
coronary stent
L. Silva Biomaterials Nanomechanical characterization of cortical bone quality
Session II: (11:15 – 12:15)
G. Malkhuuz Hydrometallurgy Use of strong brine and HCL solutions to process sulphide
concentrates with an emphasis on nickel sulfides and associated
gang
A. Chaudhary Metals Processing Modelling constitutive behaviour of aluminum alloys during DC
casting at below solidus temperatures
J. Mitchell Metals Processing Determination of strain during hot tearing by image correlation
LUNCH (12:15 – 13:15)
Session III: (13:15 – 14:15)
S. Hedge Microstructural
Engineering
High temperature oxidation behaviour of single crystal superalloy,
CMSX-10
F. Xie Hydrometallurgy Catalytic leaching of silver ore with dissolved ferric cyanide
D. Mayne Hydrometallurgy Galvanic effect between chalcopyrite and pyrite in atmospheric
leaching

MERC2005 December, 2005
Continuous Scrap Melting in an Oxy-Fuel-Fired Rotary Furnace
Yanjun Zhang
Metals Processing Group; T.R. Meadowcroft and P.V. Barr
Frank Forward Building, Room 401
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
Cheap hydrocarbon fuels will be the main energy source for high temperature melting in
the future. However, the configuration of electric arc furnaces (EAF) is not optimal to
efficiently utilize hydrocarbon energy inputs. Rotary melting furnaces (RMF) are common
in the foundry industry. Although competitive with the EAF in terms of thermal efficiency,
they remain batch processes with relatively low melting rates. Recently a new process
for continuous scrap melting in an oxy-fuel-fired RMF has been proposed with sufficient
melting capacity to replace the EAF in minimill steel operations. Model-generated results
indicate that the process can save "at-source" energy by up to 50%. However, the
process has not been physically demonstrated at any scale.
The focus of the current work is to demonstrate the feasibility of the process at a benchscale
and gather data sufficient for validation of an improved mathematical model to be
developed as part of the project. The validated model would then be used to predict the
performance of an industrial-scale operation. In order to investigate the effects of oxygen
and slag on thermal efficiency, two groups of trials have been performed for continuous
melting copper at rates up to 25 kg/h. Copper, rather than iron or steel, was chosen for
improved safety (Cu being relatively noble) while still offering a melting temperature at
least approaching that of steel. As shown in Figure1 (a), the thermal efficiency increased
almost linearly with increasing oxygen level, while it decreased with increasing of slag
thickness (Figure 1 (b)). For the industrial-scale RMF fired with 100% oxygen, the
thermal efficiency can be expected to be 70% or more due to the enlarged freeboard
volume and surface area for heat transfer.
(a)
(b)
Figure 1: (a) The thermal efficiency versus oxygen level (no slag was applied), (b) The effect of
slag thickness on the thermal efficiency (the baseline oxygen level was 53.0%)

MERC2005 December, 2005
Electrochemical deposition of calcium phosphate coating on
coronary stent
Manus Tsui
Ceramics Group; Tom Troczynski
Frank Forward Building, Room 106A
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
Coronary artery disease (CAD) is a condition caused by thickening of the artery walls
that supply blood to the heart muscle. Fatty deposits or plaques may build up inside the
artery wall blocking the blood flow. When these arteries become blocked, the heart is
deprived of oxygen and can become damaged. Severe cases can result in heart attack.
CAD is the leading causes of death in North America, 54% of all cardiovascular deaths
are due to coronary artery disease. Coronary stenting technique is widely used to battle
CAD. Coronary stents are small metallic spring-like implantable device. When
implanted, the stent act as a scaffold to keep the artery open. However, bare metallic
stent may trigger inflammatory response that lead to restenosis- the artery becomes
blocked again. A thin coating, such as hydroxyapatite (HAp) can provide a
biocompatible environment between the stent and the artery. Calcium phosphate
ceramics, especially hydroxyapatite, have gained much attention in clinically application
due to their excellent biocompatibility. Among different methods for producing HAp
coating, electrochemical deposition (ECD) was used to deposit a uniform thin film
coating (0.5 µm) on coronary stents. XRD results demonstrated that hydroxyapatite was
the main component of the coating deposited. In vitro stent expansion studies confirm
that the thin film coating show good adhesion without detachment. The thin film HAp
coating also exhibit a highly porous morphology, which is ideal for the next generation
drug eluting stent technology. Future experiments will focus on quantitative analysis of
adhesive strength, co-deposition technique, and drug eluting capability.
Figure Caption - SEM micrographs of stainless steel stent deposited with CaP via
electrochemical deposition.

MERC2005 December, 2005
Nanomechanical Characterization of Cortical Bone Quality
Leandro De Macedo Soares Silva
Biomaterials Group; Rizhi Wang and Thomas Oxland
Frank Forward Building, Room 412
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
Bone is a composite material composed of collagen, carbonated apatite mineral, water,
and other non-collagenous proteins. The bone structure inside human body is under
constant remodelling. The mechanical properties of bone and their dynamic changes
during remodelling are crucial to the health and quality of life.
Bone quality depends on three factors that will be investigated during this research,
namely: mechanical properties characterization by Nanoindentation, measurement of the
degree of bone mineralization by Quantitative Backscattered Electron Imaging (qBSEi),
and measurement of the degree of cortical bone porosity also evaluated by
Backscattered Electron Imaging (BSEi).
The main objective of this work is to relate clinical evaluation of bone health to laboratory
measurements of bone structure and properties.The understanding and combination of
these three parameters enable a more reliable and accurate reading of clinical
evaluative tools such as Peripheral Quantitative Computed Tomography (pQCT), largely
used in bone health diagnosis.
Fifteen human tibias were measured and the results will be presented along with a twoway
repeated measures analysis of variance (ANOVA).
The mechanical properties of bone are intrinsically dependent on the measurement
conditions. The degree of mineralization also affects bone mechanical properties. The
mechanical properties of bone greatly vary across the cortex and bone microstructure.
Porosity appears as a great indicator of bone quality and can drastically decrease bone
density.
A correlation between clinical pQCT and BSEi willl be presented to better understand the
diagnostics provided by pQCT.
a) Cross-section of the distal tibia; b) Detailed view cortical wall – anterior site; c) Detailed view of
an individual osteon with five indents.

MERC2005 December, 2005
Use of strong brine and HCl solutions to process sulfide
concentrates (with an emphasis on nickel sulfides and
associated gang)
Ganbold Malkhuuz
Hydrometallurgy Group; Supervisor: David B. Dreisinger
Frank Forward Building, Room 406
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
The chloride processing of base metal sulfide concentrates has recently entered a
period of renewed interest and investigation. Proper understanding of thermodynamic
properties of aqueous chloride solution is required in order to utilize the specific
properties for the leaching processes of sulfide minerals. Studies have recognized that
the ionic activity (coefficient) would be the key quantity. Available data are limited dilute
solutions and at lower temperatures. All hydrometallurgical processes operate at upper
level of chloride concentration.
Therefore, the current research is focused on two parts: thermodynamic measurements
of MgCl2-HCl mixture and the dissolution behaviour of sulfide minerals. The activity
coefficient is first estimated by a method known as Meissner's. These calculated data
were very consistent with the references. Furhter, individual ionic activities are assigned
and the effects of Al3+, Ca2+, Na+ cations on proton activity are estimated.
Second, the emf measurement method is utilized to determine experimentally activity
coeffcients beyond reference ionic strenghts and temperatures. The current work is in
the middle of activity coefficient measurement experiments for the selected mixtures with
the intention of moving on to the leaching tests.
Figure 1. Reference data (only available) for the activity coefficients of MgCl2-HCl mixture against
calculated values by Meissner's method

MERC2005 December, 2005
Modelling constitutive behaviour of aluminum alloys during DC
casting at below solidus temperatures
Alankar Chaudhary
Metals Processing Group; Dr. Mary A. Wells
AMPEL Building, Room 411
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
In the DC casting of aluminum alloys, during primary and secondary cooling non-uniform
temperature distribution occurs within the casting body and consecutively thermal
stresses are generated in the casting. Thermal contraction and solidification shrinkage
so produced may develop excessive stresses and strains which may cause defects in
ingot geometry (i.e. hot tearing, butt curl, butt swell, or rolling face pull-in). In order to
understand the development of such defects and optimize the design of casting process
to avoid or minimize occurrence of such defects, mathematical modelling is extensively
used for DC casting. Development of thermomechanical models for the Direct Chill (DC)
casting of light metals requires knowledge of the constitutive behaviour of the material
under thermomechanical conditions that are typical of those experienced during DC
casting.
This talk reviews the thermomechanical conditions experienced during DC casting and
the use of empirical equations, one internal state variable based model and two internal
variable based models to predict the high and low temperature constitutive behaviour of
aluminum alloys. Experimental data for uniaxial compression tests on aluminum alloy
AA5182 has been fitted against the empirical equation and one state variable model.
Results demonstrate the limited applicability of emprical equations. It has been
concluded that internal state variable equations may be used to better explain the
constitutive behaviour. Effect of orientation and location of specimen in the as-cast ingot,
on deformation behaviour has also be discussed for which more experiments are in
progress.
1. Figure Showing uniaxial compression test on Gleeble 3500 (Left), Typical Stress-Strain
response of AA5182 (Right)

MERC2005 December, 2005
DETERMINATION OF STRAIN DURING HOT TEARING BY IMAGE
CORRELATION
Jason Mitchell
Metals Processing Group; Dr. Steve Cockcroft
Frank Forward Building, Room 401b
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
Hot tearing refers to cracks that frequently occur within the mushy zone during cooling
from the liquid to solid state during shape and ingot casting. Both ferrous and nonferrous
alloys may be affected, and there is some evidence to suggest those with long
freezing ranges are more susceptible. Due to the nature of this defect the economic
impact is often significant and can result in an immediate productivity loss. It is therefore
important for industry to be able to better predict the susceptibility of various alloys to hot
tearing.
Various theories have been proposed and several different types of experimental
methods have been developed to interpret the properties of alloys in the semi-solid
state. However, many of these techniques do not produce good quantitative data (i.e.
strain) that can be used to calibrate a thermal-mechanical computer simulation of
casting. Existing experimental methods often measure strain indirectly by means of a
load train frozen into the end of the casting which moves at a specified loading rate.
However, local strain at the hot tear initiation site would be more valuable for computer
model calibration.
Under development is a new hot tearing test which localises strain to promote hot
tearing to occur in only one region of the casting. Images of this region captured during
solidification will be correlated with each other and used to determine strain accumulated
during hot tearing.
Image capture tests were recently conducted at The University of Queensland, Australia,
using an existing hot tear rig. The images have been correlated with one other to
determine strain using a commercial software package. Temperature data was also
collected during testing allowing alloy fraction solid data to be compared with strain
accumulation during hot tearing. Preliminary results will be presented at MMRC 2005.
Figure - Hot tear and associated strain contour map in Al-0.5% Cu alloy.

MERC2005 December, 2005
High temperature oxidation behaviour of single crystal
superalloy, CMSX-10
Subray Hegde
Microstructure Engineering Group; Ainul Akthar, Roger Reed)
AMPEL-124A
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
The continuous quest of gas turbine designers to increase the turbine inlet temperature
is limited by the high temperature capabilities of the superalloys with which turbine
components are made. Over 30 years, there have been tremendous improvements in
the high temperature properties of superalloys. Historically, the research work in the
area of superalloy designing was focused in increasing the mehcanical properties;
predominantly creep resistance. And, the surface protection, though important, received
little attention. As a consequence, the new generations of the superalloys are showing
lower corrosion resistance as against better mechanical properties when compared to
the previous generation alloys. Hence, the oxidation/corrosion study has gained
importance in the industry. In the present work the high temperature oxidation behaviour
of one such new generation nickel base single crystal superalloy, CMSX-10 has been
examined. A series of isothermal oxidation tests of the alloy was carriedout in a
thermogravimetric analyser at temperatures ranging from 800'C to 1250'C for 100hrs.
The plot of mass gain v/s time at various temperatures shows a transition from parabolic
to sub-parabolic growth. Also, mass gain (after 100hrs of oxidation) v/s temperature
curve shows an unusual behaviour (fig). The scanning electron micoscopy and XRD
analysis of the specimens provided insight into the observed anomaly.
Mass gain/Area (mg/cm sq)
4.5
4
3.5
3
2.5
2
700 900 1100 1300
Temperature (Deg C)
Variation of mass gain (after 100hrs of oxidation) with temperature showing the anomalous
oxidation bhaviour of CMSX-10.

MERC2005 December, 2005
Catalytic Leaching of Silver Ore with Dissolved Ferric Cyanide
Feng Xie
Hydrometallurgy Group; David Dreisinger
Frank Forward Building, Room 406
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
The silver extraction was usually much lower compared with that of gold during
cyanidation process. This is mainly due to their different mineralogical characteristics as
in some gold-silver ore silver may occurs dominantly as acanthite (Ag2S) other than
nature metals or alloy (such as electrum). The low solubility of silver sulfide in weak
cyanide solution results in obvious low silver recovery which sometimes could not be
tolerated while treating the high grade silver ore or concentrates. A catalytic leaching
process with dissolved ferric cyanide was investigated with the aim to raise the silver
recovery during cyanidation process. Through the stoichiometry tests, the general
chemistry of silver sulfide dissolution in ferric cyanide-cyanide solution was determined
as Ag2S + 2Fe(CN)63- + 7CN- = 2Ag(CN)32- + CNS- + 2Fe(CN)64- . It also proved
that the silver sulfide is nearly comlpetely dissolved after 48 hours leaching in 0.5g/l
Fe(III) (in hexaferricyanide) ans 0.5g/l NaCN solution while less than 5% silver recovery
was observed in absence of ferric cyanide. Catalytic and baseline leaching tests were
conducted on several Veladero and Pierina ore samples to determine the improvement
on silver recovery. The preliminary results indicate that the effect of ferric cyanide on
silver and gold recovery is not obvious. By comprehensively analyzing the NaCN and
lime consumption and the variation of the supernatant potential, it was speculated that
most of the dissolved ferric cyanides had be consumed by reductive minerals such as
sulfides. The possibility of the application the catalytic leaching process then should be
well considered.
Figure 1 Ag extraction versa leaching time for baseline and catalytic leaching
Figure 2 The effect of ferric cyanide addtion on Au and Ag recovery

MERC2005 December, 2005
Galvanic Effect Between Chalcopyrite and Pyrite In Atmospheric
Leaching
Darren Mayne
Hydrometallurgy Group; David G. Dixon
Frank Forward Building, Room 417
Department of Metals and Materials Engineering, University of British Columbia
Research Summary:
Chalcopyrite (CuFeS2) is the most abundant source of copper in the world. Historically,
this mineral was processed by smelting to produce pure copper metal. However, due to
increasing environmental regulations concerning sulphur dioxide emissions, lower grade
ores, and difficulties in selling byproduct acid, there is a demand to develop a
hydrometallurgical process to treat chalcopyrite. Sulphate-based leaching (more
specifically ferric leaching) of chalcopyrite has been investigated due to the relative
simplicity of the flow sheet. Unfortunately, chalcopyrite exhibits a passivating behavior,
which drastically limits the overall extraction of copper in a reasonable residence time.
The leaching behavior of this mineral can be viewed as an electrochemical cell, where
copper oxidation and ferric reduction occur on the mineral surface. It has been found
that the kinetics of reduction of ferric is much more rapid on pyrite than on chalcopyrite.
Therefore, a galvanic couple can be formed between these two minerals, resulting in an
overall increase in chalcopryite-leaching rate. Initial experiments conducted in stirred
tank reactors have shown that complete extraction is possible in twenty-four hours. A
study of the kinetics of the galvanic couple is the focus of the research. Parameters
such as acidity, total iron, temperature, chalcopyrite:pyrite ratio, and solution potential
are investigated on a variety of chalcopyrite sources.
Figure 1. Image of the stirred tank reactor used in the leaching experiments