Thixoforming : Semi-solid Metal Processing

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Table 8.6 Mechanical properties of the deposited coatings. Property Metallic ZrO 2 8.4 Multifunctional PVD Composites for Thixoforming Mouldsj263 Monoclinic ZrO 2 Tetragonal þ monoclinic ZrO 2 Tetragonal ZrO 2 Hardness, HUniv (GPa) 16.5 5.7 15.1 21.4 Young s modulus (GPa) 238.7 146.8 241.9 292.7 The mechanical properties of all samples are given in Table 8.6. The t-ZrO 2 exhibits the highest hardness and Young s modulus of all deposited ZrO2 modifications. 8.4.2.3 Summary for the Development of t-ZrO2 The investigations have shown that it is possible to find a process window where stabilized t-ZrO2 can be synthesized without the use of dopands such as Y2O3, CaO or MgO. The t-ZrO2 exhibits the highest hardness and Young s modulus of all deposited ZrO2 modifications. The deposition of t-ZrO2 is limited to a narrow process window. Further developments such as upscaling to an industrial coating unit are needed to apply these promising coatings to tool inserts. 8.4.2.4 Experimental Details on the Development of t-ZrO 2 on an Industrial Coating Unit For upscaling, a co-sputtering setup with two TiAl targets and two zirconium targets was used. The size of all targets was 88 500 mm. The purity of the zirconium targets was 99.2%. For the Ti50Al50 targets, the purity was about 99.5% for the titanium and 99.9% for the cylindrical aluminium inserts within the sputter track. During deposition, the samples were moved in a planetary motion to ensure a constant film thickness distribution at the substrates. Prior to deposition, the samples were ion etched in an argon atmosphere. For the etching process, an m.f. power source was used. The coatings were deposited by using a MELEC pulse power supply (SPIK 2000 A). For the TiAlZr N interlayer a total pressure of 500 mPa by reactive sputtering in a mixed atmosphere of argon and nitrogen was used. To enhance adhesion, the coating process started first with a pure TiAlN interlayer and after a coating time 1000 s zirconium was added to the process. Pre-examination showed that the adhesions with a TiAlZrN interlayer suffer in comparison with a graded one. The deposition of a ZrO2 top layer was performed by using two zirconium targets (purity 99.2%; target size 88 500 mm) and the dual cathode arrangement (power 3500 W, pulse frequency 18.5 kHz). The process was flow controlled: the argon flow was kept constant at 250 sccm while the oxygen flow was varied. The oxygen partial pressure was set by adjusting a certain voltage at the cathodes. The process parameters are listed in Table 8.7. 8.4.2.5 Results of the Deposition of t-ZrO 2 on an Industrial Coating Unit The investigations of the deposition process of the ZrO2 top layer showed nearly the same behaviour as the g-Al2O3 deposition. The properties of the deposited coatings
264j 8 Tool Technologies for Forming of Semi-solid Metals Table 8.7 Process parameters for the coating deposition. Process parameters Etching phase Interlayer TiAlZr Top coat t-(ZrO 2) Heating power (kW) 16 16 16 Process step time (s) 3600 5000 6000 Total pressure (mPa) Flow controlled 500 Pressure controlled m.f. voltage (250 kHz) (V) 650 — Bias voltage (V) — 80 (DC) 25–40 (pulsed m.f.) Nitrogen flow (sccm) — 60 — Oxygen flow (sccm) — — Varied Argon flow (sccm) 150 Pressure controlled 250 Target power density (Wcm 2 ) — 13.7 7.95 Anode voltage (V) — 70 — are strongly dependent on the working point in the hysteresis (Figure 8.20). Different points were investigated: two deposited coatings with 650 and 600 V cathode voltages are presented here (Figure 8.20). The properties of the coated samples from the laboratory coater and the industrial coating unit are compared in Table 8.8. The two working points show Figure 8.20 ZrO 2 hysteresis and two deposited coatings.
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Thixoforming Semi-solid Metal Proce
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Further Reading Herlach, D. M. (ed.
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The Editors Prof. Dr. G. Hirt Insti
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VI Contents 1.3.5.2 Other Aluminium
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VIII Contents 4.6.1 Thixocasting 13
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X Contents 7.4.2 Isothermal Non-ste
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XII Contents 9.4.1.3 Simulation Res
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Preface Semi-solid forming of metal
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XVIII List of Contributors Andreas
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XX List of Contributors Alexander S
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2j 1 Semi-solid Forming of Aluminiu
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10j 1 Semi-solid Forming of Alumini
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Table 1.1 Overview of semi-solid pr
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Part One Material Fundamentals of M
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32j 2 Metallurgical Aspects of SSM
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44j 3 Material Aspects of Steel Thi
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Temperature (ºC) 1550 1500 1450 14
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100j 3 Material Aspects of Steel Th
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106j 4 Design of Al and Al-Li Alloy
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5 Thermochemical Simulation of Phas
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here it can be assumed that the dat
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Figure 5.2 Calculated temperature v
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Figure 5.4 Composition profiles of
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It is clear that C has by far the s
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Figure 5.7 The density of X210CrW12
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5.3 Calculations for the Bearing St
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Figure 5.11 Composition profiles of
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Figure 5.14 The density of 100Cr6.
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area which is available for heat tr
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Part Two Modelling the Flow Behavio
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170j 6 Modelling the Flow Behaviour
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Page 235 and 236: 212j 6 Modelling the Flow Behaviour
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Page 334 and 335: 9 Rheocasting of Aluminium Alloys a
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Figure 9.2 Processes for the semi-s
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Two Italian companies gained the fi
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9.2 SSM Casting Processesj317 For t
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Figure 9.7 Oil pump cover for Honda
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Figure 9.9 Middle temperature cours
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Figure 9.12 Components of cartridge
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Figure 9.15 Process adapted multipa
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step-shot experiments. It is also s
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Figure 9.18 (a) Meander tool for fl
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Figure 9.19 (a, b) Wear appears in
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Table 9.2 Temperature determination
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and are plausible on the left. Furt
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Figure 9.27 Development of the micr
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some places can be observed as smal
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Figure 9.31 Simulation of the metal
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Figure 9.33 So-called Constant Temp
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Figure 9.35 Comparison of the micro
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9.4 Rheoroutej347 If rounding of th
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9.4.1.2 Parameters: Cooling to the
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Figure 9.36 Results of the 2D-MICRE
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homogeneous microstructure and no d
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grain fragment density [mm -1 ] 200
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can be considered for rheocasting o
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Figure 9.44 Microstructure of Zr/Sc
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Figure 9.45 MAGMAsoft simulation: c
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The cooling to the process temperat
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D grain diameter of a circle DGM De
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27 Doppelbauer, M. (2003) Wirtschaf
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10 Thixoforging and Rheoforging of
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1970s [7]. Also, the quality of the
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10.3 Heating and Forming Operations
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With the solution of the Equations
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10.3.1.2 Modelling of Inductive Hea
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material properties have to be cons
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10.3 Heating and Forming Operations
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Figure 10.9 Experimental results, d
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Figure 10.12 Segregation in compone
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10.3.4 Thixoforging of Steel In thi
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10.3.5 Thixojoining of Steel In the
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einforcing element. The possibiliti
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Figure 10.20 The robot controller a
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Figure 10.21 Experimental results w
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Figure 10.24 Design and working pri
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The investigations show that the rh
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Figure 10.31 Scheme of the heat tra
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Table 10.2 Definition of boundary c
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Figure 10.35 Experimental and simul
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References 1 Koesling, D., Tinius,
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steel billets into the semi-solid s
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412j 11 Thixoextrusion The followin
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414j 11 Thixoextrusion channel with
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416j 11 Thixoextrusion parameter co
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418j 11 Thixoextrusion Both concept
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420j 11 Thixoextrusion should be ju
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422j 11 Thixoextrusion Figure 11.8
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424j 11 Thixoextrusion Table 11.4 C
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426j 11 Thixoextrusion Temperature
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428j 11 Thixoextrusion impacts. Ext
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432j 11 Thixoextrusion shell format
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436j 11 Thixoextrusion Table 11.6 P
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440j 11 Thixoextrusion solidificati
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442j 11 Thixoextrusion GPa pressure
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444j Index arbitrary volume element
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446j Index equilibrium tests 141 eq
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448j Index - importance 273 ion flu
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450j Index oxygen-sensitive element
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452j Index - thixoforming 241 semi-
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454j Index - high pressure 131 - sc
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Thixoforming : Semi-solid Metal Processing

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