Thixoforming : Semi-solid Metal Processing

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Table 8.4 Deposition parameters for the multilayer system W–ZrO2. Process parameters Etching phase Interlayer tungsten Top layer ZrO2 Process pressure (Pa) 1 0.5 0.3–1 Process time (s) 1800 3600 7200 R.f. power (W) 100 — — R.f. frequency (MHz) 13.56 — — N 2,O 2 concentration (%) — — 2–16 Pulse parameters Pulse mode/pulse power (W) — DC/400 Unipolar/500 Pulse sequence (ton–/toff–) (ms) — 5/25 3.56/2.67 M.f. (kHz) — 0 33 Pulse voltage (V) — Power controlled 980–1022 Pulse current (A) — — 0.5 Table 8.5 Properties of four representative coatings. Property Metallic ZrO2 8.4 Multifunctional PVD Composites for Thixoforming Mouldsj261 Monoclinic ZrO2 Tetragonal þ monoclinic ZrO2 Tetragonal ZrO2 Depositing pressure (Pa) 1 1 0.5 0.3 Coating thickness (mm) 9.9 3.8 8.3 6 O2 (sccm) 1.76 3.96 2.07 1.7 O 2/Ar (%) 2 2 5 7 Phase composition Metallic Monoclinic Tetragonal þ monoclinic Tetragonal To study the effect of the different crystalline phase on the properties of the films, four characteristic samples were selected. By changing the O 2 to argon ratio, a drop in the deposition rate in nanometres per minute can be observed. The effect of the oxygen flow rate on the coating thickness is shown in Figure 8.18 This behaviour can be explained by the hysteresis effect of the deposition process [33]. With increasing oxygen flow rate, the coating structure changed from metallic to crystalline and finally to amorphous (Figure 8.19). The phase composition of the deposited samples was determined using XRD as described previously. By changing the oxygen to argon ratio, the experiments revealed that with a deposition pressure of 1 and 0.5 Pa only a small amount of tetragonal phase can be deposited. For the coating, the development of t-ZrO2 coatings with very small crystallite sizes is needed to stabilize this phase [34]. Calculations using the Debye–Scherer equitation show that the domain size for the t-ZrO2 coatings is in the range 4–5nm. Figure 8.19 shows the cross-sections of the investigated samples. The cross-section show in Figure 8.19c indicates a very fine-grained morphology for the tetragonal phase compared with the other three SEM images.
262j 8 Tool Technologies for Forming of Semi-solid Metals Figure 8.18 Effect of oxygen flow rate on the film thickness. Figure 8.19 Cross-section of (a) metallic zirconium structure, (b) tetragonal þ monoclinic ZrO2 structure, (c) tetragonal ZrO2 structure and (d) monoclinic ZrO 2 structure.
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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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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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