Thixoforming : Semi-solid Metal Processing

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Figure 8.16 Hysteresis behaviour and SEM image of the two working points. Figure 8.17 X-ray diffraction pattern of the different deposited coatings on the laboratory and industrial coating unit. 8.4 Multifunctional PVD Composites for Thixoforming Mouldsj259
260j 8 Tool Technologies for Forming of Semi-solid Metals of 460 V to 27.07 1.7 GPa at 560 V. The Young s modulus also increased from 246.7 24.3 GPa at 460 V to 368.6 10.16 GPa at 560 V. A result of these investigations is that the deposition process window is small and for the properties of the coatings it is necessary to operate in this window. Modern plasma diagnostic equipment can be used to control the deposition process. First investigations using optical emission spectroscopy (OES) have shown the ability to control this small process window [31]. 8.4.2 Deposition Process Development of Crystalline PVD ZrO2 The advantage of the ZrO 2-based coatings compared with the Al 2O 3 coatings is high chemical inertness against liquid steel. These results are confirmed by the material screening of Meyer-Rau [5]. Zirconium oxide occurs in three stable crystallographic phases, depending on the temperature. The monoclinic phase is stable up to 1170 C, the tetragonal phase is stable within the range 1170–2370 Candathigher temperatures the cubic phase is stable [32]. The thermal and mechanical properties depend strongly on the phase structure [34]. In comparison with the other phases, the tetragonal phase of ZrO2 offers high strength and toughness values. Various methods have been investigated to stabilize the promising high-temperature tetragonal phase at room temperature. The most common technology used is to add dopants such as Y2O3, MgO and CaO to suppress the tetragonal-to-monoclinic transformation. 8.4.2.1 Experimental Details for the Development of t-ZrO 2 The investigations on the deposition of crystalline ZrO2 were carried out on a Leybold Heraeus Z400 laboratory sputtering PVD coating machine for the development of a suitable deposition process window and a multilayer structure using tungsten as an interlayer with a high thermal conductivity. For deposition, a zirconium metal target with a purity of 99.5% and a tungsten metal target with a purity of a 99.9% were used. The argon and oxygen flow rates were independently controlled by mass flow controllers. The O2 gas concentration was determined by the ratio of O2 mass flow rate to the total mass flow rate (Ar and O2). As a pulsed power supply, an Eifler bipolar pulse generator was used. The variations of the deposition parameters are reported in Table 8.4. The substrates were heated to up to 300 C. The substrates were also precleaned by r.f. sputtering using the parameters listed in Table 8.4. 8.4.2.2 Results and Discussion By using pulsed power supplies, it is possible to deposit fine crystalline ZrO2 with different mechanical and tribological properties. The coated samples show different properties that depend strongly on the chosen process working points. The variation of the deposition parameters such as deposition pressure and oxygen flow rate allow different phases of ZrO2 to be synthesized. It is also possible to stabilize t-ZrO2 at room temperature without the use of dopands such as Y2O3, CaO or MgO. The deposition parameters of these samples are presented in Table 8.5.
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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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