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1993
Book Article
Titel
Al2O3 and ZrO2 composites with high TiC contents fabricated by tailoring oxide powders.
Alternative
Al2O3- und ZrO2-Kompositkeramiken mit hohem TiC-Gehalt hergestellt durch granulometrische Optimierung der oxidischen Pulverkomponenten
Abstract
Tailored powders give sintering activities of composites with 35 vol-percent TiC that equal those of reactive sintering (transient liquid phase by TiH2 addition) and of MgO/Y2O3 doping, but powder tailoring results in a higher strength. Surprisingly, a tailored Al2O3 powder processed together with commercial TiC (d50 = 1.2 mym, d90 = 10 mym) gives a higher strength than the use of an extremely fine grained carbide with d50 = 0.2 mym and d90 = 0.75 mym: a bending strength of 800 MPa is afforded without doping additions and without hot-pressing. The reason is a strong impact of oxide dispersion on the milling response of TiC: the smaller the oxide grain sizes the finer is the resulting carbide after homogenization milling. With nanoscale ZrO2(3mol-percent Y2O3) and commercial TiC, the carbide grain size in the sintered microstructure is less than 0.5 mym giving a bending strength of about 1100 MPa at a hardness of 16.5 GPa. High resolution TEM shows that all grain boundaries are free of amorphous phases.
Language
English
Tags
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alumina
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Aluminiumoxid
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Bruchzähigkeit
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Festigkeit
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fracture toughness
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grain size influence
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hardness
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Härte
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Korngrößeneinfluß
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martensitic transformation
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martensitische Transformation
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oxide ceramic
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Oxidkeramik
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powder processing
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Pulververarbeitung
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sintering
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Sinterverhalten
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strength
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TiC strengthened oxide ceramic
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TiC-verstärkte Oxidkeramik
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transient liquid phase
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transiente flüssige Phase
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zirconia
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Zirkoniumdioxid