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Preparation of AlON Power and Hot-pressed Sintering Behavior of AlON Ceramic Material

Author: ZhaoXiaoJun
Tutor: RuHongQiang；ZhangNing
School: Northeastern University
Course: Materials Science
Keywords: AlON SiC Hot pressing sintering Composite ceramics materials
CLC: TF124.5
Type: Master's thesis
Year: 2008
Downloads: 137
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Abstract


Spinel aluminum oxynitride (AlON) is an important compound in the Al2O3-AlN system, because it has excellent mechanical, chemical and optical properties, and thus the potential of new ceramic materials. First, the paper Al2O3 and AlN as raw materials were successfully synthesized in a nitrogen atmosphere AlON powder. The composition ratio of raw materials, synthesis temperature, holding time and different crystalline forms of Al2O3 on synthesis Alon powder content. The study showed that: the mass ratio of the raw materials of Al2O3 and AlN 81:18, synthetic processes 1750 ° C × 2h is obtained when the AlON phase content can reach above 95%, the type of crystalline Al2O3 (a and gamma), the content of the synthetic AlON little. AlON powder Second, the use of different crystalline forms Al2O3 (alpha and gamma) synthesis by hot pressing sintering pressing temperature AlON single-phase ceramic densification. The results showed that: in a N2 atmosphere unidirectional pressure 25MPa insulation 40min, with increasing pressing temperature, Alon ceramic volume density increases, the open porosity decreased Alon ceramic; when pressing temperature reached 1850 ° C, the bulk density of and open porosity, respectively, of 3.5g/cm3 and 1%, after the change is no longer obvious; the Alon powder the use of alpha-Al2O3 synthesis better than the synthesis of gamma-Al2O3 powder sintering activity, when the hot temperature AlON prepared under the same pressing conditions with the former ceramic when the low bulk density of greater than the latter, but when the the pressing temperature reaches 1900 ° C when the two powders sintered density substantially the same, able to achieve 99%. Final thesis SiC content on AlON / SiC composite ceramics densification characteristics, mechanical properties and fracture morphology. The results show that: with the SiC content increases the bulk density of the composite remained unchanged, hardness was reduced trend, flexural strength first increased and then decreased trend. When the SiC content of 8% optimum performance, the bulk density of 3.37g/cm3, hardness 18.49GPa, the bending strength is 310MPa; SiC Add AlON changed the fracture mode, within the scope of the study with the SiC Composites increasing the content of composite fracture by intergranular fracture transition to transgranular fracture, and finally into a mixed mode fracture; SiC raise the AlON / SiC composite material strength the main mechanism for SiC caused by thermal expansion mismatch and fine grain strengthening.

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CLC: > Industrial Technology > Metallurgical Industry > Metallurgical Technology > Powder metallurgy (metal ceramic technology ) > Powder molding, sintering and post-processing > Sintering process
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