構成元素間直接反応法によるSiC-AlNセラミックアロイ粉末の合成 Synthesis of SiC-AlN Ceramic Alloy Powder by the Direct Reactions between the Constituent Elements
The purpose of the present study was to synthesize SiC-AlN ceramic alloy powders (solid-solutions and their composites) by the reaction sintering of the mixed powders of Si, C and Al in a N<SUB>2</SUB> atmosphere. This present process, which employs the direct reactions between the constituent elements in the SiC-AlN system, was revealed to be effective for the powder preparation in the SiC-AlN system. The reaction was found to occur significantly above 1073 K with preferential formation of AlN and followed by SiC at higher temperature. Although Si<SUB>3</SUB>N<SUB>4</SUB> was also formed due to the reaction between Si and N<SUB>2</SUB> during the reaction sintering, its formation can be avoided by conducting the 2-step reaction sintering; first in N<SUB>2</SUB> gas containing 10%H<SUB>2</SUB> at 1073 K and subsequently in Ar gas at 1773 K. Such a process resulted in a porous product compact of SiC-AlN alloys without other phases, which can be simply pulverized to powder. X-ray diffraction showed that solid solutions were formed in the powder state although the extent of solid solution formation was not clarified. The synthesized powder was further densified by hot-isostatic pressing (HIP) at 2123 K and 200 MPa for 2 h, and the mechanical properties, such as microreaders, strength and fracture toughness, were investigated.
粉体および粉末冶金 44(3), 217-221, 1997-03-15
Japan Society of Powder and Powder Metallurgy