Speaker
Mr
Motoyasu Aoki
(Doshisha University)
Description
Fabrication of diamond/SiC=75/25~50/50vol% composites have been tried using hot isostatic pressing at 1450°C under 196 MPa for 2 h from the mixtures of diamond and Si powders. The former consisted of bimodal particle sizes Ps of 69 and 9.2 µm, and the latter average Ps of 0.60 µm. They were mixed using an alumina mortar and pestle for 30 min in ethanol thoroughly. After drying, a small amount of binder was added to the mixed powders and compacted uniaxially and isostatically (245 MPa). They were pre-heated at 950°C for 2 h in a vacuum to be densified for easy handling. Calcined mixed powder compacts wrapped with BN powder were sealed into Pyrex glass petri dish in a vacuum. They were heated with heating rate of 300°C/h, between room temperature and around 820°C in Ar gas atmosphere of 0.3-0.4 MPa, and from 820° to 1450°C with increasing pressure to 196 MPa. Archimedes method to determine the bulk densities revealed that the highest density of 96.7% has been achieved at the composition of diamond/SiC =55/45vol%, in which composition the diamond content is higher than that (45 vol%) of previous works. SEM observation on the microstructure of composites showed a little amount of cleavages at grain boundaries between diamond and SiC, which might be originated from the volume reduction around 19.3% in the formation of SiC from C + Si during HIPing. However, with decreasing the content of diamond the cleavages disappeared due to the rearrangement of diamond particles less than 35vol%.
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Primary author
Prof.
Ken Hirota
(Doshisha University)
Co-authors
Prof.
Masaki Kato
(Doshisha University)
Mr
Minoru Ueda
(Metal Technology Co., Ltd)
Mr
Motoyasu Aoki
(Doshisha University)
Mr
Yoichi Nakamori
(Metal Technology Co., Ltd)
