TiB2-1%CoBおよびTiB2-5%TaB2-1%CoB材の緻密化機構

概要

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Sintered TiB2-1%CoB and TiB2-5%TaB2-1%CoB materials have high density and high trasverse rupture strength. In the present study, the densification mechanism of the above materials has been investigated. It has been found that even a small amount (1 wt% or less) of CoB added to TiB2 or to TiB2-5%TaB2 has a remarkable effect on densification, and that the mixture of TiB2-1%CoB shows remarkable shrinkage during sintering under the die pressure of 200 kg/cm2 even at 1400°C which is lower than the melting point of CoB. These results suggest that the densification of these materials is caused mainly by an activated sintering process under die pressure. In this process, atoms on the surface of TiB2 (or TaB2) grains dissolve into the CoB phase so that a carrier phase may be formed in the contact area between the TiB2 (or TaB2) grain and the CoB phase. Then, the surface atoms on any TiB2 (or TaB2) grain can diffuse rapidly to other grains through the carrier phase.
社団法人粉体粉末冶金協会の論文