クロムホウ化物のメカノケミカル合成

抄録

Chromium and boron compounds have potential for structural applications which require high temperature strength because of their high melting point, chemical stability, hardness and strength. Ball-milling of elemental powder mixtures without external heat application has been processed as a mechanism for the mechanochemical synthesis of high melting point compounds. Chromium and amorphous boron elemental powder mixtures at atomic ratios of 1:1 and 1:2 were processed for 10-40h in a planetary ball-mill. CrB₂ was formed at a low yield after 10-30h of milling the 1:2 mixture using tungsten carbide balls. However, a single phase of CrB₂ was found by XRD, after the as-milled Cr-B (1:2) mixture was annealed at 900°C for 2h. A single phase of CrB was formed by annealing the Cr-B (1:1) mixture at 1000°C for 2h. Ball-milling of the elemental powder mixtures before annealing significantly reduced the reaction temperature necessary for chromium boride synthesis. The as-milled Cr-B (1:2) mixture contained fewer contaminations (tungsten and cobalt) than the as milled Cr-B (1:1) mixture. The lattice parameters of the chromium borides obtained agree with previously reported measurements.