توسعه مواد کاربید تیتانیوم و هافنیوم فوق سخت

on Development of Ultrahard Hafnium and Titanium Carbide Materials 

توسعه مواد کاربید تیتانیوم  و هافنیوم فوق سخت

ترجمه فصل اول ودوم

ABSTRACT

A mixture of HfC and Itc powders and a (Hf,Ti)C powder have been hot pressed with 4wt% Ni , In the absence of Ni the hot pressed temperature was 2000 C and in the presence of Ni 1650 C . The pressure of 30 MPa was applied in both cases . The starting powders were substoichiometric as deduced from XRD spectra analyses , and the (Hf,Ti)C powders consisted of a range of composition , as indicated by the width of the XRD peaks. In the absence of Ni the powders sintered without the formation of a liquid phase.In the case of HfC and TiC mixture , high – energy dry milled HfC + TiC +C black powder sintering occurred with simultaneous formation of (Hf,Ti)C Solid solution . In the presence of Ni,sintering occurred with the formation of a liquid phase . the volume fraction of the liquid phase formed was sufficieng to yield a low porosity . grain growth was less than in the case of material sintered without Ni,Probably just on account of lower sintering temperature . In the case of high – energy dry milled the reduction in particle size was observed.