摘要
Nb-doped TiC ceramic,or (NbyTi1-y) Cx,in which amount of Nb element added is increased from zero to 40Wt. %, synthisized -with self-propagating high temperature synthesis,is studied with SCF-Xa-DV,a quantum chemistry cal-culating method. The chemical bonding is studied to discuss the relation between structrues and properties. Several classes of models in which there is no vacancy,one vacancy or two vacan-cies have been calculated. From the calculated results of bond or-der, a measure of covalent bond strength,and molecule orbital contour map, it is concluded that when Nb element added in-creases, the vacancies increase correspondingly,the covalent com-ponent of chemical bonds of the samples decreases -while the met-al-bonding component increases, so the hardness and resistance of the samples decrease.
Nb-doped TiC ceramic,or (NbyTi1-y) Cx,in which amount of Nb element added is increased from zero to 40Wt. %, synthisized -with self-propagating high temperature synthesis,is studied with SCF-Xa-DV,a quantum chemistry cal-culating method. The chemical bonding is studied to discuss the relation between structrues and properties. Several classes of models in which there is no vacancy,one vacancy or two vacan-cies have been calculated. From the calculated results of bond or-der, a measure of covalent bond strength,and molecule orbital contour map, it is concluded that when Nb element added in-creases, the vacancies increase correspondingly,the covalent com-ponent of chemical bonds of the samples decreases -while the met-al-bonding component increases, so the hardness and resistance of the samples decrease.
