(Y-TZP)-Al_2O_3-TiC复合陶瓷的显微结构与力学性能

研究了(Y-TZP)-Al_2O_3-TiC复合陶瓷在无压绕结条件下的显微结构及力学性能。结果表明,其相结构由t-ZrO_2、α-Al_2O_3、TiC组成。随TiC含量增加,可相变的t-ZrO_2含量减少.当TiC<10wt％时,不仅提高了复合陶瓷的硬度、韧性,而且强度无明显下降。在特定磨损条件下,TiC含量为20wt％的复合陶瓷具有最佳的耐磨性能。     

THE STRUCTURES OF SOME MESOPHASE PITCH-BASED CARBON FIBRES

The macro-and micro-structure of two groups(high modulus and high thermalconductivity)of MP-based carbon fibres were studied using X-ray diffraction,and both scanningand transmission electron microscopy.The dominant macrostructure in cross section is of foldedpseudo-radial layers which have a tendency to form a quasi-uniform domain as the fibre modulusincreases.It is found that high thermal conductivity fibres have both missimg sector and circularcross sections(possessed predominantly by the high modulus fibre group).The microstructuralstudy indicates that apart from the fibre C700,which has a three-dimensional graphite structure,these two groups of carbon fibres all exhibit a turbostratic stacking order.Furthermore it is foundthat the turbostratic stacking thickness as determined from dark-field measurement is much largerthan the classical crystallite thickness L_c as measured from X-ray diffraction.