铂催化作用下无氢碳化制备有催化活化特性的碳化钨粉的机理及其在低温低压烧结无粘接相碳化钨中的应用

In order to sinter compact binderless tungsten carbide under low temperature and low pressure, tungsten carbide powders with catalysis activation will be prepared by hydrogen-free carbonation under the catalysis of platinum. The compact binderless tungsten carbide without abnormal grain growth can be prepared by the activation effect of platinum catalysis in the whole specimen during the whole sintering course. The improving mechanism of carbon atom activation causing by the catalysis of platinum will be studied by analyzing the effect of platinum on carbonizing process. The formation mechanism of tungsten carbide powders with catalysis activation prepared by hydrogen-free carbonation under the catalysis of platinum will be understood. The effects of catalysis activation and nanometer activation on tungsten carbide powders will be studied and the tungsten carbide powders with catalysis activation and nanometer activation will be prepared. The mechanism of the activation effect of platinum catalysis during the whole sintering course will be studied. The densification mechanism of binderless tungsten carbide by the synergistic effect of catalysis activation and nanometer activation will be understood by analyzing the effects of catalysis activation and nanometer activation on the density of binderless tungsten carbide. The mechanism of the activation effect of platinum catalysis in the whole specimen will be studied. The restraining mechanism of the abnormal growth of tungsten carbide grain causing by the catalysis of platinum will be understood by analyzing the effect of platinum catalysis on the grain size of tungsten carbide. The fracture mechanism of binderless tungsten carbide will be understood by studying the effects of the microstructure on hardness and toughness. The binderless tungsten carbide with high hardness and high ductility can be prepared by changing the content of platinum and adjusting the technology of carbonation and sintering.

为了在低温低压下烧结出致密的无粘接相碳化钨，利用铂催化作用下的无氢碳化工艺制备出有催化活化特性的碳化钨粉，并利用铂催化活化在烧结时全时段全范围的活化效果，制备出致密的没有异常晶粒长大的无粘接相碳化钨。分析铂对碳化过程的影响，研究铂提高碳原子活性的机理，理解铂催化作用下无氢碳化制备碳化钨粉的机理；分析碳化工艺对铂催化活化的影响，研究催化活化和纳米活化对碳化钨粉的协同活化机制，制备出兼有纳米活化和催化活化的碳化钨粉；分析纳米活化和催化活化对致密化过程的影响，研究催化活化在烧结过程中的全时段活化机理，理解铂催化活化碳化钨粉在纳米活化和催化活化协同作用下的致密化机理；分析铂对晶粒长大的影响，研究催化活化在整个试样中的全范围活化机理，理解催化活化抑制异常晶粒长大的机理；研究组织对硬度和韧性的影响，理解无粘接相碳化钨的断裂机制，改变铂含量及调节碳化和烧结工艺制备出兼有高硬度和高韧性的无粘接相碳化钨。

无粘接相碳化钨因具有高硬度、高导电导热率、优良的耐腐蚀性能和抛光性能而在精密光学模具和电子封装等领域具有广泛的应用前景。为了在低温低压下烧结出致密的无粘接相碳化钨，项目利用铂催化作用下的无氢碳化工艺制备出具有催化活化特性的纳米碳化钨粉末，并利用铂催化活化在烧结时的活化效果，制备出兼具高硬度和高韧性的超细晶无粘接相碳化钨。.（1）研究了铂的添加对无氢碳化制备具有催化活化特性碳化钨的影响，发现在铂的催化作用下，碳原子的活性提高，极大程度降低了碳原子进入钨晶格中的能量壁垒，从而促进了碳化过程，降低了碳化温度，并制备出具有催化活化特性的碳化钨粉末。.（2）研究了铂催化活化碳化钨粉在烧结时的致密化机理，发现碳化钨粉末中的少量铂在烧结过程中充当碳化钨分子的扩散快速通道，降低烧结活化能，提高碳化钨的自扩散能力，实现无粘接相碳化钨的烧结致密化。.（3）研究了铂催化活化碳化钨粉抑制异常晶粒长大的机理，发现过高的温度导致碳化钨晶粒异常长大，铂催化活化碳化钨粉末具有较低的烧结温度，能有效地抑制碳化钨的异常晶粒长大。.（4）研究了无粘接相碳化钨的断裂机制，发现随着晶粒尺寸的增大，无粘结相碳化钨的显微硬度降低，异常晶粒长大会导致硬度和断裂韧性的双重恶化，通过铂催化活化碳化钨粉降低烧结温度，抑制异常晶粒长大，从而制备出兼有高硬度和高韧性的无粘接相碳化钨。