聚晶金刚石复合体超高压液相烧结理论研究

 在对前人有关聚晶金刚石超高压烧结机理的综合分析与评价的基础上，通过对金刚石与不同组分的钴熔体相互作用规律，及金刚石从钴熔体中的结晶热力学与动力学的理论研究，提出了石墨优先金刚石“溶解”和金刚石石墨化“溶解”的观点，阐明了钴熔体的性质对金刚石（石墨）的浸润扩散溶解过程，以及金刚石再结晶析出过程的影响，认为在金刚石-钴烧结系统中存在三种主要烧结机构：颗粒重排，溶解-析出和聚晶固架形成机构。不同温度条件下不同碳含量钴熔体在烧结过程中，对于促进金刚石表面石墨化，进一步引起颗粒重排，实现sp³结构碳原子在金刚石颗粒间的有效迁移传递以及D-D直接结合等方面起到了十分重要的作用。根据上述金刚石超高压液相烧结理论的基本观点，可较合理地解释聚晶金刚石复合体（PDC）在超高压烧结过程中观察到的一些基本现象和实验事实。

Theoretical Study on High Pressure Liquid Sintering of Polycrystalline Diamond Compact

Based on the theoretical analysis of the interaction between diamond and melted cobalt under HP/HT conditions,the effect of temperature and carbon content of the melted cobalt on the sintering process of diamond dissolution and polycrystalline diamond growth are discussed.It is suggested that the diamond is preferable to graphite to dissolve in the melted cobalt under HP/HT and there are three sintering mechanisms in the diamond-cobalt sintering system,that is,the mechanism of diamond rearrangement,dissolution and precipitation and formation of the direct bonding of diamond to diamond.The melted cobalt with different carbon content and temperature can play an important role to weak or cease the covalent bond of diamond at its surfaces, to promote the rearrangement of diamond,to realize the transportation of diamond atoms and finally to form the diamond to diamond bonding structure of polycrystalline diamond.According to the high pressure liquid sintering theory of diamond proposed in this paper,some experimental phenomena found during the HP/HT sintering process of polycrystalline diamond compacts could be explained rationally.