聚晶金刚石摩擦表界面钝化机制与转移膜形成机理

The developments of resource exploration and drilling equipment urgently require the long-life and high-performance super hard polycrystalline diamond (PCD) cutting and wear-resisting tools. The physical and chemical properties of sliding surface and interface restrict the friction and wear properties of PCD. However, the cognition of tribochemical effect and passivation mechanism at frictional surface and interface of PCD has been not yet systematic and in-depth. Consequently, this project proposes to reveal its surface and interface passivation mechanism and transfer film formation mechanism by regulating the surface and interface effects of PCD (humidity, pH value, atmosphere, and mating materials, etc.). The systematic exploration of the influence of individual or combined effects of mating materials, atmosphere, gas pressure, hydroxyl content, hydrogen bond content, and graphitization, etc. on the tribological behaviors of PCD will be conducted. Additionally, the breakage and rehybridization bonds of C-C bonds and interface covalent bonds will be elucidated. The analysis of the microstructure, mechanical properties and evolution mechanism of the transfer film will be performed, which is beneficial to reveal the formation mechanism of the tribochemical reaction film or transfer film of the PCD. In order to establish an in-situ nanomechanical experimental characterization method for the tribochemical reaction film or transfer film, the nano-tribology experiments will be performed under various atmosphere and humidity conditions. Based on the above studies, a macro/micro relationship should be established and the cross-scale tribological mechanisms of the PCD tribochemical reaction film and the transfer film will be revealed. The expected results lay an experimental and theoretical foundation for the synthesis of superhard PCD and the development of drilling tools.

资源勘探和钻探装备开发亟需长寿命高性能超硬聚晶金刚石（PCD）切削和耐磨工具，摩擦表界面的物理及化学特性制约着PCD的摩擦磨损性能，然而对PCD表界面摩擦化学效应及钝化机制的认知尚不系统和深入。本申请提出通过调控PCD表界面效应（湿度、PH值、气氛、对磨副等）揭示其表界面钝化机制与转移膜形成机理。系统探究对磨副材料、气氛、气压、羟基含量、氢键含量、石墨化程度等因素单独或复合作用对PCD摩擦学行为的影响规律；阐述C-C键与界面共价键的断裂、重杂、转移机制，分析转移膜微观结构、力学性能、演化机制，揭示PCD摩擦化学反应膜或转移膜形成机理；建立摩擦化学反应膜或转移膜的原位纳米力学实验表征方法，开展气氛、湿度条件的纳米摩擦学试验，建立宏/微观的联系，揭示PCD摩擦化学反应膜和转移膜的跨尺度摩擦机理。预期成果为超硬PCD合成及其钻探工具开发奠定实验和理论基础。

资源勘探和钻探装备开发亟需长寿命高性能超硬聚晶金刚石（PCD）切削和耐磨工具，摩擦表界面的物理及化学特性制约着PCD的摩擦磨损性能，然而对PCD表界面摩擦化学效应及钝化机制的认知尚不系统和深入。本项目阐述了C-C键与界面共价键的断裂、重杂、转移机制，分析了转移膜微观结构、力学性能、演化机制，揭示了PCD摩擦化学反应膜、转移膜形成与跨尺度摩擦机理。.通过调控PCD表界面效应揭示了气氛环境下PCD表界面钝化效应、摩擦表界面碳键重杂化、pH值、湿度和热损伤耦合作用对PCD摩擦学性能的影响与摩擦学机理。真空条件下摩擦界面间的粘附现象可被H2O、H2分子在低压强（0.1-1Pa）时抑制，降低摩擦并减小磨损。而N2和O2不能在低压强（0.1-1Pa）下减少粘附。但O2在1000Pa下仍可呈现出较好的减小粘附的性质；PCD对磨不同配副材料时，PCD/SiO2摩擦系数较高~0.06，Al2O3为对磨副材料时摩擦系数~0.03；酸性条件下，PCD/Si3N4摩擦系数随pH值增大而先减小后增加，当pH值为0.5时，摩擦系数降至最低值0.009。碱性条件下，pH值越大对PCD/Si3N4摩擦学行为的影响越明显。湿度环境下，700℃热处理可有效改善PCD的摩擦磨损行为。.揭示了金刚石镀膜对PCD的抗氧化性、抗石墨化、冲击韧性、热稳定性及真空摩擦学性能的影响机制。B-PCD的B4C薄膜使其石墨化和氧化的初始温度提高了100℃和30℃；Ti-PCD中，TiC转变为TiO2延缓了金刚石的氧化反应，此外，TiC抑制了钴催化引起的金刚石石墨化，使其氧化和石墨化初始温度提高了50℃和100℃；Ti增强了金刚石颗粒界面间的键合，提升PCD的冲击韧性和耐磨性。.揭示了高温处理、金刚石晶粒尺寸对PCD摩擦学行为的影响机制。大粒度PCD中高含量的钴有益于形成减摩碳质转移膜，表现低摩擦行为；700℃退火热处理PCD可在不牺牲耐磨性的前提下利用钴对金刚石的催化石墨化作用获得良好的摩擦学性能。.本项目发表SCI收录论文13篇，中文期刊论文3篇，培养博士后2名，博士生研究生3名，硕士生16名，获得3项科技奖励。研究成果应用于聚晶金刚石钻头、截齿、保径器、推力轴承等钻具关键部件，推广应用于地质、煤炭、油气钻探和岩土施工等工程项目，取得了较好的经济和社会效益，为超硬PCD合成及其钻探工具开发奠定实验和理论基础。