钻头钢体织构化喷涂层的防泥包与耐磨机理

It is urgent to improve the performance and wear resistance of the PDC bit in the development technology of nonconventional energy exploration. However, the problems of PDC bit balling and wear can not be effectively solved by improving the velocity of drilling fluid through fluid dynamics and improving the wettability of drilling fluid to cuttings through physical and chemical action. To solve this problem, this project proposes to use advanced composite processing technology of supersonic flame spraying and laser surface textured to modify the steel surface of PDC bit for improving the anti-balling performance and wear resistance. The mechanical adhesion and chemical adhesion between cuttings and drill bit surface under the action of drilling fluid will be studied. The influence of texture structure on the interfacial contact state between the modified layer and the water-based drilling fluid will be excavated. The anti-balling mechanism of high hydrophobic modified layer will be revealed. The tribological behavior between the modified layer and cuttings and the wear mechanism under the drilling fluid environment is tried to be investigated. The optimum matching relationship between hydrophobic performance and wear resistance of the modified layer will be established. This project reflects the interdisciplinary fusion, and the research results will provide a theoretical basis and technical support for solving the problem of PDC bit balling and ensuring the service durability of the surface modified layer.

非常规能源勘探开发技术中，迫切需要提高PDC钻头的防泥包性能和耐磨性能，但是采用流体动力学提高钻井液流速和通过物理化学作用改善钻井液对岩屑的润湿性等方法不能有效解决PDC钻头的泥包和磨损问题。针对这一问题，本项目提出利用先进的超音速火焰喷涂和激光表面织构化复合处理技术对PDC钻头的钢体表面进行改性，以有效提升其防泥包性能和耐磨性能；研究钻井液作用下岩屑与钻头表面改性层间的机械粘附和化学粘附行为；挖掘织构结构对改性层与水基钻井液之间界面接触状态的影响规律；揭示高疏水改性层的防泥包机理，研究钻井液环境中改性层与岩屑等固相间的摩擦学行为和耐磨机理，并建立改性层的疏水性与耐磨性之间的最佳匹配关系。本项目体现了多学科的交叉融合，研究成果将为解决PDC钻头的泥包问题和保证表面改性层的服役持久性提供理论基础和技术支持。

非常规能源勘探开发技术中，迫切需要提高PDC钻头的防泥包性能和耐磨性能。本项目利用“超音速火焰喷涂+激光加工表面织构”复合表面改性技术对PDC钻头钢体35CrMo进行了表面处理；研究了表面复合改性层的疏水性能及疏水机制；基于球盘式摩擦磨损试验机分析了复合改性层的真空摩擦学性能及磨损失效机制。结果表明：（1）增大表面粗糙度可提高表面的疏水性。接触角CA与粗糙度Sa呈现正比关系，涂层表面发生了从亲水性到疏水性的转变。（2）经过复合处理的表面疏水性能均明显提高，间距100 μm的网格织构接触角最大，在干摩擦下的具有明显的减摩作用。织构覆盖率R随着织构间距的减小而增加，CA值随织构覆盖率增加而增大。CA值的增加是由于表面形貌和化学组分变化的共同作用所致。（3）干摩擦下每种织构的摩擦系数随着间距增加而增加，相同间距的网格，沟槽和凹坑的摩擦系数依次增加。在泥浆润滑条件下，三种织构的摩擦系数均高于原始表面。干摩擦下的磨损机理主要是粘着磨损和氧化磨损。在泥浆润滑下，织构表面主要发生三体磨损。项目研究成果为PDC钻头的表面性能提升和服役寿命延长提供了有益的技术支持，丰富了摩擦学研究和相关理论。