流体润滑工况下复层烧结材料的润滑特性

为解决烧结材料工作过程中形成的动压油膜易渗流进多孔基体进而导致润滑性能变差的问题，采用粉末冶金工艺制备了具有不同孔隙结构的复层烧结材料，以期实现高承载能力与良好润滑性能的统一。首先，基于Darcy定律建立了极坐标下该复层烧结材料的流体润滑模型，利用有限差分法进行数值模拟，考察了不同转速下表面Darcy流动对油膜润滑特性的影响；然后，在油润滑工况下进行端面摩擦试验，以验证模拟结果。结果表明:复层烧结材料的油膜润滑性能明显优于普通单层烧结材料，且在一定孔隙率范围内，随着表层孔隙率降低，复层烧结材料的润滑性能变得更好；计入表面Darcy流动时复层烧结材料的油膜润滑性能相对改善，改善效果随转速增加而渐趋显著；摩擦试验与数值分析所得结论具有较好的一致性。研究工作可为复层烧结材料的摩擦学性能分析与结构设计提供一定的理论基础。 

Lubrication property of multi-layer sintering material under hydrodynamic lubrication

In order to solve the problem that the hydrodynamic oil film formed during the work process of sintering materials is easy to seepage into porous medium which leads to the degradation of lubrication property, multi-layer sintered materials with different porosity structures were prepared by powder metallurgical technique to achieve the unification of high load capacity and good lubricating property. Fluid lubrication model of the multi-layer sintered materials in polar coordinates was established based on Darcy's law firstly, numerical simulation were conducted by using the finite difference method, and the effects of surface Darcy flow on the lubrication property of oil film under different rotate speeds were investigated. Then, the end face friction experiment were conducted under oil lubrication to verify the simulation results. The results show that the oil film lubrication property of the multi-layer sintered materials is much more better than that of the ordinary monolayer sintered materials. With the decrease of the surface porosity, the lubrication property of the multi-layer sintered materials becomes better in the given range of the porosity. The oil film lubrication property of multi-layer sintered materials is improved relatively when considering the surface Darcy flow, and the improving effect becoming obvious gradually with the rotate speed increases. There is a good agreement between the conclusions obtained by friction test and numerical analysis. The research work can provide theoretical bases for tribological property analysis and structure design of the multi-layer sintered material at some degree.