不同润滑条件下 B4C／hBN 复相陶瓷与灰铸铁配副的摩擦学性能

摘要

To solve the problem of poor tribological properties of pure B4 C-based ceramics,a new type of ceramics,B4 C-hBN composite ceramics,was designed and its characteristics were tested.Pure B4 C-based ceramics and B4 C-hBN composite ceramics with 30% hexagonal boron nitride (hBN)in weight were made to slide against gray cast iron (HT)separately on the MMU-5G pin-disc friction and wear testing machine.The lubrications were air,emulsion and 20# engine oil.Scanning electron microscope (SEM)was used to examine the friction surface topography.Energy dispersive spectrometer (EDS),X-ray photoelectron spec-troscopy (XPS)and X-ray diffraction (XRD)were used to investigate the friction surface and debris composition.The results demonstrate that the friction coefficient of pure B4 C-based ceramics/cast iron sliding pairs in the air is 0.5 and that of the multi-phase ceramics/cast iron pairs is 0.2.A continuous surface film composed of Fe2 O3 ,Fe3 O4 ,B2 O3 and hBN is formed on the ce-ramic pins and works as lubrication.In the emulsion lubrication,the friction coefficient of pure B4C-based ceramics/cast iron pairs is smaller than that of B4 C-hBN composite ceramics pairs.This is because the hBN in the multiphase ceramics hydrolyzes in the emulsion and results in exfoliation of the ceramics.The pairs fail to achieve fluid lubrication.In the 20# engine oil lubrica-tion,the friction coefficients of the two pairs are equal.%为了解决纯碳化硼陶瓷摩擦学性能不佳的问题，设计新型复相陶瓷碳化硼／六方氮化硼（B4 C／hBN）并探究其摩擦学性能，在 MMU-5G 型销-盘式摩擦磨损试验机上，采用纯碳化硼（B4 C）陶瓷和六方氮化硼（hBN，质量分数为30％）的 B4 C／hBN 复相陶瓷分别与灰铸铁（HT）配副进行干摩擦、乳化液润滑及20＃机油润滑下的摩擦磨损实验。采用扫描电子显微镜（SEM）观察摩擦表面形貌；采用能谱仪（EDS）、X 光电子能谱仪（XPS）、X 射线衍射仪（XRD）表征磨面和磨屑的物质组成。研究结果表明：干摩擦条件下，纯 B4 C 陶瓷与 HT 配副时，摩擦因数高达0．5，而 B4 C／hBN 复相陶瓷与 HT 配副摩擦因数降低至0．2，这是由于在复相陶瓷摩擦表面生成了由 Fe2 O3、Fe3 O4、B2 O3、hBN 组成的连续的表面膜的润滑作用；在乳化液润滑条件下，hBN 水解导致复相陶瓷剥落，使该配副未达到流体润滑，故纯 B4 C 陶瓷与 HT 配副摩擦因数低于 B4 C／hBN 复相陶瓷与铸铁配副；当采用20＃机油为润滑剂时，2配副摩擦因数相当。