NiCrAlYSi/h-BN高温可磨耗封严涂层摩擦磨损性能研究

目的加入h-BN和团聚聚苯酯分别作为固体润滑剂和造孔剂,以提高NiCrAlYSi基封严涂层的高温摩擦磨损性能。方法采用真空熔炼雾化造粒和料浆喷雾造粒技术制备NiCrAlYSi/h-BN聚苯酯复合粉体,再利用大气等离子喷涂技术制备高温可磨耗封严涂层,通过扫描电子显微镜(SEM)、能谱仪(EDS)、CSM摩擦磨损试验机和三维轮廓仪等手段,研究NiCrAlYSi/h-BN封严涂层显微结构、元素组成以及室温和800℃下的摩擦磨损性能,探究涂层在室温和800℃下的磨损机理。结果等离子喷涂NiCrAlYSi/h-BN封严涂层组织比较均匀,涂层结合强度可达15MPa,孔隙率约为32%。室温下封严涂层与DD6镍基单晶高温合金球间的平均摩擦因数为0.897,涂层磨损体积为2.09×10~8μm~3;800℃高温下平均摩擦因数为0.425,涂层磨损体积为3.22×10~8μm~3;封严涂层800℃下有良好的可磨耗性,相应对偶件的磨损较轻;高温下,封严涂层金属基相软化、h-BN的润滑作用和部分金属基相高温下生成自润滑性氧化物,是摩擦因数降低和对偶件磨损较轻的主要原因。NiCrAlYSi/h-BN封严涂层室温的主要磨损机理为涂抹、磨粒磨损和轻微氧化,高温下的主要磨损机理为切削、塑性变形、氧化和粘着磨损。结论等离子喷涂NiCrAlYSi/h-BN高温封严涂层在高温下的可磨耗性能较好。

Friction and Wear Properties of NiCrAlYSi / h-BN High-temperature Abradable Seal Coatings

Objective To improve the tribological properties of the NiCrAlYSi based seal coatings by adding h-BN and polyester into the coatings as lubrication and pore forming material, respectively. Methods The NiCrAlYSi/h-BN/ polyester composite pow-der was prepared by the technology of vacuum melting atomization and spray granulation. The NiCrAlYSi/h-BN high-temperature abradable seal coatings were prepared by atmospheric plasma-spray technology. The microstructure, elements and tribological prop-erties at room temperature and 800℃ of coatings were studied by SEM,EDS,CSM tribometer and three-dimensional contour instru-ment. The tribological mechanisms of the coatings were investigated at room temperature and 800 ℃. Results The NiCrAlYSi/h-BN abradable seal coatings had uniform microstructure and the tensile strength of the coatings was about 15 MPa. The porosity of the coating was about 32%. The room-temperature average friction coefficient between NiCrAlYSi/h-BN and DD6 alloy ball was 0. 897, and the average friction coefficient at 800 ℃ was 0. 425. The wear volume of the coatings at room-temperature and 800 ℃was 2. 09×108 μm3 and 3. 22×108 μm3, respectively. The wear performance of the coating at 800 ℃ was good and the abrasion of DD6 alloy ball was slight, which was due to the softened metal matrix phase, the lubrication of h-BN lubricant material and the for-mation of metallic self-lubricant oxide at high temperature. The main room-temperature wear mechanisms of NiCrAlYSi/h-BN coa-ting were smearing, particle wear and slight tribo-oxidation; while the main wear mechanisms at high temperature were cutting, plastic deformation, tribo-oxidation and adherence wear. Conclusion The NiCrAlYSi/h-BN high temperature abradable seal coa-tings exhibited excellent wear performance at high temperature.