高转速长寿命航天发动机涡轮泵端面密封摩擦副激光熔覆陶瓷基高温自润滑耐磨复合涂层研究

Concerning the poor wear resistance of the high performance turbo-pump mechanical seal tribological pairs in the astronautical engines, the project aims at the development and characterization of ceramic matrix high temperature self-lubricating anti-wear composite coatings on high temperature materials (austenite stainless steel, et al). The ceramic materials with excellent high-temperature wear-resistance will be used as matrix, the superalloy with excellent high-temperature oxidation-resistance as toughening phase, and the solid lubricants with superior high-temperature self-lubricating property as self-lubricating phase. The self-lubricating particles will be encapsulated by novel electroless plating/pressure infiltration techniques during precursor powder preparation. The high energy laser beam with annular central-hollow shape will be employed to fabricate the multi-phase hybrid high-temperature self-lubricating wear-resistant composite coatings on the surface of elevated temperature materials mentioned above by laser cladding, the corresponding research will be conducted on composite coatings’materials design and the laser fabrication procedure, and the mathematical model of the whole area of laser processing to reveal the evolutional law of the residual stress and the mechanisms of crack formation will be established according to the rheological theory. On the basis of systematical research on the intrinsic relationship of materials fabrication technique-microstructure evolution-tribological performance, the constitution of the composite coatings microstructure with excellent high-temperature oxidation resistance, low friction coefficients and outstanding wear-resistant capabilities in the range of 600-800 ℃ as well as their laser fabricating technique, will be developed. Therefore, the scientific theory to broaden the application of the above tribological pairs and improve the reliability of the latest astronautical engines will be established.

本项目针对高性能航天发动机涡轮泵端面密封摩擦副耐磨性能不足的缺点，拟在高温材料（奥氏体不锈钢等）表面制备陶瓷基高温自润滑耐磨复合涂层并研究其组织结构和摩擦学性能。拟以高温耐磨性能优异的陶瓷材料为基体、以高温抗氧化性能优异的高温合金为增韧相及高温自润滑性能优异的润滑颗粒为自润滑相，在原材料准备时采用化学镀/压力浸渗等手段包覆固体润滑颗粒。引入环形中空光束，采用激光熔覆技术制备出多相混杂陶瓷基高温自润滑耐磨复合涂层，开展相关复合涂层的材料体系设计及激光制备工艺研究；同时，采用流变学理论建立激光熔覆整体区域的数学模型，揭示残余应力的演化规律和开裂机理，在对复合涂层制备工艺-组织演变-摩擦学性能内在关系进行深入研究基础上，研究出在600-800℃范围内具有优异抗氧化性能、低摩擦系数和耐磨性能的复合涂层微结构组成及其激光制备工艺，为拓展上述摩擦副在航天发动机上的应用，提高其可靠性提供科学理论指导。

本项目针对液体航天发动机涡轮泵端面密封摩擦副常见高温材料奥氏体不锈钢和钛合金表面硬度低、摩擦系数大和不易润滑等性能缺点，通过材料体系设计和自润滑颗粒包覆等手段，采用激光熔覆技术在奥氏体不锈钢和Ti6Al4V合金表面制备出了一系列不同成分的NiCr/Cr3C2-WS2-CaF2、Ni60-Cu-Ti3SiC2、Ni60-Co-Ti3SiC2等陶瓷基宽温域耐磨自润滑复合材料涂层。深入研究了各涂层的物相组成、微观组织结构和显微硬度，系统评价了奥氏体不锈钢和钛合金基体和各涂层在室温-800 ℃宽温域范围内的干滑动磨损性能，深入分析了相关磨损机理及对偶件效应，取得了一些重要的研究成果：1）设计了激光直接添加合成高温自润滑耐磨复合涂层材料新体系。基于“直接添加和多相混杂强韧配合”的涂层材料设计思想，设计出采用激光熔覆技术合成以二元、三元金属硫化物、硅化物、氧化物为宽温域自润滑相的陶瓷基/金属基自润滑耐磨复合涂层材料新体系；2）成功地在304不锈钢和Ti6Al4V合金表面制备出系列陶瓷基和金属基宽温域耐磨自润滑复合材料涂层；3）提出了激光熔覆金属增韧陶瓷基耐磨复合涂层的磨损表面局部区域出现显微凹坑的新机制，建立了显微凹坑的形成模型。4）Ti3SiC2作为一种典型的MAX相陶瓷固体润滑材料，由于其独特的结构和优异的性能受到广泛关注，然而目前关于激光熔覆Ti3SiC2高温自润滑摩擦学的研究相对较少, 本项目初步研究了添加不同含量Ti3SiC2的陶瓷基高温自润滑耐磨复合涂层的高温及中低温的摩擦学性能及耐磨减摩机理。研究成果发表期刊论文15篇并标注基金资助（其中SCI检索7篇，EI检索7篇，不重复计算），授权国家发明专利2件，获2019年度湖南省自然科学奖二等奖1项。