航空液压泵关键摩擦副摩擦磨损失效是其性能失效的主要原因。为提升航空液压泵可靠性和使用寿命，针对航空液压泵关键摩擦副“软/硬”配副特性，本文基于空心阴极离子源扩渗方法研究氮碳硫多元共渗对摩擦副硬表面进行改性，以提升摩擦副摩擦磨损性能。空心阴极离子源扩渗方法是对活性屏渗氮技术的一种改进，其利用弧光放电，提高了电离率和离子密度，同时大幅缩短了升温时间。因此，利用空心阴极离子源扩渗方法制备的改性层，硬度分布均匀，相结构整齐，耐磨性和耐腐蚀性均优于传统扩渗效果。同时，在原理上，避免了传统扩渗方式带来的边缘效应、局部温度过高引起的烧样等问题。渗氮、渗碳作为较为成熟的表面处理工艺已经得到了相对充分的研究，也有少量碳氮共渗方面的研究。以上三种表面处理工艺主要是对表面硬度、耐磨性和耐蚀性的提升，但对于润滑性能改善并不明显。金属表面常用的固体润滑层为硫化物，通过渗硫，使其表面生成FeS来达到润滑作用。渗硫层由于硬度低，其耐磨性较差，自润滑效果随着改性层磨损而大幅下降甚至消失。为获得耐磨性和润滑性均好的改性层，本文结合渗氮、渗碳和渗硫三种工艺研究氮碳硫多元共渗工艺，提出了“先碳氮共渗、后渗硫”和“碳氮硫多元共渗”两种扩渗工艺，针对42CrMo、1Cr12MoV和Cr4Mo4V三种典型航空液压泵材料进行了实验对比研究，并对扩渗参数和工艺进行了优化。运用了三维白光形貌仪、扫描电镜、原子力显微镜等对改性层表面形貌进行了观察；运用纳米硬度计对改性层表面硬度进行了测量；运用EDS，XRD，XPS对其成分进行了测试以说明生成的新物质；运用聚焦离子束和透射电镜分析了晶粒，进一步确定物质种类；结合UMT标准摩擦磨损实验机、三维白光形貌仪、扫描电镜对不同改性层的耐磨性和自润滑性进行了分析研究。研究结果显示碳氮硫多元改性层的硬度、耐磨性、自润滑性和对对磨面的保护性能均有明显提升，验证了方法和工艺的有效性。
The friction and wear failure of the critical friction pairs of aviation hydraulic pumps is the main reason for its performance failure. Considering the "soft/hard" pairing characteristics of the critical friction pairs of aviation hydraulic pumps, this paper studies the nitrided, nitrocarburized, sulfured, and sulphonitrocarburized layers diffused by the hollow cathode discharging on the hard part of the friction pairs to improve the friction and wear performance of the friction pairs and increase the reliability and working life of the aviation hydraulic pump.The hollow cathode discharging is an improved method for active screen nitriding technology. It uses arc discharge to increase the ionization rate and ion density, while significantly reducing the heating time. Therefore, the modified layer prepared by the hollow cathode discharging has uniform hardness distribution, neat phase structure, better wear resistance, and superior corrosion resistance performance compared with the traditional diffusion method. At the same time, in principle, the problems of edge effects caused by the traditional diffusion method and burning samples caused by excessive local temperatures can be avoided.As a relatively mature surface treatment process, nitriding and carburizing have been thoroughly studied. Moreover, there are also a few studies on nitrocarburizing. The above three surface treatment processes are mainly to improve the surface hardness, wear resistance, and corrosion resistance performance, however, the lubrication performance with almost no promotion. The solid lubrication commonly used on the metal surface is sulfuring layer, and through the sulfurization, the surface is formed with FeS to achieve the lubricating effect. Due to the low hardness of the sulfurized layer, its wear resistance is weak, and the wear-reducing effect significantly decreases or disappears as the modified layer wears. In order to obtain a modified layer with excellent abrasion resistance and lubricity, this paper combines the three processes of nitriding, carburizing, and sulfuring and proposes two diffusing processes of "first nitrocarburizing followed by sulfurization" and "sulphonitrocarburizing ". Using proposed diffusing processes, three typical aeronautical hydraulic pump materials of 42CrMo, 1Cr12MoV, and Cr4Mo4V were experimentally studied and compared, and the corresponding infiltration parameters and process were optimized.The surface morphology of the modified layer was observed using white light three-dimensional topography, scanning electron microscope, atomic force microscope. The surface hardness of the modified layer was measured using a nano-hardness tester. This study utilizes EDS, XRD, XPS tests to illustrate the new material generated and then uses the focused ion beam, and transmission electron microscopy to analyze the crystal grains to determine the type of new components further. Using UMT standard friction and wear tester, white light three-dimensional profilometer, and scanning electron microscopy data, the lubricity and friction reduction properties of different modified layers were analyzed and studied. The results show that the hardness, wear resistance, self-lubricity, and protection of the counterparts of the sulphonitrocarburized layer are significantly improved, verifying the effectiveness of the sulphonitrocarburizing.
