Experimental research on tribological characteristics of TiAlN coated valve plate in electro-hydrostatic actuator pumps. (March 2021)

• Record Type: Journal Article
• Authors: Zhao, Jiangao; Fu, Yongling; Wang, Mingkang; Fu, Jian; Chao, Qun; Wang, Shaopeng; Deng, Ming
• Is Part Of: Tribology international. Volume 155(2021)
• Publication Date: 2021-03
• Subjects: Electro-hydrostatic actuator pump -- Valve plate -- TiAlN coating -- Tribological characteristics; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2020.106782
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: Moving towards high power density, high dynamic responsibility, and high reliability, the electro-hydrostatic actuators (EHA) have put forward great demand on the piston pumps. As a typical pump control system, EHA pumps need to maintain high efficiency in a wide range of rotational speed and pressure to implement the function of position servo. High speed and wide speed range bring great challenge to the cylinder block/valve plate interface, which has to fulfill simultaneously a bearing and sealing function. Cermet coatings are beneficial to improve the friction and wear performance of the sliding surfaces. In this study, a dedicated frictional test apparatus of cylinder block/valve plate interface has been built which could accurately simulate the working conditions of EHA pumps in a wide operational condition. Equations of the friction coefficient are established based on the combination of experiments and friction theory. When pairing with the tin-bronze cylinder block, friction coefficients of TiAlN coated and nitrided valve plate are calculated by these equations. Additionally, the wear status of these two friction pairs are evaluated by a 3D measuring laser microscope. In the wide speed range of 500–10000 rpm, the decrease percentage of friction coefficient and the wear rate for TiAlN coated valve plate are 52.55%–64.9% and 12–14% of the nitrided one, respectively. Highlights: A dedicated apparatus of cylinder block/valve plate interface has been built. This apparatus could accurately simulate the working conditions of EHA pumps. Friction coefficient equation is put forward based on the experiments and tribology. TiAlN coated valve plate can reduce friction and wear significantly.