Search

The wear resistance of 17-4PH stainless steel was improved at wide temperature (25–200 °C) by depositing multi-layered Cr/CrC/DLC coating. The results showed that the lubricating effect of the transfer layer led to a reduction of the friction coefficient to 0.03. DLC coating had a protective effect on the 17-4PH substrate, and the surface of the coating was basically not worn at 25–100 °C. This study focused on the wear mechanism and frictional chemical reaction mechanism of multi-layered coatings at wide temperatures. With the increase of temperature, the wear mechanism of DLC coating changed from abrasive wear to adhesive wear, and finally delamination. The complex tribochemical reaction in the wear process led to the dynamic change of its graphitization transformation, which affected the formation of the transition layer and the change in surface mechanical properties of the coating. This was mainly because the transition layer Cr/CrC and Si 3 N 4 played a role in inhibiting the graphitization transformation of DLC layer during the wear process, thus affecting the friction properties of DLC. [Display omitted] • The dynamic process of graphitization and the lubrication of the transfer layer lead to COF to 0.03. • The dynamic process of graphitization intensification and inhibition appears. • The graphitization of DLC is inhibited by the transition layer and the counter abrasive materials. [ABSTRACT FROM AUTHOR]

In current work, the wear resistance of CuNiAl was improved by the application of an aromatic thermosetting co-polyester (ATSP)-based coating on its surface. Tribological behaviors of the ATSP coating at stresses of 1.52, 3.04 and 3.75 MPa under different lubrication conditions (dry friction and oil) were studied by the fretting wear test. The morphology and chemical composition of the coating were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and three-dimensional (3D) optical microscope. Results showed that at the same conditions, the friction torque of the ATSP coating was lower than that of CuNiAl. Significantly, wear was reduced by more than 90% after the application of the ATSP coating. The wear mechanism of the ATSP coating was slight deformation with pits induced by plastic deformation and fatigue crack propagation. The ATSP coating underwent molecular chain breakage during wear and chemical reaction with the friction pair to form a transfer film which played an important role in the reduction of wear. • The friction and wear properties of ATSP coating under fretting wear were investigated. • ATSP coating can significantly improve the wear resistance of CuNiAl. • ATSP coatings undergo complex chemical changes during wear。. • Transfer film is an important factor in reducing ATSP friction and wear. [ABSTRACT FROM AUTHOR]

• Test method of leakage characteristics under sea depth circumstance. • Variation rules of leakage of the SHAPP with sea depth. • Influence mechanism of sea depth circumstance on the leakage of piston pump. • Method for reducing leakage of deep-sea piston pump. Seawater hydraulic axial piston pump (SHAPP) is an important component of underwater hydraulic system. However, due to the particularity of the deep-sea high-pressure environment, the precise measurement of the SHAPP has not been carried out in the past, and there is a lack of performance evaluation of piston pump based on deep-sea test. In this paper, a testing system of the SHAPP in deep sea environment was designed and established, and the leakage mechanisms of the SHAPP is mainly studied by methods of experimental research and theoretical evaluation. The results indicated that the piston and piston bush produce micron deformation under sea depth circumstance. The compaction coefficient of plane pair (slippers/swashplate and port plate/valve plate) decreases gradually with the increase of sea depth. The main reasons why the leakage increases with the increase of sea depth under a certain load are that the clearance of the piston/piston bush becomes larger, and that the sealing of the plane pair gradually deteriorates due to the reduction of the compaction coefficient. Finally, the method of reducing leakage is given, this paper will provide theoretical and experimental reference for the design and application of the SHAPP in deep-sea environment. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of parameters of ultrasonic vibration-assisted milling (UVAM) on torsional fretting wear properties of CuAlNi. Surface texture is processed on CuAlNi surfaces by the UVAM method. Fretting wear experiments on the CuAlNi surfaces are carried out by the torsional wear test rig. Further surface topography measurements using three-dimensional (3D) surface profiler, relationships between the UVAM parameters and the fretting properties of UVAM-processed samples were established. The results indicated that the UVAM-processed samples showed excellent antiwear and antifriction properties in comparison with untreated CuAlNi; this improvement is mainly due to the enhancement on abilities of storing lubricated oil and catching wear debris during the fretting wear process, as well as the increased hardness. • Surface texture is processed on CuAlNi surfaces by the ultrasonic-vibration-assisted milling (UVAM) technique. • The significantly improved fretting properties of UVAM-processed CuAlNi surfaces have been obtained. • Effects of parameters of UVAM on torsional fretting wear properties of CuAlNi are investigated. [ABSTRACT FROM AUTHOR]