In-situ Construction of Copper Phosphate Layer on Titanium Alloy Surface and Its Coupled Lubrication Mechanism with Lubrication Oil

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Titanium alloys have strong adhesion and a high wear rate, which limits their application in motion friction pairs. In this work, a stable in-situ copper phosphate (CuP) layer with a three-dimensional structure formed by interlocking CuP nanosheets was constructed on the titanium alloy surface. Under Polyalphaolefin 8 (PAO8) lubrication, the CuP layer and PAO8 formed a solid-liquid coupled lubrication system. Within this system, compared with the bare titanium alloy lubricated with PAO8, the coefficient of friction (COF) decreased by 79.60 % from 0.451 to 0.092, and the wear rate (WR) decreased by 99.69 % from 1.54 × 10-4 mm3/(N⋅m) to 4.85 × 10-7 mm3/(N⋅m). SEM-EDS results indicated that the in-situ constructed CuP layer could directly participate in the tribofilm formation, which effectively separated the contact surfaces of the friction pair and protected the titanium alloy surface from severe wear. It was the key to the significant reduction in WR. At the micro level, the results of molecular calculations showed that the interface between polar CuP nanosheets and non-polar PAO8 molecules generated Coulomb repulsion under the load, forming a solid-liquid coupled lubrication system and reducing lateral shear forces. Meanwhile, XPS analysis confirmed that the introduction of the CuP layer effectively suppressed the strong frictional chemical reaction of titanium alloy during the sliding process, reducing the formation of TiO2. This work developed an in-situ lubrication interface construction method, providing an effective solution to the problems of strong adhesion and high wear rate of titanium alloys.

This publication has 30 references indexed in Scilit: