Study on the wear resistance of micro-arc-oxidised ceramic films on the surface of TC4 titanium alloy oil well tubing in the Ordos Basin

Abstract

The use of titanium alloy oil well pipes in conventional and unconventional oil and gas explorations, developments and drillings in gas fields in the Ordos Basin is increasing. However, ensuring the safety of titanium alloy tubing is challenging because of the poor friction and wear resistance of these alloys. Herein, we strengthened the surface of a TC4 alloy oil well pipe through micro-arc oxidation to prepare oxidised ceramic films (MAO-TC4). Further, we investigated their friction and wear behaviours under different normal loads to analyse related mechanisms and improve the safety of titanium alloy oil well pipes. The results reveal a positive correlation between the coefficient of friction and wear volume under the normal load. In addition, the wear characteristics of MAO-TC4 are superior to those of the TC4 alloy in all contact forms. When paired with TC4 alloy balls, the adhesive wear and abrasive wear are dominant wear mechanisms. Meanwhile, when paired with Si₃N₄ ceramic balls, the wear mechanism is abrasive wear at the contact edge and slight oxidative and fatigue wear at the contact centre. Moreover, the MAO-TC4 alloy can effectively reduce oxidative wear. The cutting-to-plasticity ratio (f_cp) of MAO-TC4 is 0.8, and we weakened the micro-cutting mechanism to prevent material loss compared with TC4, which has an f_cp of 0.95. In conclusion, MAO-TC4 can resist frictional wear at the alloy end face of titanium alloy oil well pipes. In addition, this study provides design concepts for improving the performance of the end face in the oil and chemical design for titanium alloys.