Effect of Laser Shock Peening on the Interfacial Bonding Properties of TiN Coatings on TC4 Titanium Alloy

This paper aims to improve the bonding strength of TC4 titanium alloy and TiN coatings, the effect of laser shock peening on the interfacial bonding properties of TiN coatings on the surface of TC4 titanium alloy is explored through experimental research. Firstly, the surface was treated with different laser parameters (spot overlap ratio and power density), and the surface geometry and roughness of TC4 titanium alloy samples were measured by Wyko NT 1100 non-contact optical profilometer (NCOP), the surface residual stress of TC4 titanium alloy was measured by X350A X-ray residual stress tester, and the microhardness of impact surface was measured by HXD-1000TMSC/LCD microhardness tester; Secondly, the ion plating technology was used to prepare TiN coatings in the laser shock region, and the interfacial adhesion between the TiN coating and TC4 titanium alloy was measured by WS-2005 film adhesion automatic scratch instrument to analyze the effect of laser shock pre-treatment on the interfacial adhesion of tin coatings; Finally, the friction and wear test was used to verify the effectiveness of the laser shock strengthening pre-treatment to improve the bonding performance of the coating interface. The following experimental data were obtained: Under the test conditions of a dynamic load of 50 N, a rate of 50 N/min, and a scratch length of 4 mm, bonding force of TiN coating and substrate of the sample without laser shock treatment was 28.9 N, but after pre-treatment of laser shock peening, the adhesion was increased to 32.3 N, 33.2 N, 34.9 N, 36.8 N and 39.6 N, and the increase of interfacial adhesion by pretreatment was 11.76%, 14.88%, 20.76%, 27.34% and 37.02% respectively; Under dry friction conditions with a load of 7.5 N, a reciprocating stroke of 5 mm, a reciprocating frequency of 2 Hz, and a test time of 25 min, the wear rate of each sample was reduced to 3.79×10‒5 mm3/(N·m), 9.8×10‒6 mm3/(N·m), 8.82×10‒6 mm3/(N·m), 4.32×10‒6 mm3/(N·m) and 1.24×10‒6 mm3/(N·m) respectively. The experimental results show that the pre-treatment of laser shock peening has an effective function of improving the interfacial bonding performance of TiN coatings on the surface of TC4 titanium alloy. The results of the friction and wear test indicate that the synergistic effect of laser shock and TiN coating significantly reduces the friction coefficient and wear rate of the TC4 titanium alloy, and improves the wear resistance of the coating. Among the laser parameters, the spot overlapping rate has the most significant effect on the interface performance of the coating. When the overlap rate is 50%, the surface treatment effect of the material has good uniformity, and the best interface bonding performance and wear resistance effect can be obtained under the action of the laser parameters of 50% overlapping rate and 6.43 GW/cm² power density. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.