Preparation and properties of ultrasonic assisted laser cladding Ni-TiN coating on surface of N80 steel for oil pipeline

Ni-TiN coatings were prepared on the surface of N80 steel for oil pipeline by ultrasonic assisted laser cladding in this paper. The effects of different ultrasonic powers on the surface morphology, microhardness and wear resistance of Ni-TiN coatings were studied by scanning electron microscope, X-ray diffractometer, microhardness tester and friction and wear tester. The results indicated that when the ultrasonic power was 300 W, size of TiN particles in the Ni-TiN coating was smaller, and its average particle size was 16. 7 μm. The nickel diffraction peak of the coating became low and wide, testifying the refinement of the metal grains in the coating. Furthermore, the microhardness of the coating was the largest, and the average microhardness was 833 HV. When the ultrasonic power was 0 W, the friction coefficient of the Ni-TiN coating was the largest, and its average value was 0. 57. However, when the ultrasonic power was 300 W, the friction coefficient of the coating was the smallest, and its average value was 0. 42.