Defects, organization, and properties of TiB2–TiC Bi-ceramic phase by laser cladding in situ synthesis
Ying Zheng, Guofu Lian, Hua Lu, Changrong Chen, Xu Huang
Abstract
An enhanced Ni50A composite coating was formed on the AISI 1045 steel surface using Ti, B 4 C, and Ni50A powders. The work meticulously examined the effects of various process parameters, including laser power (800, 1200, and 1600 W) and scanning speed (4, 6, and 8 mm/s), as well as different Ti/B 4 C powder ratios (2:1, 3:1, and 4:1, mol.%) on the defect, hardness, wear resistance, and corrosion resistance of the coating. The microstructure of the coating showed that TiB 2 and TiC synthesized in situ were the key phases for coating enhancement, and there were a variety of solid solutions (FeNi 3 and Cr 2 Ni 3 ). TiB 2 particles showed dark gray hexagons and long rectangular blocks. The TiC particles mainly appeared in light gray dendritic shapes, occasionally petal-shaped and equiaxial forms, and grew around TiB 2 . The research results showed that increased laser power and the Ti/B 4 C ratio decreased coating hardness and wear resistance. When the scanning speed increased, the hardness and wear resistance of the coating were significantly improved. The main wear mechanisms of the TiB 2 –TiC ceramic phase coating were oxidative wear and abrasive particle wear. Besides, the higher laser power and Ti/B 4 C ratio reduced the defect rate of the coating and enhanced the corrosion resistance . However, as the scanning speed increased, the defect rate increased, which decreased the corrosion resistance of the coating. The comprehensive performance evaluation showed that under the conditions of the laser power of 1200 W, a scanning speed of 8 mm/s, and a Ti/B 4 C ratio of 4:1, the coating exhibited optimal performance (dilution rate = 10.928 ± 0.090 %, defect rate = 8.657 ± 0.128 %, hardness = 63.300 ± 1.159 HRC, wear volume = 0.0149 ± 0.000100 mm 3 , Ecorr = − 0.565 ± 0.001 V, Icorr = 1.058 E − 06 ± 1.528 E − 09 A ⋅ c m 2 ). The results provide an important basis for research on the high-quality and efficient strengthening technology and performance of refractory alloys .