Laser Cladding of Ti6al4v Alloy with Al2o3-Sic-Ag Modified Titanium Powder and the Accompanying Protection
B-G. Yan, B. Hu, L. Jin, L. Zhu, P-J. LV, P. Lu, F. Wang, B. Liu and K-Y. Jiang
A crack-free coating that consisted of Ti-Al2o3-Sic-Ag was prepared on the surface of Ti6Al4V alloy by laser cladding. In the composite powder Al2O3 was coated onto Ti particles by the sol-gel method to improve the crystallite and hardness, SiC whiskers were used to depress the diffusion of cracks and Ag was used to improve the thermal diffusivity during laser cladding and depress the thermal stress. A protecting nozzle was designed to prevent the Ti particles from oxidation and hydrogenation. The micro- structure of the cladding layer was lamellar β-phase, Ag and SiC whiskers played an effective role in restraining cracks. The results of microhardness testing show that the average hardness of the Ti-Al2o3-Sic-Ag clad layer is about 669 Hv1 which is 1.86 times higher than Ti6Al4V alloy. Friction and wear experiments revealed that the wear resistance of the Ti-Al2o3-Sic-Ag clad layer was 3⁄4 that of the Ti6Al4V alloy substrate.
Keywords: High power diode laser (HPDL), Ti6Al4V alloy, Ti-Al2o3-Sic-Ag composite powder, laser cladding, microstructure, microhardness, wear, thermal stress