Study On Properties Of CBN Coating By Laser Cladding On The Surface Of Titanium Alloy

As a new surface modification technology, laser cladding has been widely used in thearea of parts modification and repair, because it can produce cladding layer with goodperformance. In order to improve the hardness and wear resistance of titanium alloy surface,in this paper, with CBN powder as cladding materials, selects the method of the fore-putpowder, in the surface of TC11titanium alloy was prepared the CBN coating using the CO2laser. Afterwards through the optical microscope (OM) on the cladding shape and quality ofthe coating were analyzed in detail, and optimized the laser cladding process parameters. Inaddition, the micro-hardness of CBN coatings was analyzed by Vickers hardness tester.The experimental results show that when selecting sodium silicate as a binder, the qualityof the coating is better，meanwhile the laser cladding process parameters have a significantimpact on the quality and shape of the CBN coating. By optimizing the process parameters ofthe laser shows that the best technological parameters of preparing CBN coating is: Laserpower P=1600W, scanning speed V=5mm/s, spot diameter D=3mm,fore-put h=0.3mm.In the process of laser cladding, cladding materials CBN may react with titanium alloy toproduce hard reinforcing phase. Through the measurement, the micro-hardness of thecladding layer compared with TC11titanium alloy has been improved obviously. The averagemicro-hardness of the cladding region (1597HV) compared with titanium alloy matrixhardness (381HV) enhanced near4times, and the micro-hardness increases with the laserpower and scanning speed increasing.Besides, this paper also makes a preliminary analysis on the crack, porosity, edgecollapse produced in the process of laser cladding, and puts forward corresponding preventivemeasures to improve the quality of coating, which can also provide technical support of lasercladding in the application of preparation the CBN coating.Moreover, this paper by referring to the scratch test to establish a calculation model ofthe coating interfacial stress field, and analyzed the effect of coating thickness, crack length,width on the interfacial stress, the paper show that the bonding strength between coating and substrate is associated with the coating thickness and crack.