Study on Microstructure and Properties of Laser Alloying Coating on TRT Blades

In order to solve the problems of easy to wear and poor erosion resistance of TRT blades, laser alloying technology was used to prepare 0.35 mm thick coating on the surface of TRT blades. The coating was prepared by using alloyed iron-based powders with 1 wt% graphite phase C₃ N₄ and compared with coatings prepared by using alloyed iron-based powder without graphite phase. The results show that, the coating microstructure prepared without adding graphite phase is relatively dense, and the main material phases in the coating consists of α-Fe phase, Fe-Cr solid solution, and MnV and FeV metal compounds. The maximum hardness of the coating surface is 725 HV, the hardness is 2.9 times higher than that of the substrate 2 Cr13. The friction coefficient is unstable, but the wear amount is small. However, the coating microstructure prepared with 1 wt% graphite phase C₃ N₄ is more dense, the grains are clearly refined, and the VC, V₈ C₇ hard phases and FeN₄ are newly generated. The hardness is 783 HV, which is higher than the sample without adding graphite phase and it is 4.3 times of the hardness of the substrate. The friction coefficient still fluctuates, but the relative wear amount decreases.Therefore, the addition of the graphite phase C₃ N₄ to the alloyed iron-based powder gives the coating a better performance,which can improve the wear resistance of the TRT blade surface.