激光熔化沉积制备Ni基合金复合涂层组织与耐磨损性能研究

Microstructure and Wear Resistance of Ni-based Alloy Composite Coatings Prepared by Laser Melting Deposition

摘要:

通过激光熔化沉积技术在304NG不锈钢基体上制备Nb和WC复合强化的4级Ni基合金复合涂层，研究了Nb和WC的质量分数对该涂层微观组织、显微硬度、耐磨损性能的影响规律。结果表明：涂层与基体结合情况良好，无明显裂纹、气孔等缺陷。合金元素Nb的加入生成了新的硬质相NbC、Nb₆C₅，使共晶组织更加致密的同时也提升涂层的硬度和耐磨损性能。综合分析，添加10wt% Nb+15wt% WC的涂层表现出最优的耐磨损性能，连续的共晶组织由长条状、网状转变为分离的短条状、块状、粒状、鱼骨状4种形状，同时WC的加入使涂层的磨损机制由磨粒磨损、黏着磨损转变为疲劳磨损。

Abstract:

The Nb and WC composite-strengthened Grade 4 Ni-based superalloy coatings were prepared on 304NG stainless steel substrate by laser melting deposition technology. The effects of Nb and WC mass fraction on the microstructure, microhardness and wear resistance of the Ni-based superalloy coatings were studied. The results show that the coating is well combined with the substrate without obvious cracks, pores and other defects. The addition of alloying element Nb leads to new hard phases NbC and Nb₆C₅, which make the eutectic structure of the alloy denser and also improves the hardness and wear resistance of the coating. The coating with 10wt% Nb+15wt% WC shows the best wear resistance. The continuous eutectic structure changes from long strip and reticulation to four shapes of separated short strip, block, granular and fishbone. At the same time, the addition of WC transforms the wear mechanism of the coating from abrasive wear and adhesive wear to fatigue wear.