摘要
新兴的超高速激光熔覆技术通过对熔覆头的精巧设计,可实现激光、粉末路径最佳耦合,使粉末在飞行空间熔化且基体表面仅形成微溶池,在保证冶金结合的同时,大幅提高熔覆效率及粉末利用率,可制备厚度<100μm、稀释率<5%的均匀薄涂层。为进一步探索超高速激光熔覆涂层组织结构特点,扩展其应用范围,探讨了低功率下4种典型涂层的微观结构及性能。结果表明:超高速激光熔覆可制备120~500μm,无气孔、裂纹的高质量涂层;涂层组织致密,结合区多为粗大柱状晶,表层区以细晶为主;基体熔化区可低至数微米,稀释率可低至1%。其中,镍基碳化钨涂层、铝合金耐磨涂层硬度明显高于基体;钛合金阻燃涂层在激光烧蚀后,烧蚀坑深度降低,热影响区减小;高熵合金阻扩散涂层预氧化后形成以Al2O3为主的微米厚氧化膜,在上述涂层作用下,基体性能均得到提升。
By specially designing the cladding head,the optimal coupling of laser beam and powder flow could be achieved in the newly developed high speed laser cladding(HSLC)process.Using such head,the particles melt in flight while the surface of substrate forms a micro-melt pool,so that a coating with metallurgical bonding can be obtained due to the high deposition speeds and powder utilization rate.As a result,producing high quality coatings with thickness<100μm and dilution<5%is possible by using HSLC.In order to characterize the microstructure of the HSLC coatings and expand its applications,four different coatings with low dilution ratio are fabricated and the microstructure and properties of the coatings were studied under a relatively low laser power.Results show that high-quality pore-and crack-free coatings with thickness of 120~500μm are produced by HSLC.All coatings have compact structure with coarse columnar crystals around the interface and fine grains near the coating surface.The melt area of the substrate reaches a micrometer range,and the dilution rate is less than 1%.For the nickel-based WC coating and the wear resistance coating on aluminum alloys,the hardness of the coatings is much bigger than the that of substrate.For the burn resistant coating on titanium,the depth of the laser-melt hole and range of HAZ is significantly reduced.For the diffusion resistant coating on high entropy alloy,the oxide film(Al2O3)forms by pre-oxidation.Overall,the coatings with low dilution ratio prepared by HSLC exhibit good protection for the substates studied.
作者
娄丽艳
张煜
徐庆龙
王轲岩
澹台凡亮
李长久
李成新
LOU Liyan;ZHANG Yu;XU Qinglong;WANG Keyan;TANTAI Fanliang;LI Changjiu;LI Chengxin(State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China;Tianjin Key Laboratory of High Speed Cutting&Precision Machining,Tianjin University of Technology and Education,Tianjin 300222,China;Shandong Energy Heavy Equipment Group Dazu Remanufacturing Co.,Ltd.,Taian 271222,China)
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2020年第2期149-159,共11页
China Surface Engineering
基金
国家重点研发计划(2018YFB2002000)
国家自然科学基金(51761145108)
天津市自然科学基金(19JCQNJC03800)
关键词
激光熔覆
涂层
热喷涂
微观组织
稀释率
laser cladding
coating
thermal spraying
microstructure
dilution ratio
