摘要
粉末的熔化行为对激光熔覆过程的精确成形控制有重要影响。针对粉末预置时与激光的复杂动态热交互行为,建立高速摄像光学采集系统,检测并分析粉末熔化的动态过程,分析了不同特征阶段对粉末熔化成形特征的影响规律与作用形式,建立了可以描述熔化过程的物理模型,研究了不同特征阶段下激光与粉末的动态热物理作用机制。实验结果表明:半导体激光熔覆过程中粉末的熔化行为一般存在4个典型特征阶段,不同特征阶段的作用周期对成形参数的影响规律不同;通过对不同特征阶段的热物理行为进行分析,建立了可以描述半导体激光与粉末热交互作用的动态物理模型;通过对动态物理模型的分析,获得了激光功率、离焦量等参数对不同特征阶段热物理行为的作用机制。
Objective Laser cladding technology is widely used in coating deposition,worn surface repairing,and direct fabrication due to advantages,such as high deposition accuracy,small heat-affected zone,metallurgical bonding,and minimal dilution with the substrate.It is a surface modification technology for thin coating/layer fabrication with improved surface properties or surface defect refurbishment by forming highly resistant gradient coatings/layers on a substrate.Recently,the innovations in diode laser cladding significantly support remanufacture,and more stringent requirements have been put forward on the forming accuracy and quality.There is inadequate research on forming mechanisms in the diode laser cladding process;just depending on numerous process tests or human experience cannot effectively improve accuracy or control quality under unfavorable conditions,such as heat accumulation and stress concentration.To improve the laser cladding technology level,the development of on-line and high-speed monitoring and process controlling system is necessary.In particular,studies on powder melting behavior play a paramount role in forming mechanisms.Therefore,for fore-put powders,the characteristic behavior of the melting process was detected,and the investigation of the thermal physical characteristics was analyzed.Then,the equations of heat balance to describe the melting process were established.Finally,a model to analyze the thermal physical process in diode laser cladding process was set up.Methods To analyze the interaction process between the diode laser and fore-put powders,first,an optical acquisition system with a high-speed camera was set up to observe the powder melting process;second,based on the analysis of the collected high-speed camera data,the characteristic behavior of the cladding process was analyzed;and finally,according to the analysis of the powder melting process,the models of thermophysical processes in different characteristic stages were set up,and the heat-balance equation for each characteri
作者
朱明
王博
颜步云
杨骞
石玗
樊丁
Zhu Ming;Wang Bo;Yan Buyun;Yang Qian;Shi Yu;Fan Ding(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;Key Laboratory of Nonferrous Metal Alloys and Processing,Ministry of Education,Lanzhou University of Technology,Lanzhou,Gansu 730050,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第14期129-138,共10页
Chinese Journal of Lasers
基金
国家自然科学基金(51805234,52065041)
国家留学基金管理委员会创新型人才国际合作培养项目(CXXM2012210002)
甘肃省引导科技创新发展专项(2018ZX)
甘肃省重点研发计划(20YF3WA017)
兰州理工大学红柳优秀青年人才支持计划。
关键词
激光技术
半导体激光
表面熔覆
预置粉末
熔化行为
laser technique
diode laser
surface cladding
fore-put powder
melting process
