真空钎焊WC-10Ni/NiCrBSi包覆涂层热疲劳试验工艺研究  

Research of the thermal fatigue test process of vacuum brazing WC-10Ni/NiCrBSi coating

作　　者：许祥平[1] 刘驰 马秋杰 邹家生[1] XU Xiangping;LIU Chi;MA Qiujie;ZOU Jiasheng(Provincial Key Laboratory of Advanced Welding Technology, Jiangsu University of Science and Technology, Zhenjiang 212100, China)

机构地区：[1]江苏科技大学江苏省先进焊接技术重点实验室,镇江212100

出　　处：《江苏科技大学学报（自然科学版）》2021年第3期30-36,共7页Journal of Jiangsu University of Science and Technology:Natural Science Edition

基　　金：校企合作项目(2019-KYY-529018-0009)。

摘　　要：选用Q235B钢作为基体材料,采用镍包碳化钨颗粒作为硬质相,以BNi-2为钎料,在1080℃的温度条件下通过真空钎焊技术制备了WC-10Ni/NiCrBSi包覆涂层,对涂层试样进行热疲劳循环试验,循环次数为100次,观察试验后涂层的宏观形貌和微观结构,对涂层的物相组成以及热疲劳裂纹产生的过程进行讨论分析,对包覆涂层热疲劳试验的工艺进行研究.研究结果表明:所得涂层的最佳热疲劳上限保温时间为220 s,下限保温时间为20 s.当上限温度设置为500℃,基本观察不到试样的热疲劳行为;600℃时,涂层出现较粗大的宏观裂纹,在微观界面中观察到裂纹的萌生与扩展;800℃时,涂层出现粗大的贯穿型裂纹,将涂层完全破坏,在微观界面中观察到裂纹的加深加粗及迅速扩展.通过热力学计算可得,当试验上限温度在570℃以下,涂层的热疲劳性能受材料内部的热应力影响较大;当试验上限温度超过570℃时,涂层的热疲劳性能受热应力与粉末氧化的综合作用影响.The WC-10Ni/NiCrBSi coating was prepared by vacuum brazing at 1080℃using Q235B as the matrix,WC-10Ni particles as the hard phase,and BNi-2 as the filler metal.The thermal fatigue test was carried out on the sample for 100 times.The microstructure,phase composition,and the initiation and propagation of thermal fatigue cracks were analyzed to study the process of thermal fatigue test of the coating.The results showed that the thermal fatigue time of the coating was set to an upper thermal insulation time of 220 s,a lower thermal insulation time of 20 s.When the upper limit temperature of the thermal fatigue cycle test was 500℃,the thermal fatigue behavior of the coating was not obvious.At 600℃,the coating had obvious macro-cracks,cracks initiated and propagated at the micro-interface,and at 800℃,the coating was widely cracked.The cracks in the interface deepened and thickened and rapidly expanded.According to the calculation results of thermodynamics,when the maximum thermal fatigue temperature was lower than 570℃,the main factor affecting the thermal fatigue performance of the coating was the thermal stress caused by the difference in the thermophysical parameters of the material at high temperature.When the maximum thermal fatigue temperature was higher than 570℃The powder′s oxidation behavior and thermal stress affected the thermal fatigue properties of the coating.

关 键 词：包覆涂层 热疲劳循环 工艺 热力学分析 真空钎焊 

分 类 号：TG142.1[一般工业技术—材料科学与工程]