热处理对超音速火焰喷涂WC涂层微观结构及性能的影响

Effect of heat treatment on microstructure and properties of high velocity sprayed WC coatings

利用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计、摩擦磨损试验机、冲蚀试验机等手段研究不同温度退火热处理对超音速火焰喷涂WC-10Co4Cr涂层的微观结构、显微硬度、结合强度、耐磨性能等的影响。结果表明:当退火热处理温度低于450℃时,涂层的相组织结构未发生明显改变,显微硬度及耐干摩擦磨损性能随着热处理温度的升高而提高,并在450℃时出现峰值;当热处理温度高于450℃时,随着热处理温度的升高,涂层中WC、Co、Cr相的含量逐渐降低,大部分转化为CoWO_4、Cr_2O_5、C_6WO_6等氧化物相,涂层的孔隙率明显升高,耐泥沙冲蚀性能明显降低;当热处理温度升高到600℃以上时,涂层的结合强度开始降低;当热处理温度为850℃时,涂层整体剥落。

The effects of different heat treatment temperature on the microstructure,microhardness,bonding strength,wear resistance of high velocity flame sprayed WC-10Co4 Cr coatings were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,microhardness measurement,wear testing machine,wear corrosion testing machine,etc. The results show that the microstructure of the coatings is not obviously changed when the heat treatment temperature is equal or less than 450 ℃,the microhardness and wear resistance increase with the increase of heat treatment temperature,and there is a peak at 450 ℃. The content of WC,Co,Cr gradually decreases and most of them convert into CoWO_4,Cr_2O_5,C_6WO_6 and so on,the porosity of coatings increases significantly,the sediment erosion resistance decreases obviously when the heat treatment temperature is more than 450 ℃. The peak of dry wear resistance appears at 450 ℃. The bonding strength starts to reduce when the heat treatment temperature is more than 600 ℃.The overall spallation of coatings occurs when the heat treatment temperature is 850 ℃.