Ti6Al4V合金表面超音速火焰喷涂WC-12Co涂层组织及相分析

Microstructure and Phase Analysis of WC-12Co Coatings Sprayed on Ti6Al4V Alloy by HVOF

摘要:

采用超音速火焰喷涂在Ti6Al4V合金表面制备WC-12Co涂层，用扫描电子显微镜(SEM)、X射线衍射(XRD)、能谱 (EDS) 对涂层的组织形貌、物相结构、成分进行试验分析。结果表明：涂层中无层状分布，涂层整体致密，孔隙率低，与基体结合良好；涂层中呈团聚状的粒子与粒子之间结合紧密，颗粒为弥散分布。这是因为超音速粒子的速度高能弥补堆垛不规则造成的孔隙，降低孔隙率，提高致密度；高速粒子变形充分，利于提高活性区域的面积，利于粒子与基体、粒子与涂层的结合。涂层中组成相除WC外，有少量Co3W3C和微量的W2C，未见金属Co，Co在涂层中变成非晶态。分析认为：W2C的产生是在喷涂过程中由于WC热分解，脱碳而生成的产物；Co3W3C是Co和WC在有氧环境下的反应产物，Co3W3C含量少是由于粉末在燃烧室中停留时间短。

Abstract:

WC-12Co coating was prepared by high-velocity oxygen fuel (HVOF) spraying on Ti6Al4V alloy. The microstructure, phase structure and composition of the coating were investigated by SEM, XRD and EDS, respectively. Results show that the whole coating is dense, of low porosity and bonds well with the substrate. There is no lamination in the coating. The agglomerated particles bond closely with each other and they are dispersively distributed. It is attributed to the high speed of supersonic particles, which can make up for the pores caused by the irregular stacking fault to decrease the porosity and increase the density. The high speed particles deform sufficiently and it is beneficial to increase the area of the active region and good for the combining between the particles and the substrate, as well as particles and the coating. There are a few of Co3W3C and trace W2C besides WC in the coating; there is no metal Co, which has become amorphous. It is thought that W2C comes from the thermal decomposition of WC during spraying while the Co3W3C is the reaction product of Co and WC in the oxygen atmosphere and its small amount is due to the short time of the powder staying in the combustion chamber.