粉末致密度对碳化钨涂层结构特征的影响

利用超音速火焰喷涂技术将4种不同致密度WC10Co4Cr粉末制备成涂层。采用扫描电镜、X射线衍射仪、显微硬度计、表面粗糙度仪等设备对涂层的微观组织、结构特征进行分析。结果表明,随着致密度的降低,团聚烧结型粉末与基体撞击后更容易铺展,碳化钨微粒分布变得更均匀,形成的涂层具有更低的孔隙率和表面粗糙度;但是随着致密度的降低,碳化钨分解率升高,形成更多的脆硬相,最终使得涂层断裂韧性下降。由此可知,致密程度影响粉末颗粒在热喷涂过程中加热、加速和铺展状态,从而影响涂层的结构特征。

Effects of Powder Density on Structure Characters of the WC10Co4Cr Coating

Four kinds of WC10Co4Cr coating with different powder density were deposited by the high velocity oxygen fuel (HVOF) technique. The characters of the coating constitution and structure were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), micro-hardness tester and surface roughometer. The results indicate that the flat-pattern formation of agglomerated particles during spraying process becomes easier with the decrease of powder density. The porosity and surface roughness of WC10Co4Cr coatings decrease with the powder density decrease as well. However, the decomposing rate of WC during the spraying process increases, resulting in fracture toughness descent of WC10Co4Cr coatings. The powder density is a key factor to the coating properties, by virtue of effects on coating constitution and structure