粉末粒度对WC-Co涂层结构和性能的影响

采用低功率内送粉等离子喷涂设备,选择两种粒度不同的WC-Co粉末,在不同功率下,在不锈钢基体上制备WC-Co涂层。利用XRD、SEM等分析手段对原始粉末和涂层的显微结构和物相组成进行观察和分析,利用显微硬度仪测量涂层显微硬度。结果表明:与细粉相比,粗粉喷涂涂层的组织致密、均匀,孔隙率小。粗粉喷涂涂层显微硬度可达1500 HV以上,涂层主晶相是WC,也存在少量W2C相,随着等离子能量增加,W2C增多;细粉喷涂涂层,WC发生大量的脱碳分解,涂层主晶相是W2C,显微硬度低。因此粗粉在适当功率下更适合低能等离子喷涂。

Influence of Powder Granularity on Structure and Properties of WC-Co Coatings

The WC-Co coatings on stainless steel matrix have been synthesized by low-power plasma spraying technology,choosing two kinds of WC-Co powder(different granularity) under the conditions of varying spraying power.Scan electron microscopy(SEM) and X-ray diffraction(XRD) were used to investigate the surface morphology,microstructure and phase compositions of the coatings and primary powder.The results indicate that the coarse powder comparing with fine powder increases the compact of the coatings and reduces porosity in the coatings.The microhardness of the coatings reaches 1500HV,the primary crystalline phase of the as-sprayed coating is WC,W2C phase is also discovered in the coatings,but W2C phase increases with the increase of spraying power.Fine powder causes more decarburizing decomposition of the WC phase,the primary phase is W2C,the microhardness of the coatings is low.So coarse powder is more suitable for low power plasma spraying.