低功率等离子喷涂WC-Co陶瓷涂层组织

Microstructures of low power plasma sprayed WC-Co cermet coatings

为研究热喷涂工艺对低功率等离子喷涂WC-Co陶瓷涂层的微观组织、相组成和硬度的影响规律,以普通低碳钢Q235A为基体,采用低功率（3～6.6 kW）内送粉等离子喷涂方法,在弧电压恒定、电流增加的条件下,制备不同功率下的涂层.实验结果表明：与传统等离子喷涂WC-Co涂层相比,低功率等离子喷涂WC-Co涂层的显微硬度有所提高,而其脱C率和孔隙率大大降低;涂层中除粉末原有的WC相外,还有喷涂过程中新生成的W2C、Co3W3C和Co3W9C4相.电流增加,涂层中主相WC质量分数降低,而W2C等其他三相的质量分数增多.

An low power plasma spraying （3- 6.6 kW） method with internal particle injection was developed to investigate the influence of plasma spray parameters on the coatings microstructures, phase compositions and hardness, and some conventional WC-Co cermet coatings were prepared on mild steel Q235A substrate. The coatings were sprayed via this new technique under different plasma power by keeping arc voltage constant and changing arc current. The results show that microhardness of low power plasma sprayed WC-Co coatings is higher with much lower decarburizing rate and porosity rate compared with traditional plasma sprayed WC-Co coatings. The phase assemblage of the coatings in the XRD pattern of the original powder,includes also W2C, CO3W3C and Co3W9C4 which have been formed in spraying process. WC peak intensity decrease and those of W2C and other phases increase as the plasma arc current increasing.