超音速火焰喷涂多尺度WC-17Co粉末制备的金属陶瓷涂层的组织结构与性能

Microstructure and Properties of the Cermet Coating Prepared by Spraying Multimodal WC-17Co Powders Using HVOF Technique

在不同氧气流量(322 L/min、402 L/min、482 L/min和543 L/min)条件下,将多尺度WC-17Co粉末(60%(质量分数)纳米WC和40%(质量分数)微米WC陶瓷颗粒)通过超音速火焰(HVOF)喷涂技术在Q235钢基体上制备WC-17Co金属陶瓷涂层。采用扫描电镜(SEM)和X-射线衍射技术(XRD)分别对涂层的组织形貌和物相进行分析,并测试了涂层的硬度值和耐磨损性能。结果表明,随着氧气流量降低,涂层中WC颗粒分解更为严重,在氧气流量为322 L/min时,涂层中WC陶瓷相最少。HVOF喷涂过程中氧气流量对最终形成的涂层中W、W2C与Co3W3C相的含量及涂层的硬度值和耐磨损性能有重要影响,其与前者呈负相关,与后二者呈正相关。当氧气流量控制在543 L/min时,HVOF喷涂形成的涂层中主要物相仍为WC相;通过硬度测试发现,随着氧气流量增加,涂层的硬度值逐渐增加,在氧气流量为543 L/min时,涂层具有最高硬度值((979±52. 9) Hv0. 3)和仅为(6. 6±0. 57) mg的磨损失重量。

The purpose of the present work is to explore the microstructure and properties of the HVOF (high velocity oxygen fuel) sprayed cermet coa-ting of WC-17Co.We conducted the preparation of the cermet coatings under various oxygen flow rates (322 L/min,402 L/min,482 L/min and 543 L/min) by spraying and depositing multimodal WC-17Co powders (60% nano-WC and 40% micro-WC) onto Q235 steel substrate,and characterized and determined the coatings’ microstructures,phase compositons,microhardness values and wear resistance performances by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),hardness test and abrasion test,respectively.The results showed that the decrease of the oxygen flow rate could cause more serious decomposition of WC phase,and WC phase content reaches the minimum value at the oxygen flow rate of 322 L/min.It could also be concluded that the oxygen flow rate had significant influences on the contents of W,W 2C,Co 3W 3C phases (inverse correlation),the microhardness (positive correlation),and the wear resistance performance (positive correlation) of the resultant coating.When the oxygen flow rate during HVOF spraying process was controlled at 543 L/min,the sprayed coating had a composition principally of WC phase,a maximum microhardness value ((979±52.9)Hv0.3),as well as a small weight loss ((6.6±0.57) mg) after wear testing.