氧气流量对超音速火焰喷涂多尺度WC-17Co涂层组织结构与性能的影响

Influence of Oxygen Flow Rate on the Microstructure and Properties of High Velocity Oxygen Fuel Sprayed Multimodal WC-17Co Coatings

工艺参数对超音速火焰喷涂WC-Co涂层的组织结构、硬度、耐磨性影响较大,但相关研究较少。采用超音速火焰喷涂技术(HVOF)在4种氧气流量(322,402,482,543 L/min)下将多尺度WC-17Co粉末(含30%纳米WC和70%微米WC)喷涂在Q235钢基体表面制备WC-17Co涂层。采用扫描电镜(SEM)和X射线衍射仪(XRD)分析涂层的截面形貌和物相,测试了涂层的硬度值,通过销盘磨损试验机测试涂层的耐磨损性能,研究氧气流量对多尺度WC-17Co涂层组织结构与耐磨性能的影响。结果发现:4种氧气流量下所制备的涂层组织致密,孔隙率为0.306%~1.290%;随着氧气流量降低,涂层中WC分解更严重,当氧气流量为322 L/min时,涂层中分解相(W_2C、W和Co_3W_3C)最多;涂层的硬度随着氧气流量增加而增加,当氧气流量为543 L/min时,涂层的硬度[(933.8±29.3)HV_(3N)]是Q235钢[(183±7)HV_(3N)]的5倍;随着氧气流量增加,涂层磨损失重逐渐减小,当氧气流量为543 L/min时,涂层的磨损失重仅为(8.57±0.95)mg,耐磨损性能较基材明显提高。

Multimodal WC-17Co coatings with 30% nano-WC and 70% micro-WC were prepared on Q235 steel substrate by high velocity oxygen fuel （HVOF） under four kinds of oxygen flow rates （322, 402, 482,543 L/min）. The cross- section morphology and phase compositions of the coatings were analyzed by scanning electron microscopy （SEM） and X-ray diffractometer （XRD）, respectively. Moreover, the microhardness was measured, and the wear property of the coatings was tested by pin-on-disk equipment. Based on the above tests, the influence of oxygen flow rate on the microstructure and properties of multimodal WC - 17Co coatings was studied. Results showed that the microstructures of the coat!ngs prepared under four kinds of oxygen flow rates were dense and the range of porosity of the coatings was from 0.306% to 1.290%. With the decrease of the excessive oxygen flow rate, the decomposition of WC phase became more serious. When the oxygen flow rate was 322 L/min, more W2C, W and C%W3C phases were dominants in the coating. With the increase of oxygen flow rates, the .hardness of obtained coatings was improved. Under oxygen flow rate of 543 L/min, the microhardness value of the coating （933.8±29.3 HV3 N ） was about five times as large as that of Q235 steel substrate （ 183±7 HV3 N ）. Furthermore, as the oxygen flow rate increased, the wear loss of coating decreased. Under oxygen flow rate of 543 L/min, the wear loss of coating was only （8.57±0.95） mg, which revealed that the wear property of the coatings was improved greatly.