具备原位合成Al_2O_3的WC复合粉末与涂层的设计及制备

Design and Preparation of WC Composite Powders and Coatings with in-situ Synthesis Al_2O_3

利用球磨法将Al粉添加到亚微米结构WC-12Co粉末中,设计并制备了具有Al2O3原位合成的纳米结构WC-Co-Al粉末。XRD分析显示球磨10、30和50 h后的粉末中WC平均晶粒尺寸为93.1、39.0和44.8 nm。超音速火焰(HVOF)喷涂时,WC-Co-Al粉末比未球磨的WC-12Co粉末扁平化更好,涂层孔隙率为0.57%,比WC-12Co涂层(1.62%)更低。粉末中的Al元素与氧气反应原位生成了Al_2O_3硬质陶瓷颗粒,有效抑制了WC的氧化脱碳。WC-Co-Al涂层HV_(0.1)显微硬度为12.98±0.73 GPa,比WC-12Co涂层提高约36%,这得益于Al_2O_3颗粒的增强效应,WC晶粒纳米化和孔隙率降低。

Nanostructured WC-Co-Al powders with in-situ synthesis Al2O3 were synthesized from submicron structured WC-12 Co powder and Al powder using a ball-milling method. XRD analysis shows that the average sizes of WC grains are 93.1, 39.0 and 44.8 nm after milling for 10, 30 and 50 h, respectively. When they are sprayed by high velocity oxygen fuel（HVOF） thermal spraying, WC-Co-Al powders are more easily flattened than WC-12 Co powder without ball-milling. The porosity of WC-Co-Al coating is only 0.57% which is much lower than that of WC-12 Co coating with a value of 1.62%. During spraying Al reacts with oxygen, which effectively inhibits the decarburization of WC, and Al2O3 hard ceramic particles are in situ generated in coatings. The HV0.1 microhardness of WC-Co-Al coating is 12.98±0.73 GPa, about 36% higher than that of WC-12 Co coating, which is mainly owing to the enhancement effect of Al2O3 particles, nanocrystallization of WC phase and lower porosity.