论文部分内容阅读
采用超音速火焰喷涂在Q345基体上制备了微米WC-12Co,纳米改性WC-12Co和CeO_2改性WC-12Co涂层,利用SEM,XRD和显微硬度计等手段观察表征了涂层的微观组织、相成分和显微硬度,通过LSCM,SEM,极化实验和浸泡腐蚀实验等方法研究分析了涂层在1 mol/L H_2SO_4溶液中的腐蚀行为和腐蚀机理.结果表明:纳米CeO_2的加入可以显著降低涂层的孔隙率,有效减少局部腐蚀的发生;同时添加纳米CeO_2可以使涂层电极电位发生正移,降低腐蚀电流密度,生成稳定的钝化膜,降低涂层的维钝电流密度,提高涂层的耐腐蚀性能;纳米CeO_2改性WC-12Co涂层的腐蚀机制为由孔隙诱发的局部腐蚀,孔隙处的Co黏结相不断被腐蚀导致WC颗粒失去了支撑作用而脱落,从而露出新的Co黏结相,促进了涂层的腐蚀,使孔隙不断扩大形成腐蚀坑.而微米WC-12Co涂层和纳米改性WC-12Co涂层不仅最外层的Co黏结相被腐蚀,而且在孔隙处也发生了严重的局部腐蚀.
The microstructure of WC-12Co, WC-12Co and WC-12Co modified with nano-modified WC-12Co and CeO_2 were prepared on the Q345 substrate by supersonic flame spraying. The microstructure of the coating was characterized by SEM, XRD and microhardness tester The microstructure, phase composition and microhardness of the coatings were investigated by means of LSCM, SEM, polarization experiments and immersion corrosion tests. The corrosion behavior and corrosion mechanism of the coatings in 1 mol / L H 2 SO 4 solution were studied. Can significantly reduce the porosity of the coating, effectively reduce the local corrosion; addition of nano-CeO_2 can make the coating electrode potential positive shift, reducing the corrosion current density, the formation of a stable passivation film, reducing the coating of the blunt current density , To improve the corrosion resistance of the coating. The corrosion mechanism of nano-CeO_2-modified WC-12Co coating is local corrosion induced by pores. The cohesive phase in the pores is continuously corroded and the WC particles lose their supporting effect and fall off exposing The new Co binder phase promotes the corrosion of the coating and enlarges the pores to form the corrosion pits, while the coatings of the micro-WC-12Co and the nano-modified WC-12Co are not only corroded by the cohesive phase of the outermost Co, Pores also He had severe localized corrosion.