等离子喷涂Cr2O3/TiO2高温氧化物陶瓷 复合涂层的微观组织及电化学性能

目的 通过等离子喷涂工艺，在油气管道X70管线钢表面制备出Cr2O3/TiO2高温氧化物陶瓷复合涂层，研究该涂层的微观组织与电化学性能。方法 采用9MC Plasma Control Unit等离子喷涂系统，基于线切割尺寸为40 mm×24 mm×6 mm的X70管线钢基体表面，沉积Cr2O3/TiO2高温氧化物陶瓷复合涂层。利用金相显微镜和扫描电子显微镜观察该复合涂层的微观组织与形貌，利用X射线衍射仪分析该复合涂层的物相组成，利用电化学工作站测定该复合涂层的电化学腐蚀性能。结果 Cr2O3/TiO2高温氧化物陶瓷复合涂层由完全熔化区和半熔化区双态组成，呈典型的等离子喷涂层状结构，层与层之间结合较紧密，分布着富Cr2O3沉积区与富TiO2沉积区，无相变产生，完全熔融的TiO2液相可嵌入到未完全熔融的Cr2O3结构间隙中形成固溶结构。经电化学腐蚀性能测试，其自腐蚀电位介于-0.4 ~ -0.3 V之间，高于X70管线钢基体的自腐蚀电位-0.6 ~ -0.5 V，腐蚀倾向滞后，表现出好的抗腐蚀性能。结论 研究选取的等离子喷涂参数较合适，并成功制备出了能明显提高油气管道X70管线钢抗电化学腐蚀性且组织分布均匀的Cr2O3/TiO2高温氧化物陶瓷复合涂层。

Microstructure and Electrochemical Properties of Cr2O3/TiO2 High Temperature Oxide Ceramic Composite Coating by Plasma Spraying

The work aims to prepare Cr2O3/TiO2 high temperature oxide ceramic composite coating on the surface of X70 pipeline steel by plasma spraying, and study the microstructure and electrochemical properties of the coating. Cr2O3/TiO2 high temperature oxide ceramic composite coating was deposited on the surface of X70 pipeline steel with wire-cut size of 40 mm×24 mm×6 mm by 9MC Plasma Control Unit plasma spraying system. Then, the microstructure and morphology of the coating were observed by metallographic microscope and scanning electron microscope, the phase composition of the coating was analyzed by X-ray diffractometer and the electrochemical corrosion performance of the coating was measured by electrochemical workstation. As a result, the Cr2O3/TiO2 high temperature oxide ceramic composite coating was composed of two phases: fully melted zone and semi-melted zone and showed typical plasma spraying coating structure and the bonding between the layers was close. There were Cr2O3-rich deposition areas and TiO2-rich deposition areas, but no phase transformation occurred. The fully melted liquid phase of TiO2 could be embedded in the gap of incompletely melted Cr2O3 structure to form solid solution structure. The self-corrosion potential of Cr2O3/TiO2 coating was between -0.4 ~ -0.3 V after test of electrochemical corrosion performance and higher than -0.6 ~ -0.5 V of X70 steel. The corrosion tendency was lagging behind, so the corrosion resistance was good. The plasma spraying parameters in this study are suitable, and the Cr2O3/TiO2 high temperature oxide ceramic composite coating which can improve the electrochemical corrosion resistance of X70 pipeline steel remarkably and has uniform structure distribution is prepared successfully.