GDC电极冷却水管喷涂工艺优化及评估

Process optimization and application assessment of Al_2O_3 ceramic coatings on surface of cooling water pipe for GDC electrode

针对国际热核聚变实验堆(ITER)计划中直流辉光放电清洗(GDC)冷却水管的耐高压和热循环工况,在GDC水管上采用等离子喷涂技术制备了Al2O3陶瓷涂层,采用正交试验方法的极差分析和方差分析对等离子喷涂工艺进行了优化,得到了最佳工艺参数:电压60V、电流600A、喷涂距离100mm。在最佳工艺参数的条件下,对涂层进行了X射线衍射(XRD)分析和金相分析。结果表明,涂层表面99.9%以上的物相为Al2O3,涂层与基底结合紧密,测得涂层厚度为(324±11)μm,涂层整体厚度均匀。最后测试了涂层的耐电压能力,并对涂层进行了250次的室温至240℃热循环的试验,证明上述工艺可满足ITER苛刻工况的使用要求。

Given high-pressure and thermal cycle conditions of ITER （International thermonuclear experi- mental reactor） GDC （glow discharge conditioning） cooling water pipe, A12Oa ceramic coatings were pre- pared on the surface by plasma spraying process. The spraying process was optimized by range analysis and variance analysis of orthogonal test. Then the best processing parameters were obtained, that were： 60V, 600A and 100mm spraying distance. Under the condition of best processing parameters, the structure and properties of the coating were studied by XRD and metallography analysis. The results show that 99.9 % of the coating surface is Al2O3, and that the surface has good adhesion, low porosity and uniform thickness. The thickness of coating is （324±11）μm. Furthermore, the voltage withstand testing of the coating was performed. The thermal cycle from room temperature to 240℃ was conducted to the coating. These also show that the plasma spraying technique meets the requirements of ITER rigorous working condition.