高Cr含量镍基合金涂层的电弧喷涂制备及其抗氧化性能研究

Preparation and Oxidation Resistance of Ni-based Alloy Coating with High Cr Content by Electric Arc Spraying

目的提高高温环境下电厂设备及构件的抗高温氧化性能。方法采用电弧喷涂工艺在Q345钢表面制备高Cr含量镍基合金涂层,对涂层在750℃条件下的抗氧化行为与氧化机理进行了研究,并与未喷涂涂层的Q345钢基体的氧化行为进行了对比分析。结果 750℃高温循环氧化增重试验表明,涂层试样的氧化动力学曲线呈抛物线型,经过非线性拟合,符合抛物线方程ΔW=2.51t0.22,而无涂层基体试样的氧化动力学曲线趋于直线式增长。对氧化前后的涂层试样进行扫描电镜和X射线衍射分析显示,高温下涂层表面生成了连续的Cr_2O_3、NiO等氧化物以及具有尖晶石结构的NiCr_2O_4,这些相均匀致密地分布在涂层中,能够有效地阻碍氧原子侵入基体,抑制氧化过程的持续进行。结论采用电弧喷涂方法在Q345钢表面制备的高Cr含量镍基合金涂层,在高温下表现出良好的抗氧化性能,可有效提高Q345钢制构件的使用温度和工作寿命。

The work aims to improve high temperature oxidation resistance of power plant equipment and components in high temperature environment. Ni-based alloy coatings with high Cr content were prepared on steel Q345 by adopting arc spraying. Anti-oxidation behavior and oxidation mechanism of the coatings at 750 ℃ were investigated, and comparative analysis was carried out to oxidation behavior of steel Q345 substrate without coating. Cyclic oxidation weight increase test at 750 ℃ showed that, oxidation kinetic curve of the coated sample presented a parabola style, the curve conformed to the parabolic equation AW=2.51t0.22 through nonlinear fitting, while the oxidation kinetic curve of uncoated substrate tended grow linearly. The coated samples before and after oxidation were analyzed with SEM and XRD. Continuous constituent phases including oxides Cr2O3 and NiO as well as NiCr2O4 with spinel structure formed on the surface of coatings at high temperature. These phases were uniformly and densely distributed in the coatings, which could effectively prevent oxygen atoms from invading the substrate and inhibit the continuous oxidation process. The Ni-based alloy coatings with high Cr content prepared on steel Q345 by arc spraying exhibits good oxidation resistance at high temperature, which can greatly improve service temperature and service life of steel Q345 components.