电弧喷涂镍基涂层腐蚀及磨损行为

Corrosion and wear behavior of wire-arc sprayed Ni-based coatings

针对WTE垃圾焚烧炉过热器热腐蚀及磨损问题,设计开发了新型镍基粉芯丝材,并采用电弧喷涂方法在SA213-T2基体表面制备相应涂层.利用XRD,SEM,磨粒磨损试验机及高温箱式电阻炉等对涂层组织结构、磨损及热腐蚀行为进行研究.结果表明,所制备涂层具有热喷涂典型的层状结构,组织较为均匀致密,孔隙率在3%左右,氧化物含量较低.涂层平均显微硬度约为351.27 MPa,相对耐磨性达基体7倍以上.涂层在800℃下的热腐蚀动力学曲线呈典型抛物线形式,表面生成NiCr2O4及Cr2O3氧化膜,能够有效阻止腐蚀介质向涂层内部的渗透,使其抗热腐蚀性能远优于基体材料.

A new Ni-based cored wire was designed to prepare coatings by wire-arc spraying on SA 213-T2 substrate in order to solve the corrosion and wear problems in waste-to-energy (WTE) plants. According to X-ray diffractometry (XRD) and scanning electron microscopy (SEM) analysis, the as-deposited coatings with low content of oxide phases presented uniform and dense layered structure with porosity at around 3%. The wear resistance of the designed coating, about 7 times higher than that of the substrate, was measured by a rubber wheel abrisive testing machine. Thermo-gravimetric technique was used to investigate the high-temperature corrosion behavior of the coatings in molten salt environment (Na2SO4-10% NaCl) at 800 ℃ in a muffle furnace. As a result, the weight gain curve of the coating followed the parabolic law and presented extremely lower corrosion rates, comparing with that of the substrate, due to the formation of Cr2O3 and NiCr2O4 oxide films on the surface which prevented the diffusion or penetrating of corrosive species. Consequently, the developed coating could provide much better corrosion resistance properties than SA213-T2 substrate.