超音速火焰(HVOF)喷涂Fe-Cr基涂层的组织与耐蚀性

Microstructure and Corrosion Resistance of Fe-Cr Based Alloy Coating by High Velocity Oxy-Fuel Thermal Spraying

采用多元Fe—cr基合金（含Si、Mn、B等）作为喷涂粉末，用JP-5000超音速火焰喷枪在不锈钢基体上制备厚度约200μm的Fe基涂层。采用金相显微镜、X射线衍射仪、扫描电镜、透射电镜对涂层的组织结构进行了观察和分析，采用盐雾试验箱对涂层的耐蚀性进行了初步研究。结果表明，涂层主要由非晶、bcc晶体结构的纳米晶及微米级硼化物组成；非晶基体产生了明显晶化，形成了胞状bcc结构的纳米仪．Fe，其尺寸约为10～30nm^3，涂层致密，孔隙率约为1％。涂层的耐盐雾腐蚀的性能明显高于1Cr18Ni9Ti不锈钢。前者主要为孔蚀，后者主要为晶间腐蚀。

Approximate 200 μm thickness Fe-Cr based coatings were deposited on stainless sleel by JP-5000 high velocity oxy-fuel（HVOF） thermal spraying using multi-element Fe-Cr based powders containing element B, Mn and Si etc. The microstructures of the coatings were investigated by a combination of optical microscope（ OM ）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）and transmission electron microscopy （TEM）. Corrosion resistance of the coatings was preliminarily characterized by salt fog. The results show that coatings are mainly composed of amorphous phases, bcc nano-crystal grains and micron-grade borides. The crystals are generated from crystallization of the amorphous phases, and present cellular bcc structure α- Fe nano-crystals grains with sizes around 10 - 30 nm. The coatings are compact with po- rosity about 1%. The corrosion resistance of the coatings to salt fog is obviously higher than that of 1Cr18Ni9Ti stainless steel. The formers are characterized by pitting corrosion while the latter is expressed by intercrystalline corrosion.