Study On Heightening The Heat And Corrosion Resistant Properties Of Austenitic Stainless Steel Electric Heater

The study background of this paper was to heighten the heat and corrosion resistance of the 304 （0Cr18Ni9） austenitic stainless steel electric heater. The heat and corrosion resistant layer was obtained on the austenitic stainless steel electric heater by composite surface treatment . In order to further expand the scope of application of austenitic stainless steel, this paper also prepared the Ni-SiO₂ composite plating on the austenitic stainless steel, and systematicly study of the effects of composite plating process parameters on the structure and properties of heat and corrosion resistant layer. By means of the scanning electronic microscope （SEM） and the X-ray energy dispersive spectrum （EDS） and X-ray diffraction（XRD）, the microstructure, composition and morphologies of the layer were analyzed. The binding force, heat and corrosion resistant properties of the layer were studied by the thermal shock test machine, salt spray test machine and high temperature box type furnace. The optimum preparation parameters of the heat and corrosion resistant layer was obtained.The results showed that the heat and corrosion resistant layer obtained the uniform and dense microstructure, fine grain size. After vacuum diffusion heat-treatment, the elements of the coating and matrix successfully occurred diffusion, the coating formed into a metallurgical bonding, the binding force of coating and substrate significantly increased. Thermal shock test and salt spray test results showed that the layer had high binding force, heat and corrosion resistance. The 800℃high temperature oxidation test results showed that the high temperature oxidation resistance of Ni-SiO₂ heat and corrosion resistant layer was superior to the Ni diffused plating and the 304 stainless steel.