Study On The Preparation Of Fe₃Si Alloying Layer Deposited On Steel Surface In Neutral Molten Salt

Fe3Si intermetallic compound has excellent soft magnetic, higher high-temperature oxidation resistance, good corrosion resistance and anti-wear performance. For the sake of the preparation method of low cost to make the steel has good corrosion resistance and wear resistance, proposed by molten salt electrolysis siliconizing technology.The preparation of intermetallic compound alloying layer with high hardness deposited on Soft steel surface. Study on the influence rule of different substrate alloying elements with the performance of silicide alloying layer and micro structure contrastively. It is important to prepared good corrosion resistance, high strength and hardness, and excellent wear resistant protective surface on the steel. And it is positive to prepare intermetallic compound material.Fe3Si alloying layers were prepared by siliconizing in the molten salt on the surface of 20 steel, 2Cr13 and 0Cr18Ni9 stainless steel respectively. The sectional morphology and ingredient distribution were analyzed by a scanning electron microscopy. The phase of silicided layers was analyzed by an X-ray diffraction. The mechanical properties such as hardness and toughness were characterized through a micro-hardness tester and the self-made static press equipment. Dynamic polarization curve measure and electrochemical impedance spectroscopy technique were used to evaluate electrochemical corrosion resistance of Fe3 Si diffusion layers in H2SO4 medium. Meanwhile, the ball-disk wear test was chosen to evaluate the Fe3 Si layers wear resistance. The results show that:(1) Fe3 Si coatings were prepared in the molten salt can significantly improve the surface hardness and wear resistance, and has excellent electrochemical corrosion resistance in H2SO4 medium. The silicide layer on the 0Cr18Ni9 stainless steel surface shows the least defects in the coating structure, and has the best corrosion resistance and anti-wear among those coatings.(2) The Ni, Cr alloy elements exists in steel might speed up the siliconizing rate in the molten salt, and help the defect reduction and structure densification. The transition metal silicide(multi-elements alloying Fe3 Si Contained Ni and Cr) coating with high hardness has good appearance toughness, excellent corrosion resistance and anti-wear property.(3) The siliconizing temperature, molten salt system(neutral salt rate, siliconizing agent, LiF) and cooling way had obvious effect on the density of Fe3 Si alloyed layers. Test results show that with NaCl:KCl: NaF = 2:2:1(mole ratio) of neutral molten salt as the carrier, and Na2SiF6:Si = 5:5 as siliconizing agent, heat preservation after 4 h under 800?, take out the air cooling to room temperature preparation by Fe3 Si silicide carbonitriding layer density is best.