Corrosion Wear And Erosion Properties Of Fe-based Amorphous Alloy Coating Prepared By High Velocity Air Fuel Spraying

Coating is an effective,convenient and low-cost method to provide protection for workpiece surface.It is prepared by thermal spraying technology by heating the powder or wire of wear-resistant and corrosion-resistant functional materials to semi-melt or melt state through high-temperature flame flow and deposited on the substrate surface at a high speed.The coating can not only repair the damaged parts,but also improve the corrosion resistance and wear resistance of the parts,as well as the dimension error caused by the repair processing errors.They have been widely used in aerospace,biomedical,petrochemical,mechanical and electronic fields.Amorphous alloy has high strength and excellent corrosion resistance.It is a new type of metal material which can be widely used.In order to give full play to its excellent properties and expand its application fields,many scholars have carried out extensive research on the preparation of amorphous alloy coatings.In this paper,Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂ amorphous alloy coating was prepared on AISI 1045 steel substrate by High Velocity Air Fuel（HVAF）spraying technology.Research results show:（1）The prepared Fe-based amorphous alloy coating is mainly composed of amorphous phase,the amorphous degree of the coating is 88.95%;the coating is dense and the porosity is2.3%;the surface hardness of the coating is up to 820 HV_0.3,which is about 4 times the hardness of 1045 steel substrate.In the electrochemical corrosion test,the corrosion potential and corrosion current density of the Fe-based amorphous alloy coating were-0.458 V and 1.13×10^-5A,which were larger and smaller than those of 1045 steel substrate（-0.258 V,1.76×10-5 A）.Therefore,the Fe-based amorphous alloy coating exhibits excellent corrosion resistance in corrosive media.Moreover,after 360 hours of neutral salt spray corrosion test,no obvious signs of red rust and massive exfoliation appeared on the coating surface.It shows excellent long-term corrosion resistance.（2）During the vacuum heat treatment process,as the heat treatment temperature increasing,the degree of amorphous of the coating decreases,and the crystallization leads to an increase in the microhardness of the coating.At the heat treatment temperature of 800°C,the hardness of the coating reaches a maximum of 1124 HV_0.3.The results of the erosion-corrosion test show that as the heat treatment temperature of the coating increasing,the corrosion resistance of the coating decreases,resulting in an increase in weight loss under the same condition of pH value of the mud.When the heat treatment temperature is constant,as the pH of the mud increasing,the existing OH^-can promote the formation of a stable oxide film on the surface damaged by the erosion-corrosion process,reducing the occurrence of further corrosion,thereby reducing the erosion weight loss.（3）After vacuum heat treatment of the coating,the coating exhibits excellent wear resistance due to compositional homogenization,grain appearance and dispersion distribution of hard phases like carbide and boride.Among all the coating samples,the 800°C heat treated sample showed the best wear resistance,and the wear rate is only 1/3 of the as-sprayed sample under the same conditions.The main failure mechanisms of coatings in dry friction and wear tests are micro-delamination wear and oxidation wear.