Study On Preparation And Properties Of Fe-Based Amorphous Coatings

As an important supporting technology in the field of remanufacturing engineering,surface engineering technology is playing an increasingly important role in the field of material surface modification.Due to the relatively low cost,high strength,high hardness,high abrasion resistance and corrosion resistance of Fe-based amorphous materials,the surface engineering technology used to prepare the coating has a broad application prospect in the field of anti-corrosion and wear resistance.In this paper,the Fe-based amorphous coating was prepared on the surface of 45 steel by plasma spraying technology and laser cladding technology.The microstructure,phase composition and microhardness of the coating were characterized and analyzed by scanning electron microscope(SEM),X-ray diffraction(XRD)and microhardness tester.The experimental results show that the Fe-based amorphous coating structure prepared by plasma spraying is a typical lamellar structure,the coating has a high amorphous content,but there are some pores and microcracks in the coating.The mechanical bond between the coating and the substrate is low.The Fe-based amorphous coating prepared by semiconductor laser and preset powder has a compact structure,but a large number of cracks appear on the surface of the coating.With the increase of laser power,the number of cracks in the cladding layer increases gradually.A few cracks appeared on the surface of the remelting layer,and the microstructure of the remelting layer was transformed into crystalline phase,so the amorphous coating could not be obtained.The structure of Fe-based amorphous coating prepared by fiber laser and coaxial powder-feed is compacted.The coating contains amorphous phase.The content of amorphous and microhardness of the coating decrease with the increase of laser power.In order to improve the amorphous content of the laser cladding coating,the best process parameters in the preliminary test were selected,and the two-layer cladding test was conducted by using fiber laser and coaxial powder feeding.The results show that the two layer cladding process can improve the amorphous content of the coating.This is mainly because the two-layer cladding process reduces the dilution rate of the substrate to the cladding layer and improves the amorphous content in the coating.The coating crystallized and some cracks occurred in the cladding layer.Finally,the corrosion and wear resistance of the amorphous coating and laser cladding coating prepared by plasma spraying were compared.The results show that the corrosion performance of plasma spraying coating and laser cladding coating is obviously improved,and the corrosion performance of laser cladding coating is higher than that of plasma spraying coating.This is mainly due to the plasma spraying coating has a small number of voids and unmelted particles,providing an erosion channel for the corrosive medi um,reducing the corrosion resistance of the coating.Compared with the substrate,the wear volume of plasma spraying coating and laser cladding coating is obviously reduced,so the Fe-based amorphous coating prepared by the two processes has good wear resistance.The comparative study of Fe-based amorphous coatings prepared by plasma spraying and laser cladding shows that the laser cladding technology is more effective than plasma spraying technology for small size parts with higher performance and precision requirements.Plasma spraying technology has better advantages in large area spray field with low bond strength.