Study On Preparation And Properties Of Amorphous/Ceramic Composite Coatings

Amorphous alloys have excellent hardness,corrosion resistance,and wear resistance,and have been widely used in industry and life.At present,how to prepare amorphous coatings with better performance has become an important research direction.In this paper,Zr-based amorphous alloy coatings and Fe-based amorphous/WC ceramic composite coatings were prepared via electrospark deposition（EDM）and resistance seam welding（RSEW）,respectively.The microstructure,phase composition,hardnessand wear resistance of the coatings are investigated and analyzed.Zr-based amorphous coating was prepared on the surface of TC4 by EDM,and the wear morphology and mechanism of the coatings under different friction time were studied.The results show that the coatings mainly compose of amorphous phase,Al₃Zr₂、Ti Ni、Cu₈Zr₃andα-Zr phases.The coating thickness is about 150±10μm and metallurgically bonded to the TC4 surface.The nano-hardness value of the amorphous coating can reach up to 1251HV,which is about 3 times that of the TC4.Under different friction time,the coating exhibits a smaller wear coefficient than the substrate.When the friction time is 30 min,the wear resistance of the Zr-based amorphous coating is 4.8 times that of the substrate.The wear mechanism of the substrate TC4 is abrasive wear,while the coating is fatigue wear.Amorphous/WC ceramic composite coatings were prepared on the surface of304 via RSEW.The effects of WC content on the microstructure and properties of the composite coatings were investigated.The conclusions are as follows:The coatings mainly compose of amorphous phase,metal carbide MC and Fe-Cr phase.With the increase of WC,the Mo-rich star（Mo₂C）in the coating increases significantly,which means the dissolution of WC promotes the precipitation of Mo2C.The increase of high-hard WC and Mo₂C increases the average microhardness of the coating.The average hardness of C20（1330.50HV）is about 6.35 times that of the matrix（209.3HV）.C30 has the best wear resistance,which was approximately 20.57 times times that of the 304 substrate higher than that of the substrate.This is mainly due to the large and uniform distribution of the hard and high wear-resistant Mo₂C in the coating.The wear mechanism of the substrate 304 is abrasive wear,while the coating is adhesive wear and than turns into abrasive wear.