Study On The Tribological Properties Of Nanometer/Micrometer Crystaline Coatings Prepared By Electro-thermal Explosion Directional Spraying

Wear is one of the main materials failure forms. The economic loss resulting from wearing is enormous and unavoidable. The most adopted method to reduce wear is surface coating technology. And in hundreds of surface coating technologies, thermal spraying technology is used widely. But at the more and more rigor service conditions, the request for the coatings properties is more and more high. So the old spraying technologies are improved and new technologies are developed. Electro-thermal explosion directional spraying (EEDS) technology is one of such new developed technologies to prepare high properties coatings.In this paper, WC/Co cermet composites coatings and AISI 420 coatings were prepared by EEDS. AISI 420 coatings were also prepared by the improved high velocity arc spraying (HVAS) technology. The morphologies, compositions, phases and nano-mechanical properties of the coatings were determined by means of SEM, TEM, XRD, EDAX and nano-indentation test, respectively. Sliding wear and erosion wear properties and mechanisms were investigated. Numerical calculation and theory simulation were used to study the interface temperature, the largest melting depth, solidification speed. And experiments were operated to prove the results.The analyses of microstructures and properties of coatings show that the EEDS coatings are composed of nanometer/micrometer crystal and are characterized by uniform and compact microstructure, high hardness and elastic modulus, good bonding which mainly is a metallurgical one.The HVAS AISI 420 coatings are also compact but not as good as EEDS AISI 420 coatings. The coatings have obvious lamellar structure and the bonding is a mechanical one.The studies of wear resistances show that the EEDS WC/Co coatings have good wear resistance. The EEDS AISI 420 coatings have better wear resistance...