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Self lubrication coating can have special properties such as self lubrication and wear resistance on the basis of ensuring the excellent mechanical properties of the matrix material, and also can greatly save raw material and production time by coating lubrication. The tribological properties of the coating depend mainly on the mechanical properties of the metal matrix material and the ability of the solid lubricant film to form, replenish and transfer to the dual material in the process of friction. At present, the research on self lubricating coating consists of base metal, non metal matrix and ceramic matrix, the study of self lubricating coating for Tao Ciji; adding solid lubricant to realize self lubrication has become an important means to resolve, machinery and lubrication under harsh conditions in the ceramic coating containing BaF2, CaF2, MoS2, Mo the preparation of self lubricating material parts become a trend of the development of the field. At present, the main methods for preparing ceramic coating on steel surface are the following.
I. plasma spraying.
The plasma spraying technology due to heat the plasma flow is highly concentrated, high flow rate, controlled atmosphere, it can obtain high quality coating, both the bonding strength of the coating and the surface of the workpiece, the coating itself strength, density and purity, or deposition rate and deposition rate when spraying are high. Research shows that nano iron sulfide self-lubricating coatings can effectively reduce the friction surface of the friction and wear of plasma spraying, mainly composed of ferrous sulfide particles nanostructures prepared by plasma spraying coating. The friction and wear test results show that the coating is obviously better than after heat treatment, friction and wear properties of GCr15 steel, the friction coefficient is reduced by 1/3~1/2, the wear volume decreased 50%~70%, and the friction and wear properties under vacuum conditions than under atmospheric pressure but also good.
Two. Laser cladding.
Laser cladding is in the coating material is coated on the surface of the substrate is placed, by laser irradiation makes the thin layer and the substrate surface melting and rapid solidification, the formation of a surface coating metallurgical bonding with the substrate, which can significantly improve the matrix material wear and corrosion resistance, heat resistance, oxidation resistance. It is reported that the self lubrication composite coating is prepared by cladding the Ni45-CaF2-WS2 powder on the surface of No. 45 steel by laser cladding. The friction properties of the composite self lubrication coating are obviously reduced by friction test.
Three. Combine laser cladding technology with plasma spraying technology.
Combining these two technologies can greatly improve some performance. Nano modified composite ceramic coatings were prepared on the surface of 45 steel by using laser remelting plasma spraying technology. The nano Al2O3 powder was used as filler. The results show that the lamellar structure of the plasma sprayed coating can be eliminated under the action of laser. Compared with the ceramic coating obtained by single plasma spraying, the degree of densification of the nano modified ceramic coating is obviously improved, and the corrosion resistance of the ceramic coating is also obviously improved.
Four 、 solid phase reaction method.
The solid phase reaction method is simple and requires no expensive equipment. The prepared ceramic coating and the metal matrix have high bonding strength and good coating performance. According to reports, with SiO2 and Al as main raw material, prepared on the surface of Q235 steel with excellent properties of SiO2 ceramic coating by solid state reaction method, the abrasive wear and adhesive wear relative wear resistance increased 2.23 times and 3.6 times respectively. According to another report, using Mo powder, Fe powder, Ni powder, Al powder and Fe-B powder as raw materials, preparation of molding slurry by brush coating method to form coating on the steel substrate surface in vacuum furnace was three yuan boride ceramic coating by solid reaction process, the coating has good thermal shock performance and wear resistance.