The Research On The Coating's Property By Plasma Spraying And Laser Remelt

The characters of special material and its surface, especially the characters of machines'parts, are needed more and more higher than ever with the development of science and technology and the need of industry modernization and arm equipment, scientists of some countries have done plentiful experiments and investigations of theory about how to improve the characters of material and its surface, and they have accelerated the development of surface engineer.Plasma spraying is an important technology of surface finishing, the coat can intensify and repair the surface of material, and meanwhile, the coat can also endow the special characters of material and its surface. Laser melting is an important technology of material surface melting and aggrandizement. Therefore, this paper put forward a method that the technology of laser remelting is applied to spray the surface of material by using Al₂O₃-13%TiO₂ to intensify the surface of material, and investigate the plasma-spraying coat and the laser remelting coat, the main studies are shown as follow:1. Technology of surface engineer and coat theoryThe technology of surface engineer and the coat theory must be researched by reading a lot of papers and materials before carrying through plasma spraying and dealing with the plasma-spraying coat by using laser remelting, in order to design the logical plasma-spraying coat and make the plasma-spraying coat and the remelting coat reach to a good effect, all of these have offer theory to the research of the plasma-spraying coat and the laser remelting coat.2. Research of the plasma-spraying coatBecause the structure of Al₂O₃ nanometer pottery coat is soft, and the integrated intensity of the coat and its base is low, so the spraying materials are adjusted in this paper, the Al₂O₃-13%TiO₂ nanometer pottery materials can be acquired by appending some TiO₂ to Al₂O₃ pro rata, TiO₂ has these advantages such as smaller grain diameter and lower melting point and better felting character and so on. Spraying Ni-Al to the surface of the base can intensify the coalescent intensity before spraying Al₂O₃-13%TiO₂ to the surface.The Al₂O₃-13%TiO₂ nanometer pottery materials (for short AT-13) are sprayed to the Q235 steel base by using plasma spraying equipment, and the investigations of the AT-13 plasma spraying coat and its character are carried through by using SEM,XRD,the intensity microscope,the pull experiment machine and the abrasion experiment machine. We can draw some conclusions through the investigations: The organizations of AT-13 plasma spraying coat are thick, and there are some holes in the coat, the particles are oblate, and the main components areα-Al₂O₃,β-Al₂O₃,γ-Al₂O₃, including little TiO₂ and impurities, and we can find that the phase of Al₂O₃ occur to change in the process of spraying compared to The Al₂O₃-13%TiO₂ nanometer pottery material. The highest value of micro-intensity of the AT-13 plasma spraying coat is 998, and the average value of coalescent intensity of the coat and the Q235 steel base is 24.36MPa, the coalescent intensity of the coat and the Q235 steel base is 15MPa in the same condition, and the value increases to 60%. The value increases to 40% in wearable aspect.3. Investigation of the laser remelting coatThe paper put forward dealing with the AT-13 plasma-spraying coat by using laser manufacture technology based on the characters of laser manufacture technology and according to the technology of laser machining the surface of the parts, and some measure equipments and experiments are applied in order to research the organizations and characters of the remelting coat.We can find that the organizations and phases of AT-13 plasma-spraying coat which is dealed with by laser remelting have changed: the organizations are very close the holes disappear, the grains are smaller, and the main components of spraying coat areα-Al₂O₃, including little TiO₂, and TiAl2O5 are produced. The highest micro-intensity value of remelting coat is 1710. The coalescent intensity of the coat and the Q235 steel base is higher than 68.8MPa. The wearable character increases compared the Q235 steel remelting coat to the AT-13 plasma-spraying coat.4. ConclusionThe paper draws some conclusions based on the investigation of plasma-spraying coat and the laser remelting coat as follow:1. The structure of plasma-spraying coat are composed of sheets, thereare some holes and impurities in sheets, and the interface of the spraying coat and the base is clear, the combinative manner is mechanical manner. The spraying coat is composed ofα-Al₂O₃,β-Al₂O₃,γ-Al₂O₃,including little TiO₂ and impurities, the transitional coat is composed of Ni-Al metal.2. The structure of spraying coat become coaxial crystal and column crystal after the plasma-spraying coat is dealed with by laser remelting, there are no holes in the spraying coat, the combinative manner of the coat and the base has changed from mechanical manner to metallurgy manner. Components of the transitional coat include the coat material and the base material and the transitional material. The phase of the coat has changed,β-Al₂O₃ andγ-Al₂O₃ disappear and transform toα-Al₂O₃,and TiAl₂O₅ is produced, the crystals of the coat are smaller and evener and closer.3. The capability of the AT-13 plasma spraying coat reach to a high standard compared to Q235 steel, the density and the intensity and the combinative intensity and the wearable capability of the coat increase after changing the material and the spraying technics, though the intensity and the wearable capability is lower than the Al₂O₃ pottery coat, but its general capability is higher than the Al₂O₃ pottery coat.4. The capability index of the coat reaches a new height after the coat is dealed with laser melting, the intensity and the combinative intensity and the wearable capability of the coat increase compared to the AT-13 plasma spraying coat.