In the past ten years, researchers have used PVD (including magnetron sputtering, ion beam sputtering, radio frequency discharge ion plating, plasma plating, EB-PVD, etc.) to prepare nano-monolayer films and nano-multilayer films, and obtained nano-Ti( N, C, CN), (V, Al, Ti, Nb, Cr) N, SiC,,, TiN/CrN, TiN/A1N, WC-Co coating can be used for the corrosion resistance of wear-resistant aircraft shaft components; plasma Sprayed nano-coating has been used to seal the air path of aero-engines; nano-coating has been used for heat insulation protection of turbine blades; adding graphene and carbon nanotube composite coating has radar stealth function. When we use atmospheric pressure plasma spraying technology to prepare silicon silicide coatings on pure titanium substrates, compared with traditional manufacturing processes, atmospheric pressure plasma spraying has the advantages of time-saving and large-area manufacturing.
But silicon carbide is easy to decompose by itself at high temperature, so that the thickness and strength of the coating are not high. Therefore, three methods are proposed to solve this problem. The first is the "sol-gel method", which uses "tetraethoxysilane, TEOS" as the precursor, first grows a silica protective layer on the outer layer of silicon carbide powder, and then heats and sprays; the second method The sol-gel method is used, but "sodium lauryl sulfate, SD" is added as a surfactant to make the silica layer grow denser; the third is to add alumina to adjust the ratio of silicon carbide to alumina
For plasma spraying, the sprayed materials are aluminum oxide and yttrium oxide coatings, which are mainly used to resist damage to the cavity caused by plasma bombardment. To
Another arc spraying process is to spray pure aluminum wire to make the inner surface of the cavity with high roughness. The effect of the sharp discharge is used to capture the charged particles in the cavity and prevent these particles from affecting the yield. Common coatings in the aerospace industry include high temperature resistant thermal barrier coatings, abradable coatings, high temperature resistant metal coatings (T400, T800), and wear resistant coatings. Among them, the thermal barrier coating is mainly composed of two coatings, namely "bond coating" and "top coating", and the thermal spraying process used by these two coatings is different. In terms of bonding layer, the current common processes include "low pressure plasma spraying, LPPS", "high pressure high velocity flame, high velocity oxygen fuel, HVOF, HVAF". To
The material used in the bonding layer is MCrAlY (M = Ni, Co, NiCo, CoNi), which has a good affinity with the top layer material. At present, the mainstream of the top layer process is the use of "atmosphere plasma spraying, APS". In recent years, a considerable number of domestic and foreign scientific research units and manufacturers have used atmospheric plasma plasma plasma spraying to make the top layer. The material used on the top layer is yttrium oxide stabilized zirconia (8YSZ). This material is characterized by low thermal conductivity and relatively inexpensive compared to other insulation materials. These coatings are applied to the moving blades, stationary blades, and moving blades at all levels. Various applications such as leaf ring, combustion barrel, sealing ring, aircraft landing gear, etc. Therefore, we recommend the PEO method to replace the plasma spraying method, because the PEO film is formed by the atomic bonding of the object itself, so the adhesion is particularly strong, which is much stronger than the general external coating method (such as: plasma spraying) too much. In addition, the aluminum parts treated by PEO are more durable than general hardening, heat treatment, chromium plating, anode, ceramic spraying or nitriding treatment, and there is less corrosion.
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