Create Coating Of High Emissiviy Titanium Surface Micro-Arc Oxidation And Sol-Gel

Because the air have The role of gas viscosity, the outer surface of aircraft will be the formation of aerodynamic heating because of high speed air compression and friction when it is in the dense atmosphere for supersonic flight. The outer surface of aircraft will appear high temperature and temperature gradient, then the high temperature constantly pass to inside of vehicle from the surface of aircraft ,and lead to changing the aircraft shape , structural strength and stiffness, and appear thermal strain, material phenomena, ablation and so on. the normal flight of the aircraft will be severely affected, at the same time the heat generated by internal will transfer to the aircraft, causing the internal temperature of aircraft increased and resulting in deterioration of the internal working environment. Made a high emissivity coating to improve oxidation resistance of titaniμm alloy by using micro-arc oxidation and sol-gel method on titaniμm surface, and the heat from the surface of aircraft timely diverge by radiation, so the temperature of aircraft surface decreases. It has Practical significance.In this paper, Na3PO4 is the main salt of the electrolyte. TC4 titaniμm alloy is the substrate, power supply output voltage 460V, pulse frequency 60HZ, 45% duty cycle, micro-arc oxidation time of 15min, a capacity of 60L stainless steel cell, the electrolyte are 25L, by changing the concentration of electrolyte Na₃PO₄ produce micro-arc oxidation ceramic coating samples whose thickness is in the range of 5-20μm. Analyzed and Tested by XRD the ceramic coating is not only in addition to the anatase- TiO₂ phase, but also a small amount of rutile-TiO2 phase after 700℃calcined. Shear strength of the ceramic coating and the emission rate were tested, Found shear strength change lower With the increase of film thickness, however, in 5-20μm range shear strength is greater than 15MPa. While the ceramic coating emission rate with the variation of film thickness presented as follows: firstly increases, increases to some value, but also begins to decrease.Used Spin coating method spread sol-gel film in the ceramic layer surface, and then after calcination at 700℃formed a composite film. for different composite films test XRD, coMPared to ceramic coating appear the phase of CuO,Cr₂O₃,CoTiO₃,CaCu₃Ti₄O₁₂ respectively. Discuss the shear strength of the composite film and its emission rate, found bond strength between the composite coating and the substrate is relatively high. But also similar to the shear strength of ceramic coating, and the shear strength of ceramic coating is above 15MPa. The emissivity has been significantly improved when emissivity composite film coMPared to the ceramic coating, Which transition metal Cr composite film 3-8μm band emission rate of 0.7, 8-20μm band emission rate of 0.9.