| With the requirement of environmental protection,cleaning efficiency and surface quality,conventional cleaning processes including mechanical cleaning,chemical solvent cleaning,water-jet assisted cleaning and ultrasonic cleaning can not meet the industrial standards due to the low efficiency,poor surface quality and the scope and field of cleaning is limited,and it is easy to pollute the environment.Laser cleaning technology is considered the most potential cleaning method in the 21st century.The main advantages of laser cleaning include no pollution,no contact,low cost,good controllability,high efficiency,no pollutants during cleaning,precise cleaning of the optional area,cleaning of the dangerous areas that are difficult to reach,and high surface quality after cleaning.At present,it has been widely used in many fields such as the removal of surface paint on space shuttles,the removal of engine carbon deposits,the removal of rust on ships and other surfaces,and the removal of microorganisms.In this paper,2024 aluminum alloy is commonly used as the matrix material in the aerospace field.Its surface was uniformly coated with TB06-9,TS70-1 composite coating as the research object,and the orthogonal test and single variable test were carried out using high energy pulse laser.The carbon deposition surface of a jet nozzle(titanium alloy)and the carbon deposition surface of a engine(iron alloy)were studied by high energy pulse laser with single variable test.The following conclusions are drawn through the experiment:(1)Through orthogonal test,the influence law of laser cleaning parameters on cleaning effect was analyzed.The micro morphology,element content,three-dimensional morphology and average surface roughness of the substrate surface after cleaning are characterized and analyzed.Among the many cleaning parameters,the average laser power and pulse frequency have a greater impact on the cleaning effect and the integrity of the substrate surface after cleaning.The scanning speed will also have a certain impact,and the spot diameter has the little impact.(2)Single variable experiment of laser paint removal is studied.When the scanning speed is maintained at 500 mm/s and the energy density is 21.23 J/cm~2,the cleanliness of the surface after cleaning is best.At this time,the surface integrity of the substrate is maintained best,the grains of the outermost layer are refined,the orientation is changed,and the micro hardness is increased by 6%,and the surface performance of the substrate is improved to a certain extent.When the energy density remains constant at 24.77 J/cm~2,the smaller the scanning speed,the higher the thermal effect between the laser and the surface of the substrate,the easier the substrate is ablated,and the more easily the surface integrity is destroyed.When the scanning speed is too high,the thermal effect produced by the laser is too small,and the paint layer cannot be removed effectively.(3)The effect of laser average power on the removal of carbide from titanium alloy surface was studied.Under the condition that other cleaning parameters remain unchanged,the higher the average laser power,the greater the thermal effect,the easier the carbon on the substrate surface is to be removed,and the more easily the surface integrity is also to be destroyed.The cleaning parameters need to be continuously optimized,and the best cleaning parameter matching is selected.The effect of laser average power on the removal of carbide from iron alloy surface was studied.When the average laser power is 22.50 W,the scanning speed is 500 mm/s,the pulse frequency is 10 k Hz,and the spot diameter is 0.03 mm,after cleaning,good cleaning effect was achieved,the integrity of the matrix surface was not damaged,the topmost grain was obviously refined,and the contact angle was kept at 112.63°.The results show that laser cleaning of carbon deposition on alloy surface is an effective way. |
PDF Full Text Request