Research On Variable Density Plate With Coating Technology

Variable density plate is a kind of common optical part used in photo-electric system, this kind of filter, through changing the position of base plate, can conveniently adjust the attenuation value, thus adjust the energy of receiving signal. The parts used in our country for a certain type of anti tank in TV system. This project has changed the traditional coating method of gradual change film but adopting a new way:pulse multi-arc ion plating for nickel-chromium-iron gradual change film.In this project, we have modified a coating machine, and installed pulse multi-arc ion source on it; according to the plating technology of gradual change film, we have coated nickel-chromium-iron gradual change film and made evaluation to it.The research indicates:it is reasonable to design the shields of gradual change film to be fan mechanism, by the control to the gradual open and close of fan, the thickness of mental film deposited the part will change with the circumferential angle, the designed curve can be achieved by adjusting the speed of opening and closing the fan. At the same time, the higher the pulse multi-arc ion source pulse frequency, the slower the part rotating speed, the better the continuity of nickel-chromium-iron gradual change film. The firmness of nickel-chromium-iron gradual change film is relative with base plate clearness and temperature:The higher clearness of the substrate, the better firmness of the film; similarly, the higher temperature of the substrate, the better firmness of the film. The coated nickel-chromium-iron alloy film has the spectral characteristics curve in accordance with that required curve. Randomly select6points on a coated variable density disc and do the test, within the required wave band, the measured transmittance difference is within3%with better neutrality; the adhesion between film layer and substrate, and antifriction intensity of the film can meet the requirement of the national standard. The spectral curve and neutrality difference of the coated part can still reach the requirement after environment tests of invariable hot and humidity, low temperature and immersion. Thus it can be seen, the film layer of nickel-chromium-iron alloy gradually changed film is featured of good compactness, good repeatability of selected technological parameter and high feasibility; its firmness and chemical stability can meet the requirement of national standard.