Research On The Preparation And Application Of Aluminum Coating By Magnetron Sputtering

Anti-corrosion coating is one of the most effective, economical and common method to prevent corrosion, the aluminum coating has always been a hot spot of research at home and abroad because of its excellent corrosion resistance and good economic benefit and so on. The coating which prepared by magnetron sputtering technology is uniform, compact and adhesion well with substrate, therefore, this paper prepared aluminum coating by pulsed DC magnetron sputtering. The paper had optimized the process parameters thesingle variable method, then did the chemical conversion treatment to aluminum coating. The coating was applied to prevent NdFeB corrosion and galvanic corrosion between metals. In application of NdFeB corrosion protection, this paper discussed the structure and performance of NdFeB with aluminum after different temperature vacuum heat treatment to obtain the best heat treatment temperature for a better protective performance; and this paper also developed a highly efficient and stable aluminum coating stripping solution through the sample of NdFeB with aluminum coating to improve the utilization rate of substandard aluminum plating samples. In application of galvanic corrosion protection, the paper studied the galvanic corrosion protection between TC4,4130 and 6061 before and after coated with aluminum. The following results are gained from the experiments:(1) The best process parameters was optimized by investigating the morphology of aluminum coating on silicon after different negative bias and target current aluminum: negative bias -250V, target current 25A, the vacuum degree of work pressure of 0.45Pa, temperature 150℃, duty ratio 50%.The thickness was about 15μm after deposition 5.5h with the optimum process parameters; aluminum coating becomed more compact after chemical conversion, and the thickness of film changed little.(2) The aluminum coating on NdFeB was uniform and compact, its adhesion strength was 23MPa, the anti-NSS time is 150h, and it would be improved to 280h after chemical conversion. The best vacuum heat treatment is 600℃ for 10 minutes, then the adhesion strength is improved, anti-NSS time is 280h, and the matrix properties hadn’t changed. The stripping solution was high-efficient and stable, it’s optimal stripping process was lOg/L NaOH,30g/L Na2CO3,6g/L sodium dodecyl benzenesulfonate,2g/L EDTA-2Na, and 4g/L methenamine.(3) The aluminum coating on TC4 and 4130 were uniform and compact, their adhesion strength was 46MPa and 41MPa, the anti-NSS time was 310h and 340h.The galvanic corrosion sensitivity of TC4/6061 and TC4/4130 were class E, so they couldn’t in use directly. The galvanic corrosion sensitivity of TC4 with aluminum coupled with 4130 and 6061 were class C, it would be down to class B and class A after chemical conversion of aluminum. It was class E and class D of 4130 with aluminum and chemical conversion coupled with TC4. It was class A when 4130 and TC4 coated with aluminum and chemical conversion at the same time.