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김동수(D. Kim),김만(M. Kim),박상언(S. U. Park),남기석(K. S. Nam),장도연(D. Y. Chang),권식철(S. C. Kwon),신동수(D. S. Shin) 한국표면공학회 2001 한국표면공학회지 Vol.34 No.1
The addition of organic compound containing -COOH, -CONH₂, -CHO group such as formic acid, formamide, formaldehyde or diethyleneamine to a chromium electroplating bath results in a chromium deposit in which carbon is incorporated. Such deposits have fewer defects than chromium layers produced by a conventional method. It was found that the as-deposited layers were amorphous and auger electron spectroscopy (AES) showed that carbon is distributed uniformly in the deposit. During heat treatment, Cr-C deposits began to crystallize at 400℃, and at 800℃ they were crystallized into chromium carbides and oxides. The effects of current density, amount of additives, applied current waveform on Cr-C alloy electroplating were examined.
Potassium formate, Glycine, Oxalic acid가 황화물계 3가 크롬도금층의 조성과 전류효율에 미치는 영향
김만(M. Kim),김대영(D. Y. Kim),박상언(S. U. Park),권식철(S. C. Kwon),최용(Y. Choi) 한국표면공학회 2004 한국표면공학회지 Vol.37 No.2
Effect of potassium formate, glycine and oxalic acid in a sulfate solution on the deposit composition and current efficiency of trivalent chromium plating was studied. The trivalent chromium layers prepared by solutions with potassium formate, glycine and oxalic acid contain a few carbon inside. The solutions containing potassium formate, glycine and oxalic acid are relatively stable with pH change. The solution with the potassium formate shows 6-30% current efficiency with current density, whereas, the solutions with oxalic acid and glycine show about 5% current efficiency, respectively. The improved current efficiency is related to enough supply of chromium ions to the electrode due to the increase of pH at the front of electrode.
황화물계 3가 크롬도금욕에서 크롬-탄소 및 크롬-탄소-인합금도금의 전착과 결정화거동
김만(M. Kim),김대영(D. Y. Kim),박상언(S. U. Park),권식철(S. C. Kwon),최용(Y. Choi) 한국표면공학회 2004 한국표면공학회지 Vol.37 No.2
Chromium-carbon (Cr-C) and chromium-carbon-phosphorus (Cr-C-P) alloy deposits using trivalent chromium sulfate baths containing potassium formate were prepared to study their current efficiency, hardness change and phase transformations behavior with heat treatment, respectively. The current efficiencies of Cr-C and Cr-C-P alloy deposits increase with increasing current density in the range of 15-35 A/dm². Carbon content of Cr-C and phosphorous of Cr-C-P layers decreases with increasing current density, whereas, the carbon content of Cr-C-P layer is almost constant with the current density. Cr-C deposit shows crystallization at 400℃ and has (Cr+Cr₂₃C?) phases at 800℃. Cr-C-P deposit shows crystallization at 600℃ and has (Cr+Cr₂₃C?+Cr₃P) phases at 800℃. The hardness of Cr-C and Cr-C-P deposits after heating treatment for one hour increase up to Hv 1640 and Hv 1540 and decrease about Hv 820 and Hv 1270 with increasing annealing temperature in the range of 400~800℃, respectively. The hardness change with annealing is due to the order of occurring of chromium crystallization, precipitation hardening effect, softening and grain growth with temperature. Less decrease of hardness of Cr-C-P deposit after annealing above 700℃ is related to continuous precipitation of Cr₂₃C? and Cr₃P phases which retard grain growth at the temperature.
발포사출공정 중 스킨 형성에 따른 사출시간 선정에 관한 연구
서봉현(B.H. Seo),노상호(S.H. Noh),진광진(K.J. Jin),김상민(S.M. Kim),박대림(D.L. Park),박상언(S.U. Park) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Foam injection molding process has the advantage that it can easily achieve lightweight by create cells inside plastic products. However, foam injection molding is more difficult to optimize process conditions than normal injection molding process. In particular, if the injection time is increased for the purpose of reducing the pressure to suppress stress, it is likely that the formation of skin layer because cooling will prevent the product from foaming properly. In this study, injection analysis and experiments was conducted to optimize process conditions to reduce pressure and maximize foaming performance during the foam injection molding process.
전해도금에 의해 형성된 반도체 고속도금용 주석-납 합금피막의 첨가제 및 전해조건의 영향
정강효(K. H. Jung),김병관(B. K. Kim),박상언(S. U. Park),김만(M. Kim),장도연(D. Y. Chang) 한국표면공학회 2002 한국표면공학회지 Vol.36 No.1
Effects of additives and plating conditions of high speed electroplating were investigated. The Sn content in electrodeposit was highly decreased with increasing current density from 10A/d㎡ to 50A/d㎡, and the current efficiency on the cathode was decreased. The carbon content in the electrodeposit was decreased with increasing current density from 10A/d㎡ to 30A/d㎡, however the carbon content was highly increased in the range of 40A/d㎡~50A/d㎡. The formation of tetravalent tin and stannic oxide sludge was prevented by the addition of gallic acid in the bath. The changing of Sn content in the electrodeposit is caused by the addition of gallic acid.
김만(M. Kim),이종재(J.J. Lee),김대영(D.Y. Kim),박상언(S.U. Park),권식철(S.C. Kwon) 한국표면공학회 2004 한국표면공학회지 Vol.37 No.3
Hard chromium coating technology using hexavalent chromium bath is widely used in various industries. Because of the serious health and environmental problems of hexavalent chromium, many attempts to alternate the hexavalent chromium plating have been made over 50 years. Trivalent chromium plating is one of the challengeable technologies to alternate hexavalent chromium plating. It is relatively none-toxic. Although some papers have described hard chromium coatings produced from trivalent chromium solution, it has limited the industrialization because of chemical and electrochemical problems of trivalent chromium ions. This paper introduces a number of factors for successful trivalent chromium plating, to give a some information about trivalent chromium process.