Abstract
In this research the hard chromium electroplating process, which is one of the common methods of overlay coating was used, by using chromium acid as source of chromium and sulphuric acid as catalyst since the ratio between chromic acid and sulphuric acid is (100 : 1) consequently. Plating process was made by applying current of density (40 Amp / dm2) and the range of solution temperature was (50 – 55oC) with different time periods (1-5 hr). A low carbon steel type (Ck15) was used as substrate for hard chromium electroplating. Solid carburization was carried out for hard chromium plating specimen at temperature (925oC) with time duration (2 hr) to be followed with quenching and tempering. The phase analysis was conducted by using X– ray diffraction. The examination results show that the chromium carbides in plating layer were (Cr23C6, Cr7C3). The microhardness of hard chromium plating specimen was measured, and the results show that the high hardness was about (907HV). After solid carburization the hardness values increase and the results show that the higher hardness for chromium plating layer on low carbon steel surface was (1276 HV).
Wear apparatus type (Pin on Disc) was used to study dry sliding wear properties of low carbon steel (As received) and hard chromium plating specimens and solid carburized. The effect of applied normal load on wear rate was studied with weighting method using five normal loads (5, 10, 15, 20, 25 N) at constant sliding speed (2.198 m / sec). The results reveal that the wear rate increases with the increasing of applied normal load. A good improvement in wear resistance was noticed for hard chromium plating specimens as compared with substrate specimen. It was also seen that, the improvement in wear resistance was (94%) as compared with substrate metal when carburizing treatment is carried out on hard chromium plating specimens.
References
[2] Hyman Chessin, “Hard Chromium Plating”, Metals Handbook, Vol.5 Surface Cleaning, Finishing, and Coating ) ,9th Edition1982, PP.170-187
[3] Wells T.C. “A Review of Surface Treatments and Coatings”, Surfacing Journal, Vol.9, No.4, 1978, PP.2-9.
[4] For every problem,Asolutions Metcor inc.560boul.Arthur-sauve,saint-Eustache J7R 5A8 Web:www.metocor.biz. 2002.
[5] www.internet ,"Surface Hardening of Steel", Seven Club of Great Britain ,L7C Home ,Blatechat ,Edited April 9 ,2003.
[6] Muna K. Abbas and Khairia S.Hassun, "Effect Carburizing Medium on Fatigue Strength for Low Carbon Alloy Steel", Proceeding of the Fifth Jordanian International Mechanical Engineers Association ,2-4 April ,2004.
[7] Ahmed S. Abbas, "Hard Chromium Electroplating and Improvement the and Metallurgy", University of Technology ,Baghdad ,Iraq, 2002.
[8] Eman S. Naeem, M.Sc. Thesis, "Study of the Porosity of Different Coating Systems of Low Carbon Steel", Department of Production Engineering and Metallurgy, University of Technology ,Baghdad ,Iraq,1990.
[9] U. N. I. D. O., “Advances in Material Tech ", Monitor Vienna International Center, Austria, 1990, pp.9-11.
[10] Solov’eva Z.A. and Adzhiev B.U., “Internal Stresses of Chromium Coatings Measured During Electro deposition”, Journal of Surface Technology, Vol.23, No. 1, 1984.
[11] Nabil Zaki, “Chromium Plating” Products Finishing Directory", http://WWW.Pfonline.com /articles / pdf 0016. Htm /2000, PP.1-10.
[12] Iwai Y. , “Effects of Hard Chromium Plating on Cavitations Erosion”, Journal of Wear, Vol.128, No.2, 1988, PP.189-190.
[13] Thelining K.E.,“Steel and Its Heat Treatment”, 2nd Edition,1984, PP.449-453.
[14] Cameron T. B. “A Perspective on the Performance of Carburized Gear Steel”, Society of Automotive Engineers, 1985, PP.1921-1928.
[15] 15- Halling J., "Principles of Tribology", Published by the Macmillan Press Limited (London), 1979, PP.94 –100, PP.105 –109.
[16] Mikell P. Groover, “Fundamentals of Modern Manufacturing Materials Processes and Systems, John, Wiley & Sons, Inc., 1999.
[17] Eyre T.S, "Wear Characteristic of Metals", Tribology International, 1976, PP.203-212.
Copyright: Open Access authors retain the copyrights of their papers, and all open access articles are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided that the original work is properly cited. The use of general descriptive names, trade names, trademarks, and so forth in this publication, even if not specifically identified, does not imply that these names are not protected by the relevant laws and regulations. While the advice and information in this journal are believed to be true and accurate on the date of its going to press, neither the authors, the editors, nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.