Electroforming: An Improvised Experiment on Electroplating In the prwesses of electroplating and electroforming the chemical reactions and changes are essentially the same hut the outcome is different. In electroplating an adherent metallic costing is applied on a n article, and this coating becomes a permanent part of the article. In electroforming the metallic coating is used as a separate item. The definition adopted by the ASTM is: "Electrofoming is the production or reproduction of articles by electrodeposition upon a mandrel or mold that is subsequently separated from the deposit."' The objects obtained through this process (the eleetroforms) have the advantages2 that they can be reproduced with great fidelity and that intricate shapes may he produced. Industrially, this process is used in areas ranging from consumer products t o highly specialized items. The latter includes phonograph record masters, thin-walled foil, hypodermic needles, and sandwiches of various metals as radar wave guides of copper with interior lining of silver.' I t should be mentioned that, whereas in electroplating g w d adhesion is very important and care is taken to improve it, non-adhesion is essential in the preparation of the electrofarms. Mandrels can be prepared from a variety of compounds like passive alloys such as stainless steel. low melting.. allovs and elass or olastics after treatment for conduction. The removine of the mandrel is oerformed rithe; merhnnlmllg i,r hy mei;ini: ur iisrolving the mandrel. Our expermem is part d a laboratory sesdion on electroplating for freshman engineering students."Ve think that in addltion u, hmng relevant and exciting it teach- a lesson in using different r h a m ~ e dand physiral pnopertie~uf compounds for different or even apposite objectives. The students prepare a round-bottomed copper capsule of the approximate size 0.8 X 2 cm. The mandrel used is a shiny polished stainless steel round bottomed rod of the dimentions 0.15 X 10 em which serves as the cathode. The anodes are two copper sheets 1x 10 cm placed on both sides of the mandrel about 2 em removed. The anodes are immersed about 0.5 em deeper into the solution than the cathode. The solution used is a common electroplating solution consisting of CuSO1 5H9) ~ ~(200 . ~er). . . HnSOa . . (50 . ml) and ethanol (30 ml) dissolved in 1 1of distilled water. The eurrent used is 0.1 amo for ... eoncd. 1 hr. Atwr longer p e r i ~ hthe layer ihtained is thirkerand easier ro remove. The elecrroform is removed hy heatink the electroplated mandrel inn Bunwnflameand immersing it ina brilker of warer.Ar rhar stag? pullingoflthernpatrle iseasy. The auchors wish to thank Mrs..M. Rindginsky for helpful discussions.
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'Graham, A. K., Electroplating Engineering Handbook, 3rd edition, Van Nostrand, N.Y., 1971, p. 519-531. 2Metal Finishing, Guide Book & Directory, Metals & Plasties Puhl., Hackensakc, N.J., 1971, p. 425-433. 3Gorodetskv. .. M...J:Chem. Educ..55.66 11978). 'Department of Eduratim and Department of Chem~stry Wepartmmt of Chrmirtry Ben-Guriou University of t h e Negev B e e r Sheva. Israel
514 1 Jwmal of Chemical Education
Malka Gorodetsky" Amman Singerman6
