A Simple Method for Testing the Adhesion of Electrodeposits The adhesion of an electrodeposit to a. given substrate is very often an important property. I t is, of course, known that the adhesion of electrodeposits is influenced by the composition of the electrolyte, the operating conditions of the electrochemical cell (voltage, current density, temperature, agitation) and by the nature of the substrate and its prior history. There is, however, no simple method for evaluating the adhesion of electrodeposits, and it i5 difficult to assess the effect that the above variables have on the adhesion. A simple test that can be used with low-adhesion deposits consists in peeling off the deposit with a pressuresensitive adhesive tape. A suitable tape (e.g., surgical adhesive tape, filament tape, or Scotch tape) is cut in sections slightly longer than the width of the electrode to he tested. A small portion of one end of the tape is folded over t o provide aUhandle" for pulling. The electrodeposit is gently rinsed with distilled water, then with acetone and allowed to dry. The tape is placed across the width of the electrode pressing firmly either by hand or with a roller. Using a metal straight edge and a sharp knife the electrodeposit is slit just above and just below the tape. The adherence of the deposit is the,, tested by peeling off the tape with a sharp motion. If t.he deposit-to-srthstrate bond is stronger than the deposit-twtape bond the deposit will remain attached t o the substrate. If t,he opposite is true the deposit will he removed entirely. I n intermediate cases some portions of the deposit will be removed by the tape. Assuming that the quantity of eleotricity and the ourrent efficiency are held constant in various experiments the amount of materlal removed by the tape in the intermediate cases will he roughly proportional t o the inverse of the degree of adhesion. Semi-quantitative numerical v&es can he obtained by weighing the electrodes before and after the peel test or by weighing the test tapes. While the method dom not yield absolute values for the adhesion the dat.a obtained can he used for comparison purposes. SERGIOhU~1.4-GARZA
INXTITUTO NACIONAL DE ENERG~A NUCLEAR M B x ~ c o18, D. F.,M h x ~ c o
706
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Journal of Chemical Education
