Electrolytic corrosion test

The Electrolytic Corrosion Test. Also developed for use on nickel—chromium and copper—nickel—chromium decorative automobile parts is the electrolytic corrosion (EC) test (44). Plated specimens or parts are made anodic in a corrosive electrolyte under controlled conditions for 2 min, and then tested for penetration to the substrate. 

Table 19.2 Electrolytic corrosion test composition of test solutions (A, B) and indicators (C, ) 5S-i58...

Electrodeposited chromium coatings. Electrolytic corrosion testing Coatings cathodic to the substrate-rating of electroplated test specimens subjected to corrosion tests... 

This test was designed for electrodeposits of nickel and chromium on less noble metals, such as zinc or steel [738-740]. Special solutions are used, and the metal is polarized to + 0.3 V versus the standard calomel electrode. The metal is taken through cycles of 1 min anodicaUy polarized and 2 min impolarized. An indicator solution is then used to detect the presence of pits that p>enetrate to the substrate. Each exposure cycle attempts to simulate one year of exposure imder atmospheric-corrosion conditions. The former standard ASTM B 627, Test Method of Electrolytic Corrosion Testing (EC Test), described the method but has been withdrawn. 

ASTM Standard B 627, Test Method for Electrolytic Corrosion Testing (EC Test) (Withdrawn 1998). 

Electrodeposited chromium coatings—Electrolytic corrosion testing (EC test)... 

Various types of reference electrodes have been considered in Section 20.3, and the potentials of these electrodes and their variation with the activity of the electrolyte are listed in Table 21.7, Chapter 21. It is appropriate, however to point out here that the saturated calomel electrode (S.C.E.), the silver-silver chloride electrode and the copper-copper sulphate electrode are the most widely used in corrosion testing and monitoring. 

Guidance on conducting and evaluating galvanic corrosion tests in electrolytes is given in ASTM G71 1981 (R1986). 

In view of the electrochemical nature of corrosion, it has seemed reasonable to many investigators to assume that suitable accelerated corrosion tests could be made by observing the response to electrolytic stimulation of the corrosion processes, or by attaching particular significance to the results of quickly made electrode potential and current measurements. 

The extent of pitting is estimated by a special microscopical technique, or by the attack on the substrate using an appropriate indicator. Thus in the case of steel 1,10-phenanthroline hydrochloride is added to the electrolyte (solution B) to detect the formation of Fe ions. Alternatively, the specimens can be removed from the corrosion test solution and placed in an indicator solution, i.e. solution C for zinc-base die castings and solution D for steels. 

Test methods for determining electrolytic corrosion with electrical insulating materials Method for determination of resistance to intergranular corrosion of austenitic stainless steels copper sulphate-sulphuric acid method (Moneypenny Strauss test) Specification for electroplated coatings of tin/lead alloys... 

Electrolytic corrosion (EC) test, 9 790 Electrolytic etching, of silicon,... 

D 3482 Test Method for Determining Electrolytic Corrosion of Copper by Adhesives... 

ASTM G71-81, Standard Guide for Conducting and Evaluating Galvanic Corrosion Tests in Electrolytes, Philadelphia, PA, 1981. 

Both Ni/MH and Li-ion batteries do contain hazardous materials. Niekel/metal hydride battery packs, of course, contain nickel, which is a suspected carcinogen in some forms. However, the only hazardous material in a Ni/MH battery, as defined by federal regulations, is the potassium hydroxide (KOH)-based electrolyte (corrosive). The only characteristic hazard of any consequence for the electrode materials in these batteries is toxicity. The hazard level is determined by a test called the toxicity characteristic... 

Several ASTM standards address the susceptibility of alloys to intergranular corrosion. Stainless steels are tested for sensitization by immersion in different boiling adds according to ASTM A262 (76). Similar tests are described in ASTM G28 for Ni-rich Cr-bearing alloys (77). ASTM A262 also describes an electrolytic etch test in oxalic add, which can be used to screen prior to the more lengthy immersion tests. 

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