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Removal of epoxy embedment
Metallography
481
Letter a Removal of Epoxy E m b e d m e n t A. BACZEWSKI The Bayside Research Center of General Telephone and Electronics Laboratories Incorporated Bayside, New York
Metallographic samples are customarily embedded in an epoxy resin before being polished so that no jarring or displacement may occur. Epoxy resins are very well adapted to this technique because they solidify in the presence of catalysts to yield hard, clear, and infusible masses. However, a practical method for recovering the specimen has not been available because the resin is not only infusible but also insoluble. Although it is possible to disintegrate the resin by inducing a reaction between an epoxy resin and nitric acid at elevated temperatures, 1 this procedure can be used only with highly stable specimens. T h e method de-
scribed here allows one to safely recover metallographic specimens from the epoxy resin. T h e method is based on the property of D M S O (dimethylsulfoxide) to swell the resin and to crack it under the influence of large and rapid changes of temperature. As much of the resin as possible is removed by sawing and cutting. T h e specimen is then put into a small wire basket which is lowered into boiling dimethylsulfoxide (BP> 189°C). After 1 or 2 minutes the basket is pulled out and quickly immersed into liquid N 2 or an acetone-dry ice mixture. Alternatively, the sample may be packed in dry ice. After one or two repetitions of this procedure, the small
a The submission of Technical Letters for publication is encouraged, and such Letters may be submitted to any member of the Journal Staff. As often happens, a manuscript printed in Metallography may precipitate new work, encourage further investigation, or prompt questions and/or comments. This is as it should be, and the Letters section is a fast, expedient medium by which to publish your comments. Letters need not be restricted to comments on the work published in Metallography but may contain any significant data relative to the field of metallography. All Letters are subject to review and should be in a form suitable for publication at the time of submission. LETTER
Metallography, 3 (1970) 481-482 Copyright © 1970 by American Elsevier Publishing Company, Inc.
A. Baczewski
482 amount of remaining resin adhering to the specimen may be removed easily by hand. Two comments are in order: 1. A variety of reactions may be used to "set" epoxy resins, and various manufacturers offer catalysts of a different chemical nature. Although the method was not tested on all of them, it is to be expected that many embedding materials are similar to the
one tested, namely "Epoxide" (manufactured by Buehler Co., Evanston, Illinois). Nevertheless, it is recommended that one first test the method on a blank. 2. Vapors of dimethylsulfoxide are toxic and are capable of diffusing through the skin. Consequently great care must be taken in handling this material.
Reference 1. H. W. Schneider, Plastics Design Process. 5 (July 1965).
Accepted May 19, 1970
481
Letter a Removal of Epoxy E m b e d m e n t A. BACZEWSKI The Bayside Research Center of General Telephone and Electronics Laboratories Incorporated Bayside, New York
Metallographic samples are customarily embedded in an epoxy resin before being polished so that no jarring or displacement may occur. Epoxy resins are very well adapted to this technique because they solidify in the presence of catalysts to yield hard, clear, and infusible masses. However, a practical method for recovering the specimen has not been available because the resin is not only infusible but also insoluble. Although it is possible to disintegrate the resin by inducing a reaction between an epoxy resin and nitric acid at elevated temperatures, 1 this procedure can be used only with highly stable specimens. T h e method de-
scribed here allows one to safely recover metallographic specimens from the epoxy resin. T h e method is based on the property of D M S O (dimethylsulfoxide) to swell the resin and to crack it under the influence of large and rapid changes of temperature. As much of the resin as possible is removed by sawing and cutting. T h e specimen is then put into a small wire basket which is lowered into boiling dimethylsulfoxide (BP> 189°C). After 1 or 2 minutes the basket is pulled out and quickly immersed into liquid N 2 or an acetone-dry ice mixture. Alternatively, the sample may be packed in dry ice. After one or two repetitions of this procedure, the small
a The submission of Technical Letters for publication is encouraged, and such Letters may be submitted to any member of the Journal Staff. As often happens, a manuscript printed in Metallography may precipitate new work, encourage further investigation, or prompt questions and/or comments. This is as it should be, and the Letters section is a fast, expedient medium by which to publish your comments. Letters need not be restricted to comments on the work published in Metallography but may contain any significant data relative to the field of metallography. All Letters are subject to review and should be in a form suitable for publication at the time of submission. LETTER
Metallography, 3 (1970) 481-482 Copyright © 1970 by American Elsevier Publishing Company, Inc.
A. Baczewski
482 amount of remaining resin adhering to the specimen may be removed easily by hand. Two comments are in order: 1. A variety of reactions may be used to "set" epoxy resins, and various manufacturers offer catalysts of a different chemical nature. Although the method was not tested on all of them, it is to be expected that many embedding materials are similar to the
one tested, namely "Epoxide" (manufactured by Buehler Co., Evanston, Illinois). Nevertheless, it is recommended that one first test the method on a blank. 2. Vapors of dimethylsulfoxide are toxic and are capable of diffusing through the skin. Consequently great care must be taken in handling this material.
Reference 1. H. W. Schneider, Plastics Design Process. 5 (July 1965).
Accepted May 19, 1970