Surface Preparation of Copper for Microscope Testing

Would it not be easier to develop a sensor to detect reducing flame and sound an alarm or switch off. And don't ask me how to do it as I know zilch about brazing (which adds brazing to an extensive list).

Simon

Hydrogen embrittlement will cause the braze interface to turn into a sponge type of material. If the reaction is strong enough, it can be observed through the microscope on a conventional metallurgical cross section. For a better description of hydrogen embrittlement and how to control it, read "Brazing for the Engineering Technologist" by Mel M. Schwartz ISBN:0412595109

For cross section of the piece you have to cut it. I am afraid this may fill the cavities of sponge & you see nothing on the microscope. What is the best method for cutting & what precautions need to be taken so that I can see these microscpic cavities on the microscope.

Sample preparation for metallugical cross sectioning should be fairly straight forward. Cut the sample, mount it in plastic, rough grind, fine grind, and polish. The last step is etching which brings out the grain structure and removes any micro-defects such as those you mention. A common etch for copper is 50 ml. HNO3, 0.5 g AgNO3. The ASM Handbook, Ninth Ed., Vol. 9 has a section devoted to copper and its alloys. If you are not familiar with sample preparation, get a book, talk to suppliers of metallurgical materials, and have some samples prepared by an independent lab to use as reference.