How to determine the carbon content of a metal matrix composite?

Question

i want to determine the carbon content of a copper-graphite composite in which the carbon content is in order of 2%wt.

what is the best method?( reliable and of course economical!!)

Answer 1

I don't know much about copper-graphite alloys, but presumably it would be possible to weigh out a sample of the Cu/C composite and then dissolve the copper in nitric acid.  The graphite is inert and will be left behind - filter it out onto a weighed filter paper, wash it with water (to dissolve out copper salts and nitric acid remaining), dry it (use an oven or heat lamp, but be careful not to burn the paper and decrease its mass), and weigh the final paper and graphite.  Just subtract the mass of the paper from the paper+graphite to get the amount of graphite present.  You will need a fairly accurate balance - get one that can measure milligrams or better.

Be sure to carry out the dissolving in a fume hood or very well ventilated area - toxic nitrogen oxides will be released, and symptoms will not appear until a few hours after exposure.

This won't work if the copper has reacted with the carbon, but I don't believe it usually does.