silver brazing problem

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hi ı am ali from turkey.i am working at a diamond tool company.at the moment i am trying to silver braze a sintered metal matrix composite containing copper and tin metal powders to a steel body.i am using oxygen and natural gas.the problem is because of the the low melting point of tin, tin flows to the steel body and the mmc loses its properties before the joining process is completed.the other problem is the oxidation of copper in the metal matrix segment.what should i do in order to braze these parts?thank you
Reply:Tin is a metal that really can't be "welded" or brazed for that matter. You're pretty much stuck with soldering it with something like a lower melting point alloy to keep the mmc matrix from losing the tin due to melting. With a lower melting point alloy as low as simple 63/37 tin lead solder you should be able to solder it without melting all the tin and you'll have to use a lower temperature flame. Just apply flux and small strips of solder in between the components to be bonded and slowly heat the components and right when it melts and wets the material you'll have your joint.