Mixing fine silver with Mineral Oxides

Group,
I need the help of a chemist. I am a jeweler and work making my own alloys every week. What I am working on now is attampting to mix pure
silver or Gold (AU) with any form of a mineral oxide. What I am wondering, (while this may seem like a silly question to a chemist, which I am not so forgive me) is why one cannot mix raw mineral oxides, (pigments in raw color forms) with any pure metal such as brass copper or silver. In my pea brain, I keep thinking about mixing pigments to candle wax. That is a liquid which then becomes solid. Why can't one mix a mineral oxide in with a liquid metal, (silver) to produce a unique color? I have often made pink silver with the formula for Shibuichi, (copper and silver) but I keep thinking it might be interesting to achieve a unique color without the use of a patina. However, I don't know enought about chemistry and the moleculor issues to understand why I could or could not try this experiment. Done alot of research in texts and found NADA.
Any and all help would be appreicated. Thanks, SUZ
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Suz wrote:

HI! This may not be great advice but here is my understanding. It sounds like you are doing something called "mechanical alloying". Mixing bits of A and B together in a fine powder. This works for alloys like copper and silver as both melt around the same temperature. The colour of alloy AB is then an oxide of this metal mixture.
When mechanical alloying with an oxide, you will be making a metal matrix composite. The silver will melt at a much lower temperature than the oxide and you will not get true mixing or alloying. If you look at your creation under a microscope there will be discreet chunks of metal and oxide. As a result, the metal will not "pick up" the oxide's colour. It will also probably result in a porous and brittle piece of jewelry.
So the short answers is "they don't mix good". But I have no practical experience.
Hope this gets the discussion rolling.
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You should look at the phase diagrams. Any introductory book will suffice.
The problem is that even not all liquids mix with each other - look at a miscibility gap. In the solid phase, the miscibility is encountered is much more often. At equilibrium, you have not a single phase but rather a mixture of different phases.
Evgenii
--
http://Evgenii.Rudnyi.Ru /


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The trouble is that many oxides aren't chemically active enough to be "wet" by the liquid metal. If the metal doesn't wet the oxide, it won't stick to it.
In addition, you'll have a significant density difference. The oxide will float on top of the melt.
You could get a mechanical mixture as a powder and use powder metallurgy techniques but you'll probably be limited to small quanitites of the powder. Probably pretty good for strengthening the silver, but not very good for changing the color.
j

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John Gullotti wrote:

Yeah what JG said. ;) Covalent bonding vs. metallic bonding.
Alvin in AZ
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