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Originally Posted by RainsFire  is why cant we use a metal with a higher melting point to smelt the other one in? Like smelting bronze in a steel crucible |
actually we do that all the time...sort of
1. its easier to form a refractory than to fabricate a metal container \ refractory is generally backed up by a metal container, the refractory being sacrificial
2. most refractories contain metal, or more commonly metal oxides, aluminium, magnesium, chromium ect
3. unoxidized metals at a high rate of temperature will tend to oxidize, from air, trapped gases, oxides in the melt ect
4. the overall rate of chemical activity (whatever it is) ramps up with temperature, its known as the
Arrhenius equation and forms the basis of most
time to failure calculations, everything from computer chips to bearings
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The general rule of thumb, without solving the equation, is that for every 10°C increase in temperature the rate of reaction doubles
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5. Employing metal oxides instead of metal generally makes the sacrificial barrier more stable since its already oxidized and its already undergone that particular reaction which is likely to alter the chemical bonds with other (typically) minerals and oxides (silica for instance)
6 you can and people do melt in metal containers, but generally unless they are cheaply had, a sacrificial refractory lining makes much more sense