XPost: sci.physics, sci.materials, sci.engr.semiconductors   
   From: jdavidson135264x@hotmail.com.invalid   
      
   On 2023-03-12 5:02 PM, Jim Pennino wrote:   
   > You will be hard pressed to find specifications for the ceramic plates   
   > used for peltier devices and the most I have ever found is that they are   
   > made with alumina ceramics. Note that alumina ceramics have different   
   > properties than pure alumina.   
   >   
   > In general, alumina ceramics are weakly attacked by strong acids and   
   > bases and insoluable in water.   
   >   
   > A ceramic that is 74%, which is about the cheapest stuff anyone makes,   
   > or more alumina is concidered gas tight and will not absorb water.   
   [snip]   
      
   Many thanks! -- that's all extremely helpful.  I knew about the need for   
   heat sinks, but you provided a lot of detail that I wasn't aware about.   
      
   I'll do a bit of reading about alumina ceramics just to be sure; more   
   knowledge is always good.  I'm familiar with alumina from   
   chromatography.  And from an attempt at smelting a few decades back,   
   when we built our little smelter from alumina insulating bricks from   
   a kiln.  We discovered, to our chagrin, that using clay as a mortar   
   was NOT a good idea, as it dissolved nicely into the alumina in much   
   the same way that acetone dissolves styrofoam, when the setup got up   
   to sufficient temperatures.   
      
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