Polhe3 item material list

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  • RTV, Permatex 26C, pn 81409 High Temp RTV Silicone (Pep Boys).
  • Target cell glass properties, GE180 and Corning 1720 http://galileo.phys.virginia.edu/research/groups/spinphysics/glass_properties.html
    • Mike Souza "I have worked GE 180, Corning 1720, 1724 & 1723 along with Schott's 8252, 8253 aluminosilicates. Their prime use in industry is for lamps. It's a rugged seal to tungsten at much higher temperature then standard metal sealing glasses. In research we like it because it's low permeability to helium, its high resistivity and its dielectric properties make it a good envelope for high energy experiments. What makes it so difficult to work compared to other glasses, is its low tolerance to oxygen flames in general and its high transition temperature. So you need a high temperature reducing fire, which is why hydrogen can work nicely. With pyrex and other glasses you get to about 490 to 450c the glass is quite elastic and ready for transformation to its liquid phase. Furthermore, you have indicators like our sodium glare telling you when the glass is ready for the transition. With aluminosilicates your transition temps are from 690 to 750c. Bear in mind as well. the COE is about 44 and this is a linear number. So in the case of pyrex at 490 the COE has topped out, with soft glass the number is even lower. Aluminos are like the everready bunny its still running higher. To make matters worse, your sodium glare is non existent, because most aluminos are alkali free glasses. Reboil mostly occurs because gases can evolve within the glass and become trapped inside the bulk during the heat-up process. AT this point the oxygen from the flame makes matters worse. One thing about aluminos, that gives me greater appreciation for flamework artists is its reactivity to the flame chemistry. For most of us this is an overlooked aspect all we think about is temperature and size of a flame. This glass and color borosilicates remind us in powerful ways that there's a lot of chemistry happening when we use gases on a material that becomes soluable to the flame in its liquid phase. " from http://www.talkglass.com/forum/showthread.php?30043-aluminosilicate-glass