Sciencemadness Discussion Board

making fused quartz at a lower tenperature using silica gel

John paul III - 19-1-2021 at 19:17

Here's an idea: quartz requires 1700c to melt which is unachievable for an amateur, but fused quartz becomes syrupy at 1200°C, where a lot of kilns get up to. Could I cheat the system by using silica gel melted at 1200°c to make fused quartz glassware? Or is the silica gel not actually pure amorphous sio2?

[Edited on 20-1-2021 by John paul III]

[Edited on 20-1-2021 by John paul III]

rockyit98 - 19-1-2021 at 20:48

there is no need. just buy it, not that expensive.UV quartz sleeve / test tube. if you need fused quartz tube, UV water sterilizers have them just be careful it filled with toxic Hg vapor !more thin but long ones can be found on not working Quartz tube heaters. thin yet shorter ones are in burnt halogen flood lamps (500W to 1kW).

just because you asked, NO! silica gels are not pure .they explode when heated and some may contain toxic Co salts! also, depend on manufacturing lot of Na impurities can be theory fine SiO2 powder can be used to make stuff by sintering at 900°C, 1000°C, 1100°C, and 1250°C.

unionised - 20-1-2021 at 04:10

Quote: Originally posted by John paul III  
...fused quartz becomes syrupy at 1200°C, ...

[Edited on 20-1-2021 by John paul III]

Are you sure?
"The heat required is needed to get the Quartz glass up to 1750 to 1800°C working temperature."
"Softening Point 1683°C"

Junk_Enginerd - 25-1-2021 at 06:01

A major reason for borosilicate and soda glass to exist is that quartz glass doesn't soften. Much like a metal, it gets hot, maybe softens a tiny bit, and then it's suddenly a liquid. Maybe in an extremely narrow temp range would it be syrupy, right before it melts.

Haven't tried it myself, but that's what I've read.

unionised - 25-1-2021 at 10:14

Quartz can be worked like glass, but it has a much narrower (and hotter) temperature range.

UC235 - 25-1-2021 at 17:26

A similar idea is how the material called Vycor is produced. A very alkali-rich borosilicate glass is extensively leached with acid leaving behind porous almost pure silica. It's then heated in a kiln until it starts to soften resulting in slight shrinkage and loss of porosity.