High-Purity Quartz Tubes: Usage & Safety Tips in Furnaces

Quartz tubes start softening when exposed to temperatures above 1265°C. For safety and optimal performance, it’s recommended not to exceed a furnace temperature of 1210°C for more than three hours. The temperature resistance of quartz tubes is directly related to their purity—the higher the purity, the better the heat resistance.

Key Recommendations for Using Quartz Tubes in Tube Furnaces

1. Use of Ceramic Plugs:
   • It is essential to place ceramic plugs inside the quartz tube when heating in a tube furnace. This helps maintain an even thermal field and improves heat treatment results. Install two plugs on each side (a total of four plugs).
   • This setup helps prevent the O-ring seals in the flanges from deforming due to heat. Note that O-ring seals cannot withstand temperatures exceeding 260°C, which may compromise the seal.
2. Hydrogen Gas Safety Precautions:
   • Avoid introducing hydrogen gas into the furnace unless its concentration is well below the explosive limit. If hydrogen gas must be used, ensure thorough safety measures and avoid personnel presence on either side of the furnace during gas introduction.
   • Stainless steel tubes are recommended over quartz for hydrogen use due to their higher thermal conductivity. Water cooling is needed at both ends of the stainless steel tube to prevent overheating of the silicone O-ring seals.
3. Material Handling Inside the Furnace:
   • Ensure no reactive substances remain inside the quartz tube that might interact with SiO₂, maintaining a clean environment.
   • When heating materials, use a boat-shaped crucible rather than placing materials directly on the quartz tube to extend its lifespan.

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