Common Heating Elements Used in Glassblowing Furnaces

Glassblowing furnaces require heating elements that can withstand high temperatures, offer rapid heating, and maintain long-term stability. The most commonly used materials include:

1. Silicon Carbide (SiC) Heating Elements

Features: High-temperature resistance (up to 1500°C or more), excellent oxidation resistance.
Applications: Widely used in medium-to-high-temperature glassblowing furnaces. However, resistance increases with aging during prolonged high-temperature use.

2. Molybdenum Disilicide (MoSi₂)

Features: Exceptional oxidation resistance, with operating temperatures reaching up to 1800°C. Forms a protective layer of silicon dioxide at high temperatures.
Applications: Ideal for high-end glass processing or furnaces requiring extreme temperatures.

3. Nickel-Chromium Alloy (e.g., Nichrome)

Features: Economical, withstands temperatures up to ~1200°C, good oxidation resistance. However, may deform under continuous high-temperature conditions.
Applications: Suitable for small-scale or low-temperature glassblowing furnaces, such as for soft glasswork.

4. Platinum or Platinum-Rhodium Alloys

Features: Excellent corrosion and thermal stability. Platinum has a melting point of 1770°C.
Applications: Used in specialized applications such as optical glass manufacturing or laboratory-grade equipment. Cost is significantly higher.

5. Tungsten/Molybdenum Metals

Features: Extremely high melting points (tungsten: 3422°C). Require inert gas protection to prevent oxidation.
Applications: Common in vacuum or controlled atmosphere high-temperature furnaces.

6. Ceramic Heating Elements (e.g., PTC Ceramics)

Features: Safe, self-regulating temperature control. Limited in power and temperature range.
Applications: Used in compact devices that require precise low-temperature control.

Selection Considerations

• Temperature Requirement:
  • Soft Glass (600–900°C) → Nichrome is typically sufficient.
  • Borosilicate or Hard Glass (1000°C and above) → SiC or MoSi₂ elements are more appropriate.
• Cost Sensitivity:
  • Platinum-based elements are costly.
  • Silicon carbide provides high performance at a more economical price.
• Atmosphere Conditions:
  • For oxidizing environments, SiC and MoSi₂ are preferred.
  • For inert or vacuum conditions, consider tungsten or molybdenum elements.

Modern furnaces may also integrate hybrid heating systems or composite element designs to achieve optimal performance, efficiency, and lifespan.