How to Make a Great Glass-to-Metal Sealing Product

A few techniques to enhance GTMS products

Tube seals are commonly used in glass to metal seal (GTMS), and are composed of three parts: housing, pin, and glass. Under certain conditions of temperature and atmosphere, the glass body acts as a good insulating material to seal the housing and the pin. The sealing glass has a low air permeability (up to 10 Pa m/s), good thermal shock resistance, pressure resistance (pressure value up to 340 MPa), corrosion resistance and other properties.

There are few notable things for GTMS:

• The thermal expansion coefficients of glass and metal should be relatively close enough to reduce the internal stress of the sealing parts. However, due to the different application and sealing method, the different thermal expansion coefficients may also be wanted under certain circumstances.
• The melting point of metal is higher than the softening temperature of glass.
• The metal is required to have good plasticity and ductility.
• Glass, metal must be cleaned, otherwise it will cause air leakage or burst at the seal.
• Before some metals or alloys are sealed with glass, they need to be degassed by hydrogen.
• The sealing parts should be annealed to reduce stress.

A good GTMS product should have great thermal stability, thermal shock resistance, electrical insulation, and low air permeability. A good belt furnaces can prevent a lot of the problems above. Our HSA series GTMS furnace is great at:

• Transmission accuracy (2%).
• Temperature uniformity (± 2 °C).
• Control accuracy (± 1°C).
• Atmosphere and dew point control. Perform a consistent sealing up to 400mm belt width. Products will have an excellent oxidation consistency and a perfect product performance consistency.
• Scientific cooling control. Prevent crack and fragment. Also a better annealing that removes internal stress to prevent cracking in the subsequent process.