How to Select Tin Oxide Electrodes or Molybdenum Electrodes Based on the Glass to Be Produced

There are many kinds of glass melts with different melting temperature and raw material components, which have different requirements for the electrode during melting. Therefore, special materials of electrode will be customized for this process. 

The melting point of most glass lies around 1,400~1600℃, depending on its composition. As a result, glass production requires a great deal of heat energy. Regenerative glass furnaces, recuperative glass furnaces, oxygen-fuelled glass furnaces as well as all-electric glass furnaces are the most popular furnaces. Usually, electrodes made of molybdenum metal and tin oxide are enough for these furnaces. 

Tin oxide electrodes can be used to melt almost all different glass at temperatures below 1450°C. Due to the demand for special glass production, they can also be used in glass melting furnaces above 1650°C. While molybdenum electrodes are commonly used for melting soda-lime glass and high borosilicate glass, with a higher applying temperature and surface current intensity. Their operating temperatures can be as high as 2000 ℃.

Molybdenum electrode is made of pure molybdenum material. Its surface temperature is generally higher than the temperature of the molten glass by 200°C in the glass furnace. If the surface temperature reaches 2000℃, the loss of the electrode is also greater. Generally speaking, surface temperature is related to the current density. The greater the surface current density, the faster the loss. The most suitable surface current density should be 1.0～0.7A/cm2. When the furnace requires higher glass quality and longer serving life, lower surface current density should be required. The maximum surface current density of the electrode should not be greater than 2A/cm2. Usually, the consumption of electrode is relatively small in glass or E glass with higher iron content.

Tin oxide is a high-quality refractory material and is non-conductive. Various conductive additives are added to the tin oxide powder to become a tin oxide electrode after sintering, which has good conductivity after the temperature is higher than 1000 ℃. Tin oxide electrodes are generally recommended to be used in glass furnaces at a temperature not higher than 1450 ℃. When the rare earth glass is melted higher than 1650℃, it can still maintain very good performance, but the service life will be shortened accordingly.

The correct use of molybdenum electrode and tin oxide electrode is critical to furnace design and manufacturing engineers. The value of the electrode is often only 10% to 15% of the value of the furnace, but for glass furnaces of different glasses and designs, the correct application of the electrode is the decisive factor for the success of the furnace.

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