How to Balance the Diameter and Current Density of Molybdenum Glass Melting Electrode?

Molybdenum is the ideal material for glass melting electrodes due to its good electrical and thermal conductivity, excellent corrosion and creep resistance. Generally, the diameter of electrode ranges from 10mm to 120mm, which is mainly depended on the current density.

To melt borosilicate glass, the most common diameter of electrode is 50mm. When the current density ranges between 0.42 A/cm2 and 0.49A/cm2, the electrodes do not need to be moved forward as they have no consumption. For vertical electrodes, whether the electrode to be continued in the furnace required to be evaluated when the density value reaches 0.8A/cm2. 

For electric furnaces with a long furnace age (more than 4 years), the current density increases as the electrode is consumed. If the electrode is not ready to continue, the current density needs to be controlled at a lower value. Normally, there is little consumption for moly electrode when the current density runs below 0.6A/cm. 

When molybdenum glass melting electrode is used to smelt soda lime glass and other low-resistance glasses that have a resistivity lower than 15Ω·cm, it is difficult to control the current density below 0.6A/cm2 because of its low viscosity and low resistivity. Therefore, electrodes with φ75mm diameter are often used. In addition, the electrodes will also have different degrees of loss during operation, so the electrodes must be made continuous. From the perspective of operating cost, the plate electrode consumes less and is more suitable for electrofusion of soda lime glass.

The conductive distance of the electrode has a direct impact on the service life of moly electrode. If the distance is too close, it will be in a low-voltage and high-current state during operation. This local high power will not only reduce the life of refractory materials, but also increase the electrode loss and bring defects to the product. In addition, if the current density value is too large, the destructive effect on the electrode will be even greater. Within the allowable range of voltage that the electric melting furnace can withstand, the high-voltage and low-current operation scheme can improve efficiency on conditions that it must meet the requirements of melting process and operational safety.

If you have any inquiry of molybdenum electrode, please feel free to contact us:

Email: sales@chinatungsten.com/sales@xiamentungsten.com

Tel.: +86 592 5129696/+86 592 5129595

Fax: +86 592 5129797

Scan QR code of Chinatungsten Wechat platform to follow up the daily latest price and market of tungsten, molybdenum and rare earth.

Current Density Is Important to Service Life of Molybdenum Electrode

Current density is one of the most important parameters for designing the glass electric melting furnace, which is also a very important factor that affects the service life of molybdenum electrode. Controlling the right current density helps the extension of electrode’s working life. 

Molybdenum electrodes are simultaneously subjected to the combined effects of electricity, high temperature and corrosion during smelting. Chemical corrosion and electrochemical corrosion are unavoidable. The experimental analysis shows that the corrosion rate of the electrode is closely related to the current density in the same molten glass.

When the current density is low, the temperature of the moly electrode is lower than the molten glass’s. As the current density increases, the temperature of the electrode reaches or even exceeds the temperature difference of the molten glass. If the relationship between the corrosion rate and the temperature in the medium alkali glass is quantitatively detected, it will be found that the higher the temperature, the greater the corrosion rate. Based on the results of various research experiments, it can be judged that if the current density increases and the temperature of the electrode area rises, it will affect chemical reaction process of the electrode, change flow state of the glass in the electrode area, and finally corrode molybdenum electrode rapidly.

The temperature of electrode is proportional to the current density, and its critical current density value can be 0.4-0.7A/cm2, according to a large number of production experiments. Under this current density, 8-10mm thickness of electrode can work for more than 2 years. The maximum allowable current density is about 2-3A/cm2. In order to make the corrosion less, if it is alkali-free glass, the current load should be smaller. When the current density is less than 1.00A/cm2, the molybdenum electrode can better resist the corrosion of the molten glass. On the contrary, when the current density is higher than 1.00A/cm2, the corrosion rate will naturally increase, and bubbles will be generated on the interface between the molybdenum electrode and the molten glass.

In short, controlling the current density reasonably in glass melting is essential for the application of molybdenum electrode. Chinatungsten Online provides high-purity and high-quality molybdenum electrode worldwide. 

If you have any inquiry of molybdenum electrode, please feel free to contact us:

Email: sales@chinatungsten.com/sales@xiamentungsten.com

Tel.: +86 592 5129696/+86 592 5129595

Fax: +86 592 5129797

Scan QR code of Chinatungsten Wechat platform to follow up the daily latest price and market of tungsten, molybdenum and rare earth.