Glass was once prized as a luxury commodity, associated with intricate decorations and clear glazing in wealthy households. This was symptomatic of extensive production costs and limited knowledge of how clear glass was produced. Yet – as with many expensive goods – human industrial achievements unlocked glass production at mass scales, making it accessible to a wide consumer base. Electric glass melting furnaces were essential to this paradigm shift.

Until the 1950s, most industrial-scale sheet glass production was carried out using traditional coal or gas-fired ovens. Engineers looking to leverage the growing power of electricity to improve process efficiency eventually turned to molybdenum glass melting electrodes.

The inherent thermodynamic and electrical properties of molybdenum made it the go-to solution for glass melting electrodes, and, although alternatives like platinum and tin oxide have emerged in time, molybdenum remains the material of choice for glass melting electrodes in both electric and electrically-assisted fossil fuel furnaces.

Why Use Molybdenum Electrodes to Melt Glass?

Molybdenum (Mo) belongs to the refractory metals group with a nominal melting point of 2620°C (4748°F) and electrical conductivity in the region of 1.914×107σ. Its good electrical and thermal conductivity, coupled with excellent corrosion and creep resistance, makes molybdenum the ideal material for glass melting electrodes that are routinely subjected to oppressively high temperatures and corrosive molten glass. High purity (>99.95%) molybdenum with controlled microstructures yield glass melting electrodes of exceptional quality and extended service life. The result is a low-maintenance glass melting furnace with reduced cost of ownership over many years of service.

For more aggressive melts, it is preferable to use a premium molybdenum alloy rather than the pure metal as harsh refining agents like antimony oxide can damage standard glass melting electrodes. Adding small concentrations of zirconium in molybdenum alloys, dramatically improves corrosion resistance and empowers glassmakers in challenging industries such as fiber glass manufacturing and photovoltaics production.

Molybdenum alloys also enable greater engineering flexibility, providing furnace designers with a supreme material that can be integrated into production in a range of configurations. Glass melting electrodes in modern furnaces can be top-, side-, or bottom-entry, or vertically suspended as gobbers and stirrers.

Applications of Molybdenum-Made Glass

Glass made using molybdenum electrodes surrounds us every day. From drinking glasses to food containers and tableware, insulation to window glazing in our homes, offices, and vehicles; electronic panels for displays and solar cells; as well as a wide variety of industrial and scientific containers.

At H.C. Starck Solutions, we support a wide range of business outlets with precision-made refractory solutions for proprietary glassmaking pipelines. Our scope of work is practically limitless, covering all areas of glass production from high-performance quartz manufacturing to vaccine vials as part of the global effort to combat COVID-19.

Contact us today if you would like to learn about business opportunities using our tailormade molybdenum glass melting electrodes.