Glass melting construction materials

Large quantities of refractory materials are required for the construction of melting furnaces. The suifaces of the tank furnaces in contact with the glass melt are lined with melt cast or isostatically pressed bricks (e.g. of zirconia) and the cover over the glass tanks is manufactured from mullite or silica materials. 

Construction Materials/Refractories. The refractory materials serve three purposes They contain the glass melt, provide thermal insulation and heat transfer as needed, and act as key structural elements of the tank. The refractories are generally held in place by an open steel framework, but much of the mechanical load is born by the refractory materials themselves. Crowns are often self-supported refractory structures. The refractories must withstand or resist high temperatures, heavy loads, abrasion, and corrosion. 

In materials that are often used in construction-wood, concrete and steel—there is still an enormous variation in modulus, by a factor of 15 or so. You can also see that most polymer materials, at least in their usual melt processed form, are not very stiff at all, polyethylene having a modulus of about 150 MPa, while even a glassy polymer like atactic polystyrene has a modulus of only about 3000 MPa (about l/20th that of window glass). 

Most enamels melt at ca. 1250°C. Only a few difficult to melt frits require temperatures of ca. 1350°C. The raw materials are smelted, but not, as in glass manufacture, refined. Fig. 5.4-1. schematically. shows the construction of drum and flame-heated tank furnaces. 

Progress in glass manufacture during the nineteenth century was made by the use of selected and purified raw materials and the construction of new and better melting furnaces. 

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