Glass In Contact With Mould Materials For Container Production

The high-temperature behaviour of various mould materials and coatings was studied by subjecting to cyclic temperature changes in oxidizing atmosphere and to contact with a soda-lime-silica glass melt at 1050 deg C. In a cyclic immersion test the influence of the type of mould material, type of coating, surface roughness and of temperature on the tendency of sticking to the glass melt was investigated. In the base materials the corrosive attack mainly occurred along grain boundaries and in softer phases of the materials, starting from the surfaces. Defects in the moulded glass surfaces, worn-off particles from the moulds and microcracks due to adhesion were found to depend on the type of oxide layer formed on the mould surface.