The Infra-red Transmission of Glass in the Range Room Temperature to 1400°

JSGT 1955 V39 T003-T015

In the investigation of the radiative heat flow in glass-melting tank furnaces, measurements of the infra-red transmission of glass at high temperatures are required; such measurements also give information on the behaviour of colouring agents at high temperatures. In this paper the methods which have been used in making these measurements are discussed, and a new apparatus is described in which the sample is contained in a platinum cell with synthetic-sapphire windows. Results are reported for a number of iron-containing glasses and for a nickel glass, at temperatures up to 1400°. In the case of the iron containing glasses, the changes in absorption, which take place with increase of temperature, suggest that the iron exists in a more highly oxidised state at high temperatures. Values are given for the "radiation conductivity" – the factor governing radiative heat transfer at high temperatures – for all the glasses measured, at 1200°. For the iron-containing glasses these values vary according to the iron content and the state of oxidation, the value for "Calorex" glass being about one-fifteenth of that for a low-iron glass.

F. J. Grove & P. E. Jellyman