ZIRCONIUM NITRIDE BASED TRANSPARENT HEAT MIRROR COATINGS - PREPARATION AND CHARACTERIZATION

Transparent heat mirror coatings based on thin zirconium nitride films have been prepared using reactive magnetron sputtering. The zirconium nitride films have been sandwiched between layers of zirconium oxide. It is shown that the multilayer configuration ZrO2/ZrN/ZrO2 can be us ed as solar control coatings on window glazings. A visible transmittan ce of around 60% and a thermal emittance lower than 0.2 can be obtaine d, and the ratio between visible transmittance and total solar transmi ttance can be as high as 1.7. The influence of substrate temperature o n the optical quality of the films is evaluated and it is shown that t he crystal structure of the first oxide layer is of importance for the optical quality of the nitride. The influence of preparation conditio ns and accelerated ageing has been modelled using the optical constant s of thin films prepared under identical conditions as the films in th e multilayer coatings.