SHIELDING PROPERTIES OF OPTICAL COATINGS OBTAINED ON GLASS AND POLYMER MATERIALS

Abstract

Coatings In₂O₃ + SnO₂ (ITO) and ZrO₂ – Ni – ZrO₂ – Cu – Ni – ZrO₂ deposited on glass and polymer substrates, are presented. Their shielding properties in the optical and radio frequency wavelength ranges have been studied. Samples with coatings 120(In₂О₃ +SnО₂ ) and 90ZrO₂ /8Ni/90ZrO₂ /22Cu/5Ni/35ZrO₂ have good shielding properties (98 % of electromagnetic emission is reflected in the range of 0.7…17 GHz). ITO-coating has low surface resistance of 8…9 ohms/ square per square in combination with high light transmittance (T ~ 90 %). However, in order to achieve these properties one needs to heat the substrate up to 300…400 °C. The coating 90ZrO₂ /8Ni/90ZrO₂ /22Cu/5Ni/35ZrO₂ has surface resistance of 2…3 ohms/square per square and light transmittance of about 60 %. These values have been obtained without heating of the substrate and, as a consequence, this coating may be deposited on temperature-sensitive materials such as polycarbonate. Moreover, since 90ZrO₂ /8Ni/90ZrO₂ /22Cu/5Ni/35ZrO₂ coating is a multilayer coating containing layers of pure metals that have high electric conductivity and magnetic permeability and ZrO₂ layers with high dielectric permeability it has higher shielding effectiveness than ITO alloy coating. It has been demonstrated that ZrO₂ – Ni – ZrO₂ – Cu – Ni – ZrO₂ coatings may be used for protection of display screens since they comply with the requirements of screens of information displays devices.