Glass or ceramic cell with internal reflecting coating - which is bonded to cell to prevent peeling, esp. when the coating is exposed to corrosive gases in gas analysis appts.

摘要

The internal wall of the cell has a reflecting coating of Au or Pt which is bonded in the surface of the cell wall. The cell wall is pref. first coated with Cu which forms a bond with the wall; and then the Cu is covered by the layer, followed by heating to cause diffusion or alloying between the Cu and the Au or Pt. In one pref. process, a thin layer of Cu is formed by vacuum vapour deposition or cathodic sputtering; and the Cu is covered by a colloidal suspension of the noble metal followed by baking to form the bond. In an alternative process, the cell wall is first etched with HF to produce roughness, followed by the direct application of the colloidal suspension of the noble metal onto the wall without using the layer of Cu. Used e.g. in cells for infrared or ultraviolet gas analysis, where corrosive gases are fed through the cell and can cause peeling of the layer by penetration underneath this layer. The invention stops such peeling.