Electroless Nickel And Ion-Plated Protective Coatings For Silvered Glass Mirrors

Two methods of protecting second surface silvered glass mirrors from environmental degradation have been evaluated. One method employed silver mirrors overcoated with Al, Ni, 304 stainless steel, Cr, or an Al/Cu alloy that were prepared by ion-plating. The other method used conventional wet process silver/copper mirrors protected with a thin electroless nickel coating. These mirrors were compared with conventional paint backed silver/ copper mirrors after exposure. to elevated temperatures and water vapor. The electroless nickel coated mirrors showed consistently more resistance to these stresses than either the conventional or ion-plated mirrors suggesting that they may prove more durable for field service.*