Properties of sol-gel derived scratch-resistant nano-porous silica films by a mixed atmosphere treatment

A strengthening mechanism for sol-gel derived nano-porous silica films was studied. The silica films were prepared with the dip method from two-step c atalyzed silica sols and treated in a mixed atmosphere of ammonia and water vapor afterwards. Properties of the films were analyzed by using atomic fo rce microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), ellip sometry and an abrasion test, respectively. The experimental results have s hown that the two-step catalysis strengthens the films and the scratch resi stance of the silica films is further improved after treatment in the mixed gas. The increase in strength is attributed to the cross-linking of silica particles by randomly branched or/and entangled linear chains in the sols, more Si-O-Si bonds formed by the mixed gas treatment and structural change s in the silica films. (C) 2000 Elsevier Science B.V. All rights reserved.