Hardening of sol-gel derived hafnia gel films with a low-pressure mercury lamp

Abstract

Sol-gel derived hafnia films were hardened by ultra-violet irradiation using a low-pressure mercury lamp. The hafnia sol was prepared by the hydrolysis of hafnium hydroxide with H2O and HCOOH. The gel film was hardened to 9H as determined by the pencil test of scratch hardness immediately after UV irradiation at 16W for 40 min or longer, whereas the hardness of the films immediately after UV irradiation for less time was lower. The hardening process through UV irradiation was analyzed by temperature programmed desorption (TPD).