Fabrication and Ultraviolet Irradiation Hardening of Sol-Gel-Derived  Hafnia Films

Tomoko TAKAHASHI; Toshikazu NISHIDE

doi:10.14852/jcersjsuppl.112.0.S234.0

Journal of the Ceramic Society of Japan, Supplement 112-1, PacRim5 Special Issue

Session ID : 3

DOI https://doi.org/10.14852/jcersjsuppl.112.0.S234.0

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Host: The Ceramic Society of Japan

Co-host: Iketani Science and Technology Foundation, International Ceramic Federation, Commemorative Organization for the Japan World Exposition '70, The American Ceramic Society, The Australasian Ceramic Society, The Chinese Ceramic Society, The Korean Ceramic Society, Joint Research Consortium of Synergy Ceramics/Fine Ceramics Research Association, Nanotechnology Researchers Network Center of Japan, The Special Coordination Funds for Promoting Science and Technology, Japan National Tourist Organization, Aichi Prefectural Government, CASIO SCIENCE PROMOTION FOUNDATION, DAIKO FOUNDATION, Nagoya Convention and Visitors Bureau, The Asahi Glass Foundation, The Kao Foundation For Arts And Sciences, The Murata Science Foundation, The Ogasawara Foundation for the Promotion of Science & Engineering, ASAHI GLASS CO., LTD. Research Center, CENTRAL GLASS CO., LTD., ELECTRIC GLASS INDUSTRY ASSOCIATION OF JAPAN (EGAJ), Hattori Company, Ltd., Hitachi Research Laboratory, Hitachi, Ltd., HOYA CORPORATION, INAX Corporation, ITOCHU CERATECH CORP., Japan Cement Association, KYOCERA Corporation, KYUSHU REFRACTORIES CO., LTD., MINO CERAMIC CO., LTD., Murata Manufacturing Co., Ltd., NGK INSULATORS LTD., NGK SPARK PLUG CO., LTD., NICHIAS Corporation, NIKKO COMPANY, Nippon Electric Glass Co., Ltd., Nippon Sheet Glass Co., Ltd., NORITAKE CO., LIMITED, Tokuyama Corporation, TOTO LTD.

Papers

Fabrication and Ultraviolet Irradiation Hardening of Sol-Gel-Derived Hafnia Films

Tomoko TAKAHASHI, Toshikazu NISHIDE

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Keywords: Hafnia, UV irradiation, Hardening, Temperature programmed desorption, Sol-gel process

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Abstract

This paper describes the ultraviolet (UV) irradiation hardening of sol-gel-derived hafnia films containing oxalic acid as an organic ligand. Colloidal and viscous hafnia sols were prepared by treating hafnium hydroxide with an oxalic acid aqueous solution. The transparent gel films were hardened to scratch hardness of over 9H by UV irradiation using a high-pressure mercury lamp for 2.5-10 min. The films showed a maximum water droplet contact angle of 89°, indicating that the hardened films displayed hydrophobicity similar to that of fired hafnia films obtained at 550°C. The bonding structure of the oxalato ligands was analyzed on the basis of their FTIR spectra. It was found that an oxalato ligand bridges to Hf ions in a bond involving two metal ions. The hardening process of the hafnia gel films was investigated using the thermal programmed desorption (TPD) technique. Species of C, O, CO and CO₂ evolved from the oxalato ligands in a temperature range of 200-400°C. The amount of CO and CO₂ decreased markedly after UV irradiation, indicating that the oxalato ligands were eliminated by UV irradiation, resulting in pencil hardness of over 9H.

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