Paper number 209

CORROSION BEHAVIOR AND MECHANISM OF GLASS COMPOSITES IN ACIDIC SOLUTIONS

Tetsuya Sakai¹, Hidemitsu Hojo², Shigeru Ono², Kazuyoshi Arai³ and Ken Tsuda¹

1Department of Chemical Engineering, Tokyo Institute of Technology,
2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
2Department of Management Engineering, College of Industrial Engineering, Nihon University, 1-2-1 Izumi-cho, Narashino-shi, Chiba-ken 275-8575, Japan
3Department of Mechanical Engineering, College of Technology, Hosei University,
3-7-2 Kajino-cho, Koganei-shi, Tokyo 184-8584, Japan

Summary

Glass composites (GFRP) is being used for chemical plants in place of steel. Some GFRP show serious degradation by corrosion in liquid environments. The object of this study is to clarify corrosion behavior and mechanism of GFRP in acidic solutions. Test materials used were isophthalic type unsaturated polyester resin with E glass fiber chopped strand mat. The corrosive environments were mainly 30wt.% nitric acid solution. Corrosion behavior was evaluated by flexural strength, roughness, infrared spectrum analysis and corrosion depth. As the results of flexural strength for resin and GFRP, corrosion behavior was classified into four steps which corresponded to physical degradation by swelling, the formation of pits, oxidation corrosion and hydrolytic corrosion mechanisms. The resin with various additives of initiator, plasticizer and catalyst was investigated. When initiator and especially plasticizer contents were increased, pits, blisters and corrosion depth were increased. GFRP corrosion was classified into four regions of physical degradation, hydrolytic corrosion of the resin and corrosion of the resin - glass fiber interface. Moreover, the formation of pits was recognized as initial degradation and also after pitting corrosion, blister formation gave an abrupt increase of corrosion depth and a decrease of strength of the GFRP.

Keywords

GFRP, corrosion, hydrolysis, blister, pitting, isophthalic type unsaturated polyester resin, initiator, corroded layer-forming type.