Session: HT-07-02: Design and Analysis of High Pressure Hydrogen Equipment - 2

Paper Number: 80128

80128 - Evaluation of the Hydrogen Barrier Properties of Chromium Oxide Films Deposited on SUS304 Austenitic Stainless Steels 

Abstract

Austenitic stainless steels including SUS304 are candidate materials for the various facilities for high-pressure gaseous hydrogen, such ashydrogen station containers and piping. We have developed the passivation films mainly composed of chromium oxide in order to prevent hydrogen permeation into SUS304 and investigated the hydrogen barrier properties based on the hydrogen gas permeability test and the slow strain rate tensile (SSRT) test. The passivation films with a maximum thickness of 300 nm was formed on the surface of hot-rolled SUS304 (Ni equivalent 22.4) by a series of wet processing steps such as electro-polishing, chemical oxidation, cathode precipitation of chromium and passivation immersion. Cross-sectional views of TEM observation suggested that the film was amorphous-like-structure including many independent voids with a size of 10 to 20 nm. The hydrogen gas permeability test was performed in a hydrogen gas pressure of 400 kPa at 573 K, 673 K, and 773 K. The estimated hydrogen transmittance of SUS304 substrate with passivation coating was 2.8×10^-13 mol / (m･s･Pa) at 773 K, while that without passivation coating was 2.2×10^-11 mol / (m･s･Pa) at 773 K. SSRT test was performed in 110 MPa hydrogen and nitrogen gas atmosphere at room temperature, and strain rate was 4.17 × 10^-5 s^-1. The fracture surface of the specimen without passivation coating showed brittle and RRA was 0.61. On the other hand, the fracture surface of the specimen with passivation coating showed typical ductile such as dimple structure and relative reduction rate (RRA) was 0.88. As the passivation films did not peel, adhesion between passivation film and SUS304 surface seems to be well. From these considerations, we anticipate the developed passivation film can inhibit hydrogen embrittlement of SUS304.

Presenting Author: Kazuyoshi Kawami Asahimekki Co. Ltd

Presenting Author Biography: Kazuyoshi.kawami<br/><br/>Graduated from Department of Industrial Chemistry, Faculty of Engineering, Tottori University<br/>Joined Nihon Yushi Co., Ltd. and belonged to the Research and Development Department of Taketoyo Plant<br/>Retired from Nihon Yushi Co.<br/>Joined Kiko Electric Co.<br/>Resigned from Kiko Electric Co.<br/>Joined Asahi Mekki Corporation and belonged to the Engineering Department.<br/>Joined Asahi Plating Co.

Authors:

Kazuyoshi Kawami Asahimekki Co. Ltd
Atsushi Kinoshita Asahimekki Co. Ltd
Hisashi Yamanaka Asahimekki Co. Ltd
Yoji Fukuda Asahimekki Co. Ltd.,
Hirotoshi Enoki AIST
Takashi Iijima AIST
Seiji Fukuyama eSep Inc
Ryo Tsukane TIIT
Toshiyuki Tanaka TIIT
Takeshi Fukutani TIIT
Yoshiaki Suzuki TIIT
Hiroyasu Tamai TIIT
Takashi Ogi Hiroshima Univ.,
Motonori Tamura Yokohama professional engineers office