ORALS

SESSION: IronTuePM3-R2	Assis International Symposium (9th Intl. Symp. on Advanced Sustainable Iron & Steel Making)
Tue. 28 Nov. 2023 / Room: Dreams 2
Session Chairs: José Hamilton Tavares; Session Monitor: TBA

18:20: [IronTuePM314] OS
EFFECTS OF COMPRESSIVE STRESS ON CORRSION-PROTECTIVE QUALITY AND ITS MAINTENANCE UNDER A CORROSIVE ENVIRONMENT FOR TIN FILMS DEPOSITED BY REACTIVE HCD ION PLATING
Ken'ichi Miura¹ ; Itsuo Ishigami² ; Tateo Usui³ ; ¹Izumi Center, Osaka Research Institute of Industrial Science and Technology, Izumi, Japan; ²Osaka Prefecrure Federation of Small Business Associations, Osaka, Japan; ³Osaka University, Ibaraki, Japan;
Paper Id: 137 [Abstract]

Titanium nitride films were deposited onto SUS304 substrates under various film thickness, deposition temperatures, and substrate bias voltages. Their protective quality was evaluated by electrochemical testing in accordance with the critical passivation current density (CPCD) method. Two types of tests were employed to evaluate corrosive behavior of coated substrates: a high-temperature and high-pressure corrosion test; and a measurement of the change in anodic current density with immersion time. A scanning electron microscope was used to examine surface morphology and fractured cross-sections of the films. Residual stress in the films was determined by the sin2 method. An increase in film thickness engendered high protective quality. That protective quality was improved with increasing deposition temperature; micrometerorder pores were observed on all parts of films deposited at lower deposition temperatures, whereas few pores existed on films deposited at higher temperatures. This result indicates that these pores are one factor influencing overall protective quality. A film deposited with no substrate bias voltage displayed morphology with a typical columnar-structure; it also demonstrated complete protective quality. As the bias voltage increased, protective quality deteriorated, whereas an excess increase in the bias voltage gave rise to a slightly higher protective quality. Films with lower compressive stress had only a few pores and possessed higher protective quality, suggesting that pore formation originates in compressive stress. Corrosion tests indicated that the coated substrates corroded more rapidly as compressive stress in the film increased. The effect of compressive stress on maintenance of corrosion-protective quality was treated quantitatively. The rate of increase in the exposed area of the substrate was estimated from variation of an anodic current density with immersion time. This evaluation indicates that a decrease in compressive stress contributes greatly to maintenance of protective quality.

References:
[1] Ken'ichi Miura, Itsuo Ishigami, Masato Kuno and Hiroyuki Kaneda: Grain Size Dependence of Hardness of TiN Films Deposited by Reactive HCD Ion Plating (in Japanese), Journal of Japan Institute of Metals, 59(1995), pp.303 - 311. [2] Ken'ichi Miura, Itsuo Ishigami and Tomoyuki Mizukoshi: Effects of Preparation Conditions on Chemical Composition and Hardness of Titanium Nitride Films Prepared by Reactive HCD Ion Plating (in Japanese), Journal of Japan Institute of Metals, 63(1999), pp.949 - 958. [3] Ken'ichi Miura, Itsuo Ishigami and Tomoyuki Mizukoshi: Mixing of Oxygen in Titanium Nitride Films Formed by Reactive HCD Ion Plating (in Japanese), Journal of Japan Institute of Metals, 64 (2000), pp.508 - 517. [4] Ken'ichi Miura and Itsuo Ishigami: Effect of Residual Stress on Lattice Parameter and Hardness of Titanium Nitride Films Deposited by Reactive HCD Ion Plating (in Japanese), Journal of Japan Institute of Metals, 65 (2001), pp.972 - 980.