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Adhesive Behaviors of the Aluminum Alloy-Based CrN and TiN Coating Films for Ocean Plant
Murakami, Ri-Ichi,Yahya, Syed Qamma Bin Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.2
In the present study, TiN and CrN films were coated by arc ion plating equipment onto aluminum alloy substrate, A2024. The film thickness was about 4.65 ${\mu}m$. TiN and CrN films were analyzed by X-ray diffraction and energy dispersive X-ray equipments. The Young's modulus and the micro-Vickers hardness of aluminum substrate were modified by the ceramic film coatings. The difference in Young's modulus between substrate and coating film would affect on the wear resistance. The critical load, Lc, was 75.8 N for TiN and 85.5 N for CrN. It indicated from the observation of optical micrographs for TiN and CrN films that lots of cracks widely propagated toward the both sides of scratch track in the early stage of MODE I. TiN film began to delaminate completely at MODE II stage. The substrate was finally glittered at MODE III stage. For CrN film, a few crack can be observed at MODE I stage. The delamination of film was not still occurred at MODE II and then was happened at MODE III. This agrees with critical load measurement which the adhesive strength was greater for CrN film than for TiN film. Consequently, it was difficult for CrN to delaminate because the adhesive strength was excellent against Al substrate. The wear process, which the film adheres and the ball transfers, could be enhanced because of the increase in loading. The wear weight of ball was less for CrN than for TiN. This means that the wear damage of ball was greater for TiN than for CrN film. It is also obvious that it was difficult to delaminate because the CrN coating film has high toughness. The coefficient of friction was less for CrN coating film than for TiN film.
Fatigue Behavior of Plasma Radical Nitrided SCM435 Steel in Super-Long Life Regime
Nu Yan,Ri-ichi Murakami,Insup Lee 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.4
Fatigue behavior in a super-long life regime was investigated for plasma radical nitrided JIS SCM435 steels at room temperature in air. Specimens were nitrided at the 723 K and 823 K for 3 h and at 773 K for 1 h, 3 h, and 5 h. The fatigue strengths of the nitrided specimens were greater than that of the un-nitrided specimen. However, the fatigue strength and fracture mechanism of the nitrided specimens were markedly influenced by nitriding temperature and time. Both surface cracking and subsurface cracking, e.g. fish-eye fractures, were observed in the specimens subjected to the nitriding conditions. Hardened layers and compressive residual stress were formed on the specimen surfaces by nitriding, which led to an improvement of the fatigue strength and determined the initiation type of the fatigue cracking. Stress intensity factor at crack initiation was evaluated in fish-eye type fractures. As a result, the stress intensity factor range in the facet area indicated a constant value, approximately 3.5 MPa·m^(1/2), regardless of the fatigue life.
윤한기(Han-Ki Yoon),Ri-ichi Murakami 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The development of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and EMI. ITO and IZO films of transparent conducting thin films were produced onto plastic and glass substrates at room temperature by the inclination opposite target type DC magnetron equipment, which a metallic In2O3+SnO2 and In2O3+ZnO alloy target was used. The effects of electric properties, electromagnetic wave shielding effectiveness, gas barrier deposited SiO and SiON were investigated. In the result, the ITO thin films deposited at room temperature showed the most electromagnetic shielding effectiveness and we found that effect of the gas barrier deposited SiO and SiON in IZO thin film is very important parameter.