Papers by Keyword: Functional Film

Abstract: Shot peening is widely utilized to improve the fatigue property of mechanical parts for transportation equipment such as cars and airplanes. Also, this technology is being applied as a film-forming technology in order to improve surface quality. The authors have recently proposed new joining methods using shot peening, shot lining. In this method, the metals are bonded with the dissimilar metal by applying plastic deformation and the pressure. The thin foil can be joined to the substrate surface by the pressure generated by the hit of the shots. In this study, the formation of an Fe-Al intermetallic compound film on high-speed tool steel by shot lining and heat treatment was investigated. In the experiment, a centrifugal-type peening machine with an electrical heater was employed. The shot medium was high-carbon cast steel. The substrate was a commercial high-speed tool steel JIS-SKH51, and the foil was commercially available pure aluminium. The shot lining process of tool steel with an aluminium foil was carried out at 573K in air using a peening machine. Heat treatment was performed at diffusion temperatures from 923 to 1573K in vacuum. The lined substrates exhibited a harder layer of aluminium-rich intermetallics in the diffusion temperature range of 923 to 1173K. When the temperature of the lined substrates was more than 1273K, the surface was covered with thicker and highly anticorrosive layers of iron-rich intermetallics. We found that the present method could be used for the formation of functional films on high-speed tool steel.

Abstract: The slot coating process in the production of polymer films has a wide range of applications. However, the process cannot be systemized. This study used the computational fluid dynamics software Polyflow to analyze the slot coating process and investigate the influence that the process parameters have on the characteristics of thin-film coating to reduce the time and cost consumed in the experimental methods. The rheological characteristics of the non-Newtonian fluid used in this study were first identified by conducting experiments, and then configured in the simulation software for fitting with mathematical models. In addition, the models of the slot coating process were constructed, and the Arbitrary Lagrangian-Eulerian (ALE) calculation methods were then used in the Polyflow software. The simulation results were then compared to the experimental results and the findings reported in relevant literature, to determine the influence that the process parameters have on the characteristics of thin-film coating. The simulation results were represented graphically in a coating window plot. The comparison results indicate that the viscosity-shear rate characteristic of the material in the shear rate range of optical film coating is an excellent fit for the Cross Law. When the coating speed is too high or the amount of fluid supply is insufficient, phenomena such as break lines, uneven thickness, and air entrainment can occur.

Abstract: The goal of this work was to establish the compatibility of mat glazes with functional films known to render the surfaces with self-cleaning or easy-to-clean properties. Glazes with wollastonite, pseudowollastonite, diopside and zircon as the main crystalline phases in the surfaces were coated with fluoropolymer as well as ceramic, sol-gel derived titania and zirconia films. The glazes were soaked in typical detergent solutions used in everyday life up to four days. The surface roughness was measured with confocal optical microscope and the surface was imaged and analyzed with SEM/EDXA. When applied on wollastonite and pseudowollastonite containing glazes the functional films readily reacted in water solutions by pitting of the surface in the vicinity of the crystals. The ceramic titania and zirconia films showed better chemical resistance on wollastonite –free glazes, while the fluoropolymer film corroded in the most alkaline environments. The results indicate that functional films could be used also on rough surfaces without markedly affecting the surface topography. However, the films should be applied only on glazes with an excellent chemical resistance.