• Korean Journal of Materials Research
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• v.25 no.5
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• pp.226-232
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• 2015

High temperature plasma coating technology has been applied to recover damaged aluminum dies from wear by spraying pure aluminum and alumina powder. However, the coated mixed powder layer composed of aluminum and alumina often undergoes a detachment from the substrate, making the coated substrate die unable to maintain its expected life span. In this study, in order to increase the bonding strength between the substrate and the coating layer, a pure aluminum layer was applied as an intermediate bond layer. In order to prepare the specimen with variable bond coating conditions, the bond coat layers with a various gun speed from 10 cm/sec to 30 cm/sec were prepared with coating cycle variations ranging from three to nine cycles. The specimen with a bond coat layer coated with a gun speed of 20 cm/sec and three coating cycles exhibited ~13MPa of adhesion strength, while the specimen without a bond coat layer showed ~6 MPa of adhesion strength. The adhesion strength with a variation of bond coat layer thickness is discussed in terms of coating parameters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.314-317
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• 1997

The electrical and physical characteristics of aluminum oxide and Pt thin films on it, deposited by reactive sputtering and DC magnetron sputtering respectively, were analyzed with increasing annealing temperature(400~80$0^{\circ}C$) by four point probe, SEM and XRD. Under $600^{\circ}C$ of annealing temperature, aluminum oxide had the properties of improving Pt adhesion to SiO$_2$and insulation without chemical reaction to Pt thin films and the resistivity of Pt thin films was improved. But these properties of aluminum oxide and Pt thin films on it were degraded over $700^{\circ}C$ of annealing temperature because aluminum oxide was changed into metal aluminum and then reacted to Pt thin films deposited on it. In the analysis of the thermal charateristics of Pt micro-heater fabricated on Si07/si substrate, the temperature of Pt micro-heater is up to 41$0^{\circ}C$ with the power dissipation 1.8 watts.

• Tribology and Lubricants
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• v.19 no.5
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• Corrosion Science and Technology
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• v.3 no.4
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• pp.161-165
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• 2004

Aluminum source in an Al-Fe coating reacts with molten carbonate and develops a protective $LiAlO_2$ layer on the coating surface during operation of molten carbonate fuel cells (MCFC). However, if aluminum content in an Al-Fe coating decreases to a critical level for some reasons during MCFC operation, a stable and continuous $LiAlO_2$ protective layer can no longer be maintained. The aluminum content in an Al-Fe coating can be depleted by two different processes; one is by corrosion reaction at the surface between the aluminum source in the coating and molten carbonate, and the other is inward-diffusion of aluminum atoms within the coating into a substrate. In these two respects, therefore, the decreasing rate of aluminum concentration in an Al-Fe coating was measured, and then the influences of these two aspects on the lifetime of Al-Fe coating were investigated, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.145-148
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• 2006

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed by supersonic gas jet, and generally called the kinetic spray or cold-spray. Cold-spray was developed in Russia in the early 1980s to overcome the defect of thermal spray method. Its low process temperature can minimize thermal stress and also reduce the deformation of the substrate. Most researches on cold-spray have focused on micro scale coating, but our research team tried to apply this method to macro scale deposition. The macro scale deposition causes deformation of a thin substrate which is usually convex to the deposited side. In this research, the main cause of the deformation was investigated using 6061-T6 aluminum alloy and properties of deposited aluminum layer such as coefficient of thermal expansion, Elastic modulus, hardness, electric conductivity were measured. From the result of the analysis, it was concluded that compressive residual stress was the main reason of substrate deformation while CTE had little effect.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.26-35
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• 2024

Aluminum-induced crystallization (AIC) as a route to reduce the fabrication cost and to obtain polycrystalline Si (p-Si) thin-film of large grain size is a promising alternative of single-crystalline (s-Si) substrate or p-Si thin-film obtained by conventional methods such as solid phase crystallization (SPC) and laser-induced crystallization (LIC). As the AIC process occurs at the interface between a-Si and Al thin-films, there are various process and interface parameters. Also, it directly means that there is a certain parametric window to obtain p-Si of large grain size having uniform crystal orientation. In this article, we investigate the effect of the various process and interface parameters to obtain p-Si of large grain size and uniform crystal orientation from the literature review. We also suggest the potential use of the p-Si as a virtual substrate for the growth of various compound semiconductors in a form of low-dimension as well as thin-film as a way for their monolithic integration on Si.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.1
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• pp.57-61
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• 2006

The research on surface modification technology has been advanced to improve the properties of engineering materials. Ion implantation is a novel surface modification technology that enhances the mechanical, chemical and electrical properties of substrate's surface using accelerated ions. In this research, nitrogen ions were implanted into AC7A aluminum substrates which would be used as molds for rubber molding. The composition of nitrogenion implanted aluminum and distribution of nitrogen ions were analyzed by Auger Electron Spectroscopy (AES). To analyze the modified surface, properties such as hardness, friction coefficient, wear resistance, contact angle, and surface roughness were measured. Hardness of ion implanted specimen was higher than that of untreated specimen. Friction coefficient was reduced, and wear resistance was improved. From the experimental results, it can be expected that implantation of nitrogen ions enhances the mechanical properties of aluminum mold.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.124-130
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• 2005

The research on surface modification technology has been advanced to improve the properties of engineering materials. ion implantation is a novel surface modification technology to enhance the mechanical, chemical and electrical properties of substrate's surface using accelerated ions. In this research, nitrogen ions were implanted into aluminum substrates which would be used for mold of rubber materials. The composition of nitrogen ion implanted aluminum alloy and nitrogen ion distribution profile were analyzed by Auger Electron Spectroscopy (AES). To analyze the modified surface, properties such as hardness, friction coefficient, wear resistance, contact angle, and surface roughness were measured. Hardness of ion implanted specimens was higher than that of untreated specimens. Friction coefficient was reduced, and wear resistance was improved. From the experimental results, it can be expected that ion implantation of nitrogen enhances the surface properties of aluminum mold.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.72-73
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• 2009

In this study, we fabricated of pentacene organic thin film trasistor(OTFT), which used aluminum oxide for the gate insulator on glass substrate. Aluminum oxide for OTFTs was deposited on the gate layer by E-beam evaporation. aluminum oxide fabricated various deposition rate. In this case of the deposition rate of $0.1\;{\AA}$, the fabricated aluminum oxide gate insulator OTFT showed a threshold voltage of -1.36V, an on/off current ratio of $1.9{\times}l0^3$ and field effect mobility $0.023\;cm^2/V_s$.