• Tribology and Lubricants
• /
• v.29 no.5
• /
• pp.298-303
• /
• 2013

In this work, the effect of applied load on the wear behavior of Al/SiC composites was studied. Al/SiC composites were fabricated following the thermal spray process. Dry sliding wear tests were performed on these composites under four different applied loads, i.e., 5, 10, 15, and 20 N. The wear behaviors of the composites under these applied loads were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Under applied loads of up to 15 N, the wear rates of Al/SiC composites decreased with an increase in the applied load because of the formation of an adhesion layer on the worn surface. However in the case of an applied load of 20 N, the wear rate was significantly high because the formation and fracture of the adhesion layer were repeated continuously. These results show that the wear behaviors of the tested composites are significantly influenced owing to the applied loads.

• Corrosion Science and Technology
• /
• v.17 no.1
• /
• pp.1-5
• /
• 2018

As structural materials, magnesium (Mg) alloys have been widely used in the fields of aviation, automobiles, optical instruments, and electronic products. There are few studies on the effect of coating conditions on the compositional variation during the formation process of the conversion coatings. Rare-earth based conversion coating on AZ91 magnesium alloy was prepared in ceric sulfate and hydrogen peroxide contained solution. The element composition and valence as well as their distribution in the coating were analyzed with energy dispersive X-ray spectroscopy (EDS), Electron probe micro-analyzer (EPMA), X-ray photoelectron spectroscopy (XPS). The effect of treating process on the element composition were also studied. It was found that the conversion coating surface consists of Mg, Al, O, Ce, and the weight content of Ce in the coating was affected by the treating solution concentration and immersion time; the Ce element was distributed in the coating non-uniformly and existed in the form of $Ce^{+3}$ and $Ce^{+4}$, while the O element existed in the form of $OH^-$, $O^{2-}$, $H_2O$. Based on microscopic analysis results, the electrochemical deposition mechanism on the micro-anode and micro-cathode in the process of the coating growth was suggested.

• Korean Journal of Materials Research
• /
• v.11 no.9
• /
• pp.797-801
• /
• 2001

In this study, the solution combustion method was employed to synthesize stoichiometric mullite, and hence the attrition process was employed to prepare ultrafine mullite particles with nano size. The thermal decomposition behavior and partial pressure of equilibrium species of both oxidizer and fuel were considered during solution combustion process. The synthesized product was mullite phase with 40 nm crystalline size, and the alumina contents of the product by TEM/EDS quantity analysis was 3.12$\pm$04 mole. The result showed that the synthesized mullite was almost close to the it's stoichiometric composition. For attrition process, the dispersion behavior of the mullite suspension was controlled and was comminuted with the condition of 800 rpm for 4 hours using 0.3 mm zirconia ball media. As a result of comminution, the mean particle size was 80 nm.

• Journal of the Korean institute of surface engineering
• /
• v.45 no.2
• /
• pp.89-94
• /
• 2012

A study to replace a high temperature thermal carbonization process with microwave plasma process is carried for PAN fiber as a starting material. Near atmospheric pressure microwave plasma (1 Torr~45 Torr) was used to control to get the fiber temperature up to $1,000^{\circ}C$. Even argon is an inert gas, its plasma state include high internal energy particles; ion (15.76 eV) and metastable (11.52 eV). They are very effective to lower the necessary thermal temperature for carbonization of PAN fiber and the resultant thermal budget. The carbonization process was confirmed by both EDS (energy dispersive spectroscopy) of plasma treated fibers and OES (optical emission spectroscopy) during processing step as a real time monitoring tool. The same trend of decreasing oxygen content was observed in both diagnostic methods.

• Tribology and Lubricants
• /
• v.27 no.6
• /
• pp.351-355
• /
• 2011

Al/SiC composites were fabricated by thermal spray process, and the dry sliding wear tests were performed using the various sliding speed of 10, 30, 60 and 90 RPM through 1000 cycles. The applied load was 10 N and radius of wear track was 15 mm. Wear tracks on the Al/SiC composites were investigated using scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS). In the case of sliding speed of 10 RPM, adhesive wear behavior caused by plastic deformation of composits surface was observed. In the cases of sliding speed of 30, 60, 90 RPM, abrasive wear behavior on the adhered layer formed by debris were observed. Through this study, it was found that the wear behavior of Al/SiC composites was mainly influenced by the sliding speed.

• Journal of Sensor Science and Technology
• /
• v.28 no.2
• /
• pp.76-80
• /
• 2019

The characteristics of a titanium oxide layer prepared using a plasma electrolytic oxidation (PEO) process were investigated, using an extended gate ion sensitive field effect transistor (EG-ISFET) to confirm the layer's capability to react with hydrogen ions. The surface morphology and element distribution of the PEO-processed titanium oxide were observed and analyzed using field-emission scanning-electron microscopy (FE-SEM) and energy-distribution spectroscopy (EDS). The titanium oxide prepared by the PEO process was utilized as a hydrogen-ion sensing membrane and an extended gate insulator. A commercially available n-channel enhancement MOS-FET (metal-oxide-semiconductor FET) played a role as a transducer. The responses of the PEO-processed titanium oxide to different pH solutions were analyzed. The output drain current was linearly related to the pH solutions in the range of pH 4 to pH 12. It was confirmed that the titanium-oxide layer prepared by the PEO process could feasibly be used as a hydrogen-ion-sensing membrane for EGFET measurements.

• Korean Journal of Materials Research
• /
• v.33 no.10
• /
• pp.385-392
• /
• 2023

A solution combustion process for the synthesis of hollandite (BaAl₂Ti₆O₁₆) powders is described. SYNROC (synthetic rock) consists of four main titanate phases: perovskite, zirconolite, hollandite and rutile. Hollandite is one of the crystalline host matrices used for the disposal of high-level radioactive wastes because it immobilizes Sr and Lns elements by forming solid solutions. The solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between a nitrate and organic fuel, generates an exothermic reaction and that heat converts the precursors into their corresponding oxide products in air. The process has high energy efficiency, fast heating rates, short reaction times, and high compositional homogeneity. To confirm the combustion synthesis reaction, FT-IR analysis was conducted using glycine with a carboxyl group and an amine as fuel to observe its bonding with metal element in the nitrate. TG-DTA, X-ray diffraction analysis, SEM and EDS were performed to confirm the formed phases and morphology. Powders with an uncontrolled shape were obtained through a general oxide-route process, confirming hollandite powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using these methods.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.30 no.5
• /
• pp.163-167
• /
• 2020

Ring-shaped SiC (Silicon carbide) polycrystals used as an inner material in semiconductor etching equipment was manufactured using the PVT (Physical Vapor Transport) method. A graphite cylinder structure was placed inside the graphite crucible to grow a ring-shaped SiC polycrystal by the PVT method. The crystal polytype of grown crystal were analyzed using a Raman and an UVF (Ultra Violet Fluorescence) analysis. And the microstructure and components of SiC crystal were identified by a SEM (Scanning Electron Microscope) and EDS (Energy Disruptive Spectroscopy) analyses. The grain size and growth rate of SiC polycrystals fabricated by this method was varied with temperature variation in the initial stage of growth process.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.6
• /
• pp.120-131
• /
• 2019

Recently, the level of fine dust and ultrafine dust has reached its highest level, threatening the public's health. If the air purifier was not operated indoors, natural ventilation would not be possible. In this study, photocatalyst is applied to building materials to purify air in a passive manner. In order to use photocatalyst for LEFC(Light Emotion Friendly Concrete), it is necessary to secure self-consolidating capability. Therefore, self-consolidating performance was evaluated by slump test, J-ring test and L-box test with UHPC materials applied. Based on these results, the mixture proportion was determined, and the mechanical performance was evaluated by compressive and flexural tests. Concrete blocks were constructed with a fabrication method that improved the existing process of making LEFC. Also, the concrete block was emptied as a way to reduce the use of expensive photocatalyst. Finally, in order to identify the distribution of TiO₂, an EDS analysis was performed.

• Korean Chemical Engineering Research
• /
• v.49 no.3
• /
• pp.381-386
• /
• 2011

Chemically functionalized plant oils, namely maleinized acrylated epoxidized soybean oil(MAESO), were used as a new bio based binders for photoelectrodes of dye-sensitized solar cells. The photocatalysts were characterized by field emission scanning electron microscope(FE-SEM), energy dispersive X-ray spectrometer(EDS), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and nitrogen adsorption analyses. The surface area and number of appropriate pores were increased in the $TiO_{2}$ particles prepared using the plant oil binders in comparison with the P-25 photocatalyst, due to the larger number of functionalities. The functional groups of OH on the surface of the $TiO_{2}$ particles increased from 9.9% to 16.62%.