• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.304-304
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• 2014

Quaternary Ti-Al-Si-N films were deposited on WC-Co substrates by a hybrid deposition system of arc ion plating (AIP) method for Ti-Al source and DC magnetron sputtering technique for Si incorporation. The synthesized Ti-Al-Si-N films were revealed to be composites of solid-solution (Ti,Al)N crystallites and amorphous $Si_3N_4$ by instrumental analyses. The Si addition in Ti-Al-N films affected the refinement and uniform distribution of crystallites by percolation phenomenon of amorphous silicon nitride, similarly to Si effect in TiN film. As the Si content increased up to about 9 at.%, the hardness of Ti-Al-N film steeply increased from 30 GPa to about 50 GPa. The highest microhardness value (~50 GPa) was obtained from the Ti-Al-Si-N film having the Si content of 9 at.%, the microstructure of which was characterized by a nanocomposite of $nc-(Ti,Al)N/a-Si_3N_4$.

• Journal of the Korean institute of surface engineering
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• v.53 no.2
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• pp.67-71
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• 2020

For deposition technology using plasma, it plays an important role in improving film deposited with high ionization rate through high density plasma. Various deposition methods such as high-power impulse magnetron sputtering and ion-beam sputtering have been developed for physical vapor deposition technology and are still being studied. In this study, it is intended to control plasma using inductive coupled plasma (ICP) antennas and use properties to improve the properties of Hafnium nitride (HfN) films using ICP assisted magnetron sputtering (ICPMS). HfN film deposited using ICPMS showed a finer grain sizes, denser microstructure and better mechanical properties as ICP power increases. The best mechanical properties such as nanoindentation hardness of 47 GPa and Young's modulus of 401 GPa was obtained from HfN film deposited using ICPMS at ICP power of 200 W.

• Journal of Korea Foundry Society
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• v.4 no.2
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• pp.96-101
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• 1984

The morphologies of eutectic cell formed during solidification affect on the mechanical properties in high Cr cast iron. In order to investigate the influence of Si on the structure, five kinds of specimen containing 16.42% Cr with varying amount of Si (0.51%, 1.17%, 2.22%, 2.71%, 3.56%) were poured into shell mould preheated $330^{\circ}C$ at $1510^{\circ}C$. The effect of Si on matrix in hypo-eutctic Cr cast iron (2.48% C, 16.42%) were studied through its mechanical tests and observation of microstructure using of metallurgical microscope, EPMA, SEM and Image analyzer systematically. The results obtained from the above studies are as follows: 1. Because of ${\Delta}T$ decreasing with increasing Si content, the morpologies of colony change into uniform bar-type carbide from plate-type ones, moreover eutectic colony size (Ew) becomes narrow and spacing of carbide wider. 2. As Si content increases, the amount of carbides also increases and most of Cr were dissolved in carbides while Si in matrix. 3. The hardness, tensile strength and wear resistance were increasing while impact value decreased with increasing Si content. 4. In fracture section, small amount of dimple pattern was observed in less than 1.17% Si but more than 2.22% Si river pattern was presented.

• Journal of Korea Foundry Society
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• v.19 no.1
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• pp.77-83
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• 1999

Strip casting process, a new casting technology which makes thin strip of $0.5{\sim}5\;mm$ thickness directly from molten metal, has been dramatically developed for past 10 years and faced commercialization in the case of STS304 strip. In this study, ductile cast iron strip which is 1.1 mm thick and 100 mm wide is manufactured by the twin roll strip caster. Graphite and matrix structure of the strip can be controlled through heat treatments and the mechanical properties are examined. The microstructure of the as-cast strip consists of cementite and pearlite. Especially the equiaxed crystal zone of pearlite exists in the center region of the thickness due to the characteristics of the strip casting process. Matrix structure can be transformed into fully ferrite or ferrite/pearlite mixed structures by the different graphitization heat treatments. The heat-treated strip with ferrite/pearlite matrix structure showed higher hardness and tensile strength than that with full ferrite matrix structure.

• Journal of Korea Foundry Society
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• v.17 no.3
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• pp.267-275
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• 1997

Fabrication of high strength Mg-Li-Al alloys by squeeze casting was established by the stabilization of melt and mold temperatures, applied pressure and the refining method. The entrapment of inclusions during pouring was prevented using 30 ppi alumina foam filter. The as-cast microstructure consists of a mixture of ${\alpha}$ and ${\beta}$ phases including AILi and $MgLi_2$, Al particles, which are distributed in the ${\beta}$ matrix. The grain sizes of gravity and squeeze casting alloys were 288 ${\mu}m$ and 207 ${\mu}m$ respectively. The addition of Al in Mg-Li alloys promoted the formation of second phase particles, which were adjusted to optimize the properties of Mg-Li-Al alloys. The Mg-10wt%Li-5wt%Al alloy after heat treatment at $350^{\circ}C$ for 1 hour showed the maximum hardness value. This is due to the facts that the amounts of ${\alpha}$ and ${\beta}$ phases and their distributions are dependent upon the solution treatment temperature, and that the amounts of AILi and $MgLi_2Al$ particles are dependent upon the Al content.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.241-246
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• 2010

The viscosity of foam metal is necessary to get the pores, but it is difficult to manufacture net-shape foam, because the fluidity decreases by increasing viscosity. In this study, the A356 alloy which has good fluidity and less defect was selected and fabricated to foam metal. To understand about effect of thickening agent on foaming and mechanical properties, quantity of thickening agent was changed. The pore size, porosity and distribution of foam metal were measured by i-solution program. And compression test were performed by UTM. In case of 3.0wt% Ca in thickening agent, it is found that most of foam consist of homogeneous shape, and the growth height had the highest value of 204 mm in the all fabricated foams. The porosity was 93% and compressive strength was 3.1 MPa. In the microstructure, the $Al_2Si_2Ca$ intermetallic compound and Ti were observed. The vickers hardness value rose with increasing viscosity value.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.145-152
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• 2015

The article aims to apply a friction stir spot welding for producing the lap joint between AA5052 aluminum alloy and C11000 copper alloy. The dimension of the materials was 100 mm in length, 30 mm in width and 1.0 mm in thickness. The copper plate was set overlap the aluminum plate by 30 mm. The welding parameter was the rotating speed of 2500-4000 rpm, the pin inserting rate of 2-8 mm/min and the holding time of 6 sec. The mechanical properties test and the microstructure investigation were performed to evaluate the lap joint quality. The summarized results are as follows. The friction stir spot welding could produce effectively the lap joint between AA5052 and C11000 copper. Increase of the rotating speed and holding time directly affected to decrease the tensile shear strength of the lap joint. The optimized welding parameters in this study that indicated the tensile shear strength of 864 N was the rotating speed of 3500 rpm, the pin inserting rate of 6 mm/min and the holding time of 4sec. The experimental results also showed that the hardness of the weld metal was lower than that of the base materials.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.138-144
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• 2015

This paper is aimed to study the influence of aluminium dross from Thai aluminum casting factory on polypropylene matrix-polymer composite material properties. The summarized experimental results are as follows. An increase in the amount of aluminum dross polymer composite material affected to increase hardness, modulus of elasticity and abrasion resistance. However, the increase of the aluminum dross had no effects to change the yield strength and the melting temperature of the polymer composite material. The aluminum dross also affected to form the crystallinity at $117-122^{\circ}C$ and directly increased the rigid property of the composite materials. The microstructure examination revealed that the aluminum dross was located in a polymer matrix and affected to increase the dark colour of the polymer composite material.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.625-630
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• 2013

In this study, intermediate-mixed powders were prepared by loading zirconia powders initially in a ball-mill jar and loading alumina powders afterward; the initial-mixed powders were produced by loading zirconia and alumina powders together in the ball-mill jar. The effect of such differences in mixing method on the mechanical properties was investigated. In intermediate-mixed powders, the volume fraction of large particles slightly increased and, simultaneously, zirconia particles formed agglomerates that, due to early ball-mill loading of the zirconia powders only, were more dispersed than were the initial-mixed powders. For the intermediate-mixed powders, zirconia agglomerates were destroyed more quickly than were initial-mixed powders, so the number of dispersed zirconia particles rose and the inhibitory effect of densification due to the addition of a second phase was more obvious. In the microstructure of intermediate-mixed powders, zirconia grains were homogeneously dispersed and grain growth by coalescence was found to occur with increasing sintering temperature. For the initial-mixed powders, large zirconia grains formed by localized early-densification on the inside contacts of some zirconia agglomerates were observed in the early stages of sintering. The intermediate-mixed powders had slightly lower hardness values as a whole but higher fracture toughness compared to that of the initial-mixed powders.

• Food Science and Preservation
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• v.9 no.2
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• pp.221-227
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• 2002

Effects of adding of dandelion flour on the quality characteristics of bread were investigated. Dandelion flour was substituted at levels of 0, 0.5, 1.0, 2.0% to wheat flour for bread making, respectively. Quality characteristics of bread such as dough yield, dough microstructure, loaf volume, bread yield, crumb color, mechanical property and sensory evaluation were analyzed. Addition of dandelion flour to wheat flour increased dough yield, loaf volume and bread yield. And, addition of dandelion flour caused a decrease in the lightness and an increase in the redness. The results of texture evaluation revealed that hardness, chewiness, springiness of bread increased as the level of dandelion flour was increased. As the addition level of dandelion flour increased, flavor balance, bitterness, aftertaste, grassy odor of bread increased but overall acceptability, moistness decreased. In conclusion, bread with 0.5% leaf powder was the best quality in bread properties.