• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.543-544
• /
• 2006

The effect of the additives, $Y_2O_3$ and MgO, on the sintering and properties of $Al_2O_3-TiC$ composites was investigated. It is known that MgO is used as additive for improving densification and $Y_2O_3$ is applied as sintering aid. In this study, the amounts of TiC were varied in the range of 30-47 wt%. The 0.5 wt% MgO and also varied amounts of $Y_2O_3$ from 0.3 to 1 wt% were added into the composites. The sintering of $Al_2O_3-TiC$ composites was performed in a graphite-heating element furnace at different sintering temperature, 1700 and $1900\;^{\circ}C$, for 2 hr under an argon atmosphere. The results demonstrated that the properties of the composites sintered at $1700\;^{\circ}C$ were much better than those sintered at $1900\;^{\circ}C$. The comparisons on physical properties, mechanical properties and microstructure of composites with and without additives were reported. Comparing with other samples, $Al_2O_3-30wt%TiC$ composites with 0.5wt% MgO and $1\;wt%Y_2O_3$ exhibited the highest density of approximately 98% of theoretical and flexural strength of 302 MPa.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2002년도 제23회 학술발표회 초록집
• /
• pp.115-115
• /
• 2002

• Journal of Welding and Joining
• /
• 제21권2호
• /
• pp.50-56
• /
• 2003

Metal matrix composites(MMC) consist of metal matrix into which is distributed a second solid phase. The normal intension is to develop a material with superior mechanical properties (for example increased toughness, stiffness and wear resistance) compared to those inherent in the matrix component. In this study, WC-12%Co/low carbon steel MMC overlays have been prepared by Gas Metal Arc Welding(GMAW) according to feeding rate of WC-12%Co grit. The macro and microstructures were examined using optical microscopy (OM) and scanning electron microscopy(SEM) each other. The characteristics of hardness and wear resistance have been investigated. WC-12%Co/low carbon steel MMC overlays which have been taken good beads without porosity and cracks were manufactured by method of GMAW. Matrix of overlayed surface was seen as fish bone and faceted dendrite structures. It was known that structures were iron tungsten carbides, Fe$_{6}$W$_{6}$C which have been occurred by melting of WC-12%Co grits. After MMC had been tested by block-roll wear test it was known that WC-12%Co/low carbon steel MMC has a excellent wear resistance by exiting Fe6w6c and WC-12%Co grit. The consequence was that region of overlay with Fe$_{6}$W$_{6}$C phase has been showed a model of adhesive wear, but region of overlay with WC-12%Co grit was restrained as a result of mechanism that wear of WC-12%Co grit is not adhesive but fracture.racture.

• Carbon letters
• /
• 제3권1호
• /
• pp.13-16
• /
• 2002

The modification of coal-tar pitch has been carried out by heat treatment of pitch at different temperatures in the range ($300^{\circ}-400^{\circ}C$) for different times (2-5 hrs) in air and nitrogen. The pitch heat treated in air at lower temperature ($300^{\circ}C$) exhibit increase in softening point by $20^{\circ}C$ as compared to only $2^{\circ}C$ when treated in nitrogen. The changes are faster in air than in pure nitrogen. Pitch as such as well as after heat treatment were further treated with metal complexes by solution route. Silver intake has been found to increase from 0.5 to 0.8 % in nitrogen treated pitch while the uptake is found to decrease for pitches treated in air at $350^{\circ}C$ for 5 hrs. Experiments have also been made to incorporate silver into PAN and PAN-ox fibers through solution route. The metal intake has been found to be more in PAN-ox fibers than in PAN as such. Metal loaded carbon composites have been made by using metal loaded fibers as well as cokes. These composites as such exhibit higher surface oxygen complexes but decrease after activation.

• Advances in Computational Design
• /
• 제7권2호
• /
• pp.129-137
• /
• 2022

Compo-casting method is one of the popular technique to produce metal based matrix composites. But, one of the main challenges in this process is un-uniform spreading of reinforced subdivisions (particles) inside the metallic matrix and the lack of desirable mechanical properties of the final produced composites due to the low bonding strength among the metal matrix and reinforcement particles. To remove these difficulties and to promote the mechanical properties of these kind of composites, the WARM ARB technique was utilized as supplementary technique to heighten the mechanical and microstructural evolution of the casted Al/Al₂O₃ composite strips. The microstructure evolution and mechanical properties of these composites have been considered versus different WARM ARB cycles by tensile test, average Vickers micro hardness test, wear test and scanning electron microscopy (SEM). The SEM results revealed that during the higher warm- ARB cycles, big alumina clusters are broken and make a uniform distribution of alumina particles. It was shown that cumulating the forming cycles improved the mechanical properties of composites. In general, combined compo-casting and ARB process would consent making Al/Al₂O₃ composites with high consistency, good microstructural and mechanical properties.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.281-284
• /
• 2001

MMC was developed that had distinguished mechanical properties and light weighted. MMC has excellent mechanical properties in many ways in automotive industrial, and get into the spotlight as a light materials substituted for iron and steel. But the know-how about MMC research lack, MMC is expensive and difficult to apply the sound parts. Especially it is difficult to produce the hollow type parts composed with MMC. Therefore, hollow type parts of metal matrix composites by thixoforging process which as co-existing solidus-liquidus phase, it is very important to obtain forming condition. In this study, used materials were A357, A380, A380 $10\%$vol, and $20\%$vol SiCp, and the size of particulates were $14{\mu}m$ and $5.5{\mu}m$

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
• /
• pp.155-158
• /
• 2002

Fabrication process of metal/intermetallic laminated composites by using self-propagating high temperature synthesis(SHS) reactions between Ni and Al elemental metal foils have been investigated. Al foils were sandwiched between Ni foils and heated in a vacuum hot press to the melting point of aluminium. SHS reaction kinetics was thermodynamically analyzed through the final volume fraction of the unreacted Al related with the initial thickness ratio of Ni:Al and diffusion bonding stage before SHS reaction. Thermal aging of laminated composites resulted in the formation of functionally gradient series of intermetallic phases. Microstructure showed that the main phases of intermetallics were NiAl and $Ni_3Al$ having higher strength at room and high temperatures. The volume fractions of intermetallic phases were measured as 82.4, 58.6, 38.4% in 1:1, 2:1, 4:1 initial thickness ratio of Ni:Al.

• 제어로봇시스템학회논문지
• /
• 제10권11호
• /
• pp.981-990
• /
• 2004

Specialized propulsors for naval applications have numerous opportunities in terms of research, design and fabrication of an appropriate propulsor. One of the most important components of any propulsor is the actuator that provides the mode of locomotion. Ionomeric electro-active polymer may offer an attractive solution for locomotion of small propulsors. A common ionomeric electro-active polymer, ionic Polymer-Metal Composites (IPHCs) give large true bending deformations under low driving voltages, operate in aqueous environments, are capable of transduction and are relatively well understood. IPMC fabrication and operation are presented to further elucidate the use of the material for a propulsor. Various materials, including IPMCs, are investigated and a simplified propulsor model is explored.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1740-1750
• /
• 1993

The aluminar short fiber reinforced composite materials for hot extrusion were fabricated by semi-solid stirring method, and extruded at extrusion temperature $400^{\circ}C$ with various extrusion ratio. The hot extrusion load of volume fraction 15% metal matrix composites and base alloy Al7075 has been compared. The fiber length distribution, fiber breakage and fiber orientation are investiged to know the fiber behaviour in before and after hot extrusion. The tensile strength of the hot extruded billet are experimentally determined for different of extrusion ratios, and compared with theorically calculated strength.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1751-1760
• /
• 1993

The squeeze casting process is considered as an attractive way to form the primary product of near net shape metal matrix composites for wide use in automobile industry. To understand for infiltration limit in squeeze casting processes, the SAFFIL short fiber preform of volume fraction $10%{\sim}23%$ were fabricated by vaccum pumping and speed control press, and the optimal condition for fiber preform fabrication had been experimentally obtained. The composite materials were fabricated by forced infiltration of molten metals such as Al6061, Al7075, pure Al, AC8A, and Al2024. The infiltration distance and deformation of fiber preform are observed, and tensile strength were measured from at the room temperature.