• 한국주조공학회지
• /
• 제21권3호
• /
• pp.163-178
• /
• 2001

The squeeze infiltration process is potentially of considerable industrial importance. The performance enhancements resulting from incorporation of short alumina fiber into aluminum are well documented. These are particularly significant for certain automobile components. Aluminum matrix composite automotive parts, such as diesel engine pistons or engine blocks are produced using squeeze casting apparatus or pressure die-casting apparatus. But the solidification process gets complicated with manufacturing parameters and the factors for porosity formation have not fully understood yet. In this study the formation of porosity during squeeze infiltration has been studied experimentally to achieve an improved understanding of the squeeze infiltration process for manufacture of short-fiber-reinforced components, particularly the mechanism of porosity formation. Al-based MMCs produced under a range of conditions were examined metallographically and the porosity characterised;a kind of matrix, an initial temperature of melt, and a volume fraction of reinforcement. The densimetry and the microscopic image analysis were done to measure the amount of porosity. A correlation between manufacturing parameters and defects was investigated through these.

• 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.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
• /
• pp.184-188
• /
• 2001

The squeeze infiltration process is potentially of considerable industrial importance. The performance enhancements resulting from incorporation of short alumina fiber into aluminum are well documented. These are particularly significant for certain automobile components. But the solidification process gets complicated with manufacturing parameters and factors for porosity formation do not fully understand yet. In this study porosity defects were observed under several infiltrating conditions ; a kind of matrix, an initial temperature of melt, and a volume fraction of reinforcement. The desimetry and the microscopic image analysis were done to measure the amount of porosity. A correlation between manufacturing parameters and defects was investigated through these.

• 한국주조공학회지
• /
• 제16권6호
• /
• pp.523-536
• /
• 1996

This paper relates to fabrication processing analysis of metal matrix composites by the injection of liquid metal into a fibrous preforms. One dimensional heat transfer analysis during squeeze infiltration process of aluminum base composites has been studied. An analysis method was investigated for the temperature distribution, infiltration velocity and melt infiltration characteristics with the commercial preform with short fiber array. When molten metal is infiltrated in a fibrous preform with random orientation, phase transformation will be occurred in a region such as molten metal, solidified region, preform region and infiltration composites region. a mathematical modelling for a solidification phenomena in fabrication process of metal matrix composites using a squeeze infiltration technique was investigated by the basic relations for liquid metal into a fibrous preform. The temperature distribution of theoretical results was compared with experimental data.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
• /
• pp.195-198
• /
• 2000

The process of squeeze casting for metal matrix composites (MMCs) has been simulated numerically by using finite difference method. The governing equations to describe fluid flow through porous medium and heat transfer are applied to two dimensional model which is similar to a real system. A computational code has been developed to solve this problem. The influence on infiltration kinetics and solidification time of several parameters is investigated. Cooling curves and temperature distribution with time and position is also shown. The result can be used to design the squeeze casting for MMCs.

• 한국주조공학회지
• /
• 제22권4호
• /
• pp.184-191
• /
• 2002

This study aims to investigate on the effects of alloying elements and heat treatment on the microstructures, wear and heat resistance of Al-Si-Cu-Mg-(Ni)/SiCp prepared by the duplex process developed in previous study, which consists of squeeze infiltration (1st process) and squeeze casting (2nd process). The hardness of composite increased with decrease in SiCp size and Ni addition in both the heat exposured composite and the as-cast one. And the heat and wear resisting properties was improved by the SiCp reinforcement and the Ni addition. The wear amount of Al/SiCp composite decreased with decreasing in the size of silicon carbide particle.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2004년도 추계학술발표대회 논문집
• /
• pp.250-253
• /
• 2004

A finite element model is developed for the process of squeeze casting of metal matrix composites. The fluid flow and the heat transfer are fundamental phenomena in squeeze casting. The equations for the clear fluid flow and the flow in porous media are used to simulate the transient metal flow. To describe heat transfer in the solidification of molten aluminum, the energy equation is written in terms of temperature and enthalpy. A direct iteration technique is used to solve the resulting nonlinear algebraic equations. The cooling curves and temperature distribution during infiltration and solidification were calculated for a simplified model with pure aluminum. The developed program can be used for squeeze casting process of complex geometry, boundary conditions and processing parameter optimization.

• 한국주조공학회지
• /
• 제20권3호
• /
• pp.167-172
• /
• 2000

Squeeze casting was performed to fabricate the SiC whisker reinforced magnesium matrix composites, and the suitability of the squeeze casting for the production of the sound composites was determined by micro/macro-structures observations and tensile test. The two-directional infiltration of the melt and the removal of air during infiltration using the devised mold were necessary to produce the composites. The pressure of 100 MPa was effective for the production of composites with the SiC whisker volume fraction of 30%, but the pressure should be lower than 50 MPa in case of below 20% in the volume fraction. The SiC whiskers in the squeeze cast composites were randomly and densely aligned, and the SiC whiskers/magnesium interfaces were continuously well-bonded. The elastic modulus, 0.2% proof stress and tensile strength in the composite were about 2.5times, l0times and 4times as large as those of magnesium, respectively, indicating that the squeeze casting sufficiently provides the high strength magnesium composites reinforced with SiC whiskers.

• 한국자동차공학회논문집
• /
• 제9권5호
• /
• pp.188-194
• /
• 2001

Metal matrix composites with whisker reinforcements have significant potential for demanding mechanical applications including defense, aerospace, and automotive industries. Especially, metal matrix composites, which are reinforced with aluminum borate whisker, have been used for the part of piston head in automobile because of good specific strength and wear resistance. Aluminum alloy-based metal matrix composites with whisker reinforcements have been produced using squeeze casting method, which is kind of an infiltration method. In this study, AC4CH-based metal matrix composites with $Al_{18}B$_4$O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated mechanical properties of matrix and MMC composite were evaluated.

• 한국주조공학회지
• /
• 제17권4호
• /
• pp.402-410
• /
• 1997

Developing a salt core for squeeze casting process, two different salt cores(pure salt core and mixed salt core) were fabricated and investigated. Pure salt core was composed of 100% NaCl and mixed salt core was made by mixtures of NaCl with MgO(1%), $Na_2B_4O_7$(2%), and talc(1%) as a binder or a strengthening agent. Salt cores were compacted to various theoretical density, heat treated, and then squeeze-cast with molten Al alloy(AC8A). The compression strength of salt cores were measured and the squeeze-cast products were examined for shape retention, infiltration of molten metal into the cores, and microstructures. The shape of salt core compacted at above 75% of the theoretical density was maintained stably. The higher theoretical density of salt cores gave higher compression strength, and the compression strength of mixed salt core was higher than that of pure salt core. Namely at 90% theoretical density, the compression strength of mixed salt core was $6.3 kg/mm^2$, compared to $4.6 kgmm^2$ for pure salt core. At a squeeze casting pressure of $1000 kg/cm^2$, molten Al alloy was infiltrated into pure salt core of under 85% of the theoretical density. At squeeze casting pressure of $1000 kg/cm^2$, only mixed salt core above 90% of the theoretical density were valid, but the shape of the core was altered in the case of pure salt core at 90% of theoretical density. A key factor for developing a salt core for squeeze casting process was estimated as the ultimate compressive strength of salt core.