Yong Su Um

Foaming Characteristics of Al-Mg Alloy Foam

Al-Mg alloy foam used in this study was prepared, and Al-Mg alloy was melted by using a high-frequency induction furnace. Thickening and foaming agent were added to the molten Al-Mg alloy at a specific temperature, which was stirred. For uniform distribution of thickening and foaming agent, the impeller was rotated with high-speed about 400-1000rpm. When left in a furnace for a specific period after uniform dispersion of the foaming agent, gas was generated from the foaming agent and the cell size and distribution inside. We determined the structure of Al-Mg alloy foam using CT(Computed Tomography). The structure of Al-Mg alloy foam has homogeneous cell size at the bottom, larger cell size in the middle, and oalescence cell in the top part. To prevent this phenomenon, the viscosity and surface tension of the melt of Al-Mg alloy were controlled.

Sound Absorption Properties of Fiber and Porous Materials

The porous materials, such as glass wool or foam, are generally used to attenuate noise. The most fundamental acoustic property of these porous materials is their sound absorption coefficient. The purpose of this paper is sintered fiber and porous materials sound absorption properties investigated. Sound absorption properties of sintered Al fiber has over 0.7 of sound absorption coefficient with 800-2000Hz frequency for 0.6 relative density and 10mm thickness. NRC (noise reduction coefficient) is 0.73. Metal foam have good sound absorption rate at 2000 ~ 4000Hz.

Rheological Characteristics of Mg-Al Alloys with Ceramic Particles for Meta Foam

Foamed metal is a kind of porous material with pores in the metal matrix. One of the possible process routes is to blow gas bubbles into liquid metals. However, many metallic foams produced by this foaming method have coarse and irregular cell structures. The industrial aim is to fabricate foams with more uniform structure and cell size. It is important to understand the mechanisms and factors controlling. The rheological characteristics are the most important factors in the metal foam manufacturing. Thus this study investigated the bubble behavior of the molten metal and its two most important two parameters: surface tension and liquid viscosity. The surface tension (by the ring method) and the viscosity (by the rotation method) of Mg-Al alloy (AZ91, AM60) have been measured under pure Ar and SF6 + CO2 atmosphere. The results show that the surface tension and the viscosity of these alloys decrease with increasing temperature. The addition of Ca and SiC to Mg alloys decreases the surface tension and increases the viscosity. This anomalous behavior is related with the preferential adsorption of high activity elements on the surface.

Sound Absorption Properties of Al Foam

Aluminum foam with 0.2 g/cm3 density showed a good sound absorption property at frequencies higher than 2000 Hz. Compressed aluminum foam with an air gap of 50 mm or higher exhibited a very high sound absorption property near 400 Hz.

Development of Metal Foam for Application of Automotive Part

A study on the tensile, compression and bending test of Aluminum foam Application for auto bumper and rod. We know a more efficiency to adhesive Aluminum foam out side of part in aspect to price, weight and capacity when make auto-component using aluminum foam. We secured basis properties of aluminum foam for applying auto-component by tensile, compressive and bending test. Aluminum foam was equipped to crash core with different shape. The results of maximum loads test are higher by full> cavity> bridge> half type relationship order. And, we could know that a difference of weight of full, cavity, and bridge type is not big.

Rheological Properties of Molten Al-Cu alloys for Manufacturing Metallic Foam

The surface tension and the viscosity characteristics of molten metal are the most important factors in casting process and metallic foam manufacturing especially. The surface tension (by the modified ring method) and the viscosity (by the rotational method) of molten Al-Cu alloys have been measured under high purity Ar gas atmosphere. The surface tension and the viscosity of Al-Cu alloys were investigated in the temperature range of 660-800oC, and the effects of the additional elements were investigated at the 660~680. The result show that the surface tension and viscosity of these alloys decrease with increasing temperature together. The viscosity of Al-Cu alloys near the melting point is about 4.7 to 5.7 [mPa.s]. The effect of additional thickening elements has the tendency that is the surface tension decreased and the viscosity increased. This anomalous behavior has the relation of the preferential adsorption of high activity elements on the surface.

Dry Wear Properties of Porous Copper Fabricated by Unidirectional Solidification

We have been investigated application of the lotus type porous metal that is manufactured by the unidirectional solidification of the melt in pressurized gas atmosphere such as hydrogen or nitrogen for an air bearing development. In this study, wear properties of porous copper having cylindrical pores have been investigated. Generally, wear test is influenced by a shape, a wear test method, atmosphere and a way of lubrication. Wear test used pin on disk types wear test.

Effect of Processing Parameters on the Fabrication of Al2O3p/Al Composites by In-Situ Reaction Process of Molten Al

The effects of processing parameters such as addition type and Mg content on the fabrication of Al2O3p/Al composites by in-situ reaction process of molten Al were investigated in terms of infiltration behavior of molten Al and the variation of the microstructure and hardness of the composites. It was ascertained that additional Mg content is the most important parameter for the infiltration of molten Al. Furthermore, increase in additional Mg content and processing temperature resulted in a high infiltration ratio of molten Al and a high hardness value of the composites. However, these caused a greater scatter of the hardness value of the composites due to the nonuniform dispersion of the reinforcement phase, which arose from an excessive reaction of Mg.

Fabrication characteristics of mineral wool fiber used the waste

The development of mineral wool core sandwich panel depends on the reaction of resin on mineral wool and face sheet. The most important factors in developing the mineral wool core are optimization of the Curing system and density of the used resin. In addition, this product considers the functional effect and good environment instead of organic form core. This paper studied the curing conditions, the density of used resin, and the functional effect after manufacturing the mineral wool core.

Hydrogen Treatment of Ti Scrap

The titanium has been widely used in many fields because of its outstanding hydrogen absorption and light-strength property responsibly. And as a result, the quantity of waste Ti scrapes is growing these days. How to make good use of these waste scrapes is of great importance to both economic and environmental aspects. In the process of metal foaming, hydride metal is often used as foaming agent. In our experiment, TiH 2 was chosen as foaming agent to produce the Al foams. Ti scraps were usually produced in the machining process of panels, wire and pipes. To recycled Ti, Ti scraps of various shape like plate, chip were hydrogen-treated in self-made hydride machine. The samples were milled in a ball miller. SEM was applied to analyze the morphology of reactants. SEM was used to detect the size distribution and EDS, XRD, TG-DTA were executed to study the composition and reaction conditions to check the foaming possibility of forming agent in the production of Al foams. The result of study shows that Ti scraps have the same foaming ability.