Sang Youl Kim

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 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.

Effect on Compression Properties of Al Alloy Foam Materials by Added Si

In this study, it was investigated to determine mechanical properties of aluminum foam prepared through a batch process. The aluminum foam was prepared by adding 2wt% AlCa into molten aluminum to obtain the desirable viscosity when preparing Al foam. Internal pores were formed by added TiH 2 . While changing the amount of Si and relative density, mechanical properties were investigated by compression test. Aluminum foams compressed strength increased in proportion to the relative density. However, the aluminum foam with the relative density of 0.12 showed the highest energy absorption. Its energy absorption value was 4.2 MJ/m 3 at densification strain of 0.7.

Characteristics of Al foam with high porosity by melt foaming method

Al foams with high porosity were fabricated via melt foaming method. In this process, Ca and TiH2 are used as thickening and foaming agent. The macrostructure of aluminum foams exhibited homogeneous distribution of fine pore sizes at shorter holding time. From comparison of the actual pore sizes with ones calculated with modified Ostwald ripening, the measured pore sizes were well fitted to the calculated ones. These results suggest that hydrogen diffusion through pore walls from smaller pores to a larger one is the main process of pore evolution at least in the later period of holding. The detailed are discussed in the context.

Compressive Properties of Open Cell Aluminum Foams

The uniaxial compressive test results of several aluminum foams are compared with aluminum alloy and ppi (pore per inch) of open cell foam. The compressive stress-strain curve of aluminum alloy foams exhibits universal three deformation regions: an initial linear elastic response, and then extended plateau region with a nearly constant flow stress, a final densification as collapsed cells are compacted together. The lower the foam densities are, the longer the plateau region is, but lower densities also imply lower yield stress.

A Study on Kinetics Parameters of Titanium Hydride Powder from Its TPD Spectrum for Metal Foam

In this paper, the whole temperature programmed decomposition (TPD) spectrum of titanium hydride was acquired by the special designed set-up. After separating and simulating the TPD spectrum by using Spectrum Superposition Method (SSM), Consulting Table Method (CTM) and differential spectrum technique, the kinetics parameters of titanium hydride and corresponding equations were obtained. Using these kinetics equations, the fabrication parameters of Al alloy foam can be determined and foaming process of Al alloy melt can be predicted.

The Effect of Isothermal Heat Treatment on the Rolling Contact Fatigue of Carburized Low Carbon Microalloyed Steel

In case of the low carbon chromium steel that have widely been used for the carburized gears or rolling bearings, the austenite grain coarsening may be occasionally occurred during carburizing. To restrain this phenomenon, most of hot forged parts have been given to an isothermal heat treatment or normalizing immediately after hot forging and/or prior to carburizing. Therefore, their production cost includes unexpected additional expenses caused by such a non-value added process. To confirm the possibility of an energy saving, as well as attaining a superior fatigue life, in the production of automotive parts to be carburized, the austenite grain coarsening with the manufacturing process of the microalloyed steel, containing Nb and B as a grain refining elements, was investigated. The heat treatment characteristics and rolling contact fatigue behavior of the carburized specimens with the isothermal heat treatment were also investigated. In spite of omitting the isothermal heat treatment after hot forging, the abnormally coarse austenite grains were not found out in the carburized specimens. However, the rolling contact fatigue life of the carburized specimens, in which the isothermal heat treatment was omitted, was shorter than that of isothermally heat-treated specimens.

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.

A Study on Al-Mg Alloy Foams by Melt Foaming Method

Al-Mg alloy foams were synthesized via conventional melt foaming method. Ca and TiH2 were introduced into molten Al-Mg alloys with different magnesium contents. The macrostructures of resultant alloy foams were analyzed and correlated with compressive properties estimated by compression test. It is shown that the pore structures observed in alloy foams degraded with increasing Mg contents. This tendency was shown to be consistent with compressive characteristics of corresponding alloy foams. In detail, plateau strength was high for Al-1wt%Mg alloy foams, exhibiting a gradual decrease in plateau strength with increasing magnesium content.

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.