Fabrication of Lotus-Type Porous Aluminum through Thermal Decomposition Method

Kim, S.Y.; Park, J.S.; Nakajima, Hideo

doi:10.1007/s11661-008-9763-3

Cited by 29 publications

(30 citation statements)

References 14 publications

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“…Kim et al fabricated lotus aluminum using various kinds of compounds. 6) According to their results, Ca(OH) 2 provides higher porosity than TiH 2 and NaHCO 3 .…”

Section: Methodsmentioning

confidence: 99%

“…3,4) In another method hydrogen is supplied through thermal decomposition reaction of compounds including hydrogen. 5,6) The thermal decomposition method was developed by Nakajima and Ide in order to fabricate lotus-type porous metals without explosive gas and high pressure chamber. 5) Until now several kinds of lotus aluminum alloys have already been fabricated with hypo-eutectic Al-Si alloys 7) and hypo-eutectic Al-Cu alloy 8) by continuous casting technique in hydrogen atmosphere of 0.1 MPa.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Conditions of Unidirectional Solidification on Microstructure and Pore Morphology of Al-Mg-Si Alloys

2010

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Aluminum and Al-Mg-Si alloy ingots with pores were fabricated by unidirectional solidification through thermal decomposition of Ca(OH) 2 powders. The porosity of aluminum and Al-Mg-Si alloy were 10-17% and 0.1-2%, respectively. While the pores with 250-400 mm diameter were observed in a grain or across several grains in the aluminum ingots, smaller pores with 50-300 mm were observed in an eutectic region between primary dendrites in the Al-Mg-Si ingots. In the alloys with Mg(0.25-0.5 mass%) and Si(0.2-0.4 mass%), the unidirectional pores were aligned between columnar dendrites grown in the unidirectional solidification. With higher Mg and Si contents, the equiaxed dendrite zones with spherical pores were observed in a region with low temperature gradient. The results of thermal analysis showed that constitutional supercooling, which causes equiaxed dendrites, tends to occur with increase in Mg and Si contents and with low temperature gradient at the solid-liquid interface. Under this condition, spherical pores were evolved, because the surrounding -dendrites solidified isotropically. Therefore, it is concluded that the pore growth direction is affected by morphology of dendrites.

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“…Kim et al fabricated lotus aluminum using various kinds of compounds. 6) According to their results, Ca(OH) 2 provides higher porosity than TiH 2 and NaHCO 3 .…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Conditions of Unidirectional Solidification on Microstructure and Pore Morphology of Al-Mg-Si Alloys

2010

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“…Therefore, the pore diameter can be written as d∝P -1/3 . 19) However, the pressure dependence of the porosity and pore size cannot be explained quantitatively. It suggests that there will be another effect for suppressing the decomposition reaction with the Ar pressure.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of Lotus Nickel Through Thermal Decomposition Method of Compounds under Ar Gas Atmosphere

Kim¹,

Hur²,

Nakajima³

2009

Korean. J. Mater. Res.

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Lotus-type porous nickel with cylindrical pores was fabricated by unidirectional solidification under an Ar gas atmosphere using the thermal decomposition method of the compounds such as sodium hydroxide, calcium hydroxide, calcium carbonate, and titanium hydride. The decomposed gas does form the pores in liquid nickel, and then, the pores become the cylindrical pores during unidirectional solidification. The decomposed particles from the compounds do play a rule on nucleation sites of the pores. The behavior of pore growth was controlled by atmosphere pressure, which can be explained by Boyle's law. The porosity and pore size decreased with increasing Ar gas pressure when the pores contain hydrogen gas decomposed from calcium and sodium hydroxide and titanium hydride, ; however it they did not change when the pores contain containing carbon dioxide decomposed from calcium carbonate. These results indicate that nickel does not have the solubility of carbon dioxide. Lotus-type porous metals can be easily fabricated by the thermal decomposition method, which is superior to the conventional fabrication method used to pressurized gas atmospheres.

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“…In order to overcome this problem, Kim et al proposed a method to fabricate lotus aluminum through thermal decomposition of compounds containing hydrogen. 11) In the thermal decomposition method, hydrogen decomposed from compounds is utilized as a source of hydrogen in place of pressurized hydrogen gas. 12,13) In the present study, lotus aluminum with pores oriented in one direction is fabricated by a casting method, in which hydrogen decomposed from moisture is utilized as a source of hydrogen.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Lotus-Type Porous Aluminum Utilizing Decomposition of Moisture

Tane

Nakajima

2009

Mater. Trans.

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Lotus-type porous aluminum with cylindrical pores oriented in one direction was fabricated by a casting method utilizing the decomposition of moisture in a vacuum. Hydrogen decomposed from moisture is utilized for cylindrical pores to grow during unidirectional solidification. However, pores are not formed in the case of a casting in hydrogen or argon atmosphere, because hydrogen or argon gas pressure suppresses the pore growth. The porosity of lotus aluminum does not depend on the moisture amount, which indicates that the moisture amount is almost saturated within the amount used in this study. The average pore diameter does not depend on the moisture amount, because the pore diameter depends mainly on ambient pressure and solidification rate. The distribution of pores becomes homogeneous by decreasing melting temperature, because the rate of the reaction of moisture possibly becomes low (more suitable for pore growth) by decreasing the melting temperature.

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Fabrication of Lotus-Type Porous Aluminum through Thermal Decomposition Method

Cited by 29 publications

References 14 publications

Effect of Conditions of Unidirectional Solidification on Microstructure and Pore Morphology of Al-Mg-Si Alloys

Effect of Conditions of Unidirectional Solidification on Microstructure and Pore Morphology of Al-Mg-Si Alloys

Fabrication of Lotus Nickel Through Thermal Decomposition Method of Compounds under Ar Gas Atmosphere

Fabrication of Lotus-Type Porous Aluminum Utilizing Decomposition of Moisture

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