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Volume 42, Issue 8
Displaying 1-10 of 10 articles from this issue
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Kenji SATO, Yuri TANAKA, Hideo NAKAE1992 Volume 42 Issue 8 Pages 429-434
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe interfacial reaction of single crystal of α-SiC with molten aluminum and Al-Si alloys has been studied. The influence of silicon content in the melt on the growth of Al4C3 and an epitaxial relation between SiC and Al4C3 in the interfacial reaction have also been investigated by SEM observation. In aluminum of 99.99 mass% purity at 1273K, Al4C3 phase formed in random orientation to the SiC (0001) plane, however, the relation of SiC (1010)//Al4C3 (1010) and SiC (1120)//Al4C3 (1120) was found. The epitaxial growth of SiC (0001)//Al4C3 (0001) was promoted in the melt containing Silicon. Silicon in the aluminum melt inhibited the interfacial reaction. Al4C3 crystal grew preferentialy along the c axis in the Silicon containg melt. The growth of Al4C3 by the interfacial reaction between SiC and aluminum occurs as follows: at first SiC is etched by the melt and then Si and C atoms diffuse to the melt. Finally Al4C3 crystals nucleate and grow on the SiC crystals from the melt supersaturated with carbon. As the result, hexagonal pyramid of SiC formed at the interface between SiC (0001) planeand Al4C3 on the epitaxial growth.View full abstractDownload PDF (1751K) -
Hiromi MATSUBARA, Yoshiei SHINADA1992 Volume 42 Issue 8 Pages 435-439
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe relationship between porosity formation and shrinkage morphology has been investigated in an AC4CH alloy modified with strontium. It has been shown that strontium changes solidification morphology and porosity distribution from a concentrated to a dispersed type. Namely in a nonmodified conical casting, microshrinkages are observed beneath interior shrinkage, while microporosities are dispersed by strontium modification throughout the casting without forming the microshrinkage. Gas content and porosity volume increase with strontium additions from 50ppm to 300ppm, becoming constant with strontium over 300ppm. The volumes of interior and exterior shrinkages decrease with increases in gas content and porosity volume.View full abstractDownload PDF (865K) -
Atsushi HIBINO, Mitsuhiro TAMAKI, Yoshiaki WATANABE, Takeo OKI1992 Volume 42 Issue 8 Pages 440-445
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAluminum foil for high voltage aluminum electrolytic capacitor is etched by D. C. current in the hot chloric solution. The several studies of tunnel growth have ever studied using the hot hydrochloric acid. Effects of sulfuric acid in the hot hydrocloric acid on the tunnel etching of aluminum were studied. The concentration of sulfuric acid has no effect on the initial tunnel growth rate, but has definite effect on the limit of tunnel length. As increase in the concentration of sulfuric acid causes a decrease in the tunnel length. Initial etching pit sites scatter partially on the surface by adding sulfuric acid. The multiplication of etch tunnels occurs in sequence after previous tunnels have reached their limits of length.View full abstractDownload PDF (1080K) -
Kiyoaki OHUCHI, Shigeru IWASAWA, Shigeharu KAMADO, Yo KOJIMA, Ryuuji N ...1992 Volume 42 Issue 8 Pages 446-452
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSMg-8 mass%Li-Nd-Ag alloys with compositions of 0, 3, 6 mass%Nd and 0, 2 mass%Ag were melted in a mild steel crucible by a fluxless method. The effects of neodymium and silver additions on the microstructures and mechanical properties of the Mg-8 mass%Li alloy was investigated. The increase in neodymium resultes in the increased amount of Mg3Nd compounds and the decreased amount of the primary α phase. Silver is soluble in both the primary β phase and Mg3Nd compounds and, therefore, causes no microstructural change for ternary alloys. Work hardening of the Mg-8 mass%Li alloy is degraded by the neodymium addition because of decrease in the primary α phase, whereas it is upgraded by the silver addition. A hot-rolled binary alloy softens by isochronal annealing at temperatures above 373K. The recrystallization temperature is raised up to 423K by the addition of neodymium. Age hardening phenomena are observed for all alloys T6 heat-treated after hot-rolling. The increase in hradness is caused by the precipitation of the α phase from the supersaturated β solid solution and also due to the oxidation or loss oflithium. Tensile strengh of all hotrolled alloys decreased exponentially with increasing test temperature from room temperature to 573K. No clear improvement of both mechanical strength and heat resistance is observed by the additions of neodymium and silver. This is due to the fact that the fraction of the α phase decreases with increasing neodymium, although the amount of the Mg3 Nd compounds increases.View full abstractDownload PDF (2022K) -
Kazuyoshi KATO, Hiroshi TOKISUE, Isamu CHIBA1992 Volume 42 Issue 8 Pages 453-458
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSTurning machinability tests were performed on the magnesium alloy castings MC2 by measuring cutting resistance, cutting ratio, surface roughness, cutting temperature and chip forming. Regardless of side cutting edge angle, cutting resistance of the alloy was independent of cutting speed, and was affected remarkablly by increasing feed angle. The traversing force decreased with increasing side cutting edge angle. Both cutting ratio and shear angle increased with acceleration of cutting speed and feed. The machined surface finishing showed inferior with increasing side cutting edge angle and feed. The surface roughness with side cutting edge angle 0° was superior or nearly to that calculated theoretically on the basis of feed marks, but the surface roughness with side cutting edge angle 5 to 15° showed higher value. The cutting temperature increased with increasing cutting speed and/or feed. The rising rates of cutting temperature decreased with increase of cutting speed. The highest cutting temperature was 803K. But there was no trouble in flaming during cutting. Both large and small spiral coil type chips were easily treatable.View full abstractDownload PDF (605K) -
Isao ITOH, Yasuo OTOGURO, Takao DOI1992 Volume 42 Issue 8 Pages 459-463
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe effects of additions of tin and both tin and magnesium to aluminum on the diffusion weldability of alumina and aluminum alloys in the atmosphere were investigated. Diffusion welding treatments were carried out at temperatures between, 573 and 873K for 1.8, 3.6 and 7.2ks under pressure of 1, 2 and 4MPa. During the welding liquid tin containing magnesium filled the interface and prevented oxidation of the interface. Magnesium in liquid tin reduced a part of the oxidation film at the interface. The combined addition of tin and magnesium to aluminum produced good weldability of the couple at 873K, while the couple was not welded by the single addition of tin. However, the welding treatment in the atmosphere caused undesirable thermal stress which was not observed in vacuum. The couple welded in the atmosphere was fractured at the alumina side in the shear tension test. The thermal stress was found to be caused by the non-uniform distribution of tin at the interface of the welded joint. The uniform distribution of tin was obtained by smoothing rough joint surfaces and resulted in the released thermal stress.View full abstractDownload PDF (1366K) -
Yuichi SHIMOMURA1992 Volume 42 Issue 8 Pages 464-470
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
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Tatsuo SATO1992 Volume 42 Issue 8 Pages 471-480
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
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Shigeharu KAMADO1992 Volume 42 Issue 8 Pages 481-482
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
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Kohei KUBOTA, Kenji HIGASHI1992 Volume 42 Issue 8 Pages 483-484
Published: August 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (264K)
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