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Volume 26, Issue 3
Displaying 1-7 of 7 articles from this issue
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Shigeo OYA1976 Volume 26 Issue 3 Pages 109-110
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
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Kentaro TANIUCHI, Toshiharu KANAI1976 Volume 26 Issue 3 Pages 111-115
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe specific electrical conductivity of binary molten salt systems of LiF-KF and LiF-BaF2 was measured and the following results were obtained;
1) The melting point of lithium fluoride is 845°C and the specific electrical conductivity of potassium fluoride at 900°C is 4.306ohm-1cm-1.
2) The specific electrical conductivity of the simple eutectic system, LiF-KF was measured at 900 and 1000°C in the whole composition range, while the measurements at 800°C were made in the composition range of 20∼80mole% KF considering the melting temperature.
The conductivity decreases almost parabolically with an increase in KF content and this result is explained well by "Kuroda's approximated formula" indicating that the ionic species contributing to electric conduction are Li+, K+ and F- ions.
3) In LiF-BaF2 binary system, a compound LiF•BaF2 is formed by the peritectic reaction:
Melt+BaF2=LiF•BaF2
Considering the melting point of this binary system, the electrical conductivity was measured in the composition range of 0∼60mol% BaF2 at 1000°C, 0∼50% at 900°C and near the eutectic composition of LiF and LiF•BaF2 at 800°C. The conductivity decreases almost parabolically with an increase in BaF2 content. The conductivity also decreases with decreasing temperature at a rate of about 10% per 100°C.View full abstractDownload PDF (468K) -
Kunio OKABAYASHI, Makoto KAWAMOTO, Tsutomu KAJIMOTO1976 Volume 26 Issue 3 Pages 116-123
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSBoth the mean temperature of the apparent sliding surface (mean temperature, θm) and the average temperature of real contacting asperities (flash temperature, θf) are considerea to be directly related to friction and wear. θm of aluminum alloys was calculated from the temperature gradient of the specimen measured by thermocouples and θf was measured by the dynamic thermoelectromotive force method on a pin-disc machine using an aluminum alloy pin and a 17Cr stainless steel disc under unlubricated conditions. Specimens of Y-alloy and high silicon aluminum alloy were used. Measured values were compared with the calculated ones deduced theoretically from simple models. Linear relations between θm and μPV and between θf and μP1/2V are expected theoretically, where μ; frictional coefficient, P; load, V; sliding speed.
Under the sliding conditions of no scuffiing, a linear relation was obtained betweenθm and μPV. The θf. changed linearly with μV, but no linear relation was obtained between θf and μP1/2V since the slope varied with P. The wear rate at a constant sliding speed also increased linearly with P under the conditions of no scuffing. Although the slopes of these straight lines, which did not go through the origin, varied with the sliding speed, the values of load axis intercepts were almost constant and about -5.7 kg for Y-alloy and -4.7 kg for high silicon aluminum alloy. When the apparent load, Pa, which was the actual load plus 5.7 kg for Y-alloy and plus 4.7 kg for high silicon aluminum alloy were considered, a linear relation was found between θf and μP1/2 a V. This suggests that the effect of variation of the number of real contacting asperities with load can be eliminated by taking the apparent load into consideration. Linear relations between θm and μPV and between θf and μPa1/2 V did not hold when scuffing occurred.View full abstractDownload PDF (1000K) -
Kunio OKABAYASHI, Makoto KAWAMATO, Tsutomu KAJIMOTO1976 Volume 26 Issue 3 Pages 124-130
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe wear characteristics of Y-alloy and high silicon aluminum alloy were investigated from the point of view of sliding surface temperature. Tests at room temperature and under heated conditions were performed on a pindisc machine using an aluminum alloy pin and a 17Cr stainless steel disc at the sliding speed of 0.05-2.46 m/sec and with the load of 1.1-13.0 kg under unlubricated conditions.
The mean temperature of apparent sliding surface ("mean temperature", θm) and the average temperature of real contacting asperities ("flash temperature", θf) are considered to be directly related to wear, and it is shown that these two temperatures should be distinguished. θm is considered to be the temperature of the parts supporting asperities. For 200-250°C of θf, wear decreased with a rise of θf and was little affected by θm. Above 250°C of θf, wear increased and severe scuffing occurred at high θm. The apparent specific wear, which is the wear rate divided by the apparent load (the load plus 5.7 kg for Y-alloy and plus 4.7 kg for high silicon aluminum alloy), could be expressed by the two surface temperatures and was little affected by the sliding speed and load. From these facts, the conditions, under which the wear rate is minimum and scuffing starts, were clearly shown to depend on the mutual relation between θf and θm. Variation of the wear rate with the sliding speed could also be explained by the two surface temperatures. These results are considered to be the general characteristics of wear of aluminum alloys rubbed against iron or steel.View full abstractDownload PDF (995K) -
Ikuo HAGINOYA1976 Volume 26 Issue 3 Pages 131-138
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSOxide growth and contamination of molten Al-Mg alloys were studied by means of optical microscopy and EPMA, The observed forms of oxide were classified into granular, layer, globular and filmy types. Granular oxide of MgO was observed in the ripply surface oxide. As the ripply surface oxide grew, voids were formed in molten metal. Granular oxide was formed near the voids and dispersed into molten metal. Layer oxide, mainly composed of MgAl2O4, was observed on the metal surface as single or multiple layers. With growth of oxide layers, deformation and breakdown occurred and the fragments were dispersed into molten metal. Two kinds of globular oxide were observed; one composed of MgO and was floating on the surface of molten metal, and the other composed of MgAl2O4 and MgO, which was formed at the bend of the oxide layer and dispersed into molten metal in a similar manner as layer oxide. Filmy oxide was formed near the metal surface or void and dispersed deeply into molten metal.View full abstractDownload PDF (3571K) -
Shiro SATO, Noboru OKOSHI1976 Volume 26 Issue 3 Pages 139-149
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe free-bend tests were carried out on the butt-welded specimens of aluminum alloy 5083-0 with thickness of 22 and 50 mm, and on 5083-0 plate specimens with various thickness. Changes in the strain distribution with an increase in the bend angle were measured and cracks appeared on the convex face of the specimen were examined. The principal results obtained are as follows.
1) The maximum bending strain measured for a given bend angle increased with an increase in thickness of specimens.
2) The maximum bending strain depended on tested materials even if the specimen thickness and the bend angle were kept constant.
3) The method shown in Fig. 8 (a) is recommended for initial bending prior to the free-bend test.
4) Cracks appeared at the smaller bend angle and at the lower maximum bending strain as thickness of the specimen increased.
5) The elongation values, measured by gauge lines marked on the tension side of the weld, were very little affected by variation of gauge length.
6) The required elongation in the free-bend test for butt-welded joints of 5083-0 may be about 15-20% to assure the same ductility obtained in the side-bending test of the specimen with R/t of 3.3 where R is the punch radius and t is thickness of the specimen.View full abstractDownload PDF (1091K) -
Kazuo AKASHI, Shing-Jen SHIAO1976 Volume 26 Issue 3 Pages 150-163
Published: March 30, 1976
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2005K)
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