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Volume 18, Issue 9
Displaying 1-5 of 5 articles from this issue
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Studies on electrode potential of aluminum (1st Report)Hiroaki NAKAGAWA1968 Volume 18 Issue 9 Pages 461-466
Published: September 30, 1968
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSCorrosion resistance of aluminum and its alloys is closely related with properties of their anodized oxide film. This paper reports the corrosion resistance of the film determined by measuring electrode potentials in anodizing, for Al and Al-Si alloys.
After anodizing, the specimen was dipped in HCl-NaOH solution and its electrode potential was measured by arranging the specimen in negative pole and saturated calomel electrode in positive pole.
(1) When anodizing time was constant, holding times of the 1st and 2nd electrode potentials were longer with the increase of current density. The same results were obtained for the constant values of the product of current density and anodizing time.
(2) The 1st and 2nd electrode potentials gave constant values, in spite of variations in current density and anodizing time, as follows.
Pure aluminum: 1st electrode potential about -0.55V
2nd electrode potential-1.45--1.55V
Al-Si alloys 1st electrode potential about-0.45--0.55V
2nd electrode potential -1.35V
(3) When the product of current density and anodizing time was a constant value of 30A. min./dm2, holding times of the 1st and 2nd electrode potentials abruptly decreased with the increase of silicon content. However, they gave constant values for the specimens containing Si of 2% (which is over solubility).
(4) Under the same conditions as above (30A, min./dm2), the two electrode potentials gradually showed noble values for pure aluminum and its alloys containing up to 2% of silicon. When silicon content was above 2%, they always showed constant values for any contents of silicon.View full abstractDownload PDF (679K) -
Reactions of iron with liquid aluminum (1st Report)Noboru KOMATSU, Motoyuki NAKAMURA, Hironori FUJITA1968 Volume 18 Issue 9 Pages 467-473
Published: September 30, 1968
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThis paper reports the reactions of aluminum on various kinds of steel and cast iron immersed in pure liquid aluminum at 770°C for 0.5-128hr. Erosion or weight loss of iron during immersion decreased with the increase of carbon content in iron up to about 1% and was kept at constant for more increase of the content. However, the state of reaction zone in iron depended upon its carbon content and width. Neither diffusion layer (solid solution of iron and aluminum) nor high carbon layer was identified on the boundary between the iron matrix and the reaction zone as the results of electron-probe microanalysis. The reaction zone consisted of two layers; i. e., outer layer composed of fine particle constituents of FeAl3 and aluminum, and inner layer of intermetallic compound Fe2Al5 having columnar morphology. The microhardness of the former was Hv 500-100 and that of the latter was Hv 1, 000. In the former, the iron content gradually decreased towards outside, and on the contrary, aluminum content increased. However, in the latter, both contents of iron and aluminum were unvaried throughout the layer.View full abstractDownload PDF (1206K) -
Reactions of iron with liquid aluminum (2nd Report)Noboru KOMATSU, Motoyuki NAKAMURA, Hironori FUJITA1968 Volume 18 Issue 9 Pages 474-482
Published: September 30, 1968
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIn order to study the effects of silicon on the reaction of solid iron with liquid aluminum, iron specimens having various carbon and silicon contents were immersed in pure liquid aluminum or liquid Al-Si alloys at 700-770°C for a considerably long time.
The degree of corrosion of iron attacked by liquid aluminum was determined by the weight loss during reaction, and the properties of Fe-Al reaction zone were investigated by means of microhardness tester, X-ray diffractometer, and electron-probe microanalyzer.
When some kinds of iron were immersed in liquid Al-Si alloys, or some Fe-Si alloys were immersed in pure liquid aluminum at the temperature of 110°C above liquidus, silicon (either in iron or aluminum) had no effects on weight difference of iron specimens, but the thickness of reaction zone decreased with the increase of silicon content. Silicon in liquid aluminum did not inhibit the growth of reaction zone, but accelerated its dissolution into liquid aluminum.
When silicon was added into iron or liquid aluminum, two layers were always present in the reaction zone; i.e., one of which close to the iron matrix was composed of Fe2Al5 and the other close to aluminum was composed of the mixture of FeAl3 and aluminum. High silicon layer was formed when silicon content in Fe-Si alloys was higher than a certain limit (about 3% of Si). The solubility limit of silicon in columnar layer was determined to be 2-3% by electron-probe analysis. The hardness of reaction zone was not affected by silicon content in iron.View full abstractDownload PDF (1812K) -
Mayumi INOUE1968 Volume 18 Issue 9 Pages 483-491
Published: September 30, 1968
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAluminum corrosion induced by microbial contamination of jet fuel has become one of the most important troubles. The object of the present work is to study the corrosion of aluminum caused by the growth of fungi isolated from jet fuel system. Of the fungi isolated, Cladosporium resinae appeared to be the most predominant. Many kinds of filamentous fungi were obtained from slime of jet fuel, water layer of storage tank, and sludges on stringer and lower panel of integral fuel tank of YS-11 jet plane
Results obtained were as follows.
(1) After 330 day incubation, exfoliation and corrosion occurred with small blisters on the surface of aluminum alloy, 6061 specimen.
(2) The cross section of the 6061 specimen indicated that the corrosion pits by Cladosporium resinae were extensively evident thoughout the aluminum body.
(3) The specimens of high purity aluminum (1099 and 1100), anodized aluminum, and aluminum alloy 5052 were severely damaged by the attack of the fungus.
(4) An extruded bar of 1100 was also attacked by Cladosporium resinae. Corrosion pits began to develop after 30 day culture of the fungus.
(5) Large amounts of sludge deposits were found on the stringer and lower skin panel of the integral tank of YS-11 jet plane. Widespread corrosions were found in the area covered by the growth of the fungus.
(6) Discussions were also made over the development of tests for the effects of protective coatings.View full abstractDownload PDF (2994K) -
[in Japanese]1968 Volume 18 Issue 9 Pages 492-512
Published: September 30, 1968
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (2603K)
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