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Volume 21, Issue 3
Displaying 1-6 of 6 articles from this issue
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Hitoshi SHINJO, Fusao HAYAMA1971 Volume 21 Issue 3 Pages 103-110
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSSliding test of binary Al-Si alloys containing 22.6% of silicon was conducted with a pearlite cast iron ring in the air with no lubricants.
The principal results obtained were as follows:
(1) The types of wear were reasonably classified into the following four categories by the observation of surface appearance of the sliding rider (alloy). They were cutting surface wear, black surface wear, deposit surface wear, and Fe2O3 inlaid wear.
(2) The wear characteristics were varied as follows, depending upon the silicon content.
(a) In the case of cutting surface wear, the rates of wear were increased both in the rider and the ring with the increase of silicon content.
(b) The cutting surface wear of the hypo-eutectic alloys was governed by adhesion between the rider and the ring. Therefore, the friction coefficient was decreased with the increase of silicon content. Whereas, the primary silicon crystals in the hyper-eutectic Al-Si alloys substantially scratched the cast iron ring and the friction coefficient of these alloys was increased with the increase of silicon content.
(c) Al-Si alloys of high silicon content continued to keep the black surface wear at a considerably high sliding speed.
(3) The friction coeffcient of the black surface wear was higher than that of the cutting surface wcar. The surface roughness of the cast iron ring was fairly small in the black surface.
(4) The alloy containing 1826% of silicon revealed black spotty surface wear at a high sliding speed.View full abstractDownload PDF (2332K) -
Studies on solidified structure and properties of Al-Si-Cu alloy die castings (2nd report)Muneo SUZUKI1971 Volume 21 Issue 3 Pages 111-119
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe chill zone must be kept intact in order to prevent the lowering of properties of die castings. However, the differences in properties between the chill zone and inner parts have not yet been explained thoroughly.
This paper describes physical, mechanical, and chemical properties of both of the chill zone and inner parts of Al-12 Si-Cu-alloy (JIS ADC 12) die castings having thickness of 10mm.
The results obtained were as follows:
(1) Specific gravity of the chill zone was found to be higher by 6% than the center parts and coefficient of thermal expansion of the former was lower by 7% than the latter. Whereas, the lattice constant was found to be smaller with the increase of depth up to 1mm, and then abruptly larger approximate to the center. The cause of the above facts were due to the segregation of principal components, Si, Cu and Fe.
(2) Each of ultimate tensile strength, 0.2% yield strength, elongation, bending strength, impact strength, and fatigue strength showed a markedly higher value on the chill zone and lower by 3065% in the center part.
The values of hardness and wear resistance were found to be relatively lowered by the formation of primary α-crystals on the chilled surface. However, the maximum values were obtained on the chill zone of the die castings and the values were also lower in the inner parts. An evident correlation was found between these properties.
(3) The rates of corrosion and penetration in alkaline solutions were lower on the chilled surface rather than in the inner parts. Whereas, these rates in acidic solutions were higher on the chilled surface rather than the inner parts.View full abstractDownload PDF (1694K) -
Studies on sealing of anodic oxid efilms of aluminum (2nd report)Hiroshi KAWASE1971 Volume 21 Issue 3 Pages 120-129
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSInfluences of small amounts of various anions added to distilled water on sealing effects were studied by impedance test, dyeing test, and Kape test, and also examined by electron microscope and electron diffraction.
The anions used in these studies were PO4---, SO4--, F-NO3-and Cl-as acids, P2O7---, PO4---, SO4--, SiO3--, Cr2O7--, and Cl-as Na salts, and OH-as NaOH, KOH, and NH4OH.
Aluminum specimens, which had been anodized in sulfuric acid, was sealed for 20 min. in boiling distilled water containing a small amount of each anion.
The results obtained were as follows:
(1) PO4--- and SiO3-- gave the most harmful effects on sealing of anodic oxide films and inhibited the böhmite reaction by strong specific adsorption by the proton space charge of anodic oxide films.
(2) OH- strongly promoted the böhmite reaction which was proved by the examination with electron microscope and by electron diffraction.View full abstractDownload PDF (2666K) -
Shigeo ZAIMA, Akiyasu YUKI, Susumu KAMO1971 Volume 21 Issue 3 Pages 130-136
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe effects of four sorts of cutting fluids(i. e., Millcut solution, Diacut, molybdenum disulfide-kerosene mixture, and lard-kerosene mixture)on the roughness of drilled surfaces were examined in drilling of five sorts of aluminum alloys (i. e., 2024-T4, 6061-T6, 5056-F, 5052-F, and 1100-F). The experiments were conducted by dipping the whole of specimens in the fluids.
The results obtained were summarized as follows:
Much better results were obtained in surface roughness of drilled holes by drilling with cutting fluids as compared with that of dry drilled holes by drilling with no fluids. One of the reasons for these facts would be caused by the decrease in the growth of built-up edge by using cutting fluids. However, the surfaces obtained were rougher than the theoretical roughness calculated from the drill figure though in using cutting fluids. It would be attributed to the effect of walking phenomenon of the drill around the drilled holes.
In the range of experiments, lard-kerosene mixture and molybdenum disulfide-kerosene mixture were more effective in obtaining good drilled surfaces; but Millcut solution was not so effective.
The heat-treated alloys such as 2024-T4 and 6061-T6 showed good drilled surfaces; and the surfaces of non-heat-treated alloys such as 5056-F and 5052-F were slightly rougher, but they showed much better results as compared with the cases by dry drilling.View full abstractDownload PDF (1009K) -
Michiki HAGIWARA, Yoshio BABA, Masahisa NAOE1971 Volume 21 Issue 3 Pages 137-146
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA new process called zinc diffusion cladding was developed which shows an effect similar to that of the conventional sacrificial claddings and it is easily applied to various aluminum shapes.
The process consists of the following two stages:
(1) A thin zinc film is deposited on aluminum surfaces from alkaline zincate solutions by chemical substitution.
(2) Zinc is diffused into the basic alloy.
Distribution of zinc solute in the cladding, which affects the pitting corrosion, depended upon the amount of zinc in the deposit as well as time and temperature for diffusion. The amount of zinc was increased with the rise of solution temperature and the increase of dipping time. When the temperature for diffusion was lower, the thickness of effective layer was decreased, which reduced the life of clad. Whereas, when the temperature for diffusion was higher than the melting point of zinc, the sacrificial protection was also decreased owing to a smoother gradient of zinc concentration in the diffusion clad.
Therefore, it was concluded that the depth of pitting corrosion was restricted by the diffusion cladding at 350400°C for 224 hrs. in a similar way to that of the conventional sacrificial claddings.View full abstractDownload PDF (2156K) -
Yasuji NAKAMURA1971 Volume 21 Issue 3 Pages 147-158
Published: March 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (1529K)
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