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Volume 22, Issue 3
Displaying 1-5 of 5 articles from this issue
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Michio Inagaki, Shigeharu Naka1975 Volume 22 Issue 3 Pages 87-92
Published: May 25, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSBy the heat treatments at 1700°-2000°C under 5 kbar, the sintered graphite disks were prepared from various starting materials, such as graphitizing polyvinylchloride coke, graphitized fine powder, non-graphitizing phenol resin char and carbon beads, fluid and gilsonite cokes with onion-like texture, and the powder of PAN fibre.
From the polyvinylchloride coke and PAN fibre, the disks with high degrees of graphitization and orientation were obtained. The graphitized fine powders, phenol resin char, 1000°C-pre-heated carbon beads and fine powders of fluid coke gave the sintered disks with similar values of orientation degree, which being a little lower than that of the polyvinylchloride coke. The fluid coke and gilsonite coke gave relatively low degree of orientation. The 2000°C-pre-heated carbon beads gave the disks with high degree of graphitization, very low degree of orientation and high bulk density.View full abstractDownload PDF (2734K) -
Jirô Shibata, Shigenori Tanabe, Tôru Nakata1975 Volume 22 Issue 3 Pages 93-100
Published: May 25, 1975
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn order to investigate the sintering process of Fe-Si compacts, the dilatometric and microscopic examination of those compacts were systematically carried out. The results were summarized as follows:
1) The shrinkage of those compacts was scarcely any affected by the amount of Si in the α-iron range, but was remarkably increased with the amount of Si in the γ-iron range.
2) After the Acs transformation in the Si compositions range higher than the γ-loop limit the trans-formation γ→α occured in sequence according to the change in the Si concentration.
3) It was assumed that for the sintered Fe-Si compacts of composition over the γ-loop the sintering was accelerated because of the stable α-phase in high temperature and the easy elimination of pores owing to the finer grains.
4) It was assumed to be due to the Kirkendall effect that larger pores were temporarily left at the places where Si powders had existed in the case of carbonyl iron powder.
5) In the last stage of the sintering process, any intermediate phase was not found and the α-phase having a diffused Si remained.View full abstractDownload PDF (4926K) -
Zenshirô Hara, Kiyoaki Akechi, Masao Itabashi1975 Volume 22 Issue 3 Pages 101-106
Published: May 25, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWith the purpose to find the possibility of obtaining sound and strong composite materials by use of resistance-sintering process, mixture of steel wires or iron whiskers and iron or aluminium powders were resistance-sintered into fiber reinforced metals. The influence of the resistance-sintering conditions on the mechanical properties and micro-structures of the obtained composite products were studied. Products of 95% density-ratio were easily obtained by the process with no control of atmosphere.
In the case of composites reinforced with steel wire (tensile strength of the fiber σf=280 kg/mm2) of fiber volume ratio V f=0.20, the tensile strength of iron composite, σ c showed 58 kg/mm2 for tensile strength of iron matrix σ m=30 kg/mm2, while that of aluminium composite 56 kg/mm2 for tensile strength of aluminium matrix σ m=10 kg/mm2. Iron composite reinforced with iron whisker (of V f=0.20) showed a very large elongation.View full abstractDownload PDF (3831K) -
Tadaaki Sugita, Kazuo Suzuki, Katsunobu Nishikawa, Tatsuo Nakagawa1975 Volume 22 Issue 3 Pages 107-114
Published: May 25, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe coefficient of friction and the wear resistance of three types of alumina, that is, single crystals of sapphire (α-Al2O3), polycrystalline sintered alumina and sintered abrasive grits, on a dry stainless steel surface have been determined as a function of sliding speed. As the results, it is found that the wear of single and polycrystalline alumina appears to occur by both mechanisms, that are consisted of attritious wear with plastic flow over 20 m/s of sliding speed and fragmentation below 10 m/s, whereas the sintered abrasive grits are worn mostly by attrition with less wear rate even at low sliding speed, although, at high sliding speed, the wear is greatly increased with decreasing the bonding force of grains owing to high temperature during sliding. It is associated that the attritious wear in the single and polycrystalline alumina may be produced by chemical reactions occuring in the wear layer under high sliding speed. Also, the fragmentation resistance of alumina depends on crystallographic orientation such as plane of wear and rubbing directions, and existence of grain boundary, so that the wear resistance of the single crystals of sapphire under low sliding speed is less than that of the polycrystalline alumina.View full abstractDownload PDF (1921K) -
Hiroshi Itô, Yasuo Mihashi, Kôji Taguchi1975 Volume 22 Issue 3 Pages 115-119
Published: May 25, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSintered titanium-molybdenum compacts have the high corrosion resistance in nonoxidizing acid solution, as already reported in part I.
In this time, an experiment on the corrosion resistance compared with tantalum, which is an expensive and corrosion resistance metal, was carried out. The experiments on the improvement of the mechanical properties of the sintered Ti-30Mo compacts and also the effects of nitriding and additions of titanium carbide and titanium nitride for the improvement of wear resistance were carried out.
The results obtained were as follows;
1) On mixing methods, a mixing method without crushing was much better for the mechanical properties of sintered Ti-30Mo compacts.
2) Improved mechanical properties of sintered Ti-30Mo compacts were obtained by the vacuum sintering in a carbon vessel.
3) The mechanical strength of the sintered Ti-30Mo compact obtained reached to 170 Kg/mm2 in transverse rupture strength and 75 Kg/mm2 in ultimate tensile strength.
4) Good corrosion resistance of the sintered Ti-30Mo compacts was superior obtained in hydrochloric acid and sulfuric acid, as well as that obtain in tantalum.
5) The additions of titanium carbide and titanium nitride were effective to improve the wear resistance.View full abstractDownload PDF (1540K)
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