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Volume 24, Issue 3
Displaying 1-5 of 5 articles from this issue
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Seishi Yajima, Toetsu Shishido, Hideo Kayano, Tadaaki Amano, Yasuhiro ...1977 Volume 24 Issue 3 Pages 67-70
Published: April 05, 1977
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBy introducing an organometallic polymer, as raw materials, into powder metallurgy, a new material has been developed. In a uniform mixture of Fe-13Cr alloy powder and polycarbosilane (PC) with n-hexane, the Fe-13Cr particles were coated with PC. The product of Fe-13Cr+ 10wt%PC obtained by hot-pressing the mixture was subjected to oxidation test, high-temperature hardness measurement and wear resistance test. The new product was superior in all the properties to the one without PC addition. To search the reason, its structure was observed by transmission electron microscope. Contributing to improvement of the mechanical properties are the grains of CrSi2 and Cr7C3, about 0.1μ in size, dispersed uniformly in the Fe-13Cr+10%PC. Observation by scanning electron microscope, in study of its oxidation resistance, then showed some difference in the formation of oxidation film between Fe-13Cr and Fe-13Cr+10%PC. Thus, it has been evidenced that the new alloy produced by the powder metallurgical technique, using the organometallic polymer and ferrous alloy powders has several outstanding features, with the outlook of many applications in the future.View full abstractDownload PDF (3901K) -
Zenshiro Hara, Kiyoaki Akechi1977 Volume 24 Issue 3 Pages 71-75
Published: April 05, 1977
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTi alloys were made in air by the resistance sintering method from mixtures of powders such as Ti-Mo, Ti-Cr and Ti-Al. The alloys resistance-sintered with high power input have high tensile strength, e.g., Ti-10%Mo, 106 kg/mm2; Ti-10%Cr, 80kg/mm2; Ti-6%A1, 70kg/mm2. Corrosion resistance against 10%HCl of the Ti-Mo alloy is slightly better than that of Ti, against 35%HCl and 10%H2SO4 is almost the same as that of pure Ti, and against 10%HNO3 is slightly inferior to that. Corrosion resistance against 10%HC1 and 10%H2SO4 of the Ti-Cr and Ti-Al alloys is much inferior to Ti and against 10%HNO3 is almost the same as that. From the results above mentioned, it was considered that Ti alloys which have high strength and high corrosion resistance against inorganic acid can be manufactured by the resistance sintering, if alloying elements are properly selected.View full abstractDownload PDF (4113K) -
Wear-resistant Layers of Iron-Molybdenum-Carbon Alloy infiltrated TiC SkeletonsYasuhiko Hashimoto, Shinichirô Omori, Keiichirô Shôj ...1977 Volume 24 Issue 3 Pages 76-81
Published: April 05, 1977
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe hardfacing by the application of infiltration was examined by using the skeletons of TiC compacts set on the base metal such as iron or mild steel and the infiltrant of Fe-4.4% C-15%Mo alloy in a vacuum or in a purified hydrogen atmosphere. The infiltration proceeded successfully and the hardfaced layers which tightly adhered to the base metal were obtained.
The microstructures of the hardfaced layers were composed of TiC with surrounding structure, M3C, and the matrix of Fe, although the thickness of the surrounding structure and the amount of M3C were changed by infiltrating conditions such as infiltrating temperature or holding time at this temperature.
The hardness and the transverse rupture strength were changed by the ratio of infiltrant to skeleton and the infiltrating conditions mentioned above. However, the oil-lubricated wear-resistance did not always correspond to the hardness, and when the infiltrating conditions were suitable, the wear-resistance of this hardfaced layer was comparable to that of WC-Co cemented carbide tool material.View full abstractDownload PDF (4651K) -
Tadatoshi Honda, Hisashi Abe1977 Volume 24 Issue 3 Pages 82-87
Published: April 05, 1977
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAn investigation has been made on the influences of pore filling with copper and the formation of alloy phase on the fatigue behavior of copper infiltrated sintered iron under completely reversed bending stress.
Iron skeletons with the density of 6.51 g/cm3 were prepared from electrolytic iron powder by means of compacting at 3.3 t/cm2 and sintering for 1 hr at 1150°C in hydrogen.
Subsequently they were infiltrated with copper powder compacts for holding time of 3 min (the short infiltrating time) and 123 min (the long infiltrating time) at 1130°C in hydrogen.
Results were summarized as follows:
(1) The fatigue strength of the iron skeleton infiltrated with copper powder compact remarkably increased with infiltrating time. This was considered to be caused by the effect of pore filling with copper and the strengthening effect due to the solid solution alloying of copper with iron.
(2) At the short infiltrating time, the fatigue cracks were initiated at the edges of the specimen, non-infiltrated pores and the multiple slip band in iron matrix, and then propagated at random through iron matrix and copper phase. While at the long infiltrating time, the main fatigue cracks preferencially propagated in linking of microcracks initiated at the iron-copper boundary.
(3) At the short infiltrating time, the remarkable pattern observed on fatigue fracture surface of specimen was striation, while at the long infiltrating time, was smooth fracture facet seemed to be fractured at the iron-copper boundary.View full abstractDownload PDF (7078K) -
Jiro Shibata, Shigenori Tanabe, Kenji Suzuki1977 Volume 24 Issue 3 Pages 88-93
Published: April 05, 1977
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to investigate the effects of Cu addition on various properties of sintered Fe-Si compacts, the microscopic and mechanical examination of Fe-Si-Cu compacts, sintered and then aged at various temperatures, were carried out. The dilatometric curves of these compacts were also measured to study the sintering process. The results were summarized as follows:
1) The density of Fe-Si-Cu compacts little decreased up to 3% Cu content when the compacts were sintered at the temperature above 1220°C.
2) The controll of copper growth was due to the following reason. Cu and Si powders yielded the eutectic liquid at 802°C which succesively produced Fe3Si phase containing a small quantity of Cu with neighboring Fe powders, and then a considerable amount of Cu was surrounded with the Fe3Si phase. It seemed therefore that the liquid of Cu could not flow into the Fe particles at the melting point of Cu.
3) Fe-Si-Cu compacts particularly showed a higher strength than Fe-Cu compacts because the former was more densified and strengthened the Fe matrix by the addition of Si than the latter.
4) In the case of Fe-3%Si-3%Cu compacts sintered at 1220°C for 1 hr, we obtained a tensile strength of 78 kg/mm2 and an elongation of 3% under the condition of aging at 500°C for 2 hrs.
5) In the sintered and aged Fe-Si-Cu compacts, Si was uniformly diffused and the Cu(ε) phase was precipitated in the aFe phase.View full abstractDownload PDF (6250K)
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