著者

島 裕也 中村 龍哉 松井 裕樹 山田 義博 宮内 啓成 橋本 聡司 阿部 一雄

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.57, no.11, pp.729-733, 2010-11-15

参考文献数

13

被引用文献数

1

---

LiFePO<SUB>4</SUB>/C composite particles were prepared by gas-solid phase reaction. The reaction temperature had a detrimental effect on the purity of the composite particles. The suitable temperature was around 650°C, above and below which ferromagnetic impurities were found. The retention time influenced only the carbon deposition amount, but the excess amount of carbon caused the degradation of the electrochemical performance. The specimen prepared at the optimum conditions exhibited superior performances in both rate capability and cycle stability as well as less impedance growth during the cycling.

著者

和田 任弘 岩本 晃二 尾崎 充紀 廣 和樹

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.58, no.5, pp.275-278, 2011-05-15

---

When tapping carbon steel with a straight fluted taper pipe tap for NPT threads, the cutting section is often prone to fracture on the thread part because of the increase in chip thickness, which causes the chip to jam as the tapping process proceeds. When tapping carbon steel with a high speed steel tap (HISS tap), this adversely affects the tapping operation due to the low cutting speed. Increasing the cutting speed is effective to ensure a highly efficient tapping operation.<BR>In this study, a tapping test was conducted on a Cr-Mo steel SCM435 using various kinds of surface treated HISS tap, namely untreated taps (HISS tap), oxide treated taps, TiN coated taps, TiCN coated taps and AlCrN coated taps, to determine the effective tool material for high efficiency tapping. The main results obtained are as follows: (1) The higher cutting speed was determined to be effective in preventing fracture of the cutting part on the thread part of the tap because the chip formed both a slimmer and spiral shape when tapping at high cutting speed. (2) The AlCrN coated HISS tap showed the best wear resistance. (3) The AlCrN film had both a lower friction coefficient and higher hardness compared with the TiN or TiCN film.

著者

松田 光弘 三浦 秀士

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.47, no.6, pp.681-685, 2000-06-15

被引用文献数

3 7

---

In our previous studies on the 4600 steels produced by Metal Injection Molding (MIM) process using mixed elemental powder, the fine heterogeneous microstructure caused by the agglomeration of Ni powders was reported to be significantly effective for the improvement of mechanical properties. This study has been performed to clarify and optimize the relationship between the mechanical properties and the heterogeneous microstructure for ultrahigh strengthening the sintered low alloy steels (4600grade, 0.4 mass%C) produced by MIM process varying Ni content from 0 to 8 mass%.<BR>The tensile and fatigue strength were improved significantly with increasing Ni content to 6mass%, without loss of the ductility. This seemed to be due to the solution strengthening and the mezzo-heterogeneous microstructure which were consisted of Ni rich martensite surrounded by a network of tempered martensite. However, the tensile and fatigue strength of the steel added 8 mass% Ni were dropped by the increase of retained austenite.

著者

青峰 隆文 西嵜 照和 山本 高広

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.37, no.1, pp.114-117, 1990

---

It is known that sintered bulk samples of high Tc superconducting oxides have low critical current density and show hysteresis of critical currents in low magnetic fields. These phenomena are attributed to weak links at a grain boundary. In this work we report on the hysteresis of sintered bulk samples of high Tc superconducting oxides and of superconducting, relatively long bridges which have a constricted part made artificially. The former hysteresis is found to be very similar to the latter one. We consider that the hysteresis of sintered bulk samples of high Tc superconducting oxides occurs for the existence of superconducting, relatively long bridges and trapped flux in them.

著者

水上 正彦 山本 良治 浅田 信昭 松本 明英

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.53, no.2, pp.154-159, 2006-02-15

被引用文献数

2 7

---

Nano-sized WC powder that is expected as the raw material for nano-sized WC-Co hardmetals with high hardness and strength was developed. The reaction path and morphological change in the reaction process of WO<SUB>3</SUB> with carbon powder (direct carburization) were firstly investigated by thermogravimetric analysis. The proper reaction condition examined by the thermogravimetric analysis was developed to trial production by direct carburization facilities.<BR>The direct carburization reaction from WO<SUB>3</SUB> to WC occurred through the generation of several intermediate products in the order of WO<SUB>3</SUB> → WO<SUB>2.72</SUB> → WO<SUB>2</SUB> → W → W<SUB>2</SUB>C → WC. The nano-sized particles were generated at the stage from WO<SUB>2.72</SUB> to WO<SUB>2</SUB>. We succeeded in the development of nano-sized WC powder less than 100 nm by controlling the reaction conditions for each intermediate products.

著者

大塚 愛子 川崎 亮 渡辺 龍三 厳 泰永

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.45, no.3, pp.220-224, 1998-03-15

参考文献数

7

被引用文献数

3 12

---

Disk-shaped functionally graded materials of copper/alumina system have been fabricated by spark plasma sintering(SPS process. The graded layer consists of symmetrical compositional transition of Cu/Al<SUB>2</SUB>O<SUB>3</SUB>/Cu, which allows to achieve high heat conduction, electrical insulation and excellent in-plane electrical conductivity. The use of the FGMs as a compliant pad of conduction type of thermoelectric power conversion system offers high thermal energy density through the thermoelectric cell, resulting in the increase of the efficiency of thermoelectric energy conversion.<BR>This paper describes the process optimization including densification of metal-ceramic powder mixtures by SPS process, compositionally graded stacking of the mixed powders in a graphite die, the design of the compositional gradient on the basis of one dimensional heat conduction analysis and fabrication of Cu/Al<SUB>2</SUB>O<SUB>3</SUB>/Cu FGMs according to the predesigned compositional gradient.

著者

Goetzel C.G. Rittenhouse J.B.

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.14, no.5, pp.195-202, 1967

---

粉末冶金の製品は,一般の航空方面への応用とともに,宇宙衛星の部品として利用されるようになった.宇宙衛星の関係部品は,高度に特殊化された目的を満足させるたあに,広範な発展計画を必要とするものである.この報告では,宇宙衛星に対するいくつかの粉末冶金の応用の紹介と,実際に軌道にのった宇宙衛星に使用された粉末冶金部品および材料の二,三の例について論ずる,粉末冶金製品の例として,93日間の飛行に成功したExplorer皿、のテープレコーダー中の焼結ブAンズベアリングがあり,また航空用衛星(その中には7カ月も活動したものもある)内の,自転抑制装置に用いられた焼結マグネットなどがある.化学的浸食熱応九融点近くの表面温度などに対する抵抗が要求されるようないわゆる高温熱流に対しては,Agを溶浸させたWが用いられる.これは粉末冶金法によってのみ作られるものである.この物質を十分に管理された製造工程のもとで製作するために,複合材料に最適の実用性質を発揮させるような広範な計画が開始された.粉末冶金法で製造されたBeの利点については,特に目下計画中,あるいは設計中の人間宇宙ステーションの表面材料として,および流星群の遮蔽防御などへの応用に対して検討されている.