巻号一覧
45 巻, 5 号
選択された号の論文の16件中1～16を表示しています
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真鍋 明1998 年 45 巻 5 号 p. 398
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (96K) -
斎藤 卓1998 年 45 巻 5 号 p. 399-404
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーA new TiB2 particle reinforced ferritic steel with Young's modulus as high as 300GPa has been produced through a powder metallurgy process. This paper discusses the mechanism for providing high performance of the developed material. The phase equilibrium between TiB2 and Fe-Cr-Ti ferritic phases was determined by the CALPHAD method. Based on its thermodynamic stability, which is responsible for maintaining its own high Young's modulus of 540GPa and low density of 4.53g/cc in ferritic matrix, TiB2 particles have been proved to be the best reinforcement for improving isotropic specific Young's modulus of steels. The process designed for the application of the developed material involves power compaction, sintering, and hot forging. Hot working for the material had favorable effects not only on attaining its full densification but also on improving homogeneity of the TiB2 particle dispersion. The Young's modulus of the material agreed exactly with the theoretical one predicted by the non linear law of mixture and the specific Young's modulus could be attained to the double as high as that of conventional steel. The tensile and fatigue strength, and wear resistance were also fairly improved with increase of TiB2 particle dispersion.抄録全体を表示PDF形式でダウンロード (491K) -
三浦 秀士1998 年 45 巻 5 号 p. 405-411
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーMetal injection molding (MIM) process offers near full dense and net shaping of the complicate parts with a relatively low processing cost. Therefore, this MIM process is hoped to be an advanced powder processing technique for fabricating new and high functional materials, especially seems to be quite useful for improvement of the quality and productivity in the automotive sintered parts.
In this work, MIM process has been applied to a wide variety of ferrous materials such as structural steels (4100, 4600 systems), high speed steels, 17-4PH and martensitic stainless steels, and ferrous composites with ceramics. Several processing variations were investigated to control the carbon and microstructure for high strengthening the above steels. Comments are particularly focused on the microstructure control needed for the MIM fabrication of high performance and functional sintered ferrous material components.抄録全体を表示PDF形式でダウンロード (9773K) -
エアレート充填近藤 幹夫, 竹本 恵英, 浦田 勇1998 年 45 巻 5 号 p. 412-416
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーDimensional tolerance of complex P/M parts is improved by uniformly filling powders in a die cavity. In our previous study, the powder behavior in filling the die cavity was investigated using a visual apparatus. It was clarified that the particle size segregation occurred in filling with low flowability of powders. In order to improve the flowability of powders in a feed shoe, an aeration powder filling method has been developed by blowing a small amount of nitrogen gas into the feed shoe. The effect of aeration powder filling was confirmed using the visual apparatus. The decreasing of particle size segregation and the shortening of the filling time by improving the flowability of powders were obtained even in the case of thin die cavity filling, compared with the conventional gravity filling.抄録全体を表示PDF形式でダウンロード (4977K) -
浦田 勇, 竹本 恵英, 近藤 幹夫1998 年 45 巻 5 号 p. 417-419
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーThe improvement of weight scattering and dimensional tolerance for the purpose of net-shaping is an important issue in the manufacturing of automotive PM parts. To resolve this issue, an aeration powder filling method was developed.
It was clarified that the aeration powder filling method is effective in filling the thin and complex-shaped cavities uniformly and quickly.
Consequently, the aeration powder filling method has been applied on the actual compacting press to examine the dimensional tolerance with cup-shaped test pieces. The decreasing of the weight scattering, the uniform density, the improvement of dimensional tolerance, and the reduction in the filling time were confirmed.抄録全体を表示PDF形式でダウンロード (179K) -
浅見 淳一, 廣瀬 徳豊, 川原 正言1998 年 45 巻 5 号 p. 420-424
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーThe application range of sintered machine product can be extended by the diecompacting of lengthwise parts which is one of restrictions in a geometric shape.
In this paper, the dimensional precision of lengthwise SUS-304L sintered compacts was improved by high pressure die compacting. The stainless steel powder isdifficult to compact at high pressure because of adhesion between the powder and the die during ejection. The two-step pressing that we proposed as the high pressure die compacting has made it possible to compact at a pressure of 980 MPa.
The result is a decrease of dimensional change with increasing a compacting pressure. However, there is a definite difference between the dimensional change of the center diameter and that of the end diameter in the longituditinal direc-tion of sintered compact. It is presumed that the lengthwise sintered compact distorts, as a consequence of the uneven dimensional change. Then, the cylindri- city indicated by measurement of roundness was inspected. The cilindricity of the compact at 884MPa is reduced by approximately half, as compared with that of the compact at 490MPa. Thus, the high pressure compacting by this method was found to be effective not only for the increase of the density but also for the improvement of dimensional precision.抄録全体を表示PDF形式でダウンロード (1746K) -
三浦 秀士, 宮崎 尚敏, 森 康英, 蜂須 賀讓二, 萩田 雅俊1998 年 45 巻 5 号 p. 425-429
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーHigh performance sintered 4600 steels were obtained by Metal Injection Molding (MIM) process in our previous studies. This seemed to be due to the fine heterogeneous microstructure which were consisted of martensite surrounded by a network of tempered martensite through the segregation of Ni added as alloying element. Consequently, Ni has great effects in the heterogeneous microstructure of like this low alloy sintered steels. For example, the mechanical properties may largely change by the amount and distribution of Ni content.
In this study, the effects of Ni content (2, 4, 6 and 8mass% Ni) on the static strength and microstructures of sintered and heat-treated 4600 steels has been investigated using the conventional powder metallurgy (P/M) process. The hardness and tensile strength of sintered steels were improved with increasing Ni content. However, tensile strength of heat-treated steels were decreased by the addition of 8mass% Ni. This was seemed to be due to the appearance of retained austenite. Optimum combinaion of strength (1450MPa), elongation (2%) and hardness (40HRC) was obtained by the addition of 6mass% Ni.抄録全体を表示PDF形式でダウンロード (3711K) -
立崎 陽介, 桃澤 信幸, 阿部 正彦, 高木 研一, 西山 勝廣1998 年 45 巻 5 号 p. 430-435
発行日: 1998/05/15
公開日: 2009/12/04
ジャーナル フリーIn this study fabrication conditions, microstructure, mechanical properties and corrosion resistance of pressureless sintered magnesium alloys containing boron and metals (Ti, Zr, Co, Si, Al) were investigated. These alloys were sintered at a temperature of 913-1023K in 1 atm argon. During the liquid sintering process of Mg alloys containing boron, MgB2 particles were formed and dispersed in Mg matrix. Addition of boron and the formation of the boride improved the mechanical properties of Mg. And moreover, some metals (especially aluminum) improved the mechanical properties of Mg alloys containing boron. Especially, Mg-6vol%B alloy sintered at 1023K had a bending strength of 210MPa and the Rockwell hardness of 91HRH. Mg-6vol%Al-8vol%B alloy sintered at 1023K had a bending strength of 349MPa and the Rockwell hardness of 105HRH.抄録全体を表示PDF形式でダウンロード (2671K) -
三浦 秀士, 森川 浩光, 川上 雄士, 石橋 章義1998 年 45 巻 5 号 p. 436-441
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーMetal injection molding (MIM) process is hoped to be quite useful for improvement of the quality and productivity in the automotive sintered parts. In our previous studies, high performance ferrous sliding abrasive wear-resistant materials using prealloyed steel (SCM440) and 3mass%TiN powders were obtained by MIM process.
This study has been investigated to develop the high performance self-lubricating wear-resistant materials in the same way. A water atomized tool steel (SKD11) powder was used as the matrix and 2-8mass% CaF2 powder was added to improve the self-lubricating properties. The compacts were densified to near full density by liquid phase sintering at 1493K, and the final carbon content was controlled to be almost 1.6mass%. CaF2 powder particles were distributed uniformly in the compacts. Addition of 6mass% CaF2 powder caused a remarkable improvement of wear-resistance under non-lubricating conditions. This indicates that MIM process has enormous potential to produce high performance ferrous composites for the automotive sintered parts.抄録全体を表示PDF形式でダウンロード (5401K) -
藤木 章1998 年 45 巻 5 号 p. 442-445
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーThe economical situation of USA is very good, including automotive industries. A lot of P/M (powder metallurgy) companies have been supplying parts to automotive industries, so they are very busy now. Activities for securing QS.9000 & ISO9000 certification is very popular in USA. M&A (merger and acquisition) of P/M companies are very active between USA base companies and EU base companies. Development of new MIM technologies is very active, however the production of MIM parts is below the estimation of several years ago.抄録全体を表示PDF形式でダウンロード (3085K) -
安藤 汀1998 年 45 巻 5 号 p. 449-452
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーThe objective of this work is to investigate the effect of water vapor content in a mixed gas consisting of nitrogen and hydrogen for firing atmosphere on the micro structure and crystal phase of fired silicon powder compact. In consequence of the firing test, crystal of α-silicon nitride, α-cristobalite and α-quartz were formed in order as water vapor content grows higher and fibrous or network shaped micro structures were formed in all range. From XRD and SEM observations of the fired specimens and from phase diagram of Si-SiO2 system, the following mechanism of silicon oxide formation was suggested. At the time of the firing, first melted layer consisting of silicon and oxigen was formed on the surface of the specimen. Secondly an oxigen content of the melted layer increased further. Lastly an amorphous silicon oxide precipitated from there. By keeping on the specimen at the firing temperature, precipitation of amorphous silicon oxide and dissolution of silicon and oxigen proceeded concurrently in the melted layer. Finally silicon was completly transformed into silicon oxide.抄録全体を表示PDF形式でダウンロード (4001K) -
瀧田 朋広, 武部 克嗣, 五十嵐 廉1998 年 45 巻 5 号 p. 453-458
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーMolybdenum sheets (trade name: TEM) having elongated coarse-grain structures were developed. The grain structures were controlled by hot and cold rolling under high total reduction ratio (εt) and recrystallization treatment at 2070K of sintered Mo body with lmass% of La2O3.
The recrystallization temperatures of La2O3-doped Mo sheets which were examined in terms of Vickers hardness and optical microstructure were higher than those of pure-Mo and TZM (Mo-0.56Ti-0.086Zr-0.016C by mass%) sheets. In particular, that of the La2O3-doped Mo sheet with high εt of 99.1 % was about 1830K, 400K higher than that of the pure-Mo sheet.
The deformation resistance of TEM sheets having elongated coarse-grain structures, which was examined by sag tests at 1470K to 2070K, were superior to those of the pure-Mo and TZM sheets with equiaxial grains. In particular, deformation resistance was improved at aspect ratios (L/W) exceeding 20. Sag value of TEM sheets with L/W=150 after sag test for 36ks at 2070K was less than 1/100 that of pure-Mo sheet and less than 1/60 of TZM sheet.
The shock resistance of TEM sheets with L/W=150 at room temperature, which was examined by the falling-weight impact test, was superior to that of the pure-Mo sheet with equiaxial grains.抄録全体を表示PDF形式でダウンロード (6656K) -
筒井 唯之, 石井 啓, 小谷 純久, 上村 淳一1998 年 45 巻 5 号 p. 459-463
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーSintered materials have been widely used in various industrial fields duo to the improvement of their mechanical properties. However, the demands for reduction of production cost of sintered parts are growing in recent years. In this study, a material, which has martensitic structure obtained at a current cooling rate in conventional furnace without quenching process, has been developed in the purpose of lowering production cost. In order to obtain such a material, it is necessary to improve the hardenability of material through adding alloying elements. The alloying elements and their addition method were optimized to get a good compressibility. The amount of alloying elements was decided by the calculation of ideal critical diameter. As a result, the developed material consisted of 95% martensite and 5% bainite structure at a cooling rate of 0.15K/s, and its mechanical properties are far superior to those of the conventional materials having been heat-treated. Based on these results, the developed material has been evaluated for its practical use as the spiral bevel gear for power tool.抄録全体を表示PDF形式でダウンロード (4320K) -
大岸 秀之, 水田 明能, 長谷川 潔, 苧野 兵衛, 田村 朗1998 年 45 巻 5 号 p. 464-468
発行日: 1998/05/15
公開日: 2009/12/04
ジャーナル フリーIn the application of hard materials as a part of wear-resistant components, casting by inserting WC-based cemented carbide presents difficulties.
In a previous paper we reported that a WC-(high chromium cast iron) alloy, developed with the aim of improving the insertion property of WC-based hard materials by replacing the cobalt binder in WC-based cemented carbide with high chromium iron, had powder injection abrasion properties similar to those of the conventional WC-based cemented carbide.
In this paper, we report on the insertion bonding property of that WC-(high chromium cast iron) alloy. We obtained the following results to insert WC-(high chromium cast iron) alloy by high chromium cast iron.
(1) The WC-(high chromium cast iron) alloy was confirmed to have better insertion properties than the conventional WC-based cemented carbide, but fine cracks were observed at the joint.
(2) When the WC-(high chromium cast iron) alloy was treated by applying a cast iron coating to its surface prior to insertion, no cracks were observed at the joint and the good joint strength was obtained.抄録全体を表示PDF形式でダウンロード (4072K) -
田中 利一1998 年 45 巻 5 号 p. 469-472
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーThe origin of perpendicular anisotropy in sendust (Fe-Si-Al alloy) thin films was studied. The magnitude of the perpendicular anisotropy was evaluated from the magnetic field (saturation field) which is needed to saturate the magnetization on the hysteresis loop, for films with the hysteresis loop characteristic of the stripe domain structure caused by the perpendicular anisotropy. The perpendicular anisotropy arose regardless of the columnar structure in the films, and decreased with heat treatment at 300-400°C. The saturation field did not depend on temperature in such a way that the perpendicular anisotropy originated from the shape anisotropy. These results indicate that the perpendicular anisotropy in sendust thin films originates mainly from the anisotropy due to the magnetostriction, not from the shape anisotropy.抄録全体を表示PDF形式でダウンロード (2047K) -
鈴木 裕之, 篠崎 賢二, 黒木 英憲1998 年 45 巻 5 号 p. 473-479
発行日: 1998/05/15
公開日: 2009/05/22
ジャーナル フリーTo elucidate the causes of the superior mechanical properties of the alumina developed by the high-speed centrifugal compaction process, its microstructure development during sintering is investigated. A high purity alumina powder with a purity of 99.99% and a mean particle size of 0.22μm is dispersed in 25 mass% of ion-exchanged water, compacted applying acentrifugal force of 10, 000-20, 000g for 3ks, and sintered at 1423-1773 K for 5.4ks in air.
Homogeneous sintered compacts with a relative density of 99% or more and free from abnormal grain growth are obtained without using any additives in a wide range of sintering conditions. On tens of fracture surfaces observed, no sign of inhomogeneity such as large grain, large pore, or inclusion is observed. Instead, each specimen contains a little intergranular porosity. At low sintering temperatures, pores remain at the fbur-grain corners which. are thermodynamically the most stable sites. As the sintering temperature increases, the pores change their locations gradually from four-grain corners to three-grain edges, then to two-grain boundaries.
The strongest specimen, the one sintered at 1503K for 5.4ks, shows homogeneous equiaxed grains with equiaxed and simple-shaped pores located at four-grain comers.抄録全体を表示PDF形式でダウンロード (9387K)
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