-
[in Japanese]
1994 Volume 41 Issue 6 Pages
638
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
-
Koji Atarashiya
1994 Volume 41 Issue 6 Pages
639-643
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
A functionally gradient material block of the system A1N-M (M-Ni, Mo, W) was prepared by the method of powder metallurgy. The raw materials i.e. ultrafine particles were prepared by means of the arc-plasma processing. A compositionally gradient mixture of an ultrafine aluminum particle and M particle was pressed (200-400 MPa) in a steel die, followed by two-step sintering (873 K and 1273 K) in flowing nitrogen under null pressure.
The techniques of an ultrafine-particle mixing and a sintering process with no crystal-grain growth were invented. The nitriding reaction of aluminum is exothermic, thus, it considerably progresses by self-propagating high temperature synthesis when it has once begun.
The structures and the compositional gradient of the FGM block were examined by SEM, EDX, EPMA and XRD. The properties of the FGM blocks such as density, thermal expansion coefficient and microhardness etc. were measured.
View full abstract
-
Itsuji Yoshikawa, Sowjun Matsumura, Masuo Okada
1994 Volume 41 Issue 6 Pages
644-648
Published: June 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL
OPEN ACCESS
In nickel/zirconia composite electroplating, the influence of characteristics of zirconia powder on co-deposition of zirconia particles in the composite plating film and its mechanism were studied to increase the amount of zirconia co-deposited. The amount of zirconia co-deposited in the film by composite electroplating related with specific surface area of zirconia mainly, but had nothing with particle size. As specific surface area became lower, the amount of co-deposition increased. The surface positive charge of zirconia particles is related in co-deposition mechanism of them. Probably, it occurs due to the difference of electrostatic repulsion between electrodeposited particles and suspended particles by changing the specific surface area of zirconia particles.
View full abstract
-
Mamoru Omori, Masakazu Kawahara, Hirotaka Sakai, Akira Okubo, Toshio H ...
1994 Volume 41 Issue 6 Pages
649-652
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Functionally gradient materials (FGM) of ZrO
2(3Y) and SUS(410) were prepared using a spark plasma sintering equipment. Starting powders of SUS and ZrO
2 of 90, 80, 70, 50, 40 and 30vol% were stacked and sintered for 12 min. The temperature was 1200°C at the ZrO
2 layer and 1000°C at the SUS layer. The products were dense and free from pores. The stress due to the thermal expansion mismatch was delocalized by graded structures and no crack appeared. The compressive residual stress acted to stabilize a tetragonal phase of ZrO
2 and lower the fracture toughness of the ZrO
2 layer.
View full abstract
-
Jing-Feng Li, Noriyuki Nishio, Akira Kawasaki, Ryuzo Watanabe
1994 Volume 41 Issue 6 Pages
653-657
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Diamond cutting tools are getting increasing uses for superprecision machining. For conventional diamond tools, a vibration known as slight waviness is generated to deteriorate the machining accuracy because of the low stiffness of silver solder containing active metals used to join a diamond chip onto a metallic alloy shank. In order to overcome this problem, a diamond tool with silicon carbide shank by reaction sintering was developed. Numerical calculation by the finite element method (FEM) was carried out to clarify the thermal residual stresses between the diamond chip and silicon carbide shank with and without compositionally graded joining layers. The FEM calculation clearly showed that thermal stress between the diamond chip and silicon carbide shank was greatly reduced by inserting the compositionally graded layers. The fabrication process and performance of the developed diamond tool were also described.
View full abstract
-
Junichi Hojo, Tomomi Kajiya, Shoji Fukuoka, Kazuo Kunoo
1994 Volume 41 Issue 6 Pages
658-663
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Residual stresses of the multilayer composite disks produced by a powder metallurgical process were calculated by classical analytical techniques and finite element method. The layer composites have a structure of SiC/SiC+TiC/TiC/TiC+Ni/Ni system in which the thermal expansion coefficient increases in the order of SiC<TiC<Ni. Large tensile stresses are noteworthy in or near SiC layer in the direction parallel to interface, and over the range of SiC to TiC in the perpendicular direction along free edge. These calculations explain cracking in ceramic part of the layer composite. The stresses decrease with an increase in the number of mixture layers, according to which cracking was prevented. The two calculation methods give the similar results.
View full abstract
-
Xu Zhang, Fumiaki Miyaji, Takeshi Yao, Tadashi Kokubo, Chikara Ohtsuki
1994 Volume 41 Issue 6 Pages
664-667
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Titanium metal and its alloys coated with a hydroxyapatite by plasma spray method are widely used as hip joints and dental implants. Thus formed apatite is, however, not easy to be controlled in its composition and structure, and not easy to be strongly bonded to the substrates. In the present study, it was attempted to induce bioactivity of titanium metal by forming a thin titanium hydrogel layer on its surface with a chemical treatment. The pure titanium metal was treated with 10M-NaOH or -KOH aqueous solution at 60°C for 24h to form alkali titanate amorphous layer on its surface, then subjected to a heat treatment at 600°C for 1h to increase the thickness of the amorphous layer up to 1μm thick. Thus treated titanium metal formed a dense and uniform bone-like apatite layer on its surface via forming a titanium hydrogel layer when it was soaked in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma.
View full abstract
-
Kunihito Tokui, Susumu Sakuragi, Takuya Sasaki, Yutaka Yamada, Mamoru ...
1994 Volume 41 Issue 6 Pages
671-675
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Thermal expansion properties and mechanical properties of the sintered Fe-Ni-Co alloys (Kovar), produced by the metal injection molding process using mixed and pre-alloyed powders, were investigated.
The average thermal expansion coefficients of the Kovar between 323K and 673K were 4.82×10
-6/K for the mixed powder compacts and 5.03×10
-6/K for the pre-alloyed powder compacts in the condition of reducing carbon content, because the thermal expansion property of the sintered Kovar depends upon the carbon content. The thermal expansion coefficients of the mixed powder compacts also were influenced by nickel content changing from 27wt% to 31wt%, each of the coefficients was 4.1×10
-6/K and 11.4×10
-6/K, respectively.
Reduction of silica(SiO
2) in iron for the mixed powder improved the mechanical properties of the sintered Kovar, resulting in a tensile strength of 460MPa and an elongation of 36.4%. These properties exceed those of the sintered Kovar using pre-alloyed powder.
View full abstract
-
Kokichi Kumagai, Takashi Suzuki, Satoshi Saito, Takeshi Nomura
1994 Volume 41 Issue 6 Pages
676-680
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Electromagnetic properties of composite multilayer chip components was studied with special reference to the chemical reaction between magnetic and non-magnetic materials. It has been shown that mutual diffusion between magnetic NiCu ferrite and non-magnetic CuZn ferrite brought about the formation of high, u, NiCuZn ferrite layer, which caused the deterioration of Q-factor. Non-magnetic material of Ni-Cu-Mg-Si-O system has been newly developed for high performance composite multilayer chip components.
View full abstract
-
Atsuyuki Nakano, Takahiro Sato, Takeshi Nomura
1994 Volume 41 Issue 6 Pages
681-685
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
The effdct of microstructure on the electromagnetic properties of low temperature sintered NiCuZn ferrite has been studied with special reference to the dissociation behavior of CuOx from ferrite. The dissociation behavior is greatly affected by the ambient atmosphere during ball milling. The milling under non-oxidizing condition brings about not only the separation of CuOx from ferrite but also the deterioration of electromagnetic properties. It is thought that the oxidation of Fe contamination causes the reduction of Cu
2+ and separates CuOx(x<1) from ferrite. Nano-structure of the sintered NiCuZn ferrite will be also discussed.
View full abstract
-
Minato Ando, Masaaki Ito, Takashi Kato
1994 Volume 41 Issue 6 Pages
686-689
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Alumina ceramics have been used for insulator in electronic-power industry and in recent years, they have become main parts of microelectronic device. These ceramics usually contain 92-97w% alumina and have dielectric loss tangent of 10
-3-10
-4 level. In this study, above 97w% alumina ceramics were investigated with respect to dielectric loss tangent in microwave region to understand effect of accessory ingredients. Consequentry, tan 6 of single crystal level was obtained for alumina ceramics containing 0.2-0.3w% of accessory ingredients consisting of SiO
2:0.68, CaO:0.16, MgO:0.16 parts by weight respectivery. As for accessory ingredients, at Cat) poor compositional region, tan 6 of 10
-5 level was obtained for 0.3w% addition. Silica in accessory ingredients was expected to had principal role in reducing tang of alumina ceramic by forming homogeneous silicate in ceramic.
View full abstract
-
Osamu Kimura
1994 Volume 41 Issue 6 Pages
690-694
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Recently, multilayer electronic ceramic devices such as chip capacitors, ceramic actuators or chip inductors have been used in electronic circuit . Mutually sandwiched layers of electronic ceramics and metallic thin film electrodes are usually sintered simultaneously. Accordingly, thermal expansion mismatch stresses occur in them owing to difference in thermal expansion between their ceramic and metal layers. These stresses may result in crack or fracture formation in their ceramic layers, decrease in their capacitances or inductances, or troubles during actuator operation.
This paper describes analytical treatment of these stresses as a function of their layer number on the basis of theoretical discussion given elsewhere for residual thermal stresses in ceramic-to-metal joints .
View full abstract
-
Yuji Kaneko, Koki Tokuhara, Naoyuki Ishigaki
1994 Volume 41 Issue 6 Pages
695-700
Published: June 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL
OPEN ACCESS
For a further improvement to achieve extremely high magnetic properties of Nd-Fe-B sintered magnet, extensive investigation has been done. In order to improve the residual flux density (Br) of this magnet, it is very important to increase the amount of Nd
2Fe
14B(T
1) matrix phase up to 95% with keeping the amount of the Nd
1.1Fe
4B
4 (T
2) and Nd-rich phases, which generate the liquid phase in the sintering process, as low as posible and to densify the magnet up to the theoretical value by the liquid phase sintering. Also, in order to increase the value of intrinsic coercivity(iHc) without any additives which decrease the saturated magnetization of R
2Fe
14B intermetallic compound, it is an essential key technology to control the particle size and its distribution to be fine and uniform. Furthermore, for obtaining the super high energy magnet, it is a fundamental technology to realize the excellent alignment of T
1 grains. As a result of these investigation on controlling the chemical composition and the microstructure of this magnet, we have succeeded in obtaining the super high energy products magnet having Br=1.495T(14.95kG), (BH)max=431 kJ/m
3 (54.2MGOe), iHc=845kA/m(10.62kOe).
View full abstract
-
Hiroaki Nishio, Hitoshi Taguchi, Fumihiko Hirata, Taku Takeishi
1994 Volume 41 Issue 6 Pages
701-704
Published: June 15, 1994
Released on J-STAGE: July 12, 2010
JOURNAL
OPEN ACCESS
The rotaional hysteresis loss Wr was measured for M-type hexagonal strontium ferrite (SrM) fine particles with different average particles diameters and coercive forces Hc
CJ. The relationship between Hc
CJ, Wr, the distribution of anisotropy field H
A and the rotational hysteresis integral Rh, as well as milling effects were examined. The distribution of H
A of SrM fine particles was improved by annealing. Wr/Ms curves expanded to the low magnetic field as increasing milling time, because of increased distribution of H
A, even though Hc, remarkably decreased. The effective HA was in proportion to He, in SrM fine particles that had less milling effects. As Hc
CJ increased the rotaional hysteresis integral Rh decreased, and the magnetization switching approachs the coherent rotation mode.
View full abstract
-
Hisamichi Kimura, Atsushi Kawabata, Shuji Aizawa, Akihisa Inoue, Tsuyo ...
1994 Volume 41 Issue 6 Pages
705-708
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Amorphous Ti
65 Co
20 Si
15 powders were produced by a rotating electrode process with rapid cooling system developed by the present authors. The amorphous powders have a tear like form with smooth surface. The aspect ratio, thickness and structure of the powders can be controlled by changing the rotating speed of mother alloy electrode, the circumferential velocity(C.V.) of cooling copper roll and the distance between mother alloy electrode and cooling copper roll. The thinckness of powders decreases with an increase of the circumferential velocity of cooling copper roll and is about 25μm at the velocity of 25m/s. The highly effective production of the amorphous powders was achieved in the condition where the rotating direction of the cooling copper roll is inversed to that of the mother alloy electrode.
View full abstract
-
Osamu Terada, Hiroyuki Ike, Hisashi Suzuki
1994 Volume 41 Issue 6 Pages
709-713
Published: June 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL
OPEN ACCESS
The carbide powders (WC, VC, Cr
3C
2) having usual particle size of 1-2.5μm were finely ballmilled under a prescribed condition. Using these fine carbide powders (<0.2μm), WC-VC-Cr
3C
2-13mass%Co submicron cemented carbides (VC≤10mass% and Cr
3C
2≤8mass% in binder, respectively) were vacuum-sintered at 1320-1350°C and finally HIP-ed. Microstructures, hardness and transverserupture strength of the alloys were mainly examined.
It has been found that the properties of submicron alloys obtained in the present study are by no means inferior to those of commercially available alloys. It was noted that the ball-milled carbide powders showed a narrow particle distribution, nearly the same as that of commercial powders for preparing submicron alloys.
View full abstract
-
Takafumi Atarashi, Katsuto Nakatsuka, Junzo Shimoiizaka
1994 Volume 41 Issue 6 Pages
714-717
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
The effect of synthetic condition on the colour and magnetization of MG-Zn ferrite powders has been investigated.
The colour of the ferrite (S-1), which was prepared by heating for 3 hrs at 1200°C in air, cooling slowly to room temperature and re-heating for 6 hrs at 800°C, shows reddish, while the colour of the ferrite (S-2), which was prepared by quenching from 1200°C after firing, is dark brown.
The value of maganetization for S-2 was larger than that for the other heat treatment. It has been also confirmed that the quantity of Fe2+ ion is closely correlated to the colour and magnetization of the Mg-Zn ferrite.
View full abstract
-
Katsuhiko Igarashi, Takeshi Nomura
1994 Volume 41 Issue 6 Pages
718-722
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Degradation behavior of adhesion strength between Ag terminal erectrode and dielectric (BaNd
2Ti
4O
12+Bi
2O
3) under heat cycle test (-40°C -+85°C) has been studied with reference to the microstructure. It is shown that the solder produces a marked stress accompanied by plastic strain on the interface between Ag terminal electrode and dielectric substrate, and this stress breaks the interface during heat cycle test. The degradation behavior was strongly affected by the properties of solder. The degradation was accelerated by using high temperature solder. It is important to control the microstructure of the interface. Addition of CuO to Ag terminal electrode was effective to suppress the degradation of adhesion strength.
View full abstract
-
Hakaru Sadano, Kazumasa Okadome, Tsuyoshi Arakawa
1994 Volume 41 Issue 6 Pages
723-726
Published: June 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL
OPEN ACCESS
Crystalline powders of Si and Co in the composition ratio varying from Si:Co=1:2 to 2:1 were mechanically alloyed by a laboratory ball mill in an inert atmosphere. The amorphization reaction proceeded according to a second-order reaction. The reaction rate decreased with increasing the Co-content. Moreover, crystallization behavior was investigated by differential thermal analysis and the measurement of saturation magnetization. The saturation magnetization of milled Si-Co powders was maximum at 60-80 mol% of Co-content and was larger than that of the corresponding mixture of crystalline powders. Also the saturation magnetization of amorphous Si-Co powders decreased abruptly at a temperature of which the transformation of an amorphous state into a crystalline state began to occur.
View full abstract
-
Mitsuo Ueki, Hiroyuki Kodama, Hisashi Suzuki
1994 Volume 41 Issue 6 Pages
727-731
Published: June 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL
OPEN ACCESS
The characteristics such as growth rate, microstructure and quality of Al
2O
3 film coated on WC-β
t-Co cemented carbide (having TiC and TiN thin films) were investigated as a function of H
2S content in CVD atmosphere. It was found that the growth rate of Al
2O
3 film sharply increased; the columnar structure of the film was promoted; the sulphur content in Al
2O
3 film increased; the difference in film thickness between edge and flat of specimen decreased with increasing H
2S content. It was noticed that the strength of Al
2O
3 film and adhesive strength between Al
2O
3 and TiN-TiC films would lower by using H2S contained atmosphere.
View full abstract
-
Yuji Kaneko, Naoyuki Ishigaki, Kunio Kitajima, Nobuo Takusagawa
1994 Volume 41 Issue 6 Pages
732-738
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Effects of Fe-powder addition on sintering behavior, magnetic properties and corrosion resistance of Nd-Fe-B sintered magnets have been investigated. Fe-powder addition to Nd-Fe-B ternary alloy powder is very useful to control the constituent phases of the sintered magnets. When Fe-powder is added to the ternary alloy powder, Fe-powder reacts with the liquid phase formed from the ternary alloy powder and generates the Nd
2Fe
14B main phase(T
1) during the sintering process. As a result, residual flux density (Br) of magnets prepared by the Fe-powder addition method increases with incerasing the content of T
1 phase. Furthermore, corrosion resistance of the magnets has been improved with decreasing the content of Nd-rich phase due to Fe-powder addition.
View full abstract
-
Saburo Sano, Kiichi Oda, Yasuo Shibasaki, Tomoya Matayoshi, Yasunari K ...
1994 Volume 41 Issue 6 Pages
739-741
Published: June 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL
OPEN ACCESS
Sintering of low soda alumina was studied using a high-power 915MHz microwave plasma in N
2-Ar flow at an atmospheric pressure. By using high-density slip carted green body (relative density: 64%), crack free sintered bodies have been obtained within 600s at an input microwave power of 5kw up to final densities higher than 97%. The microwave plasma sintered body shows a fine microstructure and high density compared with a conventionally sintered body.
View full abstract