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Volume 44, Issue 4
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[in Japanese]1997 Volume 44 Issue 4 Pages 312
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (83K) -
Jan Tengzelius, Mats Larsson1997 Volume 44 Issue 4 Pages 313-316
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn the production of PM components the dimensional scatter must be kept to a minimum. Due to the demand for narrow tolerances the components may need sizing or other secondary operations which increase production costs. New high strength material cannot however be sized due to the high hardness which means that the tolerances after sintering must be very close. This makes it important to consider the scatter in dimensional change when selecting material for PM components.
A model to calculate the scatter in dimensional change is suggested. The dimensional scatter on produced components can be estimated by using a mathematical model. This model includes the variations in mix composition, important compacting and sintering variables. It also take into account the Influence from these variables on the dimensional change.
With this model different base powders, alloys and manufacturing processes can be compared to find the most efficient alternative for achieving the best dimensional precision of PM parts.
The need for lowest total cost coupled with demands for high strength make it necessary to improve the dimensional tolerances for the parts after sintering.View full abstractDownload PDF (246K) -
Ryoichi Kanie1997 Volume 44 Issue 4 Pages 317-322
Published: April 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThrough long-term studies and progress in the engineering field, various biomaterials have been developed and put to excellent practical use in the medical field, bringing much benefit to human recipients. However, there are many inorganic materials and products being tried that are incompatible with the organic constituents of the human body. Unexpected tissue reactions sometimes follow the introduction of these materials into the body. Therefore, the development of new biomaterials is critical to improvements in patient care. Advances in the development of useful biomaterials requires engineers who understand the mechanisms of tissue reaction as well as medical investigators who understand the properties of these materials and can conceive of medical applications for such products.
In the field of orthopaedic surgery, in particular, metal alloys, high molecular-weight substances, and ceramics have been used in artificial joints, fracture fixations, and others. There has been a recent rise in applications of titanium, high density polyethylene, and hydroxyapatite.View full abstractDownload PDF (1561K) -
Yoshihiro Tada, Masao Sakamaki1997 Volume 44 Issue 4 Pages 323-328
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA powder metallurgical technique for the production of foamed cellular metals with very low apparent densities has been studied. Aluminum powder mixed with a powdered foaming agent, e.g. titanium hydride or zirconium hydride, is extruded at an elevated temperature below the decomposition temperatures of the foaming agents to achieve gas-tight fully densed compacts. Expansion into a porous cellular aluminum is performed by heating the compact to decompose the foaming agent to evolve gas. As the resistance of the aluminum matrix against expansion rapidly decreases by melting, a highly porous cellular aluminum is obtained by heating the compact in a temperature range above the solidus line of the matix. The foamed aluminum produced by free expansion usually shows excessive bulging which is accompanied with a rather large surface roughness and micro-cracks on its bulged surface. A use of a steel sleeve to restrict the bulging of the compacts during expansion is effective both to improve the surface quality and to achieve a higher porosity of the foamed products by preventing the evolved gas to leak.View full abstractDownload PDF (1813K) -
Kanji Notomi, Tokimune Shioura1997 Volume 44 Issue 4 Pages 329-333
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe new P/M stainless steel called "PM21" for cutlery was produced by the Gas Atomization plusHIP process. The microstructure, mechanical properties, corrosion resistance and cutlery properties of the steel were investigated in comparison with conventionally cast and forged alloy steels and a P/M high speed steel. The studies indicated that PM21 has a lot of carbides and a fine homogeneous carbide structure that confers high toughness and high wear resistance. Additionally, PM21 has a much higher corrosion resistance than that of SUS440C stainless steel. The studies also showed that the cutlery properties of PM21 are far superior to those of conventional steel.View full abstractDownload PDF (2286K) -
Akihiko Otsuka, Hironori Tanizaki, Kunihiko Iwasaki1997 Volume 44 Issue 4 Pages 334-339
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTi-Al2O3 functionally graded material (FGM) is tentatively fabricated by dry jet spraying of ultrafine particles (UFPs) onto a Ti substrate and subsequent temperature-gradient sintering. The FGM layer is formed by gradually decreasing the ratio, r=Ti/(Ti+Al2O3), during the dry-jet spraying. It is found to be effective to add Ti-or Zr-hydrides to the Ti substrate to decrease the number of cracks which appear in the FGM layer due to the difference in the amounts of shrinkage during sintering. Since the composition range between r=1 and r=0.5 is known to show large shrinkage, it is better to start the dry-jet spraying from r=0.5 than to start from r=1 to decrease the size of voids. Despite the existence of the skipped r range, the r in the sintered composite changes from r=1 to r=0, which is considered to be due to the abnormally rapid diffusion of Ti atoms. The fabrication of an FGM in the shape of a cylinder with locally different diameters is also tried and it is found that by adjusting the pressure of isostatic pressing of the dry jet sprayed composite the formation of cracks in the neighborhood of the protrusions is suppressed.View full abstractDownload PDF (5104K) -
Atsushi Nakahira, Kazunori Kijima, Jackie Ying1997 Volume 44 Issue 4 Pages 340-344
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHydroxyapatite is a typical bio-material as an implant for bone and teeth. In this work, the nano-meter size hydroxyapatite precursor was synthesized through the chemical precipitation method Effect of the heat-treatment of hydroxyapatite nano-meter size precursor on particle size, crystalline size and crystallinity was studied. Heat-treatment was done at 550, 700 and 900°C in air atmosphere. Futhermore, the sintering behavior of this nanocrystalline hydroxyapatite after the heat-treatment was investigated. The microstructure of these hydroxyapatite precursor and heat-teated hydroxyapatite was observed by FE-SEM and TEM. The synthesis parameters were investigated in order to synthesize the nanometer-size hydroxyapatite powder.View full abstractDownload PDF (1401K) -
Naoyoshi Sato, Takeshi Nomura1997 Volume 44 Issue 4 Pages 345-350
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMnZn ferrite granules were made under different conditions. By using these granules, effect of water content on the compaction behavior has been studied. The granules were characterized by strength, deformation modulus, apparent density and flow rate. The relationship between compacting pressure and intergranular pores has been studied. It was found that the compaction behavior was affected mainly by water content, and that the bending points were observed in the graphs of pressure and compaction density. The reason for these bending points was considered by pressure between upper punch and lower punch was decreased when increasing of water content. Water resulted in amelioration of pressure transmission.View full abstractDownload PDF (2786K) -
The Effects of Dispersion of Additives on Sintering Process of SrTiO3 System Semiconductive CeramicsNoriyuki Mabuchi, Noriyuki Kozu, Kiyoshi Tanaka, Yoshiaki Iguchi, Hiro ...1997 Volume 44 Issue 4 Pages 351-355
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of the dispersion condition of sintering aids(Al2O3, SiO2) on the grain size of sintered body of SrTiO3 semiconductive ceramics has been studied. When sintering aids was dispersed uniformly, the grain size of sintered body became small with narrow distribution. As a result the process of sintering, it was found that the dispersion condition of sintering aids affected the grain size resulted from the change in density of nuclei formation.View full abstractDownload PDF (4659K) -
Tohru S. Suzuki, Yoshio Sakka, Keijiro Hiraga1997 Volume 44 Issue 4 Pages 356-361
Published: April 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAl2O3-15vol%ZrO2 composites were produced by colloidal process. Dispersed suspensions consisting of α-Al2O3 and ZrO2 fine powders were prepared by adjusting the pH value and salt concentration, or adding appropriate amounts of polyelectrolyte. The dispersion of powder particles was characterized by rheological measurement. In multicomponent particle systems, long range particle segregation occurs due to different particle size and specific gravity. The segregation decreases with increasing the salt concentration and/or solid content in the suspensions. The suspensions were consolidated by slip casting and cold isostatic pressing (CIP). They were sintered at temperatures from 1573K to 1793K for 2h in air. The microstructures were observed by SEM. For the specimen sintered at 1673K, the density was more than 98% and the grain size of Al2O3 matrix was 0.42μm. At 1723K, the density was about 99.5% and the grain size was 0.59-0.70μm.View full abstractDownload PDF (2218K) -
Naotoshi Sato, Osamu Terada, Hisashi Suzuki1997 Volume 44 Issue 4 Pages 365-368
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt has been well known that aluminum is apt to adhere to WC-Co cemented carbide tools, when, for instance, different parts made of aluminum alloys are cold-worked using the above tools. The phenomenon was studied as a function of carbide grain size, cobalt content and surface roughness of the tools. It was found that the tendency of adhesion became larger with increasing carbide grain size, cobalt content and surface roughness. It was also found that aluminum was also apt to adhere to the other materials besides cemented carbide. The phenomena were discussed in detail from a viewpoint of the nature of aluminum showing strong deoxidation.View full abstractDownload PDF (2585K) -
Toyohisa Fujita, Balachandran Jeyadevan, Eiichi Kuzuno, Toshiharu Tana ...1997 Volume 44 Issue 4 Pages 369-373
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe molded tourmaline/Sr-ferrite pellets is prepared by mixing tourmaline and Sr-ferrite powders with polyester resin and hardened under electric and magnetic fields. The piezoelectric-g-constant and magnetic flux density of the molded pellets were investigated.
Tourmaline particles in the molded pellet oriented toward the electric field direction for electric field strengths more than 0.5kV/mm, and the piezoelectric-g-constant of the molded pellets increased for any increse in the electric field strength. Also the piezoelectric-g-constant of the molded pellet showed a sharp increase when the thickness of the molded pellet became less than 1mm.
The magnetic flux density of molded tourmaline/Sr-feffite pellet hardened under magnetic field depended on the Sr-ferrite content.View full abstractDownload PDF (3377K) -
Kazuo Asaka1997 Volume 44 Issue 4 Pages 374-380
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe influences of the particle shape and size of iron powders on the diffusion bonding of assembled iron-base green compacts during sintering were investigated. It has been clarified that the bonding strength is mainly influenced by the specific surface areas of iron powders. As reduced iron powders show larger specific surface areas and diffusibility of other elements such as carbon than atomized iron powders, the bonding strength of reduced iron powder specimens is higher than that of atomized iron powder specimens. The specific surface areas being influenced by the particle size, smaller size powders show higher bonding strength. Therefore, atomized iron powders which show the same specific surface areas as reduced powders show the same bonding strength.View full abstractDownload PDF (6878K) -
Sebastian Diaz De La Torre, Hiroki Miyamoto, Hiroyuki Satake, Jiro Kaw ...1997 Volume 44 Issue 4 Pages 381-386
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSComputer simulation was done to determine the extent to which the Zeolite-5A (LTA) molecular sieve is able to adsorb a number of unwanted gases and liquids, as a first step for designing a filter device using honeycomb tailored zeolite-5A, directed to reduce environment pollution problems. Since the presence of stored water in the sieve plays an important role in the course of the adsorption process of certain systems, simulation was focused to predict the zeolite's capacity having different H2O content for several adsorbates. Moreover, Ca2+ cations of the mineral were replaced by various cations to get an insight on its adsorption capacity for both CO2 and NH3 gases. The results confirm the hydrophilic character of the mineral and afford several adsorption isotherms at 300K. In all studied cases, the zeolite-5A's adsorption capacity decreases asymptotically as the H2O content within its cavities is higher. The replacement of Ca2+ with Li+ or Na+ cations enhances the sieve's efficiency in about 20 and 10% for the CO2 and NH3 adsorbates cases, respectively.View full abstractDownload PDF (384K) -
Synthesis of Colored Mica, Coated with Titanium Dioxide and Electroless Plated NickelAsa Kimura, Katsuhiko Yagi, Fukuji Suzuki1997 Volume 44 Issue 4 Pages 387-392
Published: April 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA colored pearly luster pigment without any coloring materials was developed by electroless nickel plating onto titanium dioxide coated mica (TiO2-mica) which showed interference color. Various appearance colors could be obtained by controlling the thickness of TiO2-mica plate. Their appearance colors and blightness were almost equal to the interference color of TiO2-mica of a raw material. SEM analysis showed that TiO2-mica were coated with ultra fine nickel particles (particle size < 5nm). Furthermore, XPS analysis showed that the oxidation states of the nickel particle on the TiO2-mica could be controlled with the drying temperature or through the calcinating process. Ni(OH)2 and Ni were found in the sample treated at 25°C for 24 hr, and Ni2O2 and Ni at 150°C for 24hr. Nickel particle composed of Ni2O2 and Ni was stable at further calcination, because of the passive valence state Ni2O2.View full abstractDownload PDF (2884K)
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