粉体および粉末冶金
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
56 巻, 5 号
May
選択された号の論文の10件中1~10を表示しています
研究
研究
  • 小林 めぐみ, 藤本 憲次郎, 伊藤 滋
    2009 年 56 巻 5 号 p. 225-231
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    Alkali ions were co-precipitated with titanium hydroxide gels. When Ti(SO4)2 solution was added to KOH solution with K:Ti=10:1 (in molar ratio), the potassium remains in the precipitated gel, in spite of several times of washing. Excess amount of alkali and pH>9 were the essential conditions for the co-precipitation. Similar results were obtained for the other alkali elements; Li and Na. Nano-sized particles of K2O-6TiO2, Li2O-TiO2 and Na2O-3TiO2 with 20-30 nm in size were respectively obtained by heating the precipitates at 500 or 600°C.
    In addition, the thin films of alkali titanates were obtained on Si substrate by dripping Ti(SO4)2 solution and MOH solution for 30-60 min.
  • 佐藤 仁俊, 飯島 志行, 冷 永華, 李 継光, 倉嶋 敬二, 吉田 貴行, 神谷 秀博, 石垣 隆正
    2009 年 56 巻 5 号 p. 232-235
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    Highly dispersed ethanol suspensions of spindle-type Fe-Co particles were obtained by the addition of oleic acid with applying ultrasonication. By using this suspension, spindle-type Fe-Co nanoparticles were coated by a uniform silica layer without agglomeration by a sol gel method, in which the total surface area of core Fe-Co nanoparticles and the reaction rate of TEOS were fully controlled. The silica-coated Fe-Co nanoparticles were annealed at 773K in nitrogen-4 % hydrogen mixture gas to reduce surface oxide layer of Fe-Co nanopartilces. The silica-coating densified by the heat treatment led to the substantial improvement of the oxidation-resistant property.
  • 杉井 一星, 藤本 憲次郎, 伊藤 滋
    2009 年 56 巻 5 号 p. 236-240
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    In order to obtain the material having a flat temperature dependence in dielectric constant, Ba(ZrxTi1-x)O3 powder compacts with different compositions were piled and sintered under HIP pressure and atmospheric pressure. The Ba(ZrxTi1-x)O3 obtained under 200 MPa of HIP pressure revealed the flat temperature dependence of dielectric constant being 3800 over the temperature range of 5∼52°C. Although this material had excellent flatness in temperature dependence, this dielectric constant was lower than that expected. This seemed to be due to the residual stress caused by HIP pressure. The piled Ba(ZrxTi1-x)O3 was also obtained under atmospheric pressure by calcining the starting powder mixtures sufficiently. This material revealed a higher dielectric constant of 5000 over the temperature range of 16∼30°C. However, this temperature dependence curve showed 5 peaks corresponding to five compositions. The dielectric material having excellent flat temperature dependence, which showed 8200 of dielectric constant over the temperature range of −1∼26°C, was obtained by using nine different compositions and by controlling the amounts of the powders. In addition, dielectric constant 5900 was obtained over the temperature range of 0∼45°C by atmospheric sintering of the Hiped Ba(ZrxTi1-x)O3.
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総報
研究
  • 木村 正宏, 清水 透, 安達 悟
    2009 年 56 巻 5 号 p. 243-247
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    Commercial MIM processes use thermal debinding and solvent debinding; the former requires a long debinding time, while the latter involves the use of toxic solvents. We have been investigating the application of supercritical CO2 extraction method to debinding process, which promises to overcome these drawbacks. For actual application of this process, we need to overcome two problems. The first one is that the process requires the high-cost pressure vessels, and the second one is low solubility of binders in supercritical CO2. In the process developed by Takishima and others, the latter problem is resolved by using of activated carbon as an adsorbent; this method is efficient and fast but introduces the additional problem that used activated carbon becomes waste. Here we propose the use of a liquid solvent as an adsorbent. This method allows easier treating of the adsorbent and higher binder extraction. The dissolved binder can be re-extracted from the adsorbent by distillation. Moreover, the extraction pressure can be decreased with using this method, and the cost for the pressure vessel can be reduced.
  • 長田 稔子, 田中 良知, 三浦 秀士, 徳岡 輝和, 西岡 隆夫
    2009 年 56 巻 5 号 p. 248-252
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    Ferrous soft magnetic materials are required several efforts to realize high performance. In powder metallurgy processing, both high density and high purity are necessary to obtain the excellent soft magnetic properties. Metal injection molding (MIM) process is an effective technique to produce the high density and more complex shaped parts from Fe-Si hard metal powders.
    In this study, MIM process using several types of Fe-6.5Si powders were performed, and their magnetic properties were investigated. Moreover, in order to improve the density and purity of injection molded compacts, the thermal debinding and sintering atmospheres were mainly investigated. The sintered compacts which have lower oxygen content showed high density and good soft magnetic properties.
  • 伊藤 芳典, 植松 俊明, 佐藤 憲治, 三浦 秀士, 新家 光雄
    2009 年 56 巻 5 号 p. 253-258
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    It has been found that the sintered MIM Ti-6Al-4V alloy compacts were strengthened by addition of fine Mo powder because of the microstructural modification. In this study, the metal injection molding process has been applied to strengthen Ti-6Al-4V compacts by addition of Fe or Cr powders, which are the same beta stabilizing elements as Mo and are more cost effective powders as compared to Mo powder. The effect of Fe or Cr contents and sintering conditions on the mechanical properties, oxygen content and microstructures of the sintered compacts were mainly investigated. The microstructures of sintered compacts were consisted of acicular alpha phase and intergranular beta phase, and the acicular alpha phase showed fine with increasing Cr content. The tensile strength of sintered compacts was increased with increasing Fe or Cr contents, and the effect of Fe addition for strengthening the sintered compacts was larger than Cr or Mo addition. Eventually, the tensile strength of sintered compacts added 2 mass% of Fe was improved to be 1010 MPa with 11.2 % of elongation, and the compacts added 4 mass% of Cr showed the excellent tensile strength of 1040 MPa with 16.1 % of elongation.
  • 伊藤 芳典, 植松 俊明, 佐藤 憲治, 三浦 秀士
    2009 年 56 巻 5 号 p. 259-263
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    The properties of sintered Ti-6Al-4V alloy compacts have been clarified by using various mixed or Ti-6Al-4V alloy powders under the various process conditions. From these studies, there were tendencies that the tensile properties of sintered Ti-6Al-4V alloy compacts were affected by oxygen content and relative density of sintered compacts rather than process conditions. In this study, the properties of injection molded Ti-6Al-4V alloy compacts obtained from previous studies were comprehensively investigated to clarify the effect of oxygen content and relative density on the tensile properties. The tensile strength of injection molded Ti-6Al-4V alloy compacts was significantly increased with increasing the oxygen content of sintered compacts up to 0.5 mass%, and the strength also increased with increasing the relative density of sintered compacts. Although the elongation of injection molded Ti-6Al-4V alloy compacts reduced drastically at above 0.35 mass% of oxygen content, they showed excellent ductility above 10 % of elongation up to 0.35 mass% of oxygen content. Eventually, the tensile strength (σ) of injection molded Ti-6Al-4V alloy compacts were greatly correlating with oxygen content (O) and relative density (ρ) of sintered compacts as shown in the experimental equation: σ (MPa)=700O (mass%)+10ρ (%)-315
  • 長田 稔子, 冨永 昌尚, 三浦 秀士
    2009 年 56 巻 5 号 p. 264-267
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    Producing micro size parts by metal injection molding (μ-MIM) needs more sophisticated technique than conventional MIM. Especially, to fill the micro groove cavities which size are smaller than 10 μm with feedstock by μ-MIM technique, much smaller particle size of powders than that of conventional MIM are required. Also, various properties such as powder loading and viscosity of feedstock, debinding behavior of compacts, relative density and mechanical properties of sintered compacts would be changed by using fine powders. In this study, the effects of particle size of powders on the properties of stainless steel (SUS316L) compacts were investigated for μ-MIM processing. The sintered compacts using fine powder which mean particle size is 3 μm showed high density and tensile strength.
  • 西籔 和明, 田中 茂雄
    2009 年 56 巻 5 号 p. 268-273
    発行日: 2009年
    公開日: 2009/06/30
    ジャーナル オープンアクセス
    A micro-planetary gears made of stainless steel has been developed by micro metal powder injection molding (μ-MIM) process. In this study, the accuracy and the quality of ultra-compact planet gear (module: m=0.07 mm, number of teeth: z=24) was evaluated. Cross-sections of the gear teeth were observed with a digital microscope and dimensions of the teeth were measured with a digital image processing. The variations in dimensions and shape of gear teeth were systematically investigated for mold, green and sintered parts, and heat treated ones. The accuracy classes of the ultra-compact planet gear were defined from four shape variations of gear teeth, i.e. total runout, single pitch deviation, accumulated pitch deviation and tooth profile deviation. The accuracy class was concluded as JIS N class seven which is a comparatively high precise level for practical applications.
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