スマートプロセス学会誌
Online ISSN : 2187-1337
Print ISSN : 2186-702X
ISSN-L : 2186-702X
9 巻 , 4 号
選択された号の論文の5件中1~5を表示しています
  • 趙 研, 安田 弘行, 當代 光陽, 上田 実, 竹山 雅夫, 中野 貴由
    2020 年 9 巻 4 号 p. 180-184
    発行日: 2020年
    公開日: 2020/07/18
    ジャーナル フリー
    TiAl rods were fabricated by electron beam melting followed by hot isostatic pressing(HIP)and the microstructure and high temperature fatigue properties were examined focusing on HIP temperature. Unique layered microstructure consisting of a duplexlike region and equiaxed γ grain layers(γ bands)is formed in as built samples. The layered microstructure is completely replaced by fully lamellar microstructure by HIP treatment at 1633 K, while it can be maintained at 1523 K or 1463 K. In addition, the volume fraction of the α2 phase in the γ bands can be controlled by selecting HIP temperature, according to the phase diagram of the alloy. The rods subjected to the HIP treatment at 1523 K or 1463 K exhibit higher fatigue strength at 1023 K than as built rods and HIPtreated cast alloys. It was found that the high fatigue strength of the rods at low cycle fatigue life region is caused by inhibition of the crack initiation due to the high ductility. On the other hand, the strength at high cycle fatigue life region is possible to be improved by the suppression of pores and precipitation of the α2 phase in the γ bands though the HIP treatment under appropriate conditions.
  • 清水 那弥, 桐原 聡秀
    2020 年 9 巻 4 号 p. 185-189
    発行日: 2020年
    公開日: 2020/07/18
    ジャーナル フリー
    Silicon carbide(SiC)ceramics have been used for a variety of applications in the aerospace industry. However, using a conventional SiC molding technology, manufacturing of a complicated shape with high accuracy is significantly difficult. Stereolithography can easily produce complex shapes. The stereolithography based additive manufacturing of ceramic materials has been widely reported; however, the manufacturing of a ceramic with high refractive index such as SiC with this technique is substantially difficult. In this paper, the challenges of SiC ceramic stereolithography were visualized and discussed using electromagnetic field simulation. The effects of curing ability of SiC slurries that varies with particle size and stereolithography parameters were further studied in detail. Finally, complex shaped SiC ceramic precursor with high accuracy and promising quality was successfully fabricated. This study demonstrated that the stereolithography based additive manufacturing had a significant potential to realize high refractive index ceramics such as SiC.
  • 清水 那弥, 桐原 聡秀
    2020 年 9 巻 4 号 p. 190-193
    発行日: 2020年
    公開日: 2020/07/18
    ジャーナル フリー
    Ligneous composite structures composed of micro woodchips dispersed photosensitive resins were fabricated by using stereolithographic additive manufacturing. The composite resin with woodchips dispersion were spread on a substrate by using a mechanical knife edge. An ultraviolet laser beam of 355 nm in wavelength was scanned to draw a cross sectional solid pattern. A composite precursor was obtained successfully thorough continuous laminations. In this investigation, artificial trees of conifers and shrubs were designed and fabricated successfully according to mathematical theories of golden angles and Fibonacci series to propagate the branches naturally, respectively. The miniature trees will be applied to create artificial forest models in numerical simulations of atmospheric circulations including fine particles mass transfers.
  • 伊藤 竜也, 桐原 聡秀
    2020 年 9 巻 4 号 p. 194-198
    発行日: 2020年
    公開日: 2020/07/18
    ジャーナル フリー
    Thermoacoustic converters with channels bundle structures were fabricated by using stereolithographic additive manufacturing. Thermodynamic expansions and contractions caused by acoustic vibrations can realize effective heat exchanges between gaseous phases and solid walls. Alumina fine particles were dispersed into photo sensitive acrylic resin to create high viscosity pastes for a lamination processing. Ultraviolet laser beam was scanned on the spread paste surface to form a cross sectional pattern. Through the layer stacking, solid component according to solid design was processed. Obtained precursors were dewaxed and sintered in the air atmosphere. In the ceramic components, part accuracies and fine microstructures were measured and observed by digital optical microscopy and scanning electron microscopy. The hexagonal fluid channels with graded aperture sizes were designed and manufactured by using computer aided systems to increase the thermoacoustic conversion efficiencies.
  • 迎井 直樹, 田代 真一, Anthony B. MURPHY, 井上 芳英, 菅 哲男, 田中 学
    2020 年 9 巻 4 号 p. 199-207
    発行日: 2020年
    公開日: 2020/07/18
    ジャーナル フリー
    Cold cracking sensibility is severe problem in the welding fabrication of large-scale steel structures. In order to solve this problem, a low hydrogen welding process using a special torch has recently been developed and shown to be effective for cold cracking. In this process, a torch having a double nozzle is applied to perform welding while sucking a part of the shielding gas from the inner nozzle. Due to the feature of the process, there is a concern about shieldability, but there have been no reports on this point. Therefore, in this study, the shielding property against the lateral wind was evaluated by fluid simulation. The calculated results of the model were in good agreement with the observed results by the Shadowgraph method and the nitrogen content of weld metal. In addition, a comparison simulation with a conventional torch shows that this process has no clear difference in shielding performance compared with the conventional process, and good shielding performance is ensured. This is because the torch structure in which the inner nozzle protrudes also effectively works for the shielding property in order to improve the reduction effect of diffusible hydrogen.
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