著者

横田 耕三 村井 俊介 品川 一成

出版者

公益社団法人日本セラミックス協会

雑誌

日本セラミックス協会学術論文誌 : Nippon Seramikkusu Kyokai gakujutsu ronbunshi (ISSN:18821022)

巻号頁・発行日

vol.114, no.1336, pp.1138-1143, 2006-12-01

被引用文献数

2 4

---

The influence of particle size distributions of submicron high-purity α-alumina powders on forming and sintering behavior in an agglomerate-free condition were investigated. Nine kinds of alumina powders with the same median diameter (d_<PM50>=0.53μm) and different geometrical standard deviations (σ=1.2-2.0) in lognormal particle size distributions were prepared by blending spherical-like commercial α-alumina powders, and were also adjusted to near ideal distributions so that σ of a mass distribution was comparable with one of the number distribution. In order to prevent the agglomerate and contamination of the impurities, forming was performed by means of the colloid process, i.e., the slip casting method using the porous alumina molds. Relative densities of green compacts and bodies sintered at up to 1300℃ increased with increasing σ, but densities of bodies sintered at 1500℃ or more increased with decreasing σ. The width of the grain size distributions of those bodies increased with increasing σ. The abnormal grains over 30μm of the grain size generated at more than 1.7 of σ for alumina bodies sintered at 1700℃ and those grains contained many pores. The powder with a narrow distribution in size is better to fabricate a translucent material.

著者

宮内 創 横田 耕三

出版者

一般社団法人 粉体粉末冶金協会

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.67, no.8, pp.441-446, 2020-08-15 (Released:2020-08-15)

参考文献数

14

被引用文献数

1

---

This research evaluated the effect of nitrogen absorption into austenitic stainless steel in selective laser melting (SLM) process. Microstructures and mechanical properties of SUS316 specimens fabricated by SLM in different atmosphere, nitrogen and argon, were investigated. The results of microscopy observation of as-built specimen fabricated in nitrogen showed a fine cellular microstructure. In contrast, coarse columnar grains grew up from melt pool boundaries were observed in the microstructure of as-built specimen fabricated in argon. The ultimate tensile strength, yield strength and hardness of as-built specimen in nitrogen were considerably higher than those of specimen in argon and conventionally processed material. These were considered to be the cause of the difference in microstructures and nitrogen absorption. Post-SLM solution heat treatment (SHT) reduced the tensile strength and hardness of both specimens and improved their ductility. However, the tensile strength and hardness of the specimen in nitrogen were still higher than those in argon.