著者

小川 和洋 庄子 哲雄 青木 久彦 藤田 範生 鳥越 泰治

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.66, no.647, pp.1370-1376, 2000-07-25

被引用文献数

4 2

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A two-layer plasma sprayed thermal barrier coating on Ni base superalloy substrate was characterized. The coating was comprised of an inner layer of MCrAlY bond coating and an outer layer of 8wt% yttria stabilized zirconia (YSZ) thermal barrier coating (TBC). After aging, the reaction layer at interface between YSZ and MCrAlY was observed. The reaction layer had two different contrast layers in the SEM images. One was black which was closer to MCrAlY and the other was gray which was closer to YSZ. The thickness of both layers increased with aging. Also countless porosities at the gray layer and microcrack at YSZ were observed. Most of the macrocrack grew through the porosities. From this viewpoint one may say that the mechanism of macrocrack formation is a deterioration of adhesion which was accompanied by an increase of the porosities or the microcrack.

著者

高橋 秀明 庄子 哲雄 鈴木 正彦

出版者

Japan Society of Corrosion Engineering

雑誌

防食技術 (ISSN:00109355)

巻号頁・発行日

vol.28, no.5, pp.292-302, 1979-05-15 (Released:2009-10-30)

参考文献数

16

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Based upon linear elastic fracture mechanics approach, a damage tolerance design philosophy for light water reactor pressure vessel and piping components where the presence of a significant crack is acceptable, was reviewed with special reference to stress corrosion cracking and corrosion fatigue subcritical crack growth.The published data of failure analysis were discussed from a viewpoint of fracture mechanics evaluation. Here, weld toe cracking in crude oil pipe-lines in Canada, and corrosion-pit initiated cracking in low pressure turbine discs at Hinckley Point ‘A’ and turbine shafts at Ferrybridge power stations in England were compared and discussed. Hence three parameters such as mechanical, metallurgical and environmental factors are taken into consideration.

著者

鄭 巍巍 庄子 哲雄 糸藤 春喜 張 建華

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.80, no.3, pp.176-185, 2016 (Released:2016-02-25)

参考文献数

18

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The purpose of this study is to analyze the microstructure and chemical composition of the oldest heavy section cast iron cannon in China, which was manufactured at the early Ming dynasty in the year of 1377 with the inscription of Hongwu. It is worthwhile to study any characteristic casting processes and advancement of the heavy section casting technology during the Ming dynasty because the cannon technology could be developed based upon the leading technology of that age. This cannon has been preserved and displayed at Shanxi Province Art Museum. Some microstructural analysis was performed on site by use of portable grinding and polishing tools for the metallurgical examination. In addition, more detailed metallurgical examination by EDX, XPS, high temperature optical microscope (OM) and DSC analysis was performed on a small sample taken from the cannon. Chemical analysis was also performed on the grinding chips and powder collected during the metallurgical surface preparation. A thermodynamic phase diagram was calculated by CALPHAD method for the material with the same chemical composition as measured. After the detailed metallurgical examination and chemical composition analysis, it turned out that the cannon has a chemical composition range of minor elements as: C: 1.36-1.8 mass%, S: 0.58-0.78 mass%, P: 0.61-0.81 mass%, Si: 0.45-0.61 mass%, and shows a uniform hypereutectoid microstructure. Taking into account the evidence of no microstructural gradient from a surface to inside which is not common in ancient decarburized cast iron, the cannon is highly likely to be made by a cast steel rather than by a cast iron.    Non-metallic inclusions are observed both by OM and by a scanning electron microscope (SEM) on the sample. A high temperature optical microscope with an in-situ heating capability was used to directly observe any phases with a lower melting temperature. Also DSC analysis was performed on the sample to examine any phase change at some specific temperature. Based upon these observations and analysis, it was concluded that the Hongwu cannon was made by cast steel with a hypereutectoid microstructure. This microstructure contained a eutectic phase in pro-eutectoid cementite, which suggests a formation of steadite Fe-Fe3C-Fe3P with a low melting temperature of 1227 K. This finding strongly suggests that, instead of cast iron technology, cast steel technology had already existed and was put in use for heavy-section cannon production during early Ming Dynasty in China.