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Start Over Topic acetic acid Publication Year Range Last 10 years Language japanese
4 results

1. 高保磁力 Sm2Fe17N3 磁石粉末の合成.

Author

岡田　周祐, 高木　健太, and 橋本　龍司

Subjects
ACETIC acid, COERCIVE fields (Electronics), SURFACE cleaning, CRYSTAL structure, WORLD records, SAMARIUM
Abstract

In this paper, we report on our group’s efforts to improve the coercivity of Sm2Fe17N3 powder, especially on reducing the particle size to submicron scale, smoothing the particle surface, and suppression of the formation of coarse particles by developing a new reduction-diffusion process. During the course of a series of these works, it was revealed that the washing step, which is performed to remove excess Ca, supplied hydrogen into the Sm2Fe17N3 crystal structure, and induced unfavorable elongation of the crystal structure along the c-axis. To avoid this problem, the powders were subjected to dehydrogenation treatment, demonstrating reasonably high coercivity values that we expect from the known relationship between particle size and coercivity. It was also found that the conventional dissolution and the removal of impurities by acetic acid were roughening the particle surfaces. Thus, development of an alternative process to acetic acid cleaning prevented the surface roughening and showed the further improvement of the coercivity. Finally, the development of a new uniform reduction-diffusion reaction using a rotary furnace brought about a breakthrough for further improvement of coercivity by suppressing the formation of coarse particles. As a result, we succeeded in synthesizing Sm2Fe17N3 anisotropic powder with an ultra-high coercivity (i.e. the current world record) of 31.7 kOe, and also showed that the powder can maintain a coercivity higher than 10 kOe at 200°C. [ABSTRACT FROM AUTHOR]

Published
2023
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2. 白色顔料開発を目指したチタニア被覆シリカ複合中空粒子の合成.

Author

藤 正督, 飯田 隆寛, 高井 千加, 冨岡 達也, and Razavi-Khosroshahi, Hadi

Subjects
CHELATES, TITANIUM dioxide, CHEMICAL reactions, VISIBLE spectra, ACETIC acid
Abstract

Titania coated silica hollow particles were developed as a white pigment to prevent their sedimentation during storage. The hollow silica particles used in this study have porous structure, which is expected to have both scatter and transmit visible light to help to improve the titania's covering power. The template for such porous structure was prepared by gathering nano-sized calcium carbonate via CO2 gas bubbling method. For the titania coating, acetic acid was used to control too quick chemical reaction of titania precursor by forming chelate compound. The molar ratios of water/titania and reaction temperature were optimized. The obtained titania coated hollow silica particles exhibited higher whiteness than the commercial TiO2. [ABSTRACT FROM AUTHOR]

Published
2019
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3. Control of Pollutants in a Display Case

Subjects
空気清浄化, ガス濃度予測, 展示ケース, 酢酸, display case, air purification, gas concentration prediction, acetic acid
Abstract

One problem in the museum environment is air pollutants in airtight display cases, some of which cause adverse effects on artifacts inside.Their gases,especially acetic acid gas, are mainly emitted from interior materials used in display cases. There are two systems for reducing the level of pollutants inside the enclosure.One is an active adsorption filter fan system and the other is a ventilation fan system that takes the clean air from the exhibition room.The present paper reports on the test using these systems to control acetic acid gas pollutants in a display case. Several measurements were conducted to see air distribution, air exchange rate and acetic acid gas concentration in a display case. The display case used in the experiments was made for environment test. Performance of active adsorption air filter within enclosures and ventilation effect by the fan were also measured. As a result it was found that acetic acid gas concentration in the display case decreased to 30% by using an adsorption filter fan system and it became of equal level to that in an exhibition room by using a ventilation system. Effects of control of pollutantsby each system were evaluated by using ventilation volume with clean air (i.e. equivalent ventilation volume). Changes of gas concentration in the display case were estimated through prediction formula using factors of equivalent ventilation amount and operating period of the fan. From the results it was estimated that good air environment in the display case was maintained by operating an adsorption filter fan system for about two hours a day.

Published
2016

4. Change in Gas Concentration in a Display Case

Subjects
display case, change in gas concentration, acetic acid, chamber test, 展示ケース, ガス濃度推移, 酢酸, チャンバー試験
Abstract

Recently, display cases in museums have improved in airtightness.On the other hand, there is a risk that artifacts in display cases may be exposed to chemical gases if there is gas emission from the interior materials used in the display cases. Also it is thought that gas concentration increases with time. However, change in gas concentration in display cases has not been made clear until now.To confirm such a change,it is necessary to repeat gas sampling in a specific time cycle and to keep the display cases closed during test period. But if the cases are kept closed, confirming change in gas concentration is difficult since measuring devices cannot be easily set or removed.In order to solve this problem,a display case was made for environmental testing and gas concentration was measured. This paper reports the change in acetic acid gas concentration in the display case as confirmed by measurement. It also compares the acetic acid emission rate of the interior materials obtained from the measurement of the display case and that obtained from chamber test. As a result, it was found that there was little difference in emission throughout the experiment. Gas concentration obtained by the measurement was corrected by removing the effect of gas sampling. This corrected gas concentration was consistent with that obtained through prediction formula based on initial gas concentration. In addition, emission rate of the interior materials obtained by chamber test and by the present measurement was similar. From these results, it was found that it is possible to predict change in gas concentration in display cases by obtaining initial gas concentration and that chamber test is an effective method to estimate gas concentration in display cases.

Published
2015