Showing papers in "Clay science in 1994"
TL;DR: In this article, the microporous structures of SiO 2 -TiO 2 sol pillared clays were investigated using NMR spectroscopy, and the pore diameters were determined to be 1.0-1.04 nm, which is much smaller than the expansion of the basal spacing of about 3 nm by the pillaring.
Abstract: 129 Xe nuclear magnetic resonance (NMR) spectroscopy was used to investigate the microporous structures of SiO 2 -TiO 2 sol pillared clays. The chemical shift of xenon adsorbed in the pillared clays was measured as a function of xenon pressure on the samples prepared by air-drying followed by calcination at temperatures of 200°-500°C. From the chemical shifts extrapolated to zero pressure, the pore diameters were determined to be 1.0-1.04 nm, which is much smaller than the expansion of the basal spacing of about 3 nm by the pillaring, and rather comparable to the dimensions estimated from a nitrogen adsorption study. As for the pillared samples prepared by a supercritical drying, the 129 Xe NMR measurement gave a chemical shift corresponding to the pores having an average diameter much larger than those of the air-dried samples
5 citations
TL;DR: The Denbekoba deposit of the Amakusa pottery stone is considered to have been formed by hydrothermal alteration subsequent to the intrusion of rhyolitic magma.
Abstract: Mineral parageneses and high-low inversion temperature of quartz at the Denbekoba deposit of the Amakusa pottery stone have been investigated by X-ray powder diffraction, differential thermal analysis and polarizing microscopy. The main constituent minerals of the pottery ores are quartz and sericite. Kaolinite, dickite, tosudite, rectorite, calcite, siderite and residual feldspar are also contained in some ores. The deposit is considered to have been formed by hydrothermal alteration subsequent to the intrusion of rhyolitic magma. The central zone of the alteration is rich in sericite, kaolinite and rectorite. Tosudite is abundant in the intermediate zone between the central zone and the weakly altered zone. The central zone appears to have been subjected to conspicuous alteration at a late stage. The high-low inversion peak in the DTA curve for the quartz is broad and the peak temperature is 4-23°C lower than that of standard quartz. Quartz samples in the central zone have higher inversion temperature as compared with those in the outer alteration zones. Moreover, the quartz samples in the central zone also show another low-temperature broad peak which may be due to the quartz having formed in the late stage of the alteration
4 citations
TL;DR: In the shell molding process, catalytic decomposition of phenolic resin on resincoated sand in the presence of sepiolite was investigated in this paper, and the results indicated that the sepiolites has promoted thermal decomposition as catalyst.
Abstract: In the shell molding process, catalytic decomposition of phenolic resin on resincoated sand in the presence of sepiolite was investigated. Phenolic resin-coated sand mixed with sepiolite liberated less amounts of smoke and irritating gases than that without sepiolite not only in the molding, but also in the casting. The results indicate that the sepiolite has promoted thermal decomposition of the irritating gases as catalyst. The bending strength of the mold decreased with the increasing sepiolite contents
3 citations