油滴天目斑点を構成する磁鉄鉱

DOI 機関リポジトリ Web Site

書誌事項

タイトル別名
  • Magnetite in Yuteki-Temmoku (Oil-Spot) Glaze
  • ユテキ テンモク ハンテン オ コウセイスル ジテッコウ

この論文をさがす

抄録

Yohen-Temmoku and Yuteki-Temmoku are the most important and beautiful potteries among the so-called Temmoku glazes. Although prompt and remarkable development of technics in the fields of ceramics and potteries industry in recent years, reproduction of the Yohen-Temmoku is not successful up to the present. Yuteki-Temmoku, on the other hand, has been commonly produced in Japan and in the U.S.A. since laborious exprimental works of ironcontaining glazes by SAWAMURA (1940). Most of these Yuteki-Temmoku glazes were produced according to the composition proposed by SAWAMURA. However, there are only few researches concerning the Temmoku glaze from the stand point of mineralogy. Consequently, the mineralogical constituents of the Temmoku glaze have not been established. Under such circumstances, the present research aims to establish the mineralogical constituents of the Yuteki-Temmoku glaze whose starting composition is that proposed by SAWAMURA (1940), and further, to explain the formation mechanism of the Yuteki-spot (oil-spot) based on the experimental result. The starting composition of the Yuteki-Temmoku glaze is as follows; Fukushima feldspar (whose chemical composition is SiO_2=68.0, Al_2O_3=17.4, Fe_2O_3=0.06, TiO_2=0.01, CaO=0.39, MgO=0.02, K_2O=12.25, Na_2O=3.05 and ignition loss=0.3wt.%, respectively): 58.44, Silica 9 pure quartz): 22.24, Limestone (pure calcite): 4.77, Talc: 4.59, Iron (III) oxide (almost pure and very finegrained hematite): 7.21, Manganese carbonate (pure rhodochrosite): 2.70 and Cobalt (II,III) oxide: 0.05wt.%, respectively. When the glazed bowl was heated gradually up to 1280℃ and kept 2 hours in a gas furnace, many dark spots ranging from 1 mm to 10 mm in diameter were formed on the deep black silicate glass. The mineral constituent of the spot is found to be the aggregates of very fine-grained magnetite crystals less than few microns in size. It was confirmed that the magnetite contains about 10wt.% of cobalt with very small amount of manganese (less than 0.5wt.%) and the cubic lattice dimension, a_0=8.368 Å, was comparable to that of pure magnetite. Microscopic observations indicate that the glaze contains many small bubbles (less than 0.5 mm in diameter) and a remarkable concentration of magnetite around the bubbles is characteristic. The formation mechanism of the Yuteki-spot is considered as follows; At the elevated temperature (1280℃), two immiscible phases, one is silica-rich liquid and the other is iron-rich phase, are developed in the molten glaze. At such high temperature, decomposition of Fe_2O_3 which is one of the main constituents of the glaze produces O_2-bubbles in the molten glaze. The iron-rich phase (probably liquid) with relatively lower viscosity concentrates around the bubbles. Then, some of these bubbles join together and grow up to larger bubbles, and then, these larger bubbles reach to the surface against the higher viscosity of the silica-rich liquid. Thus, on the surface of the glaze, the Yuteki-spot (oil-spot) appears as the result of breakdown of the bubbles.

収録刊行物

  • 学報

    学報 26 65-71, 1982-03-20

    金沢美術工芸大学

詳細情報 詳細情報について

問題の指摘

ページトップへ