Proceedings Volume 15, PT. 2

Proceedings Volume 15, PT. 2

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: is its main title to excellence, while the porosity of the other is essential to the fulfilment of its function. And yet, with such obvious and direct importance attached to this word "vitrified" no clear and generally accepted definition is in use, and the word is being used in diverse senses to the disadvantage of the whole public. No single step of more importance toward the standardization of clay products can be taken than the definition of this term. The first great stumbling block in clearing up this unfortunate situation is the fact that there are two allied, but nevertheless clearly distinct, points of view in regard to the use of the term. These may be characterized as the chemical and the physical conceptions. The Chemical Meaning Of Vitrification. Vitrification is understood among clayworkers to be the chemical process by which a clay is hardened by heat. It is essentially a process of silicate formation. A clay may be burnt at temperatures below 900 C. without any appreciable silicate formation taking place, in which case, there is virtually no increase in hardness or strength over the dried condition. At 900 C, or above, the granular structure begins to yield to the cementing action of silicates formed by combinations of the different minerals present. This cementing material at first is formed in small quantities, and if the burn is stopped at this stage, a weak, friable and porous product is formed. At higher temperatures it may be abundant enough to fill the voids and to thoroughly bind the unfused matter together. This produces a strong, tough product. In some clays, the whole mass of the mineral material may tend to combine at about the same time, forming altogether too much silicate matter to have the...
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Product details

  • Paperback | 108 pages
  • 189 x 246 x 6mm | 209g
  • United States
  • English
  • black & white illustrations
  • 1236776119
  • 9781236776112