NDLI: The production of porcelain for electrical insulation

Content Provider	IEEE Xplore Digital Library
Author	Riddle, Frank H.
Copyright Year	1920
Abstract	The raw materials should be carefully tested before using. China and ball clays should be tested for fired color, porosity at the regular burning temperature, fineness of grain, etc. Ball clays should be tested for raw physical strength. The grain size of quartz is of particular importance and the fine grain sizes should be determined by elutriation or water separation. Feldspar should fuse to a glass with the fusion of pyrometric cone No. 8, 1280 deg. cent. (2336 deg. fahr.), and its color, degree of glassiness, amount of deformation, etc. noted. The composition and formation of porcelain in firing are briefly described. The limits of composition are wide but the quality of the final product will vary with the composition. Special porcelains for use as spark plug cores are made by eliminating feldspar and quartz and substituting synthetic calcines. During firing the mechanical water is first expelled. Chemically combined water is driven off at 500 deg. cent. (932 deg. fahr.). Alpha quartz assumes the beta form at 575 deg. cent. (1067 deg. fahr.) with a similar expansion in volume. Shrinkage and condensation of the volume of the clay substance takes place at 900 deg. cent. (1652 deg. fahr.). Continued firing contracts the porcelain and decreases the porosity, the feldspar finally melting and gradually taking the more refractory clay and quartz into solution or assisting in converting it into other materials, particularly the clay which breaks up into sillimanite and free silica. The solution of the quartz depends upon grain size and heat treatment. On account of volume change of the quartz grains, it is evident that the fired porcelain, in which the quartz grains are in intimate contact with the glassy groundmass will be placed in a condition of stress after cooling down as the quartz contracts more rapidly than the rest of the porcelain. Naturally the greatest strain occurs around the largest quartz grains and clearly demonstrates the necessity for fine grinding. The properties and testing of porcelain are described. Ordinary porcelain has a tensile strength of from 3000 to 6000 pounds per square inch and a coefficient of lineal thermal expansion of from 4 to 9 × 10⁻⁶ per degrees centigrade, while special porcelains have a strength as high as 12,000 pounds and an expansion as low as 2.7 × 10⁻⁶.
Starting Page	631
Ending Page	635
Page Count	5
File Size	3883228
File Format	PDF
ISSN	03606449
Volume Number	42
Issue Number	6
Language	English
Publisher	American Institute of Electrical Engineers
Publisher Date	1923-06-01
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Porcelain Firing Vitrification Glazes Color
Content Type	Text
Resource Type	Article

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1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
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9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

The production of porcelain for electrical insulation — II

The production of Porcelain for electrical insulation — V

The production of Porcelain for electrical insulation — VII

Electrical porcelain

Manufacture of electrical porcelain

The production of Porcelain for electrical insulation — VI

The production of porcelain for electrical insulation — IV

The production of porcelain for electrical insulation — I

The compositions and properties of electric porcelain materials in China

The production of porcelain for electrical insulation — II

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