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Determining Surface Density Degree of Sintering or Porosity

IP.com Disclosure Number: IPCOM000078168D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Fraser, HR: AUTHOR [+4]

Abstract

It has been found that the measurement of the Vickers microhardness of a glass surface, yields considerable information about the nature and properties of that glass.

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Determining Surface Density Degree of Sintering or Porosity

It has been found that the measurement of the Vickers microhardness of a glass surface, yields considerable information about the nature and properties of that glass.

The completeness of sintering of a powder compact can be quantitatively assessed by comparing the Vickers hardness to a control, which is known to have been completely fired. For example, the firing of CORNING 7070* powder is generally performed at a minimum of 810 degrees C to give complete densification. Utilizing the same firing time but reducing the temperature to 790 degrees C, produces a glass film whose Vickers hardness is reduced by 15% from the completely densified sample.

Changes in stress at the surface of the glass can be measured. Due to the small size of the indent, generally about 10-15 Mu in length and 1 Mu deep, this stress change can be observed in very small areas. For example, it is possible to measure the change in hardness of a glass surface in the immediate vicinity of an evaporated chromium film.

The strength improvement of glass produced by hydrofluoric acid etching is paralled by an increase of 15% in the Vickers hardness and, as that strength improvement decays with time and temperature, the Vickers hardness exhibits a corresponding reduction in value. * Product of Corning Glass Works.

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