Browse Prior Art Database

Crack Arrest in Glasses And Ceramics

IP.com Disclosure Number: IPCOM000120737D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Chance, DA: AUTHOR [+2]

Abstract

Disclosed is a structure for preventing crack propagation by stress corrosion in class, ceramics, glass and ceramic mixtures, and crystallized glass ceramics.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 95% of the total text.

Crack Arrest in Glasses And Ceramics

      Disclosed is a structure for preventing crack propagation
by stress corrosion in class, ceramics, glass and ceramic mixtures,
and crystallized glass ceramics.

      Above a threshold stress-intensity factor, the velocity of a
crack in a ceramic, glass or glass ceramic is known to be strongly
influenced by the environment -1,2-.  In particular, at normal
temperatures and pressures, water is known to influence the
time-dependent strength of these materials by behaving as a stress
corrosion agent.  It is sometimes necessary, therefore, to protect
these materials from the environment when they are stressed in
tension.

      A method of protecting stressed glass, ceramic and glass
ceramic structures from exposure to the environment is shown in the
figure.  Metal coatings consisting of an adherent layer, a ductile
layer and a corrosion-resistant layer are used to protect the
underlying glass or ceramic structure.  Evidently, both sides of such
structures can be protected.  A metallization consisting of
approximately 0.1 micron of Cr, 1 to 10 microns of Cu, and 0.5 to 1.0
micron of Au is satisfactory for most materials, but many other
metallizations are also suitable.

      References
-1-  S. W. Wiederhorn, "Influence of Water Vapor on Crack Propagation
in Soda-Lime Glass," J . Am . Ceram . Soc . 50, 8, 407-414 (1967).
-2-  S. M. Wiederhorn, E. R. Fuller, Jr. and R. Thompson,
"Micromechanisms of Crack Growth in C...