Strength of glass ceramic S0115M and its joints based on optical contact

Abstract

1. Breaking strength for joints based on optical contact with a contact area of 680 mm2 is 1.11 MPa for rectangular cross section specimens. Specimens with an annular configuration and a contact area of 150 mm2 have the highest ultimate strength σf=2.45 MPa. 2. Ultimate strength in axial tension and compression for cylindrical specimens made of optical glass ceramic with high microroughness of the lateral surfaces RZ≤0.63 μm is 59.1 and 2008 MPa respectively, and this exceeds the ultimate breaking strength of joints based on optical contact with an area of 150 mm2 by factors of 24 and 820. 3. In absolutely brittle materials of the optical glass ceramic type forces of mutual attraction operate in annular crack zones predicted by the Leonov-Panasyuk model for the limiting condition, and they promote closing together of the crack sides. It may be assumed that the magnitude of these mutual attraction forces for the crack sides is not less than the breaking stress for joints based on optical contact established in this way. 4. In critical articles of the shell type made of glass and glass ceramic loaded by external hydrostatic pressure, it is possible for cracks to develop during operation. It is not possible to detect these cracks visually due to closing together of the sides after removal of a tensile load. In order to provide reliable operation of similar articles there is considerable practical interest in the search for experimental methods making it possible to reveal cracks in these objects.