Method of Investigation of the Fracture Toughness of Junctions for Elements Made from Float Glass and Glassceramics Zerodur

V.P. Maslov & V.E. Lashkarjov Institute of Semiconductor Physics of HASU
Yu.M. Rodichev, G.S. Pisarenko Institute for Problems of Strength of HASU

The development of strong adhesion junctions of structure elements made from float glass and glassceramics Zerodur is an important problem concerned with improvement of the glass product quality, namely, of the laminated glass, building and transport glazing and instrument-making industry. Most of the strong junctions of these elements have a brittle mode of the fracture. So appropriate methods of theirs fracture toughness evaluation must be worked out.

The method of investigation of fracture toughness of junctions for the elements made from float glass and from glassceramics Zerodur with zero thermal expansion coefficient was developed. Method of fracture tests under shear, rupture and bending foresees the forming of initial crack of adjusted shape and sizes directly at the assembling of appropriate standard or original specimens. The specimens in the form of assembled beams, plates, «Т»- and «Г»-shaped elements were chosen starting from peculiarity of designed combined structure. Method enables to evaluate the fracture toughness of brittle material junctions made using the most of known bonding techniques (diffusion bonding, gluing and soldering).

Appropriate techniques of required initial crack forming for different types of junctions made of the polymeric and non-organic adhesives as well as for rigid super-thin (thickness about 100 nm) precision nano-junctions based on the use of refractory and fusible metals were developed.

Method was tested at the investigation of junction fracture resistance for details made of float glass and glassceramics. The bending strength of elastic-brittle super strong nano-junctions was about 30…65 MPa and critical values of fracture toughness factor КIC were up to 1…1.4 MPa√m. The results which are necessary to estimate carrying capacity of junctions under the tear, bending and shear were received with taking into account the specific edge exfoliations and other flaws of the adhesion layer. The influence of the extent of edge and surface microcrack mode defects of details made of the glass and glassceramics Zerodur on the testing results may be considered by this method too. Results of the tests are correlated satisfactorily with testing data received using the specimens of junctions cut from real assembled structures and from models of advanced products for aerospace technique.

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The Authors

Dr. Yurii Rodichev Dr. Head of the Department G.S.Pisarenko Institute for Problems of Strength of NASU Scientist and specialist on glass and ceramics constructional strength. Design and testing of glass and ceramics structures for different spheres of technics. Dr. Yurii Rodichev is the Head of the ... Read more