LAUSR

Glass–metal joining is important for improving efficiencies of heat collecting units employed in linear parabolic sun collector systems. Soda lime silicate glass tube–titanium inset joining was made by using propane/O2 flame working in air. Optic and scanning electron microscope investigations of joined samples showed oxidation of titanium in air and its reaction with glass leading bubble formation. ANSYS14 Multiphysics modeling of residual joining stress levels suggested that titanium inset and soda lime silicate glass had rather low residual stress levels due to close thermal expansion coefficients. For the used sample dimensions with uniform glass tube shape, highest residual maximum principal stress was ≈ 60 MPa and minimum principal stress was ≈–40 MPa for the glass at joining interface. However, glass shape was found to be affecting residual stresses during bonding and shape defects like groove formation increased residual minimum principal stress levels to –90 MPa near joining interface. Some microcracking of glass was also observed in groove region. Bubble formation in glass near reaction interface was also found to be involving crack formation and its propagation as well. Therefore, controlling glass shape and interfacial reaction was found to be important for successful titanium inset–soda lime silicate glass tube joining by flame working in air.