Evaluation of the critical processing parameters of ormosil coatings on the increase of the strength of glass

Organically modified silicate (ormosil) materials were used as coatings on glass products in order to increase their strength. Microscope glass slides were indented by a Vickers indenter, coated, thermally treated and their strength was determined under four-point bending. The results revealed that the glass strength increase depends on the solution composition as well as the curing parameters, i.e. temperature and time. It was found that when the amount of solvent is above 15 pct., there is no significant increase in the glass strength, while the optimum curing temperature is approximately 200°C. Curing at low temperatures requires extremely long curing times in order to achieve maximum strength, while curing at high temperatures results in damage to the coating due to burn out of the organic part. The mechanical strength results were interpreted using infrared (IR) spectroscopy. The latter enabled the detection of the formation of different bonds between the elements of the coating and revealed that the maximum strength is achieved when the intensity of CC bond absorption of the coating acquires a maximum value, representing an optimum curing condition. With regard to the strengthening mechanisms, it was deduced that the increase in the glass strength was due to the filling of surface flaws by the ormosil solution.