New generation processing of glass by chemical tempering

Chemical tempering is one of the important methods used to increase strength of glass. It is widely used in industry like aircraft and display devices. A novel method of chemical tempering was conducted using ordinary furnace to achieve a temperature of 450, 500, and 550 oC, for several hours. A clay coating paste was used on glass. This clay mixed with potassium nitrate salt with two different volume concentrations (46.7 vol.%, 63.7 vol.%). Three contact time (8, 12, 16 hours) were used in this study. Also, two different glass slide thicknesses (1 mm, 4mm) were used. XRF test used to determine chemical composition of glass, surface residual stresses test to determine optical properties, hardness test (HV), (3-points) bending test, SEM, EDX to determine the depth of potassium penetration, FTIR test to measure the transmittance of light and ballistic impact test to determine strength of glass for bulletproof applications. The achieved results were shown a quality similar to glass tempered with the method using molten salt bath Furance. The strength of glass was increased about 3.5 folds in case of thin glass, 3 folds increased in case of thick glass tempered at 450 oC, and increased 4.75 folds in case of thick glass tempered at 500 oC, compared with untreated glass. While optical and mechanical properties were failed for the thick glass tempered at 550 oC. The hardness was increased about (15 % in case of thin glass), and in case of thick glass (9 % for glass tempered at 450 oC, 14% for glass tempered at 500 oC, and 12% for glass tempered at 550 oC). The depth of potassium penetration was 20 𝝁m in case of thin glass, and 15,30,70 𝝁m for 450,500,550 oC respectively for tempering process of thick glass. The transmittance of glass increased about 12% in case of thin tempered glass, and decreased about 13% for thick glasses tempered at 500, 550 oC, in addition to that, the thick glass tempered at 450 oC did not show any change in transmittance.