Preparation And Application Of Chemical Tempered Molten Salt Resuscitation Glass

Chemical tempering has become the main method of strengthening cover glass.At present,the cover glass used in the market is mostly lithium aluminum silicon glass,and the Li⁺radius is small.In the process of ion exchange strengthening,the Li⁺in the glass is easy to be exchanged into the molten salt,the Li⁺in the molten salt gradually increases,and the effective ion concentration decreases,resulting in the reduction of ion exchange efficiency and the activity of molten salt.At present,the commonly used method to improve the reactivity of salt bath is to add molten salt additives,but this method has some problems such as unrecyclable,high cost and secondary pollution of molten salt.To solve these problems,it is proposed to prepare a"resurrection"glass based on sodium-aluminum-silicon system to remove impurity ions in the deactivated molten salt and improve the activity of molten salt.The properties of high sodium resurrected glass,the resurrecting effect of molten salt and the recycling application of high sodium resurrected glass were studied.（1）Preparation and properties of high sodium resurrected glass.Na₂O-Al₂O₃-Si O₂ glass is prepared.The content of Na₂O and Al₂O₃ in the glass formula is high.Al（OH）₃ is selected to introduce Al₂O₃,which is easy to combine with other materials and melt at 1600℃for 4 h.XRD results show that the glass is amorphous.With the increase of Al₂O₃/（Al₂O₃+Si O₂）molar ratio,[Si O₄]involved in the glass network structure decreases,[Al O₄]increases,and the void in the glass network increases,forming an ion exchange channel inside the glass structure,which is more conducive to ion exchange.Therefore,G4（Na₂O 40wt%,Al₂O₃ 25wt%,Si O₂ 35wt%）is preferred to revive the deactivated molten salt.The average elastic modulus of the glass is about67.59GPa.The glass has certain mechanical properties,which is conducive to the later tablet forming and the resurrection of the deactivated molten salt.（2）Study on resurrecting effect of high sodium resurrecting glass.A molten salt ratio of 7:3potassium nitrate to sodium nitrate was used,and the inactivation of molten salt was simulated by adding Li⁺to the molten salt.When the Li⁺concentration reaches 3 mg/g,the bending strength of the reinforced glass is lower than 3 times the bending strength of the original glass,and it is assumed that the molten salt has been inactivated at this time.The light transmittance of the original sheet glass is 93.6%,the light transmittance of the strengthened glass after using the resurrection glass to treat the molten salt is about 93.56%,and the light transmittance of the strengthened glass after using Na₃PO₄ to treat the molten salt is only about 87.7%.After 14 h of reaction with Na₃PO₄,the bending strength of the reinforced glass reaches 304.91 MPa,which is increased by 263.33 MPa.After 6 h of reaction with resurrection glass,the bending strength of reinforced glass can reach 326.37MPa,which is increased by 284.79MPa.And the microhardness of the strengthened glass is enhanced from 6.34 GPa of the original glass to 7.46 GPa after using the revived glass to revive the molten salt.The elastic modulus increased from 72.37 GPa to75.07 GPa,and the DOL value increased from 11μm to 24μm,which increased by 13μm.The mechanical properties of glass were improved,and the reactivation effect of revived glass on inactivated molten salt was significantly better than that of Na₃PO₄.（3）Study on recovery and utilization of high sodium resurrected glass.The high alumina glass is made by remelting the doped high sodium resurrected glass and lithium aluminium silicon glass.The Tg and Tc ranges of the high alumina glass were close to each other,and the thermal stability of the glass did not change much.The XRD pattern showed that the glass showed an amorphous state.With the increase of the doping amount of the reactivated glass,it can be seen from the infrared and Raman spectra that the increase of[Al O₄]involved in the structure of the glass network leads to the increase of the void of the glass network,and the stability of the tetrahedron of[Al O₄]is worse than that of the tetrahedron of[Si O₄].The glass structure gradually deteriorates,and the microhardness and elastic modulus of the glass gradually decline.When the doping mass of resurrected glass is 10%,the microhardness of high-aluminum glass decreases from 7.79 GPa to 7.67 GPa,and the elastic modulus decreases from 90.56 GPa to 89.33 GPa,both of which are very small.The structural properties of the glass are relatively stable,and the high-sodium resurrection glass has the value of recycling.