Preparation Of Cover Glass And Its Ion Exchange Enhancement For Display

R₂O-Al₂O₃-Si O₂（R=Li,Na,K）alkali-aluminosilicate electronic glasses are the current favored system of cover lens in domestic and foreign due to their good thermal,mechanical,optical,chemical,dielectric properties and adaptability to chemical strengthening properties.The glass compositions were constructed and optimized based on the alkali-aluminosilicate electronic glass system,and the reasons for the mixed alkali effect and the change law of the composition-structure-property of the basic glass were investigated.Simultaneously,the glasses were chemically strengthened,and the impact of the composition change on the ion exchange depth and performance was investigated,providing theoretical reference and experimental basis for the development of cover glass.The following findings were obtained from the researches:（1）（14-x）Na₂O-x Li₂O-86[Si O₂,Al₂O₃,B₂O₃,P₂O₅,Zn O,Sn O₂]（x=0,3,7,11,14 wt%）series glasses were prepared by traditional melting and cooling method.Varied Na₂O/Li₂O mass ratios have different effects on the structure and characteristics of glasses.The results show that as the Na₂O/Li₂O mass ratio decreases,the density of the glasses increases at first,then decreases,with the L7 glass having the highest density（2.4282 g/cm³）;the molar volume of the glasses gradually decreases;the ability of the glasses to resist HF gradually decreases,and the L7 glass has the highest density（2.4282 g/cm³）.The molar volume of glasses diminishes over time,and the ability to resist HF declines as well.The capacity of glasses to resist Na OH first increases and then declines.Furthermore,the transition temperature and crystallization temperature steadily reduce and the microhardness from 550 kg/mm²increases to 581 kg/mm²first and then decrease to 540 kg/mm².The glass with both Na₂O and Li₂O has a greater dielectric constant and lower dielectric loss at 1 MHz than the glass with only one alkali metal oxide.The density,alkali resistance,and dielectric characteristics of the glasses reveal mixed alkali effect as the Na₂O/Li₂O mass ratio is gradually changed.（2）（5.4-x）P₂O₅-x B₂O₃-94.6[Si O₂,Al₂O₃,Li₂O,Na₂O,Zn O,Sn O₂]（x=0,1,2,3,4,5.4 wt%）series glasses were prepared by traditional fusion cooling method,and the effects of different P₂O₅/B₂O₃ mass ratios on the structure and properties of glasses were studied.Different P₂O₅/B₂O₃ mass ratios were investigated for the influence on the structure and characteristics of glasses.The results show that as the mass ratio of P₂O₅/B₂O₃decreases,the glass density increases first and then decreases,and the molar volume gradually decreases.The acid resistance increases first and then decreases,while the alkali resistance decreases first and then increases.The temperature of the crystal is not visible;the microhardness from 557 kg/mm² increases to 561 kg/mm² and eventually drops.When P₂O₅ and B₂O₃ coexist in the same glass,[BPO₄]and[Al PO₄]tetrahedral structures develop,improving the network structure.（3）（79.5-x）Al₂O₃-x Si O₂-20.5[Si O₂,Al₂O₃,Li₂O,Na₂O,Zn O,Sn O₂]（x=55,56,57,58,59,60 wt%）series glasses were prepared by traditional melting cooling method.The effects of different Al₂O₃/Si O₂ mass ratios on the structural properties of glasses were studied.The results show that with the decrease of the mass ratio of Al₂O₃/Si O₂,the glass density does not change significantly,among which the density of the S56 glass is the highest（2.4241 g/cm³）,and the density of the S58 sample is the lowest（2.4055 g/cm³）.Furthermore,the molar volume gradually decreases and the acid resistance and alkali resistance are opposite.S56 sample has better acid resistance,but the weight loss in alkali solution is relatively large;the glass transition temperature first decreases and then increases,and the crystallization temperature is not obvious;the microhardness gradually increases.（4）Among the glasses of（14-x）Na₂O-x Li₂O-86[Si O₂,Al₂O₃,B₂O₃,P₂O₅,Zn O,Sn O₂],the ion exchange layer of L0 and L14 glasses is the deepest,followed by L3 and L11,and L7 is the lowest.When the Na₂O/Li₂O mass ratio is 3.67,the comprehensive performance of the glass is the best.Among the（5.4-x）P₂O₅-x B₂O₃-94.6[Si O₂,Al₂O₃,Li₂O,Na₂O,Zn O,Sn O₂]system glasses,the ion exchange layer of B0 and B3 glasses is the deepest,and the exchange layer of B5 glass is the shallowest.When the mass ratio of P₂O₅/B₂O₃ is 1.7,the comprehensive performance of the glass is better.In（79.5-x）Al₂O₃-x Si O₂-20.5[Si O₂,Al₂O₃,Li₂O,Na₂O,Zn O,Sn O₂]system glass,the ion exchange depth and the hardness after exchange of glass with higher content of Al₂O₃ are higher than those of glass with lower content of Al₂O₃.It has a certain promotion effect on the ion exchange of glass.Compared with the glass without ion exchange treatment,the hardness of the glass after ion exchange is obviously improved.（5）With the gradual change of the Na₂O/Li₂O mass ratio in the glass,the density,alkali resistance and dielectric properties of the glass have obvious mixed alkali effects,which originate from the combined action of two main factors.One is the depolymerization of the glass network structure by the free oxygen introduced by Na₂O and Li₂O,which leads to the loosening of the glass structure;the other is that the repulsive force between the two different ions of Na⁺and Li⁺is stronger than that of a single alkali metal ion（Na⁺or Li⁺）,leading to the weakening of the depolymerization effect of free oxygen on the network structure.The change of the Na₂O/Li₂O mass ratio will cause the change of the primary and secondary roles of the above two factors,so that some properties of the glass appear extreme values.