Research On The Increasing The Strength Of Building Ceramic Tile By Ion-Exchange

China is the world’s largest producer and exporter of building ceramics,with annual output exceeding 10 billion m².But high production means consuming a large amount of raw material resources and energy,at the same time to the environment,resources caused greater pressure.It is imperative to produce thin and reduced ceramics,and increasing the mechanical strength of ceramics is a effective way to achieve this goal.Ion exchange strengthening is a good reinforcement method with simple process.The strengthened samples have the advantages of no deformation,high strength,no self-explosion,high impact resistance and high surface wear resistance,and have a favorable application prospect in the field of building ceramics.In this study,the low temperature ion exchange method is used to strengthen the building ceramic tiles.Through the K⁺-Na⁺ exchange between molten salt and ceramic tile.The "pinning effect" is produced on the surface of the ceramic tile and forming a layer of compressive pre-stress to improve the strength.The effects of strengthening process,molten salt composition and composition of ceramic body on ion exchange strengthening effect and mechanical properties of ceramics were studied.The main research contents are as follows:The influence of ion exchange time and temperature on the effect of ion exchange strengthening ceramic tiles: using AR.KNO₃ as molten salt,the ceramic tiles are immersed and treated by ion exchange at different time and temperature.The results show that K⁺-Na⁺ ion exchange mainly occurs in glass phase of ceramic,and the existence of crystal phase and gas phase hinders K⁺ diffusion.the thickness of the exchange layer increases with the exchange time.after 450℃ and 5 h treatment,the flexural strength of the tiles can be increased from 63 MPa to 103 MPa,and the increasing rate can reach 63.49%.The microhardness can be increased from 504 kg/mm2 to 706 kg/mm² the increasing rate reaches 40.08%.The bulk density is basically not affected by ion exchange.The influence of molten salt composition on ion exchange was studied.The results show that the Na⁺,Ca²⁺ contained in the TP.KNO₃ and the Fe³⁺ introduced by the container into the molten salt will hinder the ion exchange(Ca²⁺>Na⁺>Fe³⁺).The effect of strengthening after introducing 3 mol% KHCO₃ into TP.KNO₃ is close to that of AR.KNO₃.The addition of KHCO₃ can introduce CO₃^2-,Ca CO₃ generated in combination with Ca²⁺ to reduce the concentration of Ca²⁺,so as to remove impurities.The addition of KOH speed up the ion exchange process,and the effect is best when the amount of addition is 0.5 mol%.But after adding excessive KOH,it will make the ceramic surface seriously corroded and reduce the ceramic strength.Effect of Na₂O content in ceramic body on ion exchange strengthening: the content of Na₂O in ceramic body was changed by adding different contents of albite based on the use of raw ceramic body powder in the factory to study its effect on the enhancement effect of ion exchange.The results show that the Na₂O content in the ceramic body can be increased to 2.00-2.27 wt% by adding albite,which can promote K⁺-Na⁺ exchange,increase K⁺ content and compressive stress,and improve the effect of ion exchange strengthening.However,the ceramic tiles will be over burning with Na₂O content more than 2.27 wt%,resulting in a decrease in the appreciation of the flexural strength.