Influence Of Different Oxides On The Performance Of Lead-free SiO₂-B₂O₃-R₂O System Glass

Lead glass has many virtues,such as high refractive index,high density.All these excellences make lead glass used in manufacturing advanced table wares,lamps and lanterns,jewelry and artwork-production.But the Lead in Lead vessel will dissolve when the vessel is used to contain alcohol or acidic beverage.Therefore the glasses with high Lead will pollute circumstance and be harmful to the health of people.Nowadays Lead is forbidden in many European countries and Japan.Just so,the study about lead-free glass becomes more and more important and essential.In this paper,lead-free glasses are of interest for research and applications because of their unique characters such as high refractive index,good chemical durability,and this kind of glass won't pollute circumstance and endanger the health of worker.Take optical performances,environment health and producing cost into account,the basic composition was:SiO₂ 46.7%,ZnO 5.0%,CaO 3.3%,B₂O₃ 8.4%,K₂O 23.3%,Na₂O 13.3%(weight percent).The influence of SrO,TiO₂/ZrO₂ and rare-earth oxides on Lead-free SiO₂-B₂O₃-R₂O system was studied in this paper.The density and refractive index increased with the increase of contents of SrO. When w(SrO)=32%,Lead-free glass with density of 2.89g/cm³,refractive index of 1.548 and transmission of 86%was prepared.Whereas glasses with SrO had bad chemical durability.In order to improve the chemical durability of glass,TiO₂ and ZrO₂ was added into glass.The results indicated that TiO₂ and ZrO₂ were able to improve chemical durability greatly,simultaneity increase the tendency of crystallization.In this system,the crystallization took place when 28%ZrO₂ or 32%TiO₂ adding in.The density and refractive index increased with the increase of ZrO₂ or TiO₂.When w(ZrO₂)=25%,the density of sample was by 2.86g/cm³,the refractive index by 1.5399 and transmission by 85%.When w(TiO₂)=28%,the lead-free glass with density of 2.84g/cm³,refractive index of 1.532 and transmission of 81%was prepared.On the other hand,because of the yellow color brought by TiO₂,so TiO₂ is not a good choice to prepare colorless glass.When ZrO₂ or TiO₂ was as an additive in the glass,the key problem was to avoid crystallization.Rare-earth oxides were easy to make glass colored,but the high refractive index colorless glass doping La₂O₃ could be prepared.The results inDicated that the density as well as refractive index increased firstly and then decreased with the increase of doping contents of La₂O₃.When w(La₂O₃)=18%,it was found the density of Lead-free sample was by 3.0280g/cm³,the refractive index by 1.5608 and transmission by 91%.The glass with less than 18wt%La₂O₃ had good chemical durability.