Study On Lithium Disilicate Glass-ceramics Doped With Fluorapatite

Biological glass-ceramics have good biological properties and mechanical processability.It has a promising future in the fields of department of orthopedics,dentistry and bone tissue engineering.Among them,lithium disilicate glass-ceramics has become one of the most promising dental restorative materials for clinical application because of its excellent mechanical properties,suitable semi permeability and so on.Lithium disilicate glass-ceramics were relatively simple,lithium disilicate glass-ceramics for dental materials in China rely on import,the price is expensive,which limits its development.Fluorapatite active ceramic has good biocompatibility,good chemical stability,has a certain anti acid capacity.However,because of the low strength,poor toughness and poor mechanical properties of fluorapatite bioceramics,many scholars have actively explored the combination of fluorapatite and other materials in order to improve the application of fluorapatite bioceramics.This paper is intended to have better biocompatibility fluorapatite doped into the lithium disilicate glass-ceramics,which in order to prepare a dental restorative material having excellent biocompatibility and good mechanical properties.Lithium disilicate glass-ceramics and fluoroapatite-doped lithium disilicate glass-ceramics were prepared by sintering method,X-ray diffraction analysis,scanning electron microscopy,computer-controlled electronic universal testing machine,automatic microscopy hardness tester and other methods were used to study the effect of heat treatment system and composition on crystal phase composition,micro-morphology,sintering performance and mechanical properties of glass-ceramics.Through the study,the following results have been achieved:1.Lithium disilicate glass-ceramic was prepared by sintering method.The crystallization behavior of lithium disilicate glass-ceramic under different heat treatment conditions was studied.In the temperature range of 800?860?,the main crystal phase of the sample is Li2Si2O5.As the temperature increases,the crystallinity gradually increases;the crystal structure is gradually transformed from spheroid to rod like crystal,and the crystal size gradually increased;the shrinking rate first increases and then decreases,the apparent porosity and the water absorption rate decrease as the heat treatment temperature increases,and the volume density gradually increases;All samples can obtain good sintering effect,the apparent porosity of the sample at 860? is 1.01%,the water absorption is 0.41%,the bulk density is 2.4 g/cm3,and the hardness is 663HV.2.High purity fluorapatite powder was prepared by aqueous solution method,the preparation of fluorapatite and glass powder under the ratio of 2:8,3:7 and 5:5 was preliminarily studied.At 820?,the glass-ceramics samples with main crystalline phases of fluoroapatite and lithium disilicate can be prepared by the three groups of ratios.When the content of fluorapatite is 20%,the crystal grains of the sample are evenly distributed,the aspect ratio is moderate,and it has excellent interlocking structure and good mechanical properties.3.The doping of fluorapatite and basic glass powder under 2:8 was studied.The influence mechanism of heat treatment on the crystallization characteristics,micromorphology,sintering properties and mechanical properties of the glass samples was analyzed.In the same proportion,the temperature has a certain influence on the lithium disilicate glass doped with fluoroapatite:When the temperature rises above 800 ? the types of precipitated crystals in the glass-ceramics essentially do not change,mainly including Li2Si2O5,Ca5(PO4)3F,Li3PO4 and SiO2 crystal phases;In the temperature range of 800?840?,the size of the rod-like crystals increases with the increase of the sintering temperature,uniformly distributes in the glass matrix,and forms interlocking microstructures;With the increase of sintering temperature,the shrinking rate gradually increased,the apparent porosity and water absorption rate gradually decreased and then increased,and the bulk density first decreased and then became consistent;In the temperature range of 800?840 C,the microhardness of the sample increases first and then decreases,and the compressive strength increases.The composite glass-ceramics prepared at a crystallization temperature of 820? have good sinterability,uniformly distributed crystallites in the glass matrix,and have good mechanical properties.Among them,the composite effect is better in the ratio of 8:2 at 820?.