scholarly journals Improved performances of lithium disilicate glass-ceramics by seeds induced crystallization

2020 ◽  
Author(s):  
Ting Zhao ◽  
Mei-Mei Lian ◽  
Yi Qin ◽  
Jian-Feng Zhu ◽  
Xin-Gang Kong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Comprehensive Properties ◽  
Aesthetic Appearance ◽  
Small Crystals ◽  
Bimodal Grain Size ◽  
Glass Compositions

Abstract Self-reinforced lithium disilicate (Li2Si2O5, LD) glass-ceramics were hot pressing sintered by introducing 5 wt% Li2Si2O5 crystal seeds into two different glass compositions of SiO2-Li2O-P2O5-ZrO2-Al2O3-K2O-La2O3 (7C LD) and SiO2-Li2O-K2O-La2O3 (4C LD). The results show that the seeds play an important role in the crystallization inducement, microstructural and properties improvement of the glass, especially for the glass powder without the nucleating agent of P2O5. The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributes to the improvement of the performance especially the fracture toughness. The specimen of 4C LD glass with the addition of 5 wt.% Li2Si2O5 seeds exhibited the best comprehensive properties with a good flexural strength (396 ± 7 MPa), improved fracture toughness (3.31 ± 0.19 MPa·m1/2) and comparable translucency as IPS e.max. This research will provide a new idea and method for the improvement of the fracture toughness of lithium disilicate glass-ceramics without affecting its aesthetic appearance, and lay the foundation for its clinical applications.

scholarly journals Improved performances of lithium disilicate glass-ceramics by seed induced crystallization

2021 ◽  
Author(s):  
Ting Zhao ◽  
Mei-Mei Lian ◽  
Yi Qin ◽  
Jian-Feng Zhu ◽  
Xin-Gang Kong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Comprehensive Properties ◽  
Aesthetic Appearance ◽  
Small Crystals ◽  
Bimodal Grain Size ◽  
Glass Compositions

AbstractSelf-reinforced lithium disilicate (Li2Si2O5, LD) glass-ceramics were hot pressing sintered by introducing 5 wt% Li2Si2O5 crystal seeds into two different glass compositions of SiO2-Li2O-P2O5-ZrO2-Al2O3-K2O-La2O3 (7C LD) and SiO2-Li2O-K2O-La2O3 (4C LD). The results show that the seeds play an important role in the crystallization inducement, and microstructural and property improvement of the glass, especially for the glass powder without the nucleating agent of P2O5. The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributing to the improvement of the performance especially the fracture toughness. The specimen of 4C LD glass with the addition of 5 wt% Li2Si2O5 seeds exhibited the best comprehensive properties with a good flexural strength (396±7 MPa), improved fracture toughness (3.31±0.19 MPa·m1/2), and comparable translucency as IPS e.max. This research provides a new idea and method for the improvement of the fracture toughness of lithium disilicate glass-ceramics without affecting its aesthetic appearance, and lays the foundation for its clinical applications.

scholarly journals Improved performances of lithium disilicate glass-ceramics by seeds induced crystallization

2021 ◽  
Author(s):  
Ting Zhao ◽  
Mei-Mei Lian ◽  
Yi Qin ◽  
Jian-Feng Zhu ◽  
Xin-Gang Kong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Comprehensive Properties ◽  
Aesthetic Appearance ◽  
Small Crystals ◽  
The Aesthetic ◽  
Bimodal Grain Size

Abstract Self-reinforced lithium disilicate (Li 2 Si 2 O 5 ) glass-ceramics were hot pressing sintered by introducing 5 wt% Li 2 Si 2 O 5 crystal seeds into two different glass systems. The results show that the seeds play an important role in the crystallization inducement, microstructural and properties improvement of the glass, especially for the glass powder without the nucleating agent of P 2 O 5 . The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributes to the improvement of the performance especially the fracture toughness. The 4C5S specimen exhibited the best comprehensive properties with a good flexural strength (396 ± 7 MPa), improved fracture toughness (3.31 ± 0.19 MPa·m 1/2 ) and comparable translucency as IPS e.max. This research will provide a new idea and method for the perfect matching of the fracture toughness and the aesthetic appearance of lithium disilicate glass-ceramics, and lay the foundation for its clinical applications.

scholarly journals Improved performances of lithium disilicate glass-ceramics by seeds induced crystallization

2020 ◽  
Author(s):  
Ting Zhao ◽  
Mei-Mei Lian ◽  
Yi Qin ◽  
Jian-Feng Zhu ◽  
Xin-Gang Kong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Comprehensive Properties ◽  
Aesthetic Appearance ◽  
Small Crystals ◽  
The Aesthetic ◽  
Bimodal Grain Size

Abstract Self-reinforced lithium disilicate (Li 2 Si 2 O 5 ) glass-ceramics were hot pressing sintered by introducing 5 wt% Li 2 Si 2 O 5 crystal seeds into two different glass systems. The results show that the seeds play an important role in the crystallization inducement, microstructural and properties improvement of the glass, especially for the glass powder without the nucleating agent of P 2 O 5 . The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributes to the improvement of the performance especially the fracture toughness. The 4C5S specimen exhibited the best comprehensive properties with a good flexural strength (396 ± 7 MPa), improved fracture toughness (3.31 ± 0.19 MPa·m 1/2 ) and comparable translucency as IPS e.max. This research will provide a new idea and method for the perfect matching of the fracture toughness and the aesthetic appearance of lithium disilicate glass-ceramics, and lay the foundation for its clinical applications.

Formation of NaNbO3 Crystals in Dielectric Glass and Glass-Ceramics of a Na2O-Nb2O5-Al2O3-SiO2 System

2008 ◽  
Vol 55-57 ◽  
pp. 229-232 ◽  
Author(s):  
S. Thongsaeng ◽  
Anuson Niyompan ◽  
Rungnapa Tipakontitikul ◽  
Kamonpan Pengpat
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Glass Production ◽  
Nucleating Agent ◽  
Aluminum Silicate ◽  
Phase Identification ◽  
Dielectric Glass ◽  
Xrd Patterns ◽  
Glass Compositions

Dielectric glass and glass-ceramics were derived from Na2O-Nb2O5-Al2O3-SiO2 system. Small amount of TiO2 were also introduced into glass compositions to study crystallization behavior of the glass with present of this nucleating agent. Conventional melt-quenching technique was employed for a glass production and the selected bulk glass samples were subjected to the heat-treatment process at appropriate temperature. After six different glass compositions were produced, and by observation with necked eyes, all obtained glass samples are in light brown color and some samples were opaque due to crystallization took place during quenching. Phase identification through XRD patterns show that there were 3 phases, NaNbO3, NaNbO8 and a sodium aluminum silicate compound, found in those opaque glass samples. NaNbO3 is a predominant phase in all samples. Fortunately, clear transparent glass was obtained from the composition with no TiO2 addition. Heat treatment of this glass did not induce phase change, three aforementioned phases still present. Increasing heat treatment time promoted a higher of observed intensity of NaNbO3. But the NaNbO3 crystalline size was not significantly developed with time. The dielectric response of the NaNbO3 crystals in the glass-ceramics samples are influenced by presence of other crystalline phases.

scholarly journals Characterisation and Properties of Lithium Disilicate Glass Ceramics in the SiO2-Li2O-K2O-Al2O3System for Dental Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Naruporn Monmaturapoj ◽  
Pornchanok Lawita ◽  
Witoon Thepsuwan
Keyword(s):  
Glass Composition ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agents ◽  
Fine Grained ◽  
Melting Glass ◽  
Heterogenous Nucleation ◽  
Dental Applications ◽  
Slight Amount ◽  
Glass Compositions

This work proposes four different glass formulas derived from the SiO2-Li2O-K2O-Al2O3system to investigate the effect of glass composition on their crystal formations and properties. Glass LD1 was SiO2-Li2O-K2O-Al2O3system with the addition of P2O5and CaF2as nucleating agents. In Glass LD2, a slight amount of MgO was mixed in order to increase the viscosity of the melting glass. Finally, the important factor of Si : Li ratio was increased in Glasses LD3 and LD4 with compositions otherwise the same as LD1 and LD2. The results found that P2O5and CaF2served as a nucleating site for lithium phosphate and fluorapatite to encourage heterogenous nucleation and produce a fine-grained interlocking microstructure of lithium disilicate glass ceramics. MgO content in this system seemed to increase the viscosity of the melting glass and thermal expansion coefficient including the chemical solubility. Increasing the Si : Li ratio in glass compositions resulted in the change of the microstructure of Li2Si2O5crystals.

scholarly journals P2O5 AS AN EFFECTIVE NUCLEATING AGENT OF LITHIUM DISILICATE GLASS-CERAMICS

2005 ◽  
Vol 19 (0) ◽  
pp. 36-41 ◽  
Author(s):  
WOLFRAM HÖLAND ◽  
VOLKER RHEINBERGER ◽  
CHRISTIAN VAN'T HOEN ◽  
ELKE APEL
Keyword(s):  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Nucleating Agent

Effect of Glass Compositions on Crystallization and Mechanical Properties of Lithium Disilicate Glass Ceramics for Dental Crown

2013 ◽  
Vol 747 ◽  
pp. 194-197
Author(s):  
Naruporn Monmaturapoj ◽  
Pornchanok Lawita ◽  
Witoon Thepsuwan
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Crystal Formation ◽  
Indentation Fracture ◽  
Graphite Mold ◽  
Heat Treated ◽  
Indentation Fracture Toughness ◽  
Glass Compositions

This work proposes three different glass formula derived from the SiO2-Li2O-K2O-Al2O3 system to investigate the effect of glass compositions on their crystal formation and mechanical properties. Glass LD_1 was SiO2-Li2O-K2O-Al2O3 system with adding P2O5 and CaF2 as nucleating agents. In Glass LD_2, a few amount of MgO was mixed to improve the viscosity of the glass. Finally, an important factor of Si:Li ratio was increased in Glass LD_3. Glass batches were melted at 1500°C and cast into a graphite mold which was annealed at 400-500°C before heat treatment at 700, 750, 800 and 850°C. XRD results can be indexed Li2Si2O5, Li2SiO3, Ca5(PO4)3F and SiO2 as an early crystallization when heat treated at 700°C. After heat treatment at 750-850°C, the intensity of SiO2 disappeared and the peaks associated to Li3PO4 appeared; meanwhile, Li2Si2O5 increased in intensity. Adding MgO resulted in decreasing the viscosity of the glass with no significant effects on the formation of lithium disilicate. By increasing Si:Li ratio, the peak of SiO2 more obviously observed. SEM results revealed the development of microstructure from plate-like to interlocking rod-shaped crystals in all glasses. The highest indentation fracture toughness and biaxial flexural strength found in all glass ceramics heat treatment at 800°C because the finest microstructure observed at this temperature, except LD_3 heat treated at 850°C, which obtained the finest microstructure. LD_1 heat treated at 850°C presented the best chemical solubility 59 μg/cm2.

scholarly journals Effect of PEG-based binder concentration on the mechanical properties of lithium disilicate glass-ceramics prepared by low-pressure injection moulding

2021 ◽  
Vol 15 (3) ◽  
pp. 238-245
Author(s):  
Arnon Kraipok ◽  
Pratthana Intawin ◽  
Manlika Kamnoy ◽  
Suchittra Inthong ◽  
Wilaiwan Leenakul ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Injection Moulding ◽  
Glass Powder ◽  
Acetic Acid Solution ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Sintered Sample ◽  
Low Pressure ◽  
Bending Test ◽  
Pressure Injection

Lithium disilicate (LD) glass-ceramics are extensively employed in restorative dentistry because their superior aesthetic properties and hardness are similar to natural teeth. The aim of this work is to investigate the mechanical properties and chemical solubility of lithium disilicate glass-ceramics prepared by the low-pressure injection moulding using the PEG-based binder. The glass-to-binder ratio was varied as 60:40, 55:45, 50:50 and 45:55 vol.%. The sintering conditions of 800?C with 2 h dwell time were selected according to thermal analysis. Phase formation, microstructure and mechanical properties of the prepared samples were characterized by XRD, SEM, microhardness and three-point bending test, respectively. Besides, the chemical solubility of the system was investigated by the immersion test in acetic acid solution. XRD analyses of the sintered sample confirmed the presence of only one prominent crystalline phase of LD. SEM result showed that the porosity increased with decreasing glass powder content. The mechanical properties of the LD glass-ceramic samples tended to decrease when the proportion of the glass powder decreased, while the chemical solubility tended to increase. The mechanical properties of the glass-ceramics, i.e. the highest density value, Vickers hardness and flexural strength were 2.55 g/cm3, 6.80GPa, and 176MPa, respectively. These results could be useful in developing these LD glass-ceramics for their optimal use in dental applications.

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