Deformation and fracture of mica-containing glass-ceramics in Hertzian contacts

1994 ◽  
Vol 9 (3) ◽  
pp. 762-770 ◽  
Author(s):  
Hongda Cai ◽  
Stevens Marion A. Kalceff ◽  
Brian R. Lawn
Keyword(s):  
Glass Ceramic ◽  
Material Removal ◽  
Glass Ceramics ◽  
Fatigue Properties ◽  
Base Glass ◽  
Compressive Stresses ◽  
Contact Loads ◽  
Deformation And Fracture ◽  
The Matrix ◽  
Microstructural Design

The Hertzian indentation response of a machinable mica-containing glass-ceramic is studied. Relative to the highly brittle base glass from which it is formed, the glass-ceramic shows evidence of considerable “ductility” in its indentation stress-strain response. Section views through the indentation sites reveal a transition from classical cone fracture outside the contact area in the base glass to accumulated subsurface deformation-microfracture in the glass-ceramic. The deformation is attributed to shear-driven sliding at the weak interfaces between the mica flakes and glass matrix. Extensile microcracks initiate at the shear-fault interfaces and propagate into the matrix, ultimately coalescing with neighbors at adjacent mica flakes to effect easy material removal. The faults are subject to strong compressive stresses in the Hertzian field, suggesting that frictional tractions are an important element in the micromechanics. Bend-test measurements on indented specimens show that the glass-ceramic, although weaker than its base glass counterpart, has superior resistance to strength degradation at high contact loads. Implications of the results in relation to microstructural design of glass-ceramics for optimal toughness, strength, and wear and fatigue properties are discussed.

scholarly journals Effect of Different Concentrations of Titanium Oxide (TiO2) Addition on the Crystallization Behaviour and Some Properties of Alkaline Earth Aluminosilicate Glass-Ceramics

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Z.S. Aliyu
Keyword(s):  
Glass Ceramic ◽  
Minimum Weight ◽  
Glass Ceramics ◽  
Aluminosilicate Glass ◽  
Base Glass ◽  
Ceramic Samples ◽  
Melting Technique ◽  
The Matrix ◽  
Quaternary Base ◽  
Tio2 Addition

Glass-ceramics in the CaO-MgO-Al2O3-SiO2 quaternary base glass system was produced via melting technique using feldspar, limestone and magnesite as sources of starting materials. Glass-ceramics production involves making a base glass, annealing and cooling to room temperature and then reheating the base glass to nucleation and crystal growth temperatures. Characterization of the produced glass-ceramics was carried out using a scanning electron microscope (SEM). The effects of the crystallization process on some properties such as hardness, chemical durability in acid and alkali media of samples were determined. The results portrayed that glass-ceramic samples to which various amounts of TiO2 (2,4,6,8 and 10 wt.%) were incorporated showed the formation of crystalline phases dispersed in the matrix of their respective residual glassy phases. Significant improvement in hardness, as well as minimum weight loss, were recorded for all the glass-ceramic samples. On the contrary, the glass samples did not crystallize despite subjecting them to heat treatment, their hardness values were low and they were not resistant to acid (1M HCl) and alkali (1M NaOH) attacks. The inability of TiO2 addition to fully transform them into glass-ceramics remains a shortcoming. However, the glass-ceramic samples obtained from this study can be used for tiling works.

Study of Glass-Ceramic Waste Forms

1997 ◽  
Vol 506 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Ioudintsev ◽  
B.S. Nikonov ◽  
B.I. Omelianenko ◽  
T.N. Lashtchenova
Keyword(s):  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Matrix Glass ◽  
Crystalline Phases ◽  
Cell Parameters ◽  
The Matrix ◽  
High Level ◽  
Similar Unit

ABSTRACTSince the early of the 1990s the method of inductive melting in a cold crucible (IMCC) has been applied at SIA “Radon” for production of various wasteforms, including glasses and Synroc-type ceramics. Sphene-based glass-ceramics composed of glass and crystalline phases were considered as appropriate wasteform for High Level Waste immobilisation. Investigation of two glass-ceramic specimens prepared with the IMCC has been performed using optical microscopy, XRD, SEM/EDS, and TEM methods. The samples produced consist of vitreous and crystalline phases. The vitreous phase consists of two varieties of glass formed by the immiscibility of the initial melt onto two separate liquids. One of the glasses is observed as spherical microinclusions in the matrix glass. The glass of the microspheres are differed from the matrix glass composition by higher contents of Ca, Ti, Ce, Sr, Zr (or Cr), while the matrix glass contains higher amounts of Si, Al, and alkalies. The crystalline phases with sphene- and perrierite-like structures have been also occurred. Their total quantity reaches up to 50 vol.%. The synthetic perrierite has similar unit-cell parameters with its natural mineral analogs with the only exception in two-fold value of c dimension. Zr, Ce, and Sr are incorporated into synthetic sphene and perrierite, while Cs is hosted by the glass phases.

scholarly journals Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

2020 ◽  
Vol 10 (8) ◽  
pp. 2836 ◽  
Author(s):  
Rashi Sharma ◽  
Rebecca Welch ◽  
Myungkoo Kang ◽  
Claudia Goncalves ◽  
Cesar Blanco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramic ◽  
Volume Fraction ◽  
Glass Ceramics ◽  
Post Heat Treatment ◽  
Base Glass ◽  
Parent Glass ◽  
Crystal Phases

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

scholarly journals Surface Plasmon Resonance Enhanced Spontaneous Upconversion and Stimulated Emissions in Glass Ceramics Containing Ba2LaF7 Nanocrystals

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Sai Li ◽  
Wei Lu ◽  
Qihua Yang ◽  
Dacheng Zhou ◽  
Jianbei Qiu ◽  
...  
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Glass Ceramic ◽  
Visible Region ◽  
Glass Ceramics ◽  
Random Lasing ◽  
Ag Nps ◽  
The Matrix ◽  
Quenching Method

Glass ceramics containing Yb3+, Er3+ codoped Ba2LaF7 nanocrystals were fabricated via melt quenching method and the subsequent heating treatment. The formation of Ba2LaF7 nanocrystals in the glass ceramics was confirmed by X-ray diffraction (XRD) and transmission electron microscope (TEM). The spontaneous upconversion (UC) emission and the stimulated counterpart as a random lasing action of Er3+, which were related to the characteristic transitions of Er3+ ions, were achieved in the Yb3+, Er3+-doped Ba2LaF7 nanocrystals embedded glass ceramic hybrid. Furthermore, the absorption spectra verified the surface plasmon resonance (SPR) band of Ag, which precipitated from the matrix glasses as Ag nanoparticles (NPs). By incorporating Ag NPs in the glass ceramic hybrid, spontaneous UC emission intensity of Er3+ in visible region was significantly enhanced, while the threshold of the random lasing was decreased from 480 to 350 nJ/cm2.

Zn2+- Controlled Crystallization and Microstructure in K-Li-Mg-B-Si-Al-F Glass

MRS Advances ◽  
2018 ◽  
Vol 3 (60) ◽  
pp. 3525-3533 ◽  
Author(s):  
Mrinmoy Garai ◽  
Anoop K. Maurya ◽  
Shibayan Roy
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Glass Ceramics ◽  
Network Modifier ◽  
Base Glass ◽  
Controlled Crystallization

Abstract Text:The crystallization of (9-X) K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2-X PbO/BaO/ZnO (X =0/5) composition (wt.%) were studied by means of dilatometry, DSC, XRD, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg.). A characteristic exothermic hump is found to be appeared in DSC thermograph at the temperature range 800-950°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (>11.5×10-6/K, 50-800°C).Vickers Microhardness of base glass-ceramic (5.12 GPa) is increased when contains ZnO (5.26 GPa). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).

In Vitro Dental Cutting of Feldspar and Leucite Glass Ceramics Using an Electric Handpiece

2012 ◽  
Author(s):  
Xiao-Fei Song ◽  
Jianhui Peng ◽  
Ling Yin ◽  
Bin Lin
Keyword(s):  
Material Removal Rate ◽  
Glass Ceramic ◽  
Material Removal ◽  
Removal Rate ◽  
Chip Thickness ◽  
Glass Ceramics ◽  
Undeformed Chip Thickness ◽  
Normal Forces ◽  
Specific Material ◽  
Abrasive Cutting

Glass ceramics are important restorative materials in dentistry. They are used as veneer-core bilayer all-ceramic or metal-fused ceramic restorations or monolithic inlays/onlays/crowns to replace missing or damaged tooth structures for aesthetic and functional purposes. However, glass ceramic materials, such as feldspar and leucite glass ceramics, which are subject to this investigation, are brittle and easily induced microfractures in abrasive cutting using dental handpieces and coarse burs. In this paper, we investigated the dental abrasive cutting characteristics of feldspar and leucite glass ceramics using a high-speed electric handpiece and coarse diamond burs. Cutting forces, specific removal energy, surface roughness and morphology were investigated as functions of specific material removal rate and maximum undeformed chip thickness. The results indicate that increasing the specific material removal rate or the maximum undeformed chip thickness resulted in increases in both tangential and normal forces, but a decrease in specific removal energy for both ceramics. Tangential, normal forces and specific removal energy were significantly larger in up cutting than those in down cutting. Surface roughness for the two ceramics was not affected by the specific removal rate or the maximum undeformed chip thickness. Both microfrature and ductile microcutting morphology were observed in the machined surfaces for both ceramics. There existed a brittle to ductile transition trend when decreasing the specific material removal rate or the maximum undeformed chip thickness for the two ceramics. In comparison with feldspar glass ceramic, leucite glass ceramic generated better surfaces due to its more ductile deformation occurring in dental cutting.

Factors Affecting the Wear Behavior of Monolithic Zirconia and the Antagonists: Literature Review

2020 ◽  
Vol 2 (1) ◽  
pp. 4-11
Author(s):  
Marcia Borba ◽  
Paula Benetti ◽  
Giordana P. Furini ◽  
Kátia R. Weber ◽  
Tábata M. da Silva
Keyword(s):  
Literature Review ◽  
Glass Ceramic ◽  
Wear Behavior ◽  
Glass Ceramics ◽  
Surface Treatments ◽  
Human Tooth ◽  
Initial Surface ◽  
Monolithic Zirconia ◽  
Feldspathic Porcelain

Background: The use of zirconia-based ceramics to produce monolithic restorations has increased due to improvements in the optical properties of the materials. Traditionally, zirconiabased ceramics were veneered with porcelain or glass-ceramic and were not directly exposed to the oral environment. Therefore, there are several doubts regarding the wear of the monolithic zirconia restoration and their antagonists. Additionally, different surface treatments are recommended to promote a smooth surface, including glaze and several polishing protocols. To support the correct clinical application, it is important to understand the advantages and limitations of each surface treatment. Objective: The aim of this short literature review is to investigate the factors that may affect the wear of monolithic zirconia restorations in service and their antagonists. Methods: Pubmed/Medline database was accessed to review the literature from a 10-year period using the keywords: zirconia, monolithic, prosthesis, wear. Both clinical and in vitro studies were included in the review. Results: Studies investigated the effect of several surface treatments, including grinding with diamond- burs, polishing and glazing, on the surface roughness, phase transformation and wear capacity of monolithic zirconia. The wear behavior of monolithic zirconia was frequently compared to the wear behavior of other ceramics, such as feldspathic porcelain, lithium disilicate-based glassceramic and leucite-reinforced glass-ceramic. Human tooth, ceramics and resin composites were used as antagonist in the investigations. Only short-term clinical studies are available (up to 2 years). Conclusion: Literature findings suggest that zirconia monolithic restorations are wear resistant and unlikely to cause excessive wear to the antagonist, especially when compared to feldspathic porcelain and glass-ceramics. Monolithic zirconia should be polished rather than glazed. Yet, none of the polishing systems studied was able to completely restore the initial surface conditions of zirconia after being adjusted with burs. More clinical evidence of the antagonist tooth wear potential of monolithic zirconia is needed.

scholarly journals Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1321
Author(s):  
Tomasz K. Pietrzak ◽  
Marek Wasiucionek ◽  
Jerzy E. Garbarczyk
Keyword(s):  
Glass Ceramic ◽  
Electronic Conductivity ◽  
Glass Ceramics ◽  
Temperature Stability ◽  
Ceramic Materials ◽  
Glassy Matrix ◽  
Oxide Glasses ◽  
Thermal Transitions ◽  
Stability Range ◽  
Conductivity Enhancement

This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting oxide glasses. Various nanostructured systems have been described, including glass-ceramics based on ion conductive glasses (silver iodate and bismuth oxide ones) and electronic conductive glasses (vanadate-phosphate and olivine-like ones). Most systems under consideration have been studied with the practical aim of using them as electrode or solid electrolyte materials for rechargeable Li-ion, Na-ion, all-solid batteries, or solid oxide fuel cells. It has been shown that the conductivity enhancement of glass-ceramics is closely correlated with their dual microstructure, consisting of nanocrystallites (5–100 nm) confined in the glassy matrix. The disordered interfacial regions in those materials form “easy conduction” paths. It has also been shown that the glassy matrices may be a suitable environment for phases, which in bulk form are stable at high temperatures, and may exist when confined in nanograins embedded in the glassy matrix even at room temperature. Many complementary experimental techniques probing the electrical conductivity, long- and short-range structure, microstructure at the nanometer scale, or thermal transitions have been used to characterize the glass-ceramic systems under consideration. Their results have helped to explain the correlations between the microstructure and the properties of these systems.

Novel Glass-Ceramics for Dental Application by Sol Gel Technique

2008 ◽  
Vol 396-398 ◽  
pp. 153-156 ◽  
Author(s):  
Xanthippi Chatzistavrou ◽  
E. Hatzistavrou ◽  
Nikolaos Kantiranis ◽  
Lambrini Papadopoulou ◽  
Eleana Kontonasaki ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Preparation Method ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Dental Restorations ◽  
Gel Technique ◽  
Gel Preparation ◽  
Dental Applications ◽  
Potential Use

The aim of this study was the fabrication using a sol-gel technique of a new glass-ceramic with potential use in dental applications. The characterization of the composition and microstructural properties of the produced material confirmed the similarity between the new sol-gel derived glass-ceramic and a commercial leucite based fluorapatite dental glass-ceramic. The produced material has potential application in dental restorations and it is expected to exhibit better control of composition, microstructure and properties due to the intrinsic advantages of the sol-gel preparation method.

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