Oxynitride Glasses and Glass Ceramics

1992 ◽  
Vol 287 ◽  
Author(s):  
Stuart Hampshire
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Heat Treatments ◽  
Oxynitride Glass

Silicon nitride based ceramics contain oxynitride glass phases at the grain boundaries which can impair subsequent high temperature properties. Investigations of bulk glasses in various M-Si-Al-O-N systems have been carried out and it has been shown that up to 15 atomic % N can be incorporated into these oxynitride glasses. Studies have revealed that nitrogen increases the viscosity, hardness and glass transition temperature of the glasses. Heat treatments of the glasses to form crystalline phases have been reported but further improvements are possible if glass-ceramic processes using two-stage heat treatments are introduced. The development of oxynitride glasses and the effects of nitrogen on properties are reviewed and the optimisation of glass-ceramic heat-treatments are reported.

High-temperature carbon plastics based on thermoreactive polyimide binder

2020 ◽  
pp. 89-102
Author(s):  
M. I. Valueva ◽  
I. V. Zelenina ◽  
M. A. Zharinov ◽  
M. A. Khaskov
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strength Properties ◽  
High Glass Transition Temperature ◽  
Reinforced Plastics ◽  
Carbon Plastics ◽  
Fundamental Possibility ◽  
Fiber Reinforced Plastics

The article presents results of studies of experimental carbon plastics based on thermosetting PMRpolyimide binder. Сarbon fiber reinforced plastics (CFRPs) are made from prepregs prepared by melt and mortar technologies, so the rheological properties of the polyimide binder were investigated. The heat resistance of carbon plastics was researched and its elastic-strength characteristics were determined at temperatures up to 320°С. The fundamental possibility of manufacturing carbon fiber from prepregs based on polyimide binder, obtained both by melt and mortar technologies, is shown. CFRPs made from two types of prepregs have a high glass transition temperature: 364°C (melt) and 367°C (solution), with this temperature remaining at the 97% level after boiling, and also at approximately the same (86–97%) level of conservation of elastic strength properties at temperature 300°С.

Viscoelastic Behavior of Segmented Elastomers

1967 ◽  
Vol 40 (4) ◽  
pp. 1105-1110 ◽  
Author(s):  
Stuart L. Cooper ◽  
Arthur V. Tobolsky
Keyword(s):  
Hydrogen Bonding ◽  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Behavior ◽  
Temperature Transition ◽  
Hydrogen Bonding Interactions ◽  
Structural Nature ◽  
Hard Segments

Abstract Viscoelastic behavior of linear segmented elastomers was examined. The unusual properties found in spandex systems are also observable in hydrocarbon block co-polymers, indicating that hydrogen bonding interactions are perhaps not essential. Low temperature properties of segmented systems are governed by the structural nature of the associated flexible segments, which determines the value of the major glass transition temperature (Tg). It appears that an association of the hard segments provides a broad temperature range of enhanced rubbery modulus. This occurs between the major Tg and a secondary high temperature transition.

Experimental Research on Mechanical Behavior of GFRP Bars under High Temperature

2011 ◽  
Vol 71-78 ◽  
pp. 3591-3594 ◽  
Author(s):  
Xiao Lu Wang ◽  
Xiao Xiong Zha
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
High Temperatures ◽  
Glass Fibers ◽  
Ultimate Tensile Stress ◽  
Gfrp Bars ◽  
Tensile Test Result

Experimental results on tensile mechanics properties of GFRP bars at high temperatures are present in this paper. Thirty commercially produced GFRP tensile specimens of 8mm diameter were tested at high temperature ranging from 10°Cup to 500°C. Tensile test result indicates that, the ultimate tensile stress has significant reduction at two temperature zones, one is glass transition temperature of epoxy resin (80-120°C), with strength degradation 22%, the second is the soften temperature of glass fibers(about 400°C), the strength decrease drastically with almost linear rate and remained 33% residual strength at 500°C. The elastic modulus remained unchanged until glass transition temperature of epoxy resin, and the modulus declined linearly with the temperature elevating. Stress-strain relationships of GFRP bars exhibit liner performance even at high temperatures.

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).

scholarly journals Structural Features and Synthesis of CeO2-Doped Boroaluminosilicate Oxyfluoride Transparent Glass Ceramics

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenlin Wang ◽  
Laifei Cheng
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Ceramics ◽  
Structural Features ◽  
Temperature Decrease ◽  
Silicate Network ◽  
Network Modifier ◽  
Transparent Glass ◽  
Pass Through

This study investigated the effects of CeO2on structure and synthesis of boroaluminosilicate transparent glass ceramics containing CaF2nanocrystals prepared through isothermal crystallization of the melt-quenched glasses with composition 54SiO2–10B2O3–13Al2O3–14Na2O–3ZnO–2Li2O–4CaF2doped with 0–1.2 mol% CeO2. CeO2in polyvalent states acting as network modifier leads to disruption of the silicate network and the conversion of [BO3] to [BO4] generating the nonlinear variations in crystallization, and thermodynamic and optical features. Glass transition temperature and the crystallization temperature decrease firstly and then increase with the increase of CeO2content. Correspondingly, the size of CaF2nanoscale crystals and the absorption coefficient of the glass ceramics are found to pass through a maximum and then decrease with increasing CeO2addition. Increasing CeO2concentration and elevating treating temperature lead to red-shift of absorption edge and transparency deterioration of glass ceramics.

Viscosities of Oxynitride Glass and the Effects on High Temperature Behaviour of Silicon Nitride-Based Ceramics

2005 ◽  
Vol 287 ◽  
pp. 259-264 ◽  
Author(s):  
Stuart Hampshire ◽  
Michael J. Pomeroy
Keyword(s):  
Glass Transition ◽  
Rare Earth ◽  
High Temperature ◽  
Silicon Nitride ◽  
Volume Fraction ◽  
Temperature Behaviour ◽  
Rare Earth Cation ◽  
Intergranular Films ◽  
Oxynitride Glass ◽  
Earth Cation

M-Si-Al-O-N glasses (where M = Y or rare earth cation) are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of these oxynitride glass phases determine the properties of the material, in particular, high temperature mechanical behaviour. Investigations on oxynitride glass formation and properties have shown that nitrogen increases the glass transition and softening temperatures, viscosity, elastic modulus and hardness. By changing the cation ratios or the type of rare earth cation incorporated, properties such as viscosity can be increased further. This paper provides an overview of oxynitride glasses and outlines the effect of composition on properties such as glass transition temperature and viscosity. These effects have important implications for silicon nitride based ceramics where amorphous intergranular films control high temperature properties such as creep resistance.

scholarly journals Dynamic Moduli of Polybutylene Terephthalate Glass Fiber Reinforced in High-Temperature Environments

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 483
Author(s):  
Carmelo Gómez ◽  
Jorge Mira ◽  
F.J. Carrión-Vilches ◽  
Francisco Cavas
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Fiber ◽  
Storage Modulus ◽  
Fiber Content ◽  
Polybutylene Terephthalate ◽  
Dynamic Moduli ◽  
Over Time

The aim of this work was to show the evolution over time of the dynamic moduli in components made of Polybutylene Terephthalate reinforced with glass fiber when they are held to temperatures close to the glass transition temperature over time. For this purpose, PBT samples reinforced with short, glass fibers of Ultradur® material with 0%, 20%, and 50% in weight content were tested. Dynamic moduli showed an increment with glass fiber content showing a nonlinear behavior with the temperature. The evolution of storage modulus was depicted by means of a modified law of mixtures with an effectiveness factor depending on temperature and fiber content, whereas the evolution over time was obtained with a time–temperature transformation generated with the TTS Data Analysis software of TA-instruments for a given temperature. Storage modulus showed a linear relationship with glass fiber content when components were held to temperatures near to their respective glass transition temperature, obtained from the maximum of loss modulus curve with temperature. In summary, the value and evolution of dynamic moduli of PBT samples improved with glass fiber content, allowing us to increase the durability of components when they are submitted to high-temperature environments.

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