The Preparation and Characterisation of Oxynitride Glasses and Glass-Ceramics PDF Download
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Author: Stuart Hampshire Publisher: ISBN: Category : Languages : en Pages : 96
Book Description
The objective was to study the effect on properties (such as microhardness, glass transition, crystallization temperature, viscosity, etc.) of replacing oxygen by nitrogen in sialon-based glasses containing rare-earth cations and to study the formation of glass-ceramics by controlled crystallization of these oxynitride glasses and to assess the effects of this on properties. Glasses were prepared by melting appropriate oxides and nitrides in boron nitride lined crucibles, melting at 1700 C under nitrogen and casting into preheated graphite moulds followed by annealing. Characterization of the glasses was carried out by differential thermal analysis (DTA) to ascertain the glass transition and crystallization temperatures and standard techniques used for microhardness and viscosity. Nitrogen increases the glass transition, microhardness and viscosity for constant cation ratio glasses and also inhibits crystallization. From DTA, suitable heat-treatment schedules were designed to produce fine-grain glass-ceramics. Optimization of these heat treatments was by measuring the changes (increases) in microhardness. Fully amorphous glasses can be prepared easily in large batches (approx. 100g) in many M-Si-Al-O-N systems. Work concentrated on Neodynium and Y-sialon glasses which undergo homogeneous nucleation at Tg+50 (C) followed by crystal growth at Tc-40 (C) each for 2.5 hours. (AW).
Author: Stuart Hampshire Publisher: ISBN: Category : Languages : en Pages : 96
Book Description
The objective was to study the effect on properties (such as microhardness, glass transition, crystallization temperature, viscosity, etc.) of replacing oxygen by nitrogen in sialon-based glasses containing rare-earth cations and to study the formation of glass-ceramics by controlled crystallization of these oxynitride glasses and to assess the effects of this on properties. Glasses were prepared by melting appropriate oxides and nitrides in boron nitride lined crucibles, melting at 1700 C under nitrogen and casting into preheated graphite moulds followed by annealing. Characterization of the glasses was carried out by differential thermal analysis (DTA) to ascertain the glass transition and crystallization temperatures and standard techniques used for microhardness and viscosity. Nitrogen increases the glass transition, microhardness and viscosity for constant cation ratio glasses and also inhibits crystallization. From DTA, suitable heat-treatment schedules were designed to produce fine-grain glass-ceramics. Optimization of these heat treatments was by measuring the changes (increases) in microhardness. Fully amorphous glasses can be prepared easily in large batches (approx. 100g) in many M-Si-Al-O-N systems. Work concentrated on Neodynium and Y-sialon glasses which undergo homogeneous nucleation at Tg+50 (C) followed by crystal growth at Tc-40 (C) each for 2.5 hours. (AW).
Author: R. Abramovici Publisher: ISBN: Category : Languages : en Pages : 45
Book Description
The purpose of this work was to study the change of physical properties of certain glasses and the corresponding glass-ceramics as a consequence of incorporation of nitrogen. Five series of glasses and their crystallized samples of Me-Si-Al-O-N (Me = Li, Ca, Mg, Ca+Mg, Mg+Li) system were prepared and studied. The criteria for selecting the composition within each system were: potential crystalline phases, castability of the melts below 1600 C, and in some cases, solubility of nitrogen in the melts. Melting of the glasses was performed in alumina or slip cast silica crucibles, in air and also in nitrogen, with acceptable results as far as their corrosion resistance was concerned. Nitrogen retention was of 61.7 - 74.2% for glasses melted in air (in covered crucibles) and 79.4 - 90.7% for those melted in nitrogen atmosphere. Glass transition and dilatometric softening temperature, thermal expansion coefficient and microhardness were measured. The crystallized samples were examined also by XRD and SEM.
Author: Jesus Ma. Rincon Publisher: Springer Science & Business Media ISBN: 3662038714 Category : Technology & Engineering Languages : en Pages : 247
Book Description
This monograph stems from lectures given during the summer course at the University of La Laguna. It includes the main characterization techniques useful nowadays for ceramics, glasses and glass-ceramics, reviews the new microscopes for characterizing materials, and gives an overview of inorganic materials such as zeolites.
Author: Robert P. Gleisner Publisher: ISBN: Category : Languages : en Pages : 46
Book Description
It has been shown that the substitution of nitrogen for oxygen in oxide glass structures enhances bond strength, which results in glasses having outstanding properties. These oxynitride glasses have higher elastic moduli, tensile strength, hardness, and better corrosion resistance than oxide glasses. Previous work at MTL demonstrated techniques for making significant quantities of these oxynitride glasses. It was also recognized that these glasses had the potential to be formed into glass fibers. Such glass fibers would have potential applications in high-performance composites. Keywords: Oxynitride glass, Glass fibers, Physical properties, Composite materials. (JES).
Author: M.H. Lewis Publisher: Springer Science & Business Media ISBN: 9400908172 Category : Technology & Engineering Languages : en Pages : 388
Book Description
The emergence of synthetic ceramics as a prominent class of materials with a unique combination of properties has been an important part of the materials-science scene over the past 20 years. These 'high-technology' ceramics have varied applications in areas utilizing their exceptional mechanical, thermal, optical, magnetic or electronic properties. A notable development of the 1970s was that of 'Si-based' ceramics (Si3N4' SiC and 'Sialons') as high-temperature engineering solids. More recently the zirconia-based ceramics have evolved as a class of material with significant improvements in fracture-toughness. In the 1980s we are on the threshold of development of ceramic-matrix composites with the promise of over coming major limitations in engineering design with 'brittle' ceramics and the development of novel properties unattainable with monolithic micro structures. Throughout this period there have been significant but less well-publicized developments in the field of glass-ceramics and glasses. It is the purpose of this publication to review selected topics within this important area of materials science. A key element in understanding the relation between properties and microstructure is a knowledge of atomic arrangement in ceramic phases. Recent developments in NMR and X-ray absorption spectroscopies have had considerable impact on studies of atomic co-ordination in glasses and crystalline ceramic materials and are reviewed in Chapters 1 and 2. Glass-ceramics are derived from the parent glasses by controlled crystal lization and have properties dictated, in part, by the efficiency of crystal nucleation within the glass volume.
Author: Mary R. Reidmeyer Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
"The preparation techniques and properties of phosphorus oxynitride glasses produced from sodium metaphosphate and nitride compounds are reported. A preliminary survey of possible nitride additives to sodium metaphosphate is presented along with an extended study of the two most promising nitrides, AIN and Mg3N2. Properties reported include: nitrogen content, dissolution rate in water, thermal expansion coefficient, softening point, glass transformation temperature, density, refractive index, microhardness, and infrared absorption"--Abstract, leaf 1
Author: Stuart Hampshire
Author: Stuart Hampshire
Author: Vincent Morrissey
Author: R. Abramovici
Author: Jesus Ma. Rincon
Author: Robert P. Gleisner
Author: M.H. Lewis
Author: 
Author: Ralph Anthony Chavez
Author: Mary R. Reidmeyer
Author: John Andrew Fernie