Sintering Of Glass Research Articles

An optical technique based on silicate glass sintering for temperature mapping

AbstractThermal paints have been used for decades by the gas turbine engine community to map surface temperature with low resolution. A novel thermal paint based on the sintering of a lead‐silicate glass powder was developed that can map maximum temperature with high resolution (±5°C) over a 60°C range beginning at the glass transition temperature (). The paint exhibited excellent adhesion to nickel‐based superalloy components due to similar coefficients of thermal expansion between the superalloy and glassy ceramic coating. An optical transition was qualitatively and quantitatively observed using scanning electron microscopy, ultraviolet‐visible (UV‐VIS) reflectance spectroscopy, and visual inspection. UV‐VIS reflectance spectroscopy was used to confirm the optical transition observed by the naked eye and quantitatively assess the transition of the thermal paint with high resolution. This technique for obtaining high resolution experimental temperature maps can aid the performance, efficiency, and reliability of gas turbine engines.

Investigation of glass sintering to improve strength and interfacial interactions in glass‐to‐AISI 316L metal joints

AbstractThe relationship between sintering and glass‐to‐metal bonding, which are almost the initial and the last stages of glass‐to‐metal seal production, has been demonstrated in this study. In this context, a type of barium alkali silicate glass was prepared, and thermal properties were determined by differential thermal analysis, dilatometer, hot‐stage microscope, and high‐temperature viscosity analysis. Detailed porosity investigations were examined with an optical microscope and ImageJ quantitative analyses, after binder removal and sintering processes carried out at different temperatures and times. An increase in porosity was observed when the sintering and binder removal temperatures and times were increased. The bending strength of the sintered glass sample was decreased with the increment in porosity. A typical housing material AISI 316L stainless steel was used for preparing glass‐to‐metal joints. The high porosity after sintering caused larger bubbles to form after bonding and reduced the shear strength. The effect of sintering conditions on the interfacial interaction for glass‐to‐metal joints are revealed by cross‐sectional scanning electron microscopy–energy‐dispersive spectrometer analyses. Atomic force microscopy analyses and contact angle measurements were conducted to supplement investigation. This study addressed that the mechanical strength and chemistry of glass‐to‐metal joints showed strong dependency on glass sintering conditions.

The effects of PEG molecular weight on fused silica glass sintering by using nano silicon oxide powder

The effects of PEG molecular weight on fused silica glass sintering by using nano silicon oxide powder

Syntheses and characterization of Twofold Nepheline-Combeite Glass-Ceramics for Dental Application

Synthesis of glass-ceramics with a combination of specific crystalline phases can lead in materials with superior chemical, physical and mechanical properties. The aim of this study is to outline the potential of synthesizing a novel glass system which crystallise into two crystalline phase's nepheline-combeite and provide an end monolithic glass-ceramics via sinter crystallization route for dental applications. Four novel glass compositions based on the Na2O-CaO-Al2O3-SiO2 system were synthesized using the melt-quench method. Glasses were designed to contain 6 mole % of CaO and a total of 35 mole % of Al2O3 and Na2O. Experimental glasses were ground into fine powders and then sinter crystallized to monolithic glass-ceramics. The developed glasses and glass-ceramics were characterized using DSC, Dilatometry, X-ray diffraction, Nuclear Magnetic Resonance (MAS-NMR) and scanning electron microscopy. This study shows how the nepheline phase can be produced in combination with other secondary crystalline phases which allow tailoring of the chemical, physical and thermal properties of both the starting glasses and the end glass-ceramics, including their thermal expansions coefficients, glass transition temperatures, softening points, sintering and melting temperatures.

Sintering and foaming of bioactive glasses

AbstractSintering, crystallization, and foaming of 44.8SiO2–2.5P2O3–36.5CaO–6.6Na2O–6.6K2O–3.0CaF2 (F3) and 54.6SiO2–1.7P2O3–22.1CaO–6.0Na2O–7.9K2O–7.7MgO (13–93) bioactive glass powders milled in isopropanol and CO2 were studied via heating microscopy, differential thermal analysis, vacuum hot extraction (VHE), Infrared spectroscopy, and time‐of‐flight secondary ion mass spectrometry. Full densification was reached in any case and followed by significant foaming. VHE studies show that foaming is driven by carbon gases and carbonates were detected by Infrared spectroscopy to provide the major foaming source. Carbonates could be detected even after heating to 750°C, which hints on a thermally very stable species or mechanical trapping. Otherwise, dark gray compact colors for milling in isopropanol indicate the presence of residual carbon as well. Its significant contribution to foaming, however, could not be proved and might be limited by the diffusivity of oxygen needed for carbon oxidation to carbon gas.

Sintering and thermal expansion behaviors of glass and glass–YSZ composites as self‐repairable seals for SOFC

AbstractGlass and glass–ceramics are used as sealants in solid oxide fuel cell (SOFC) because their thermophysical properties can be tailored to meet the stringent requirements of the SOFC stack. The processing, sintering, and thermal expansion behaviors of self‐healing and non‐crystallizing glass and glass containing 10%–30 wt.% non‐reacting yttria‐stabilized zirconia (YSZ) are studied. The addition of inert YSZ to glass significantly retarded the sintering behavior. Thermal expansion behaviors of glass and glass–YSZ are also measured to study the role of YSZ addition on the glass transition, softening point, and coefficient of thermal expansion (CTE). It is shown that the densification is controlled by the viscous sintering mechanism, in which the addition of YSZ increased the effective viscosity of the glass–YSZ as evident from higher glass transition and softening temperatures and decreased CTE. These results demonstrated that the addition of YSZ to glass is promising for achieving optimum thermophysical properties useful as seals for SOFC.

Structure and sintering behavior of BaO–SrO–B2O3–SiO2 sealing glass for Al2O3 ceramic substrates

BaO–SrO–B2O3–SiO2 sealing glass for Al2O3 ceramic substrates was prepared and the effect of B2O3 on its structure, sintering behavior, and properties was studied. Owing to the fluxing action of B2O3, the glass transition temperature, sintering temperature, and crystallization temperature of the sealing glass were decreased with increasing B2O3. With an increase in the B2O3/SiO2 ratio, the average bridge oxygen number of the glass network first increased and then decreased, and the boron abnormality phenomenon was detected at a B2O3/SiO2 ratio of 0.55, at which the polymerization degree of the glass network was maximized. Furthermore, the precipitation of BaAl2Si2O8 crystals was promoted and the crystallinity of the sealing glass was increased, inhibiting sintering densification and weakening the material. The sealing glass with a B2O3/SiO2 ratio of 0.55 sintered at 800 °C for 10 min showed the best properties: a thermal expansion coefficient of 7.89 × 10−6 K−1, flexural strength of 114.28 MPa, Vickers hardness of 622.98 HV, dielectric constant of 12.14, and a dielectric loss value of 4.11 × 10−3. After the sealing glass was co-sintered with the Al2O3 ceramic substrate, the interface was tightly bonded. This indicates the great potential applicability of BaO–SrO–B2O3–SiO2 sealing glass for Al2O3 ceramic substrate packaging.

Upcycling of Pharmaceutical Glass into Highly Porous Ceramics: From Foams to Membranes.

The present COVID-19 emergency has dramatically increased the demand for pharmaceutical containers, especially vials. End-of-life containers, however, cannot be easily recycled in the manufacturing of new articles. This paper presents some strategies for upcycling of pharmaceutical glass into various porous ceramics. Suspensions of a fine glass powder (70 vol%) are used as a starting material. Highly uniform cellular structures may be easily prepared by vigorous mechanical stirring of partially gelified suspensions with added surfactant, followed by drying and firing at 550–650 °C. Stabilization of the cellular structures at temperatures as low as the glass transition temperature (Tg) of the used glass is facilitated by thermal decomposition of the gel phase, instead of viscous flow sintering of glass. This finding enabled the preparation of glass membranes (∼78 vol% open porosity), by direct firing of hardened suspensions, avoiding any surfactant addition and mechanical stirring. The powders obtained by crushing of hardened suspensions, even in unfired state, may be used as a low-cost sorbent for dye removal.

Hot Sintering of Melts, Glasses and Magmas

Research Article| May 01, 2022 Hot Sintering of Melts, Glasses and Magmas Fabian B. Wadsworth; Fabian B. Wadsworth Department of Earth Sciences, Durham University, Durham, United Kingdom fabian.b.wadsworth@durham.ac.uk Search for other works by this author on: GSW Google Scholar Jérémie Vasseur; Jérémie Vasseur Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany j.vasseur@lmu.de Search for other works by this author on: GSW Google Scholar Edward W. Llewellin; Edward W. Llewellin Department of Earth Sciences, Durham University, Durham, United Kingdom ed.llewellin@durham.ac.uk Search for other works by this author on: GSW Google Scholar Donald B. Dingwell Donald B. Dingwell Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany dingwell@lmu.de Search for other works by this author on: GSW Google Scholar Reviews in Mineralogy and Geochemistry (2022) 87 (1): 801–840. https://doi.org/10.2138/rmg.2022.87.17 Article history first online: 01 May 2022 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Fabian B. Wadsworth, Jérémie Vasseur, Edward W. Llewellin, Donald B. Dingwell; Hot Sintering of Melts, Glasses and Magmas. Reviews in Mineralogy and Geochemistry 2022;; 87 (1): 801–840. doi: https://doi.org/10.2138/rmg.2022.87.17 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Magma may fragment as it ascends through the volcanic plumbing system to the Earth surface, forming volcanic ash and pyroclasts (Scheu and Dingwell 2022, this issue). If the pyroclastic products of fragmentation are deposited hot, they can stick, coalesce, and weld together, re-amalgamating into coherent magma. Subaerial deposits include welded, lava-like, and rheomorphic ignimbrites (Branney et al. 1992; Andrews and Branney 2011), and welded fall deposits proximal to an eruptive vent (Houghton and Carey 2015). Welding occurs in the sub-surface at conduit margins (Gardner et al. 2017; Wadsworth et al. 2020... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

High-efficiency preparation of zircon ceramics using borosilicate glass as sintering additive

Synthesis of zircon (ZrSiO4) ceramics suffers from high sintering temperature and long holding time. Herein, we reported a novel method to synthesize ZrSiO4 ceramics using borosilicate glass as sintering additive, and the influences of the borosilicate glass content and sintering temperature on the phase evolution and microstructure of the obtained ceramics were investigated in detail. The results indicated that the addition of borosilicate glass had significant effect on the phase evolution and properties of the obtained ceramics. The formation of ZrSiO4 was enhanced with increasing the content of borosilicate glass and sintering temperature. At sintering temperature of 1400 °C and holding time of 6 h, the formation efficiency of ZrSiO4 phase was up to 91.27 wt%. Moreover, ZrSiO4 ceramic with high compactness was obtained with the weight ratio of borosilicate glass to zircon in the range of 0–0.25. The results demonstrated that ZrSiO4 ceramics can be effectively prepared by using borosilicate glass as sintering additive.

Rapid Pressureless Sintering of Glasses

Silica glasses have wide applications in industrial fields due to their extraordinary properties, such as high transparency, low thermal expansion coefficient, and high hardness. However, current methods of fabricating silica glass generally require long thermal treatment time (up to hours) and complex setups, leading to high cost and slow manufacturing speed. Herein, to obtain high-quality glasses using a facile and rapid method, an ultrafast high-temperature sintering (UHS) technique is reported that requires no additional pressure. Using UHS, silica precursors can be densified in seconds due to the large heating rate (up to 102 K s-1 ) of closely placed carbon heaters. The typical sintering time is as short as ≈10 s, ≈1-3 orders of magnitude faster than other methods. The sintered glasses exhibit relative densities of >98% and high visible transmittances of ≈90%. The powder-based sintering process also allows rapid doping of metal ions to fabricate colored glasses. The UHS is further extended to sinter other functional glasses such as indium tin oxide (ITO)-doped silica glass, and other transparent ceramics such as Gd-doped yttrium aluminum garnet. This study demonstrates an UHS proof-of-concept for the rapid fabrication of high-quality glass and opens an avenue toward rapid discovery of transparent materials.

Electrochemical stability of a NASICON solid electrolyte from the lithium aluminum germanium phosphate (LAGP) series

Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics from NASICON series was synthesized using two different methods: single heat treatment and glass sintering with concurrent crystallization of a pressed pellet, which exhibit ionic conductivity of 4.15 × 10−4 S cm−1. The electrochemical stability window was investigated by cyclic voltammetry, utilizing a mixture of powder solid electrolyte, carbon, and binder as the working electrode, resulting in the Li/LAGP/LAGP+C/Au configuration. As a comparison, conventional set-up for cyclic voltammetry was also used, resulting in the Li/LAGP/Au setup. An electrochemical stability window around 3.5 V was found.

Improved stability and film formability of oil-based silver nanoparticle suspensions by addition of polystyrene

In this study, we focused on how to develop an oil-based stable suspension of conductive silver ink and improve its film formability on the substrate. Silver nanoparticles (Ag-NPs) were first prepared in water with addition of oleic acid (OA) and butyl amine (BA) as co-stabilizing agents. The water medium was then replaced by an organic solvent to prepare the organic silver conductive ink. The synthesized Ag-NPs with an average particle size of about 13.3 nm were stabilized by steric hindrance of the attached OA− as proved by FTIR analysis and surface zeta potential. The Ag-NPs had higher stability in cyclohexane than in hexane, owing to the increased interaction between the long alkyl chain in OA− and cyclohexane. The stability was more than one year in cyclohexane with little change in particle size. Conductive films were obtained by drop-coating the organic Ag-NP inks on glass slide and sintering up to 250 °C. Moreover, addition of polystyrene at 1 wt % into the cyclohexane increased the wettability of conductive ink on the substrate and improved the film formability and integrity while preventing oxidation during sintering. A uniform and hydrophobic Ag-NP film was obtained with a sheet resistance of 0.64 Ω/Sq.

Kinetics of viscous flow sintering of glass–zircon composites. Effect of zircon volume fraction and particle size distribution

Viscous flow sintering of glass–zircon composites was studied by isothermal and constant-rate heating experiments. The sintering curves fitted very well to the developed kinetic model, based on the Kohlrausch–Williams–Watts (KWW) function. Increasing the zircon volume fraction and decreasing the zircon–glass particle size ratio was verified to slow down the sintering rate. The combined effect of these variables on sintering was interpreted on the basis of percolation theory. The influence of temperature on the composite sintering rate corresponded to the influence of this variable on glass matrix flowability. Dimensionless relationships between the kinetic parameters and zircon volume fraction and the particle size ratio were obtained, which were independent of the thermal treatment used.

Novel Experimental Strategy for Determining the Temperature Field During Spark Plasma Sintering of Metallic Glasses

Novel Experimental Strategy for Determining the Temperature Field During Spark Plasma Sintering of Metallic Glasses

The effect of TiO2 and B2O3 on sintering behavior and crystallization behavior of SrO–BaO–B2O3–SiO2 glass-ceramics

To explore the influence of TiO2 and B2O3 contents on the sintering behavior and crystallization of SrO–BaO–B2O3–SiO2 glass-ceramics, the glass-ceramics with different TiO2/B2O3 ratios were prepared by sintering at 800 and 850 °C for 10 min. The results showed that the glass transition temperature and sintering temperature increased with increasing the TiO2/B2O3 ratio. The average bridging oxygen number decreased from 2.44 to 2.07, which revealed that the polymerization degree of the glass-ceramics decreased. With increasing the TiO2/B2O3 ratio, the crystallinity of the glass-ceramics and the homogenization of grains size were improved, and the precipitation of the SrTiO3 phase was promoted. The sample with a TiO2/B2O3 ratio of 0.62, which achieved excellent densification sintered at 850 °C for 10 min, showed a dielectric constant of 18.11, a dielectric loss of 3.93 × 10−3, and a thermal expansion coefficient of 10.04 × 10−6 K−1, indicating that the SrO–BaO–B2O3–SiO2 glass-ceramics have great potential in the application of low-temperature cofired ceramics.

Coupling additive manufacturing and low-temperature sintering: a fast processing route of silicate glassy matrix

PurposeThe low-temperature sintering of silica glass combined with additive manufacturing (AM) technology has brought a revolutionary change in glass manufacturing. This study aims to carry out in an attempt to achieve precious manufacturing of silicate glassy matrix through the method of slurry extrusion.Design/methodology/approachA low-cost slurry extrusion modelling technology is used to extrude silicate glassy matrix inks, composed of silicate glass powder with different amounts of additives. Extrudability of the inks, their printability window and the featuring curves of silicate glassy matrix are investigated. In addition, the properties of the low-temperature sintering green part as a functional part are explored and evaluated from morphology, hardness and colour.FindingsThe results showed that the particle size was mainly distributed from 1.4 µm to 5.3 µm, showing better slurry stability and print continuity. The parameters were set to 8 mm/s, 80% and 0.4 mm, respectively, to achieve better forming of three-dimensional (3D) samples. Besides, the organic binder removal step was concentrated on 200°C–300°C and 590°C–650°C was the fusion bonding temperature of the powder. The hardness values of 10 test samples ranged from 588 HL to 613 HL, which met the requirements of hard stones with super-strong mechanical strength. In addition, the mutual penetration of elements caused by temperature changes may lead to a colourful appearance.Originality/valueThe custom continuous AM technology enables the fabrication of a glass matrix with 3D structural features. The precise positioning technology of the glass matrix is expected to be applied more widely in functional parts.

Study on low temperature sintering behavior and dielectric properties of BaTi4O9/La2O3-B2O3-CaO microwave dielectric ceramic

In this paper, La2O3-B2O3-CaO (LBC) glass ceramics were sintered at low temperature to density BaTi4O9 (BT4) microwave dielectric ceramics. The effects of composition ratio and sintering temperature on the micromorphology, phase composition and microwave dielectric properties of LBC/BT4 multiphase ceramics were investigated. Experimental results showed that LBC microcrystalline glass and BT4 happened between the ceramic interface reaction obviously, and with the increase of microcrystalline glass content and sintering temperature increases, density, dielectric constant epsilon εr value and the quality factor Qf value were increased after the first decrease. And the resonant frequency temperature coefficient of τf value with the increase of LBC content decreases, and with the increase of sintering temperature, it goes up and then it goes down. When the content of LBC glass ceramics is 50 wt%, LBC/BT4 multiphase ceramics sintered at 875 °C for 2 h have good microwave dielectric properties εr = 26, Qf = 8000 GHz, τf; = +150 ppm/°C.

Consolidation and mechanical properties of ZrCu39.85Y2.37Al1.8 bulk metallic glass obtained from gas-atomized powders by spark plasma sintering

This manuscript proposes subjecting gas-atomized powders of ZrCu39.85Y2.37Al1.8 metallic glass to spark plasma sintering (SPS). This bulk metallic glass (BMG) sinters at a temperature between its crystallization (Tx) and glass transition (Tg) temperatures, found to be 457 °C and 368 °C, respectively, via Differential Scanning Calorimetry (DSC). Several samples were sintered at different temperatures within the mentioned range (380, 390, 400, 415 and 430 °C). Experimental results confirmed successful sintering of the BMG by SPS at 390 °C and a pressure of 35 MPa. Fully amorphous compacts with almost 100% relative density were sintered at this temperature, reaching Young's modulus, Vickers hardness and compression strength values of 64.7 GPa, 396 HV0.3 and 1174 MPa, respectively. Sintering at higher temperatures involved crystallization of the sample. Results suggest that ZrCu39.85Y2.37Al1.8 metallic glass fabricated by SPS is a promising material for applications in different sectors, particularly jewelry, due to the wear resistance conferred by its hardness.

Differences in microstructure and mechanical properties between Y‐TZP and AL2O3‐doped Y‐TZP/bioglass ceramics

AbstractY‐TZP (YZ) and Al2O3‐doped Y‐TZP (AYZ) bioceramics with addition of different contents of a refractory bioglass were fabricated. The influence of the glass addition and sintering temperature on the densification behavior, microstructure, and mechanical properties of YZ and AYZ was studied. The developed ceramics contained small amounts of ZrSiO4 and Ca2P2O7 phases within the ZrO2 matrix. The incorporation of glass to YZ promoted the ZrO2 phase partitioning and enhanced the ZrO2 grain growth at all the sintering temperatures, whereas the glass addition in AYZ prevented the Y2O3 redistribution between ZrO2 grains and limited the ZrO2 grain growth at 1300–1400°C. The hardness of the samples with glass was not significantly altered by using either YZ or AYZ. A slight increase in the fracture toughness with increasing glass content was found for YZ, while the fractured toughness of AYZ decreased by the glass addition. The more pronounced ZrO2 phase partitioning of YZ with glass decreased the flexural strength, whereas AYZ maintained almost unaltered its flexural strength at a high level by the glass incorporation.