Cellular-structure glass formed with phlogopite-type mica powders and carbonate compounds

Cellular-structure glass or foamed glass has been fabricated from mixtures of recycled colorless soda-lime waste glass powders and three separate different foaming agents by a simple sintering process. One of the mixtures consisted of glass powders and a locally produced mica powder of the phlogopite-type, which act as a foaming agent as well as a component of the glass-mica composite material. The other mixtures consisted of glass powders and a carbonate compound, now with calcium carbonate and one with sodium carbonate. The fabricated cellular-structure of the glass-mica composite material is found to have superior mechanical and thermal properties when compared with the cellular-structure glass formed with the carbonate compounds. The mechanisms of the formation of the cellular-structure by the two systems are discussed.     

Formation of cellular-structure glass with carbonate compounds and natural mica powders

Cellular-structure glass, or foamed glass, has been fabricated from mixtures of recycled colourless soda-lime waste glass powders and three separate different foaming agents by a simple sintering process. One of the mixtures consisted of glass powders and locally produced mica powders of the phlogopite-type, which act as a foaming agent as well as a component of the glass-mica composite material. The other mixtures consisted of glass powders and a carbonate compound, one being calcium carbonate and the other being sodium carbonate. The fabricated cellular-structure of the glass-mica composite material is found to have superior mechanical and thermal properties when compared with the cellular-structure glass formed with the carbonate compounds. The mechanisms of the formation of the cellular-structure by the two systems are discussed.     

Optical properties of soda-lime float glass from spectroscopic ellipsometry

Optical properties of soda-lime glass manufactured by the float process were investigated using spectroscopic ellipsometry and intensity transmission measurements. Thickness and optical properties of surface layers on the air and tin sides were determined with ellipsometry. The tin side surface layer shows a graded refractive index with a non-linear profile. Intensity transmission data were used to quantify absorption in the bulk glass. Transmission-mode generalized ellipsometry characterized residual birefringence in the bulk glass. Birefringence effects on ellipsometric delta data were corrected using a simple empirical offset with 1/wavelength dependence. A general optical model for soda-lime glass is presented which can be used for subsequent analysis of coated soda-lime glass and other transparent substrates.     

Fabrication of transparent continuous oxynitride glass fiber-reinforced glass matrix composite

Unidirectional-aligned continuous SiCaAlON fiber-reinforced glass matrix composites have been fabricated and their light transmittance was measured. Optically transparent composites with the fiber volume fraction from 0.03 to 0.10 were fabricated by a hot-pressing method. The light transmittance of the composite perpendicular to the fiber axis in the wavelength range from 200 to 700 nm was measured, and found to decrease with the increase of the fiber volume fraction. This decrease is explained by the theory proposed by the authors (Hl and YK). The major source of a light transmittance loss of the composite originates from a phase change of transmitted light in the composite.     

HA-n-ZrO2核壳层复合陶瓷微粉材料的制备与表征

采用水热-沉积原位分步反应法.制备了羟基磷灰石(HA)-氧化锆(ZrO2)复合微粉,采用XRD和TEM对复合微粉的物相、形貌和大小进行了表征.对复合微粉进行模压成型、热处理制备了复合陶瓷试样,并测试其力学性能.结果表明:所得复合微粉以纳米级四方相ZrO2为核心,逐层包覆HA,形成核-壳层结构(HA-n-ZrO2);...     

Stress corrosion of aligned glass fibre-polyester composite material

Abstract

The main features of the stress-corrosion failure of glass-reinforced plastic tanks and vessels are described. Model experiments using a modified double cantilever beam test have been made on aligned composite materials tested in 0·6M HCI. The rate of crack growth normal to the fibre direction depends on stress intensity. The crack-tip fracture processes for cracks growing in the velocity range 10^?9 to 2 × 10^?8 m S^?l have been determined using fractographic techniques. The stresses in the fibres before fracture at the crack tip have been estimated from the size of the mirror zones. A major feature of stress corrosion is the planar nature of the crack surface and, at low stress intensities, fracture occurs without interface cracking or debonding. An estimate of the strain energy release rate has been made from an analysis of the stress fields at the crack tip and the mechanisms of crack growth. The results are in reasonably good agreement with experimentally determined values.

MST/64     

Development of nano-macroporous soda-lime phosphofluorosilicate bioactive glass and glass-ceramics

We have extended the usefulness of bioactive glass-ceramics for the repair and reconstruction of hard tissues by introducing F ions that are known to be beneficial, especially in dentistry. Nano-macro multimodal porosity in soda-lime phosphofluorosilicate bulk samples was introduced by the recently developed melt-quench-heat-etch method. The choice of starting glass composition is based on 48SiO₂–2.7P₂O₅–xCaF₂–yCaO–zNa₂O where x = 0, 1, 4, 8, 10, 12, and (y + z) = 49.3 − x (mol%). The effect of thermal and chemical treatment on the microstructure of samples is characterized by SEM, XRD and EDX. We find the formation of many crystalline phases, but mainly sodium calcium silicate, calcium phosphate, fluorapatite and calcium silicate. The bioactivity of soda-lime phosphofluorosilicate glass-ceramics is assessed by monitoring the formation of hydroxyl apatite (HA) layer: fluorapatite phase accelerates the rate of HA layer formation; the initial composition and multi-modal porosity are other key parameters that impact the formation of HA. The present porous glass-ceramics should be superior candidates for use in dental bone regeneration.

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Fabrication, mechanical properties and thermal stability of a novel glass matrix composite material reinforced by short oxycarbide fibres

An aluminosilicate glass matrix composite material reinforced by randomly oriented SiC-based (Tyranno) chopped fibres was fabricated. Slurry dipping and hot-pressing techniques were used to prepare dense composites containing 45 vol% fibres uniformly dispersed in the glass matrix. The mechanical properties and fracture mechanisms of the composite under flexion and compression loading were studied. In flexure, the composite showed higher modulus and strength than the unreinforced glass. However, in compression, the strength of the composite was lower than that of the monolithic glass. Considering the potential application of the material at high temperatures, the thermal aging behaviour of the composite in air at temperatures between 500 and 700°C was investigated. The composite retained its room-temperature compressive strength after exposure for 26 h at 500°C. The variation of compressive strength measured after exposures at higher temperatures was ascribed to mechanisms of fibre/matrix interface oxidation and to the softening of the glass matrix.     

Improvement in ballistic impact resistance of a transparent bulletproof material laminated with strengthened soda-lime silicate glass

This study evaluates the ballistic impact resistance of soda-lime silicate glass strengthened by ion exchange for application in lightweight and thin bulletproof materials. The maximum flexural strength values of the strengthened glass with thicknesses of 3, 4, 8, and 10 mm were 0.63, 0.68, 0.73, and 0.77 GPa, respectively, values that were 3.5 times higher than that of the parent glass. By laminating polycarbonate and multilayer defense film with the strengthened glass, we achieved a ballistic limit velocity of 973.8 m/s, which was 16% higher than the standard. Also, the transmittance satisfied the standard for bulletproof windows.     

The effect of mica dehydration on the fabrication of cellular glass-mica composite solids

Investigations have been conducted to show that hydrated mica flakes are one of the essential starting components for the development of a cellular-structure glass mica composite solid by sintering mixtures of natural mica powders of the phlogopite type and ground glass powders prepared from recycled soda-lime waste glass. Studies show that if the water of crystallization is removed from the mica structure by heating prior to mixing and reaction with the glass grains, the development of the cellular structure in the sintered glass-mica composite solid is partially or totally suppressed depending on the extent of the thermal dehydration of the mica powders.     

Fabrication and mechanical properties of glass fibre reinforced thermoplastic elastomer composite

The paper investigates the effects of fabrication conditions on mechanical properties of glass fibre reinforced thermoplastic elastomer composites. The impregnation time was varied between 5 and 30 min and the cooling conditions were rapid and gradual cooling. Tensile testing was carried out on samples with different fibre orientations. Double Cantilever Beam (DCB) tests were carried out to evaluate the fracture toughness of the composites. The degree of crystallinity and morphology of the composite were studied by using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Impregnation of matrix resin into glass fibre was found to be complete before 30 min and tensile properties increased with increasing impregnation time. SEM micrographs of fractured surfaces revealed poor adhesion between the matrix and the reinforcing agent. Due to the flexible nature of the composite, the fracture toughness (G_IC) could not be determined because of the formation of ridges on the surface.     

Fabrication and characterization of silk fibroin/bioactive glass composite films

Composite films of silk fibroin (SF) with nano bioactive glass (NBG) were prepared by the solvent casting method, and the structures and properties of the composite films were characterized. Fourier transform infrared (FT-IR) spectroscopy analysis shows that the random coil and β-sheet structure co-exist in the SF films. Results of field emission scanning electron microscope (FESEM) indicate that the NBG particles are uniformly dispersed in the SF films. The measurements of the water contact angles suggest that the incorporation of NBG into SF can improve the hydrophilicity of the composites. The bioactivity of the composite films was evaluated by soaking in 1.5 times simulated body fluid (1.5 × SBF), and formation of a hydroxycarbonate apatite (HCA) layer was determined by XRD and FESEM. The results show that the SF/NBG composite film is bioactive as it induces the formation of HCA on the surface of the composite film after soaking in 1.5 × SBF for 7 days. In vitro osteoblasts attachment and proliferation tests show that the composite film is a good matrix for the growth of osteoblasts. Consequently, the incorporation of NBG into the SF film can enhance both the bioactivity and biocompatibility of the film, which suggests that the SF/NBG composite film may be a potential biomaterial for bone tissue engineering.     

空心玻璃微球-混凝土复合材料的破坏与耗能的研究

为了获得的制作工艺简单的孔隙材料,利用水泥和空心玻璃微球制成含有孔隙的复合材料,并将该复合材料制成圆柱壳体,进行水下内爆炸实验。通过水下爆炸测试系统得到了爆炸过程中水中超压波形,并结合高速摄影技术捕捉壳体的变形破坏过程。实验结果表明,药柱爆炸后1.5ms,爆炸载荷在复合材料柱壳中形成破裂分界面;柱壳的破坏类型依次为顶部的气泡脉动、中间的爆炸冲击波的膨胀压缩和底部的应力波的拉伸破坏。结合水中超压经验公式和超压的实测值计算了水中冲击波能量占总爆炸能量的比例,计算结果表明空心玻璃微球-混凝土复合材料对爆炸能量能具有良好的耗散作用。     

Physico-mechanical properties and structure of diamond polycrystalline composite materials produced from variously dispersed powders

A nanostructural diamond composite material having grains of average size 0.08 μm and hardness corresponding to the hardness of diamond composite materials with grains of average size 30 μm has been produced using nanotechnologies of powder materials. Temperature dependences of hardness of nanostructural diamond composites of various dispersions have been compared. The thermostability of a diamond composite has been shown to depend not only on the composition of a sintering aid but on the size of diamond powders as well. Our findings have indicated that the material obtained holds promise in finishing products of nonferrous metals and alloys instead of natural diamonds.     

Strengthening and toughening of soda-lime glass by a reinforced coating

The strength and toughness of soda-lime (container) glass have been enhanced by factors of 2 and 40, respectively, by a 0.1 mm coating of polyurethane containing 6–9 wt% silicon carbide whiskers in random orientation. The strength measurements were made using a standardized procedure and a biaxial ring-on-ring flexure rig. The toughness enhancement has been shown to be due to crack-branching and fibre pull-out mechanisms in the coating, which bridges any strength-limiting flaws in the underlying glass.     

空心玻璃微珠/PP复合材料的制备及性能研究

采用共混与注塑工艺制备出空心玻璃微珠/PP复合材料.通过高倍偏光显微镜、傅里叶红外光谱仪(FTIR)、扫描电镜(SEM)等对材料的结构进行了表征,重点研究了未改性与改性的空心玻璃微珠对PP复合材料力学性能影响.结果表明:改性后的空心玻璃微珠在PP复合材料中分散均匀而且具有致密的内部结构,并明显的改善复合材料的拉伸、弯曲强度,最佳填充量为15%.     

Use of recycled glass as a raw material in the manufacture of Portland cement

Scrap glass is a solid waste from daily recycling. Most of the waste glass is sodium-lime-silicate glass which has, more or less, similar chemical compositions to clay, a raw material in cement manufacturing. Therefore, we utilize the solid waste in cement raw mix by replacing part of the clayey component. In this study, the effects of the glass in cement raw mix on clinker burning were investigated. The experimental results show that the addition of the glass into cement raw mix (1) results in the formation of more liquid phase between 950°C to 1250°C compared with conventional raw meals; (2) decreases C₃S content in the clinker; and (3) increases NC₈A₃ content, which leads to flash setting and poor strength development of the cement. Therefore, it is necessary to increase the SG value [SG=SO₃?100%/(1.292 K₂O+0.85 Na₂O)] of the clinker when the glass is present in the raw mix.     

Thermo-mechanical damage modeling of a glass–phenolic composite material

This study is on the development of a thermo-mechanical damage model (TMDM) for glass–phenolic composite materials subject to high temperature and thermal radiative environments. The damaged composite is expressed as two regions of non-charred and charred materials. Homogenization methods are used to formulate the damaged material in terms of the volume fractions associated with composite fiber, resin and char. Equations are derived that employ Darcy’s law to account for the gas transport within the structure. Mechanical response of the composite is taken into account by solving a homogenized system of linear elasticity equations which introduces the gas-phase pressure in a self-consistent manner. A finite element method is developed to solve the thermal and mechanical equations for a two-dimensional clamped composite beam subject to thermal radiative heating. Overall, good agreement is obtained between the numerical predictions and experimental data for temperature and gas pressure. Results show the decomposition of the resin and char formation create local stress concentrations across the pyrolysis front. The origin of these stresses are from thermal expansion and contraction across the front and the generation of locally high pore gas pressures from resin decomposition.