Measurement of effective thermal conductivity of a glass fibreboard standard reference material

This paper describes the results of thermal conductivity measurements on NBS SRM 1450 glass fibreboard insulation (1970 lot) at temperatures from 87 K to 340 K. The measurements were performed in an atmosphere of dry nitrogen at a pressure near 84 kPa (630 mm Hg). The results are analysed and compared to NBS certification data and to literature data for similar material.     

Measurement of effective thermal conductivity of glass fibre blanket standard reference material

This paper describes the results of thermal conductivity measurements at temperatures from 84 K to 360 K on a glass fibreblanket insulation which is intended to be a Standard Material (SRM). The measurements were performed in an atmosphere of dry nitrogen at a pressure near 84 kPa (630 mm Hg). The results are analysed and compared to literature data for similar material.     

Chemically modified glass fiber as a matrix-free reference material for volatile compounds

Difficulties with obtaining suitable reference materials, which are applied for validation of analytical procedures and calibration of measured devices used in gaseous examinations (atmospheric air, indoor air, workplace atmosphere), are one of the most important challenges that stand in front of analytics. Known gaseous standard mixtures preparation techniques, both static and dynamic, are burdened with lots of inconveniences and disadvantages, which can be responsible for false analytical results. It appears that a very important step in the way of obtaining suitable reference materials useful in gaseous analysis is the technique of thermal decomposition of surface compounds. The paper describes a new type of matrix-free reference material-chemically modified glass fiber, which significantly makes it easier and simplifies the usage of reference materials produced using this technique.     

Novel basalt fibre reinforced glass matrix composites

A novel hot-pressing technique for the manufacturing of basalt fibre reinforced glass matrix composites was investigated. Two-dimensional (2D) fibre mats were sandwiched between borosilicate glass powder layers, thus configuring a much simpler processing route than that commonly employed for the production of fibre-reinforced glasses. Besides economic benefits, the use of fibre mats may lead to technologic advantages due to the possibility of readily coating the fibres with a suitable material (e.g. titanium oxide) by means of the sol-gel method. The coating of basalt fibre mats with TiO₂ is proposed for preventing the fibres from an excessive adhesion to the glass matrix. The developed composites containing 15 vol% of 2D-fibre reinforcement exhibited promising bending strength (∼90 MPa) and desirable “graceful” fracture behaviour without catastrophic failure. Thus the present study represents a convenient approach for production of advanced low-cost fibre reinforced glass matrix composites for structural applications.     

Properties of glass concrete reinforced with short basalt fibre

Experimental work was carried out to develop information about the properties of glass aggregate concrete reinforced with chopped basalt fibre. Recycled waste mixed colour glass was used as a partial replacement (20%, 40%, and 60% by weight) for the natural fine aggregate with different volume fractions of fibre (0%, 0.1%, 0.3%, and 0.5% by total mix volume). The combined effect of the glass and the basalt fibre on the mechanical properties of the fresh and hardened concrete was investigated. The heat transfer through the thickness for this type of concrete was also investigated. A statistical analysis was also carried out to investigate the variance of the data for each mix. The test results and the statistical analysis indicated that there is a slight reduction in the compressive and splitting tensile strength with the increase in the glass content above 20%. Using basalt fibre leads to an enhancement in it for all mixes and there is an optimum content of fibre in each percentage of glass sand which gives higher strength. A slight decrease in the heat transfer through the concrete specimens was also observed.     

Structural behaviour of basalt fibre reinforced glass concrete slabs

Small-scale slab tests at ambient and elevated temperatures, conducted on horizontally unrestrained simply supported slabs, are presented in this paper. The aim of this research is to investigate the structural behaviour of concrete produced from different percentages of glass sand (20, 40, and 60 % by weight) and reinforced with different volume fractions of basalt fibre (0, 0.1, 0.3, and 0.5 % by total mix volume), when subjected to large vertical displacement. The results were also compared against similar structural members with concrete that did not contain glass or fibres. The results showed that the fracture of the reinforcement was the mode of failure for all the slabs and the load carrying capacity was enhanced above the theoretical yield-line load. For the slabs tested at elevated temperatures, the enhancement due to membrane action was at least twice as high as that recorded in the ambient temperature tests. The slabs with higher glass sand and basalt fibre content also exhibited greater enhancement and failed at higher displacement. The results also showed that the enhancement in the concrete with glass aggregate and basalt fibre was greater than that in concrete that contained no glass or fibre by up to 26 and 31 % at ambient temperature and in fire respectively.     

Lithium isotope separation with tunable diode lasers

A laser-isotope-separation study of lithium has been performed with two-step excitation involving UV laser radiation and a visible tunable-diode laser. The method yields a high degree of selectivity by tuning the narrow-linewidth diode laser to the D1 or D2 levels of the lithium atom. Selective laser excitation is simplified by the use of the tunable diode laser and the overall approach benefits from the application of a compact mass selector that includes a precision magnetic sector and an ion beam that is designed specifically for light atoms such as lithium.     

Phase composition of metamorphosed basalt and its sintering products

The phase composition of metamorphosed basalt from the Myandukha occurrence, Arkhangelsk oblast, has been determined by X-ray diffraction. Using differential scanning calorimetry and thermogravimetry data, we examined the effect of phase composition and particle size on the thermal behavior of ground basalt. The phase composition of the sintering products of the magnetic and nonmagnetic components of the basalt has been investigated.     

Lithium conducting glass ceramic with Nasicon structure

Lithium ion conducting glass and glass ceramic of the composition Li_1.4[Al_0.4Ge_1.6(PO₄)₃], have been synthesized. The monolithic glass pieces on thermal treatment resulted in single-phase glass ceramic with the Nasicon structure. Experiments with different electrodes proved that the lithium electrodes provide accurate values for the ionic conductivity using impedance spectroscopy. σ_ionic of the glass ceramic was found to be 3.8×10⁻⁵ S cm⁻¹ at 40°C with an activation energy (E_a) of 0.52 eV. The corresponding values for the glass are 2.7×10⁻⁹ S cm⁻¹ and 0.95 eV, respectively. The Arrhenius dependence of σ_ionic with temperature in glass and glass ceramic is interpreted with a hopping mechanism from which the microscopic characteristics of the lithium cation motion are deduced.     

Tensile behavior contrast of basalt and glass fibers after chemical treatment

Basalt and glass fibers were treated with sodium hydroxide and hydrochloric acid solutions respectively for different periods of time. Both the mass loss ratio and the strength maintenance ratio of the fibers were examined after the treatment. The morphologies of the fiber surfaces were characterized using scanning electron microscopy and their compositions were analyzed using energy dispersive X-ray spectroscopy. For the basalt fibers, the acid resistance was much better than the alkali resistance. Nevertheless, for the glass fibers, the acid resistance was nearly the same as the alkali resistance. Based on the experimental results, possible corrosion mechanisms are addressed.     

Effects of cylinder material on the composition and properties of natural-gas reference standards on prolonged storage

The shelf life of a reference material is determined by the stability of its composition and properties, and that of natural gas on prolonged storage is dependent on the cylinder material. The best stability is provided by cylinders made of aluminum and stainless steel. The position of a carbon-steel cylinder does not affect the stability of the physical properties when samples of the reference material are taken for analysis. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 65–66, August, 2000.     

Equilibrium composition of products of melting of main minerals involved in the composition of basalt

Using the method of thermodynamic simulation, the equilibrium composition of products of heating of plagioclases, pyroxenes, peridots, and magnetite is determined in a temperature range of 1000–1400°C in inert, oxidizing, and reducing atmospheres. The possibility of controlling the products of melting and crystallization of the above minerals is shown, and the behavior of a series of accessory metals (Ti, Mn, Cr, V) in these processes is evaluated.     

Modelling basalt fibre reinforced glass concrete slabs at ambient and elevated temperatures

The analysis of tests conducted on small-scale slabs at ambient and elevated temperatures is presented in this paper. The slabs were produced from a new type of concrete containing different levels of glass sand and basalt fibre. Two methods were used for this purpose: a simplified method developed previously and a finite element method, using the software package ABAQUS. For the slabs at ambient temperature, the results showed a good correlation for the load–displacement relationship between the test and the two models up to the failure loads. For the slabs at elevated temperature, the ABAQUS model gave a reasonable prediction for the temperature–displacement relationship while the simplified method gave a conservative prediction for the maximum allowable vertical displacement. As a result, the simplified method underestimated the temperature at which the reinforcement fracture occurs for this type of concrete slab, incorporating glass sand and basalt fibres. Further work is required to remove this conservatism from the simplified design method for this type of concrete.     

Electronic conduction in basalt glass and glass-ceramics - correlation with magnetite crystallization

The d.c. conductivity measurements have been made in a wide range of temperature on a basalt glass heat-treated at different temperatures to form magnetite particles. Small polaron hopping mechanism is operative in the as-annealed glass between Fe²⁺ and Fe³⁺ ions in the isolated state. This mechanism is operative in the heat-treated samples between these ions in the magnetite grains. The d.c. conductivity at 473 K and the activation energy show significant changes around 700° C, when magnetite forms in the basalt glass, which has been correlated with the magnetic data on these samples. TSPC and TSDC data are interesting, but the data analysis is complicated by the possible occurrence of Verwey transition in the small particles of magnetite. Preliminary a.c. conductivity data support the small polaron hopping mechanism.     

Determining plasma isotope composition from high-resolution spectra

Translated from Izmeritel'naya Tekhnika, No. 2, pp. 36–38, February, 1989.     

异辛烷纯度标准物质的研制

该文研制异辛烷纯度标准物质,采用差示扫描量热法和质量平衡法开展纯度定值研究工作。质量平衡法研究中使用气相色谱面积归一化法对主成分异辛烷和有机杂质进行色谱含量测定,同时结合电感耦合等离子质谱、离子色谱、灰分测试方法和卡氏水分仪对原料中的无机杂质准确定量。在确认原料主成分和杂质性质稳定的条件下,进一步采用差示扫描量热法测定异辛烷的纯度,并开展均匀性和稳定性考察和数据统计分析。对标准物质的不确定度进行了系统性的评估和数学拟合。经考察该标准物质均匀性良好,在1年内性质稳定,特性量值准确。研制的异辛烷纯度标准物质纯度值为99.86%,相对扩展不确定度为0.26%(k=2)。     

Effect of basalt fiber hybridization on the impact behavior under low impact velocity of glass/basalt woven fabric/epoxy resin composites

The low velocity impact behavior of E-glass/basalt reinforced hybrid laminates, manufactured by resin transfer moulding technique, was investigated. Specimens prepared with different stacking sequences were tested at three different impact energies, namely 5 J, 12.5 J and 25 J. Residual post-impact mechanical properties of the different configurations were characterized by quasi static four point bending tests. Post-impact flexural tests have been also monitored using acoustic emission in order to get further information on failure mechanisms. Results showed that basalt and hybrid laminates with an intercalated configuration exhibited higher impact energy absorption capacity than glass laminates, and enhanced damage tolerance capability. Conversely, the most favorable flexural behavior was shown by laminates with symmetrical sandwich-like configuration (E-glass fiber fabrics as core and basalt fiber fabrics as skins).     

Passive and SMA-activated confinement of circular masonry columns with basalt and glass fibers composites

Fiber Reinforced Polymer (FRP) composites are widely used for strengthening and conservation of historic masonry, even if research problems are still open. The mechanical behavior of masonry columns having a circular cross section, confined with glass and basalt FRP systems was studied in this paper. An extended experimental investigation is presented in order to show the results of axial compression tests on circular masonry columns built with natural blocks (calcareous stone). Active confinement was also studied by using a novel technique that employs Shape Memory Alloys (SMA). Totally twenty-four masonry columns were built, instrumented and tested. Different fibers, strengthening schemes and matrix/adhesive were used for the confinement of the columns.Unstrengthened columns were tested as reference specimens. Axial strain of the columns and tensile strain of the fibers in the direction perpendicular to the primary axis of the columns were measured with the applied load. Experimental results revealed the effectiveness of the FRP-confinement for masonry columns. Active confinement was found to be effective at early loading stages since an increased stiffness of the SMA/GFRP-confined columns was measured.A prediction of the compressive strength was obtained by using the model of the Italian guidelines CNR DT 200 (National Research Council) in order to compare the experimental results with the design approach, also for new types of fiber like basalt which were not included in the technical codes. Finally, the experimental results were compared with theoretical values calculated according with to two existing analytical models in order to test their effectiveness for the analyzed configurations.     

Lithium borosulphate glasses: an analysis of glass transition temperature results

Lithium borosulphate glasses have been prepared in three different series: (a) (42·5 −x)Li₂O:57·5 B₂O₃:xLi₂SO₄; (b) 42·5Li₂O: (57·5 −x)B₂O₃:xLi₂SO₄ and (c) 42·5Li₂O:57·5B₂O₃:xLi₂SO₄. The glass transition temperature (T _g) of these glasses has been analysed on the basis of the fraction of four coordinated boron which governs the glass structure. The analysis reveals that the addition of Li₂SO₄ in series (a) and (b) gives rise to increased value of N₄ whereas, in series (c) it increases the number of non-bridging oxygens.     

Squeeze flow testing of glass mat thermoplastic material

The anisotropic flow behaviour of glass fibre/polypropylene glass mat thermoplastic (GMT) has been investigated using axisymmetric squeeze flow testing between parallel circular plates. The material has a continuous swirled fibre mat construction and is manufactured by the melt-impregnation technique. Constant plate velocity squeeze flow tests have been carried out under isothermal conditions to cover a range of strain rates. Modelling of squeeze flow behaviour has been based on two simple expressions: one assumes pure shear flow during testing, while the other assumes pure biaxial extension (plug flow). The modelling results suggest that biaxial extension dominates the isothermal squeeze flow process, with apparently negligible shear flow effects.