Fused Quartz Tube Research Articles

Anisotropic expansion in gypsum-bonded cristobalite investment mold.

Expansion of a gypsum-bonded investment mold was investigated using a fused quartz tube pattern. Two hours after mixing, a fusible alloy was cast into the space around the pattern induced by setting expansion. The other molds were heated up to 700 degrees C, then a dental silver alloy was cast into the space around the pattern induced by total expansion of the mold. Thickness of the castings was measured at every thirty degrees on seven cross-sections. The setting expansion was almost uniform, but the total expansion was not. Especially, a large amount of total expansion was produced toward the open ends of the casting ring and toward a seam of the asbestos liner. The thermal expansion of the mold was anisotropic because the investment was a mixture of calcium sulfate and silica, and was affected considerably by its environment.

Point contact ultrasonic transducer of waveguiding structure for high-frequency operation

This letter presents a new type of Hertzian-contact transducer of waveguiding structure operating in the MHz range. The transducer is composed of a fused quartz tube and a radially-polarized annular piezoelectric element bonded to one of its ends. The edge-bonded shear-wave transducer effectively excites a surface wave on the interior surface of the tube. A small bullet pin made of quartz is inserted and fixed on the other end of the tube to make a point contact and transmit the wave energy to a specimen to be inspected. Using a pair of these transducers, we have succeeded in exciting and detecting surface acoustic waves as well as Lamb waves in the 3 MHz frequency range.

High-density volatiles in the system C-O-H-N for the calibration of a laser Raman microprobe

Three methods have been used to produce high-density volatiles in the system C-O-H-N for the calibration of a laser Raman microprobe (LRM): synthetic fluid-inclusion, sealed fused-quartz-tube, and high-pressure-cell methods. Because quantitative interpretation of a Raman spectrum of mixed-volatile fluid inclusions requires accurate knowledge of pressure- and composition-sensitive Raman scattering efficiencies or quantification factors for each species, calibrations of these parameters for mixtures of volatiles of known composition and pressure are necessary. Two advantages of the synthetic fluid-inclusion method are that the inclusions can be used readily in complementary microthermometry (MT) studies and that they have sizes and optical properties like those in natural samples. Some disadvantages are that producing H 2O-free volatile mixtures is difficult, the composition may vary from one inclusion to another, the exact composition and density of the inclusions are difficult to obtain, and the experimental procedures are complicated. The primary advantage of the method using sealed fused-quartz tubes is its simplicity. Some disadvantages are that exact compositions for complex volatile mixtures are difficult to predict, densities can be approximated only, and complementary MT studies on the tubes are difficult to conduct. The advantages of the high-pressure-cell method are that specific, known compositions of volatile mixtures can be produced and that their pressures can be varied easily and are monitored during calibration. Some disadvantages are that complementary MT analysis is impossible, and the setup is bulky. Among the three methods for the calibration of an LRM, the high-pressure-cell method is the most reliable and convenient for control of composition and total pressure. We have used the high-pressure cell to obtain preliminary data on 1. (1) the ratio of the Raman quantification factors for CH 4 and N 2 in an equimolar CH 4 N 2 mixture and 2. (2) the spectral peak position of ν 1 of CH 4 in that mixture, as well as in pure CH 4, at pressures up to 690 bars. These data were successfully applied to natural inclusions from the Duluth Complex in order to derive their compositions and total pressures.

Fabrication of long-length high-strength single-mode silica fibres

The letter reports an alternative approach to the realisation of long, low-attenuation, high-strength single-mode optical fibres suitable for high bit-rate transmission over long distances in adverse environments. We show that low attenuation (less than 0.45 dB km) can be achieved in combination with high proof-test levels (1% – 2% strain) in fibre lengths greater than 5 km, using natural fused-quartz tubing, and report a 15 km fibre having an attenuation of 0.44 dB km which survived a proof test at 1% strain.

Microbending losses of P 2 O 5 -doped graded-index multimode fibre

Measurement results showing that the cabling loss of P2O5-doped MCVD graded-index multimode fibre increases for wavelengths longer than 1.3 μm have been obtained. This letter investigates the cause for this loss increase. It also has been found that the loss increase is caused by P-OH bond absorption near the core-cladding boundary, where OH ions are diffused from the fused-quartz tube.

A note on the formation of fulgurites

SummaryA phenomenon similar to the sand tube fulgurite has been observed in experimental work carried out to compact and sinter metal powders using high voltage discharges. The sand tube fulgurite is a fused quartz tube formed by the passage of a lightning discharge. Further experiments, in which a high voltage discharge was passed from a pointed electrode held above a large volume of copper powder, through to an earthed plate, give a copper product with the characteristic fulgurite morphology. This result suggests that the quartz sand can behave as a good conductor in the lightning discharge, perhaps due to conducting coatings on the surface of the sand particles.

酸素プローブの参照極について

The reference electrode is one of the important factors affecting oxygen sensor performance. In our previous paper, it was shown that Fe+FexO mixture was an excellent reference electrode of the oxygen probe for industrial uses.In this study, it is shown that iron powder without addition of iron oxide acts in practice as a reference electrode of Fe+FexO for continuous monitoring of oxygen in melts or gases. From the observation of the reacted area between the stabilized zirconia solid electr lytes and the reference electrode of Fe+FexO in air at high temperatures, it is concluded that magnesia stabilized zirconia is superior to calcia or yttria stabilized zirconia for Fe+FexO reference electrode.In the study using a calcia stabilized zirconia pellet sealed into a fused quartz tube for rapid determination of oxygen in liquid metals, Cr, Mo or Fe powder without addition of Cr2O3, MoO2 or FeO showed actually the oxygen potential corresponding to Cr+Cr2O3, Mo+MoO2, or Fe+FexO, respectively.

Thermal expansion of a fused quartz tube in a dimensional stability test facility

A facility to monitor the dimensional stability of structures of arbitrary size or shape under varying temperature and pressure conditions is described. Real-time linear displacements are measured with a modified Michelson laser interferometer to a resolution of less than one part in 10(7) and an accuracy of approximately 2 parts in 10(7) for approximately 1 m gauge lengths. Verification of the system accuracy with a quartz tube required considerations of its fabrication and compositional characteristics.

Automated ’’float’’ method for determination of densities of molten salts

A new system for measuring densities of molten salt systems is described. The system consists of an accurate metal block furnace, the temperature of which can be changed linearly in time, a fused quartz tube containing quartz floats loaded with a ferromagnetic material, a differential transformer wound with platinum wire, an amplifier, a digital voltmeter, an interface, a paper tape punch, and a recorder. The advantages of the system are its ease of operation compared to other ’’float’’ methods, and the possibility of looking at highly colored melts and also melts having a high vapor pressure.

Photodecomposition of chloromethanes adsorbed on silica surfaces

Irradiation of CCl4, CFCl3, and CF2Cl2 in the presence of C2H6 in vessels containing silica sand or fused quartz tubing results in the formation of chlorine-containing products. The formation of these compounds occurs at wavelengths extending up to approximately 400 nm, that is, at wavelengths well beyond the absorption threshold of the chloromethanes in the gas phase. It is suggested that CCl4 adsorbed on silica surfaces photodissociates to yield CCl3 and CCl2 species. The poor material balance obtained in these experiments indicates that several of the chlorine-containing fragments are strongly adsorbed on the surface. At a CCl4 pressure of 13 Pa (0.1 torr), photolysis with 366 nm light in the presence of sand results in the decomposition of one molecule for every 104 photons striking the surface. Under otherwise identical conditions, the photon-induced breakdown of CFCl3 and CF2Cl2 is respectively only 10 percent or 3 percent as efficient.

The catalytic effect of geologic samples on the deuterium (tritium)-water exchange reaction as studied with a quadrupole mass filter

Abstract Evidence of exchange reactions between tritium gas and water has been observed in gas sampled from the vicinity of nuclear detonations. The purpose of this investigation, using deuterium gas as a surrogate for tritium, is to determine the catalytic effects of typical underground materials on the exchange reactions between hydrogenic species and water as a function of temperature. The apparatus constructed for these experiments consists of a constant pressure gas inlet system, a fused quartz tube containing the catalyst to be studied, and a quadrupole mass filter. The temperature range of the experiments was from ambient to 900 °C. The two gases, D2 and H2O, were mixed in the inlet system and then allowed to pass through the catalyst bed and into the mass filter through a glass leak. The results obtained can be summarized as follows: (1) the reaction is surface catalyzed; (2) equilibration takes place rapidly at room temperature and above, using platinum sponge as a catalyst; (3) for catalytic samples of tuff, alluvium, sandstone, and shale, the onset of observable reaction was between 400 to 500 °C with large amounts of products formed at 600 °C and above when the temperature was increased from ambient to 900 °C over a 6- to 8-hr period; and (4) deuterium and water appear to exchange at 200–300 °C in outgassed, partially decomposed limestone, presumably due to the catalytic activity of CaO and MgO.

Thermal Expansion of Silver Iodide

The linear thermal expansivity of polycrystalline silver iodide has been measured with a "Fused-Quartz Tube" apparatus in the temperature range 170 - 500 °C, the mean linear thermal expansion coefficient being αt 180=(2.607 + 0.00182 t) 10-5 (°C-1). An irregular change in the thermal expansivity was found close to 432 °C where an order-disorder transition has been reported.

907. A bakeable and direct joint between a fused quartz tube and a metal one: L Verhayden et al, J Sci Instrum, ( J Phys E), Ser 2 1 (2), 1968, 145–147

907. A bakeable and direct joint between a fused quartz tube and a metal one: L Verhayden et al, J Sci Instrum, ( J Phys E), Ser 2 1 (2), 1968, 145–147

A bakeable and direct joint between a fused quartz tube and a metal tube

A method is described for joining fused quartz tubes to Kovar tubes under vacuum, using inductive heating. The leakages obtained are less than 1 ntorr 1 s?1 after tests and the joints can operate at a temperature of 400?C and at 20 atm (gauge pressure) or in vacuum.

Lithium content of GaAs single crystals

Gallium arsenide crystals grown by the Bridgman and floating-zone techniques have been examined for Li by means of special analytical procedures based on the flame spectrometer. Approximately 10 16 cm −3 Li has been found in both doped and undoped GaAs. Polycrystalline GaSb showed less than 5 × 10 15 cm −3 Li, the limit of detection. Fused quartz used in the crystal preparation is suggested as a possible source of Li contamination. The Li content of fused-quartz tubing ranges between 10 17 and 5 × 10 18 cm −3 Li. Synthetic-quartz tubing contains < 3 × 10 15 cm −3 Li. A convenient, rapid and non-destructive method for determining lithium (> 10 15 cm −3 Li) in semiconductors and other materials is described.

FUSED-QUARTZ EXTENSOMETER FOR SECULAR, TIDAL, AND SEISMIC STRAINS

A description is given of two fused-quartz extensometers located in mountain tunnels at Dalton Canyon and Isabella in Southern California and designed for observing long-period seismic-wave strains, earth tidal strains, and secular strains. They consist essentially of instruments for measuring and recording variations in the separation of two piers by comparison with a length standard of fused-quartz tubing. The sensitivity for secular strains, denned as the least detectable strain increment, is approximately 10^(−7). For tidal and seismic-wave strains, the sensitivity is higher—a 1-mm deflection of the recorder represents a strain increment of 5.2 × 10^(−10). In both cases the maximum usable sensitivity is limited by ground-strain unrest or noise, generated by wind, barometric-pressure variations, temperature variations of the surface layers of the ground, and variations in ground-water saturation.

Sensitized Fluorescence of Tin

Several Sn lines have been observed in sensitized fluorescence and in a low voltage Tesla discharge. The fluorescence and the discharge were produced in a fused quartz tube containing Sn and Hg and heated by a blow torch and Bunsen burners. A Hanovia SC 2537 tube was used as a light source. The Sn lines observed in fluorescence with their estimated intensities are 4525 (2), 3801 (2), 3331 (4), 3262 (10), 3175 (3), 3034 (10), 3009 (2), 2863 (2), 2840 (10), 2851 (1), 2706 (8), 2661 (3), 2547 (2), 2430 (1), 2355 (0.2). The most intense Sn lines except 3034 are those of low energy discrepancy with excited Hg atoms. The abnormally high intensity of Sn 3034 which agrees with a corresponding effect in the sensitized fluorescence of Pb may indicate a new selection rule for collisions of the second kind.