Piston-cylinder Type Apparatus Research Articles

Direct measurement and calculation of rubber bulk modulus by piston-cylinder method using conventional mechanical testing equipment

This article describes a method to directly measure the bulk modulus of rubber using a piston-cylinder type apparatus. The function of the testing apparatus is to reliably transfer load to the water inside the vessel and allow for the accurate and continuous measurement of volumetric displacement as the contents are compressed. During the test, load is applied to a piston-cylinder containing the rubber test sample and water using a conventional mechanical testing load frame. Load and the travel of the piston are recorded by a load cell and extensometer, respectfully. A brass or stainless steel plug of the same dimensions as the test sample is tested as a control sample to isolate the compliance of the system, including the compressibility of water and compliance of the o-rings which seal the piston-cylinder system. The results from this control test are used to decouple the compliance of the system from the sample test results. Load-linear displacement data are mathematically converted to pressure-volumetric displacement data, from which bulk modulus is calculated. The test apparatus and method are validated using the known bulk modulus of water. Finally, the bulk moduli for two similar rubbers are evaluated. The validity of the results and limitations of the device are discussed.

H2-H2O immiscibility in Earth’s upper mantle

Immiscibility between water and hydrogen-rich fluids may be responsible for the formation of super-reduced mineral assemblages and for the early oxidation of Earth´s upper mantle. In the current study, we present new data on the critical curve in the H2-H2O system to 1400 ℃ and 4 GPa. We utilized a synthetic fluid inclusion method to trap fluids at high P–T conditions within quartz and olivine crystals. Experiments were performed in a piston-cylinder type apparatus, employing a double-capsule technique. The inner capsule contained the crystal and fluids of interest, while the outer served as oxygen fugacity buffer, maintaining f(O2) at the iron-wüstite (Fe-FeO) equilibrium. Our results suggest that below ~ 2.5 GPa, the critical curve has a mostly linear slope of 200 ℃/GPa, while at more elevated pressure it becomes significantly steeper (400 ℃/GPa). This implies that in most of the modern, reduced upper mantle, water and hydrogen are immiscible, while localized heating events, such as rising plumes, may close the miscibility gap. The steep increase of the critical curve at high pressure observed in this study implies that even for very hot geotherms in the early Archean or the late Hadean, H2-H2O immiscibility likely occurred in the deeper parts of the upper mantle, thus making a plausible case for rapid H2 loss as a mechanism of early mantle oxidation. To constrain the geochemical fingerprint of this process, we performed a series of element partitioning experiments to unravel how the H2-H2O unmixing may affect element transfer. Noble gases such as Xe as well as methane are preferentially incorporated in the hydrogen-rich phase, with a XeH2O/XeH2 ratio of ~ 8. This partitioning pattern may, for example, explain the underabundance of Xe isotopes produced by fission of Pu in the mantle. These Xe isotopes may have been removed by a primordial H2-H2O unmixing event during the early stages of planetary evolution.

Effects of pressure on electrical property of BaIrO 3

The in situ high-pressure measurements of electrical resistivity versus temperature for weak ferromagnetic BaIrO 3 have been performed, using a Cu–Be piston–cylinder-type apparatus up to 1.0 GPa at 80–300 K. The electrical resistivity is increasing with pressure. The pressure derivative of Curie temperature ∂ T c / ∂ P is equal to −6.1(2) K/GPa, and the relative pressure dependence ∂ ln T c / ∂ P is equal to −3.4(1)%/GPa, which indicates that BaIrO 3 is a weak itinerant ferromagnet.

Solubilities of nitrogen and noble gases in silicate melts under various oxygen fugacities: implications for the origin and degassing history of nitrogen and noble gases in the earth

Solubility experiments for nitrogen and noble gases (Ar and Ne) in silicate melts were conducted using two experimental configurations: one was conducted at 1 atmospheric pressure, T =1300°C and oxygen fugacity ( fO 2) of IW + 0.9 (i.e., 0.9 log units higher than the iron-wüstite buffer) and the other at high pressures ( P total ∼ 2 × 10 8 Pa), 1500°C and fO 2 ∼ IW + 6. For the former experiment, isotopically labeled-nitrogen ( 15N 15N-enriched) was used to distinguish dissolved nitrogen from contaminating atmospheric or organic nitrogen and to examine dissolution mechanisms of nitrogen in silicate melts. The results obtained for the two series of experiments are consistent with each other, suggesting that Henry's law is satisfied for fN 2 of up to ∼250 atm (2.5 × 10 7 Pa). The results are also consistent with our earlier results (Miyazaki et al., 1995) obtained at highly oxidizing conditions ( fO 2 ∼ IW + 10). All these results support physical dissolution of nitrogen as N 2 molecules in silicate melts for fO 2 from ∼IW + 10 down to ∼IW. The observed solubility (Henry's constant) of nitrogen (3–5 × 10 −9 mol/g/atm) is comparable to that of Ar (2–4 × 10 −9 mol/g/atm), and much lower than that of Ne (11–14 × 10 −9 mol/g/atm) at 1300°C. A preliminary experiment was also performed for partitioning of nitrogen and noble gases between clinopyroxene (cpx) and basaltic melt using a piston cylinder-type apparatus at 1.5 GPa and at 1270 to 1350°C. The obtained cpx/melt partition coefficient of nitrogen is 0.06, slightly lower than those of noble gases (∼0.1 for Ne to Xe), suggesting that nitrogen is as incompatible as or even slightly more incompatible than noble gases. The present results imply that a large nitrogen/Ar fractionation would not be produced by magmatic processes. Therefore, the two orders of magnitude difference between the N 2/ 36Ar ratios in the Earth's atmosphere (∼10 4) and that in the mantle (∼10 6) must be explained by some other processes, such as incomplete segregation of metal blobs into the core and their later oxidation.

Lithium/nickel mixing in the transition metal layers of lithium nickelate: high-pressure synthesis of layered Li[Li xNi 1− x]O 2 oxides as cathode materials for lithium-ion batteries

Novel compositions Li[Li x Ni 1− x ]O 2, 0< x<0.2, with a layered structure, have been prepared under high-pressure in an oxygen-rich atmosphere using a piston-cylinder type apparatus. A new structural feature of these compositions as compared to well-known Li[Ni]O 2 is the development of mixed [Li x Ni 1− x ]O 2-layers in addition to nearly pure Li-layers. The replacement of Ni 3+ by Li + in nickel-rich layers is compensated for by the appearance of Ni 4+ ions. The use of Li[Li x Ni 1− x ]O 2 as a cathode material in a lithium ion cell shows a different electrochemical behavior as compared to Li[Ni]O 2. Below 4.6 V the cell capacity is always below 115 mA g −1. On increasing the voltage upper limit, an irreversible transformation into a solid with a stoichiometry to Li x NiO 2 takes place. On further cycling Li[Li x Ni 1− x ]O 2 displays a reversible lithium insertion, reaching a capacity of about 190 mA h g −1 between 5.0 and 2.7 V after several cycles.

High-pressure synthesis of Ga-substituted LiCoO2with layered crystal structure

LiGayCo1−yO2 solid solutions with a layered crystal structure (0 ≤ y < 0.75) were prepared under high-pressure (3 GPa) at 850 °C using a piston–cylinder type apparatus. This is in contrast to the solubility of Ga in the layered LiCoO2 structure at atmospheric pressure, which is strongly limited, and reaches a maximum value of y = 0.1 at 700 °C. The structure of Ga substituted LiCoO2 is characterized by XRD analysis and IR spectroscopy. It has been found that Ga substitutes for Co in the CoO2 layer (3a site), while Li and O are in their normal positions (3b and 6c, respectively). The progressive replacement of Co by Ga leads to a linear increase in the mean M–O bond distance and to a smooth decrease in frequency of the main vibration of the GayCo1−yO2 layer, thus indicating a random Co/Ga distribution. The electrochemical performance of LiGayCo1−yO2 as a cathode material in lithium ion cells has been evaluated in potentiostatic and galvanostatic experiments. The de-intercalation voltage of the LiGayCo1−yO2 solid solutions increases and the reversible capacity decreases with increasing gallium content.

EXPERIMENTAL DETERMINATION OF GARNET-SPINEL COEXISTING LHERZOLITE FACIES AND TRACE ELEMENT DISTRIBUTION

The pressure-temperature location of garnet and spinel lherzolite facies boundary is often critical for understanding mantle dynamics. We have investigated the boundary by experiments using natural starting materials. For compositions close to the model primitive mantle at constant temperature of 1360°C, garnet-in boundary is approximately 2.3 GPa while spinel-out is at approximately 2.6 GPa. The redistribution of trace elements during the garnet break down reaction (i.e. olivine[ol] + garnet[gt] = orthopyroxene[opx] + clinopyroxene[cpx] + spinel[sp]) lags behind phase equilibrium and product opx and cpx “inherit” the REE abundances from reactant garnet. Diffusion equilibration for trace elements takes several hundred thousand years for pyroxenes over distance of 500µm at 1200°C. The pressure-temperature data for garnet-spinel transformation are inadequate particularly under near solidus conditions in natural peridotite compositions. Previous experimental studies have demonstrated that compositional effects on the location of garnet-spinel facies boundary in simple systems were considerable (e.g. Nickel, 1986; O’Neill, 1981). Addition of chrome shifts the boundary to higher pressures, but the data are not sufficient for extrapolating the results to natural compositions. For natural systems, experimental studies of the transformation boundary are limited in number (Jenkins and Newton, 1979; O’Hara et al., 1971) and their results span over a range approximately 10 kbar. Furthermore, experimental results for the transformation boundary near solidus (above 1300°C) do not exist. Our experiments were aimed at determining where garnet and spinel become stable at near solidus condition (e.g. 1360°C). In addition, the phase rule predicts a range of pressure- temperature conditions for the existence of transitional garnet-spinel lherzolite zone, because the degree of freedom is more than two for the garnet break down reaction in the natural system. This suggests that the garnet-in boundary is located toward the lower pressures than the spinel-out boundary. We circumvent the problem, that is caused by sluggishness of reaction, by monitoring rates of the garnet breakdown and growth reactions. Model parameters corresponding to chemical affinity are determined from time dependent progresses of the reaction. These parameters are used to extrapolate the condition where reaction rate is zero, that is equilibrium. The results show that at 1360°C garnet-in boundary is located at 0.3 GPa lower pressure than spinelout boundary. Garnet and spinel can coexist in the range of pressure. It should be noted that the 0.3 GPa pressure range for the coexistence is difficult to resolve by the conventional reversal reaction method (Koga et al., 1998). Trace elements that reside in garnet have to be redistributed during the garnet break-down reaction. Peridotite samples that have experienced the decompression often display incomplete trace element redistribution in newly formed minerals. Trace element measurements on experimental charges demonstrate that product opx and cpx “inherit” the trace element abundance from the reactant garnet, and there are no recognizable differences in abundance of trace element between opx and cpx. Thus, while major element abundances in pyroxenes are in equilibrium as demonstrated by experimentally calibrated geothermobarometers, trace element redistribution is incomplete. This may be caused by the differences in diffusivities of major and trace elements. The disequilibrium trace element distribution similar to experimental results could be expected in rocks under went rapid decompression. Indeed, The trace element distribution among fine grained rims around garnet consisting opx, cpx, and spinel in peridotite xenoliths from Lashaine, Tanzania closely resembles experimental results. Time scales for equilibration of pyroxenes can be modeled by diffusion. A model involving a spherical grain with a constant composition boundary, and a model with adjacent finite length slabs of opx and cpx, are compared under various diffusivities and boundary conditions in cooling histories. The results show persistence of disequilibrium for 7-800k years at high temperature (1200°C), and fractionated zoning of rare earth elements due to D(Yb) > D(La). Starting materials are mineral separates from garnet lherzolite from Pali Aike, Chile for garnet break down and spinel lherzolite from Kilbourne Hole, USA for garnet production reaction. Experiments are conducted at the conditions at 1360°C and from 1.8 to 3.0 GPa, with the run duration spanning form 2 to 200 hours. The run conditions were achieved by 2.54 cm diameter piston-cylinder type apparatus, with Ba- CO3 as pressure transmitting medium. Pressure calibrations were done by the CaTs break-down reaction (Hays, 1967) and An-Sp lherzolite transformation for CMAS system at subsolidus and above solidus conditions (Kushiro and Yoder, 1966). Volume fractions of product phases are measured from the digitally captured back-scattered electron images with the combination of x-ray images. Major element compositions are measured by electron probe. Trace elements abundances are measured by ion probe.

Measurement of Ultrasonic Wave Velocities in Solid under High Pressure

A new method for the measurement of ultrasonic wave velocities in solid under very high pressures up to 14 GPa has been developed. In a pressure range below 4 GPa a piston-cylinder type apparatus was employed. In an extended pressure range up to 14 GPa a double stage split-sphere type high pressure apparatus was used. A pulse-echo-overlap method was adopted for the wave velocity measurement with a piston-cylinder apparatus. Meanwhile, a simple pulse transmission method is the only applicable method in the higher pressure range. Examples of data for NaCl and baked pyrophillite are presented.

Analysis of pressures generated in a piston-cylinder type apparatus

Pressures generated in a piston-cylinder type apparatus have been analyzed as a function of experimental path. From general consideration of solid pressure media and experimental history six characteristic P-T curve types of an arbitrary specimen have been deduced. The observed melting curve of a specimen is found to be dependent on a maximum initial pressure in an experiment cycling downward (defined herein) and also to be convergent to a certain upper boundary (i.e., its true melting curve) when the pressure cell used has a negative anvil effect. It is concluded that the variation of observed melting temperatures (or any other characteristic temperature or parameter) of a specimen at a given external pressure is bounded by its true melting temperature (or by its true physical parameter), which is an open upper bound. On the basis of these properties the so-called upper boundary method for close approximation to the true P-T curve of a specimen has been derived. When this method is used, the inherent strength of solid pressure media is simply obtainable as a by-product, which can be defined by the lower boundary of its melting temperatures measured at a given external pressure.

An Experimental Study on the Deformation of Materials under Hihg Hydrostatic Pressures : 1st Report, On the Deformation of Cylinders under Internal and External Pressures

There has been published a number of papers on the plastic behavior of metals under hydrostatic pressures but few investigation is reported on the elasto-plastic properties of metals, where high accuracy is required in measurements. In the conventional piston-cylinder type apparatus where the deformation of the specimen together with the hydrostatic pressure is produced by a movement of a piston, an error in stress-measurement is likely to be induced by a frictional force acting between piston and cylinder. A new apparatus using cylindrical specimens which are subjected to the internal and external pressures, has been developed in order to eliminate the error due to the frictional force. The strains and the difference in the internal and the external pressures were measured with high accuracy using wire strain gages. The effect of hydrostatic pressure up to 5 000kg/cm2 has been studied on the deformation of aluminum and on the yield of low carbon steel. The strss-strain curve and the ultimate pressure of cylinders exhibited little change in aluminum but an increase in its ductility was observed. There was little change in the lower yield point of low carbon steel.

Detection of Pressure-Induced Transformations by measuring the Change of Inductance

The pressure in a simple piston-cylinder type apparatus was calibrated by detecting volume change associated with polymorphic transformation of the specimen as the change of inductance of high frequency coil wound on the specimen. The flow of pressure transmittor of pyrophyllite during compression was also studied by means of the same method. Specimens used were KNO3 and AgI, which were known to have the transformation at a pressure of 3.6 and 3.0 kbar at room temperature, respectively. Results are summarized as follows:(1) The transformtion points of the specimens were measured with good accuracy and reproducibility in spite of a small volume of specimen, about 8.7% of the total volume of pressure cell. (2) Loss of pressure in the present high pressure apparatus and arrangement of pressure cell was as small as about 3%. This fact seemed to be caused from the reduction of friction between pistons and cylinder by using a Myler and asbestos composite paper and from pressure multiplication by the steel disks used. (3) At the moment pressure was reached 3 kbar, the flow of pyrophyllite was found to be completed. At 1 kbar, however, it required about 5 min. to complete the flow of pyrophyllite. The flow of pyrophyllite was greatly affected by the arrangement of pressure cell.The present method is expected to be used for detecting the transformation associated with the change in dielectric constant or magnetic susceptibility.

Dense form of germanate orthoclase (KAlGe3O8)

Orthoclase (KAlSi3O8) is one of the most abundant minerals that contain potassium as a main constituent element. No natural polymorph of this mineral with denser structure has been found, nor has one been made in laboratory [Boyd, l964]. In the present study a new dense form of germanate orthoclase (KAlGe3O8) was synthesized during a preliminary study on the determination of solid solubility of germanate leucite (KAlGe2O6) in germania (GeO2). Proper proportions of solutions of KOH and Al(NO3)3 and powder of GeO2 were carefully mixed, evaporated, and fired at 600°C to decompose Al(NO3)3 into Al2O3. An X-ray powder diffraction of the product revealed that a mixture of GeO2 and amorphous material had been made. The starting material prepared in this way was charged in a platinum capsule and heated and hydrostatically compressed for 1 hour at 980°C and 25 kb in a piston-cylinder type apparatus.