Anvil press

Last updated

A multi-anvil press, or anvil press is a type of device related to a machine press that is used to create extraordinarily high pressures within a small volume.

Contents

Anvil presses are used in materials science and geology for the synthesis and study the different phases of materials under extreme pressure, as well as for the industrial production of valuable minerals, especially synthetic diamonds, as they mimic the pressures and temperatures that exist deep in the Earth. These instruments allow the simultaneous compression and heating of millimeter size solid phase samples such as rocks, minerals, ceramics, glasses, composite materials, or metals and are capable of reaching pressures above 25 GPa (around 250,000 atmospheres) and temperatures exceeding 2,500 °C. This allows mineral physicists and petrologists studying the Earth's interior to experimentally reproduce the conditions found throughout the lithosphere and upper mantle, a region that spans the near surface to a depth of 700 km. In addition to pressing on the sample, the experiment passes an electric current through a furnace within the assembly to generate temperatures up to 2,200 °C. [1] Although Diamond anvil cells and light-gas guns can access even higher pressures, the multi-anvil apparatus can accommodate much larger samples, which simplifies sample preparation and improves the precision of measurements and the stability of the experimental parameters.

The multi-anvil press is a relatively rare research tool. Lawrence Livermore National Laboratory's two presses have been used for a variety of material property studies, including diffusion and deformation of ceramics and metals, deep-focus earthquake, and the high-pressure stability of mineral phases.

History

The 6-8 multi-anvil apparatus was introduced by Kawai and Endo [2] using a split steel sphere suspended in pressurized oil, later modified [3] to use the hydraulic ram. In 1990, Walker et al. [4] simplified the first compression stage by introducing the removable hatbox design, allowing ordinary machine presses to be converted into multi-anvil systems. A variety of assembly designs have been introduced and standardized including the Walker castable, [5] and the COMPRES assemblies. [6] Recent advances have focused on in-situ measurements, and standardizing materials and calibrations.

Basic design

A typical Kawai cell 8–6 multi-anvil apparatus uses air pumps to pressurize oil, which drives a vertical hydraulic ram to compress a cylindrical cavity known as a hatbox. This cavity is filled with six steel anvils, three facing up and three facing down, that converge on a set of eight tungsten carbide cubes. The interior corners of these cubes truncated to fit an octahedral assembly. These octahedra range from 8 mm to 25 mm on edge and are typically composed of magnesium oxide or another material that deforms ductilely over the range of experimental conditions, to make sure the experiment is under hydrostatic stress. As this assembly is compressed, it extrudes out between the cubes, forming a gasket. A cylinder is drilled out between two opposite faces to accommodate the experiment. Experiments that require heating are surrounded by a cylindrical graphite or lanthanum chromite cylinder furnace, which can produce considerable heat by electrical resistance. However, the graphite furnace can be troublesome at higher pressures due to its tendency to transform into diamond. The DIA multi-anvil is the main alternative to the Kawai cell: it uses six anvils to compress a cubic sample. [4]

Theory

In principle, the multi-anvil press is similar in design to a machine press except that it uses force magnification to amplify pressure by reducing the area over which force is applied:

This is analogous to the mechanical advantage utilized by a lever, except the force is applied linearly, instead of angularly. For example, a typical multi-anvil could apply 9,806,650 N (equivalent to a load of 1000 t) onto a 10 mm octahedral assembly, which has a surface area of 346.41 mm2, to produce a pressure of 28.31 GPa inside the sample, while the pressure in the hydraulic ram is a mere 0.3 GPa. Therefore, using smaller assemblies can increase the pressure in the sample. The load that can be applied is limited by the compressive yield strength of the tungsten carbide cubes, especially for heated experiments. Even higher pressures, up to 90 GPa, have been achieved by using 14 mm sintered diamond cubes instead of tungsten carbide. [7]

Measurements in the Multi-Anvil

Most sample analysis is conducted after the experiment is quenched and removed from the multi-anvil. However, it is also possible to perform measurements in-situ. Circuits, including thermocouples or pressure variable resistors, can be built into the assembly to accurately measure temperature and pressure. Acoustic interferometry can be used to measure seismic velocities through a material or to infer density of materials. [8] Resistivity can be measured by complex impedance spectroscopy. [9] Magnetic properties can be measured using amplified nuclear magnetic resonance in specially configured multi-anvils. [8] The DIA multi-anvil design often includes diamond or sapphire windows built into the tungsten anvils to allow x-rays or neutrons to penetrate into the sample. [10] This type of device gives researchers at synchrotron and neutron spallation sources the capacity to perform diffraction experiments to measure the structure of samples under extreme conditions. [11] This is essential for observing unquenchable phases of matter because they are kinetically and thermodynamically unstable at low temperatures and pressure. [12] Viscosity and density of high-pressure melts can be measured in-situ using the sink float method and neutron tomography. In this method a sample is implanted with objects, such platinum spheres, that have different density and neutron scattering properties compared to the material surrounding them, and the path of the object is tracked as it sinks, or floats, through the melt. Two objects with contrasting buoyancy can be used simultaneously to calculate the density. [8]

Applications

Pressure, like temperature, is a basic thermodynamic parameter that influences the molecular structure, and thus the electrical, magnetic, thermal, optical and mechanical properties of materials. Devices like the multi-anvil apparatus allow us to observe the effect of high pressure on material structure and properties. Multi-anvil presses are occasionally used in industry to produce minerals of exceptional purity, size and quality, especially high-pressure high-temperature (HPHT) synthetic diamonds and c-Boron-Nitride. However, multi-anvils are high cost devices, and are very adaptable, so they are more often used as scientific instruments. Multi-anvils have three main scientific uses: 1) to synthesize novel high-pressure material; 2) to change the phases of a material; 3) to examine the properties of materials at high pressures. In materials science this includes the synthesis of novel or useful materials with potential mechanical or electronic applications, such as high-pressure super conductors or ultra-hard substances. [13] Geologists are primarily concerned with reproducing the conditions and materials found in the deep earth, to study geological processes that cannot be directly observed. Minerals or rocks are synthesized to find what conditions are responsible for different mineral phases and textures.[ citation needed ] Geoscientists also use multi-anvils to measure the kinetics of reactions, density, viscosity, compressibility, diffusivity and thermal conductivity of rock under extreme conditions. [14] [15]

Related Research Articles

In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. High pressure usually means pressures of thousands (kilobars) or millions (megabars) of times atmospheric pressure.

Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington.

<span class="mw-page-title-main">Synthetic diamond</span> Diamond created by controlled processes

Lab-grown diamond is diamond that is produced in a controlled technological process. Unlike diamond simulants, synthetic diamonds are composed of the same material as naturally formed diamonds—pure carbon crystallized in an isotropic 3D form—and share identical chemical and physical properties.

<span class="mw-page-title-main">Allotropes of carbon</span> Materials made only out of carbon

Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene. Larger-scale structures of carbon include nanotubes, nanobuds and nanoribbons. Other unusual forms of carbon exist at very high temperatures or extreme pressures. Around 500 hypothetical 3‑periodic allotropes of carbon are known at the present time, according to the Samara Carbon Allotrope Database (SACADA).

<span class="mw-page-title-main">Diamond anvil cell</span> Device for generating extremely high pressures

A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 100–200 gigapascals, although it is possible to achieve pressures up to 770 gigapascals.

<span class="mw-page-title-main">Material properties of diamond</span>

Diamond is the allotrope of carbon in which the carbon atoms are arranged in the specific type of cubic lattice called diamond cubic. It is a crystal that is transparent to opaque and which is generally isotropic. Diamond is the hardest naturally occurring material known. Yet, due to important structural brittleness, bulk diamond's toughness is only fair to good. The precise tensile strength of bulk diamond is little known; however, compressive strength up to 60 GPa has been observed, and it could be as high as 90–100 GPa in the form of micro/nanometer-sized wires or needles, with a corresponding maximum tensile elastic strain in excess of 9%. The anisotropy of diamond hardness is carefully considered during diamond cutting. Diamond has a high refractive index (2.417) and moderate dispersion (0.044) properties that give cut diamonds their brilliance. Scientists classify diamonds into four main types according to the nature of crystallographic defects present. Trace impurities substitutionally replacing carbon atoms in a diamond's crystal structure, and in some cases structural defects, are responsible for the wide range of colors seen in diamond. Most diamonds are electrical insulators and extremely efficient thermal conductors. Unlike many other minerals, the specific gravity of diamond crystals (3.52) has rather small variation from diamond to diamond.

<span class="mw-page-title-main">Stishovite</span> Tetragonal form of silicon dioxide

Stishovite is an extremely hard, dense tetragonal form (polymorph) of silicon dioxide. It is very rare on the Earth's surface; however, it may be a predominant form of silicon dioxide in the Earth, especially in the lower mantle.

Post-perovskite (pPv) is a high-pressure phase of magnesium silicate (MgSiO3). It is composed of the prime oxide constituents of the Earth's rocky mantle (MgO and SiO2), and its pressure and temperature for stability imply that it is likely to occur in portions of the lowermost few hundred km of Earth's mantle.

<span class="mw-page-title-main">Aggregated diamond nanorod</span> Nanocrystalline form of diamond

Aggregated diamond nanorods, or ADNRs, are a nanocrystalline form of diamond, also known as nanodiamond or hyperdiamond.

Pressure experiments are experiments performed at pressures lower or higher than atmospheric pressure, called low-pressure experiments and high-pressure experiments, respectively. Pressure experiment are necessary because substances behave differently at different pressures. For example, water boils at a lower temperature at lower pressures. The equipment used for pressure experiments depends on whether the pressure is to be increased or decreased and by how much. A vacuum pump is used to remove the air out of a vacuum vessel for low-pressure experiments. High-pressures can be created with a piston-cylinder apparatus, up to 5 GPa and ~2000 °C. The piston is shifted with hydraulics, decreasing the volume inside the confining cylinder and increasing the pressure. For higher pressures, up to 25 GPa, a multi-anvil cell is used and for even higher pressures the diamond anvil cell. The diamond anvil cell is used to create extremely high pressures, as much as a million atmospheres, though only over a small area. The current record is 560 GPa, but the sample size is confined to the order of tens of micrometres.

<span class="mw-page-title-main">Ringwoodite</span> High-pressure phase of magnesium silicate

Ringwoodite is a high-pressure phase of Mg2SiO4 (magnesium silicate) formed at high temperatures and pressures of the Earth's mantle between 525 and 660 km (326 and 410 mi) depth. It may also contain iron and hydrogen. It is polymorphous with the olivine phase forsterite (a magnesium iron silicate).

<span class="mw-page-title-main">Ho-Kwang Mao</span> Chinese-American geologist

Ho-Kwang (Dave) Mao is a Chinese-American geologist. He is the director of the Center for High Pressure Science and Technology Advanced Research in Shanghai, China. He was a staff scientist at Geophysical Laboratory of the Carnegie Institution for Science for more than 30 years. Mao is a recognized leading scientist in high pressure geosciences and physical science. There are two minerals named after him, Davemaoite and Maohokite.

Solid hydrogen is the solid state of the element hydrogen, achieved by decreasing the temperature below hydrogen's melting point of 14.01 K. It was collected for the first time by James Dewar in 1899 and published with the title "Sur la solidification de l'hydrogène" in the Annales de Chimie et de Physique, 7th series, vol. 18, Oct. 1899. Solid hydrogen has a density of 0.086 g/cm3 making it one of the lowest-density solids.

Mineral physics is the science of materials that compose the interior of planets, particularly the Earth. It overlaps with petrophysics, which focuses on whole-rock properties. It provides information that allows interpretation of surface measurements of seismic waves, gravity anomalies, geomagnetic fields and electromagnetic fields in terms of properties in the deep interior of the Earth. This information can be used to provide insights into plate tectonics, mantle convection, the geodynamo and related phenomena.

<span class="mw-page-title-main">Iron–hydrogen alloy</span>

Iron–hydrogen alloy, also known as iron hydride, is an alloy of iron and hydrogen and other elements. Because of its lability when removed from a hydrogen atmosphere, it has no uses as a structural material.

<span class="mw-page-title-main">Griggs apparatus</span>

Griggs apparatus, also referred to as a Griggs rig, is a modified piston cylinder high pressure apparatus used to create an environment of high pressure, high temperature and to impart a deviatoric stress on a sample of material. It was conceived in the 1960s.

The D-DIA or deformation-DIA is an apparatus used for high pressure and high temperature deformation experiments. The advantage of this apparatus is the ability to apply pressures up to approximately 15 GPa while independently creating uniaxial strains up to 50%.

<span class="mw-page-title-main">Piston-cylinder apparatus</span>

The piston-cylinder apparatus is a solid media device, used in Geosciences and Material Sciences, for generating simultaneously high pressure and temperature. Modifications of the normal set-up can push these limits to even higher pressures and temperatures. A particular type of piston-cylinder, called Griggs apparatus, is also able to add a deviatoric stress on the sample.

The geochemistry of carbon is the study of the transformations involving the element carbon within the systems of the Earth. To a large extent this study is organic geochemistry, but it also includes the very important carbon dioxide. Carbon is transformed by life, and moves between the major phases of the Earth, including the water bodies, atmosphere, and the rocky parts. Carbon is important in the formation of organic mineral deposits, such as coal, petroleum or natural gas. Most carbon is cycled through the atmosphere into living organisms and then respirated back into the atmosphere. However an important part of the carbon cycle involves the trapping of living matter into sediments. The carbon then becomes part of a sedimentary rock when lithification happens. Human technology or natural processes such as weathering, or underground life or water can return the carbon from sedimentary rocks to the atmosphere. From that point it can be transformed in the rock cycle into metamorphic rocks, or melted into igneous rocks. Carbon can return to the surface of the Earth by volcanoes or via uplift in tectonic processes. Carbon is returned to the atmosphere via volcanic gases. Carbon undergoes transformation in the mantle under pressure to diamond and other minerals, and also exists in the Earth's outer core in solution with iron, and may also be present in the inner core.

Alvin Van Valkenburg, Jr. was an experimental physicist, geologist, geochemist, and inventor, known as one of the four co-inventors of the diamond anvil cell (DAC).

References

  1. ↑ Studying the Earth's Formation: The Multi-Anvil Press at Work Archived 2010-05-28 at the Wayback Machine // LLNL
  2. ↑ Kawai, N.; Endo, S. (1970). "The generation of ultrahigh hydrostatic pressures by a split sphere apparatus". Review of Scientific Instruments. 41 (8): 1178–1181. Bibcode:1970RScI...41.1178K. doi:10.1063/1.1684753.
  3. ↑ Kawai, N.; Togaya, M.; Onodera, A. (1973). "A new device for high pressure vessels". Proceedings of the Japan Academy. 49 (8): 623–6. doi: 10.2183/pjab1945.49.623 .
  4. 1 2 Walker, D.; Carpenter, M.A.; Hitch, C.M. (1990). "Some simplifications to multianvil devices for high pressure experiments". American Mineralogist. 75: 1020–8.
  5. ↑ Walker, D. (1991). "Lubrication, gasketing, and precisionin multianvil experiments". American Mineralogist. 76: 1092–1100.
  6. ↑ Leinenweber, K.D.; Tyburczy, J.A.; Sharp, T.G.; Soignard, E.; Diedrich, T.; Petuskey, W.B.; Wang, Y.; Mosenfelder, J.L. (2012). "Cell assemblies for reproducible multi-anvil experiments (the COMPRES assemblies)". American Mineralogist. 97 (2–3): 353–368. Bibcode:2012AmMin..97..353L. doi:10.2138/am.2012.3844.
  7. ↑ Zhai, S.; Ito, E. (2011). "Recent advances of high-pressure generation in a multianvil apparatus using sintered diamond anvils". Geoscience Frontiers. 2 (1): 101–6. Bibcode:2011GeoFr...2..101Z. doi: 10.1016/j.gsf.2010.09.005 .
  8. 1 2 3 Chen, J.; Wang, Y.; Duffy, S.; Shen, G.; Dobrzhinetskaya, L.P. (2011). Advances in High-Pressure Techniques for Geophysical Applications. Elsevier. ISBN   978-0-08-045766-6.
  9. ↑ Katsura, T.; Sato, K.; Ito, E. (1998). "Electrical conductivity of silicate perocskite at lower-mantle conditions". Nature. 395 (6701): 493–5. Bibcode:1998Natur.395..493K. doi:10.1038/26736.
  10. ↑ Kato, T.; Ohtani, E.; Morishima, H.; Yamazaki, D.; Suzuki, A.; Suto, M.; Kubo, T.; Kikegawa, T.; Shimomura, O. (1995). "In situ X ray observation of high-pressure phase transitions of MgSiO3 and thermal expansion of MgSiO3 perovskite at 25 GPa by double-stage multianvil system". Journal of Geophysical Research: Solid Earth. 100 (B10): 20475–81. Bibcode:1995JGR...10020475K. doi:10.1029/95JB01688.
  11. ↑ Nishiyama, N.; Wang, Y.; Sanehira, T.; Irifune, T.; Rivers, M.L. (2008). "Development of the Multi-anvil Assembly 6-6 for DIA and D-DIA type high-pressure apparatuses". High Pressure Research. 28 (3): 307–314. Bibcode:2008HPR....28..307N. doi:10.1080/08957950802250607.
  12. ↑ Schollenbruch, K.; Woodland, A.B.; Frost, D.J.; Wang, Y.; Sanehira, T.; Langenhorst, F. (2011). "In situ determination of the spinel–post-spinel transition in Fe3O4 at high pressure and temperature by synchrotron X-ray diffraction". American Mineralogist. 96 (5–6): 820–7. Bibcode:2011AmMin..96..820S. doi:10.2138/am.2011.3642.
  13. ↑ Schilling, J.S. (1998). "The use of high pressure in basic and materials science". Journal of Physics and Chemistry of Solids. 59 (4): 553–568. Bibcode:1998JPCS...59..553S. doi:10.1016/S0022-3697(97)00207-2.
  14. ↑ Mysen, Bjorn O.; Richet, Pascal (16 June 2005). Silicate Glasses and Melts: Properties and Structure. Elsevier. ISBN   978-0-08-045771-0.
  15. ↑ Giordano, D.; Russel, J.K.; Dingwell, D.B. (2008). "Viscosity of Magmatic Liquids: A Model". Earth and Planetary Science Letters. 271 (1–4): 123–134. Bibcode:2008E&PSL.271..123G. doi:10.1016/j.epsl.2008.03.038.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.