Pressure Dependence Research Articles

Solubility of H2S-CH4 mixtures in calcium chloride solution: Insight from molecular dynamics simulations

This study uses equilibrium molecular dynamics (EMD) simulations to gain microstructural insight into and predict crucial properties of gas-brine mixtures affecting sour gas reservoir development. The effects of pressure, temperature, gas composition and salinity on the solubility and density of H2S-CH4 mixtures in pure water and CaCl2 brine were investigated at industrially relevant conditions (temperature range of 280 − 340 K, pressures up to 20 MPa, and a salinity range of 4.78 − 17.32 wt%). The force fields used in the MD simulations were validated using experimental data for pure H2S and CH4. The results showed that the solubility of pure H2S and CH4 in pure water increases with pressure, with the latter having a higher solubility. For H2S-CH4 mixtures, the solubility of H2S increased while that of CH4 fell with increasing H2S mole fraction, with the solubilities of the two gases intersecting at an H2S mole fraction of 0.28. Further, the solubility of H2S shows a greater pressure dependence than that of CH4, and H2S gas tends to reach saturation in pure water. In calcium chloride solution, the gas solubility decreases as the ions reduce the interaction between water and gas molecules. The solubility of H2S gas is a stronger function of the ion concentration compared with CH4, and increases 6-fold as the H2S mole fraction increases from 0.5 to 0.8. The overall solubility ranges were 0.45 to 3.48 mol/kg for H2S and 0.15 to 0.25 mol/kg for CH4.

Including the Ensemble of Unstructured Conformations in the Analysis of Protein's Native State by High-Pressure NMR Spectroscopy.

The analysis of pressure induced changes in the chemical shift of proteins allows statements on structural fluctuations proteins exhibit at ambient pressure. The inherent issue of separating general pressure effects from structural related effects on the pressure dependence of chemical shifts has so far been addressed by considering the characteristics of random coil peptides on increasing pressure. In this work, chemically and pressure denatured states of the cold shock protein B from Bacillus subtilis (BsCspB) have been assigned in 2D 1H-15N HSQC NMR spectra and their dependence on increasing hydrostatic pressure has been evaluated. The pressure denatured polypeptide chain has been used to separate general from structural related effects on 1H and 15N chemical shifts of native BsCspB and the implications on the interpretation of pressure induced changes in the chemical shift regarding the structure of BsCspB are discussed. It has been found that the ensemble of unstructured conformations of BsCspB shows different responses to increasing pressure than random coil peptides do. Thus, the approach used for considering the general effects that arise when hydrostatic pressure increases changes the structural conclusions that are drawn from high pressure NMR spectroscopic experiments that rely on the analysis of chemical shifts.

Analyse des Nativen Zustands von Proteinen durch Hochdruck NMR‐Spektroskopie unter Berücksichtigung des Ensembles Unstrukturierter Konformationen

AbstractDie Analyse druckabhängiger Änderungen der chemischen Verschiebung von Proteinen erlaubt es, Aussagen über strukturelle Fluktuationen zu machen, die diese bereits bei Umgebungsdruck aufweisen. Das Problem, allgemeine Effekte, die mit einer Erhöhung des hydrostatischen Drucks einhergehen, von strukturell bedingten Effekten auf die chemische Verschiebung zu trennen, wurde bisher durch das Einbeziehen der Eigenschaften unstrukturierter Modellpeptide angegangen. In dieser Arbeit wurden chemische Verschiebungen in 2D 1H‐15N‐HSQC Spektren von chemisch als auch druckdenaturierten Zuständen des Kälteschockproteins B aus Bacillus Subtilis (BsCspB) zugeordnet und ihre Abhängigkeit von Änderungen des hydrostatischen Drucks ausgewertet. Die durch hydrostatischen Druck denaturierte Polypeptidkette wurde verwendet, um allgemeine Effekte von strukturbedingten Effekten auf 1H und 15N chemische Verschiebungen zu trennen. Daraus resultierende Interpretationen der druckabhängigen Änderungen der chemischen Verschiebungen werden im strukturellen Kontext diskutiert. Es wurde festgestellt, dass das Ensemble unstrukturierter Konformationen von BsCspB anders auf eine Erhöhung des Drucks reagiert, als es unstrukturierte Modellpeptide tun. Daraus kann geschlussfolgert werden, dass der Ansatz, mit dem man allgemeine Effekte, die durch eine Erhöhung des Drucks hervorgerufen werden, abschätzt, die strukturellen Rückschlüsse ändert, die anhand einer Analyse von chemischen Verschiebungen getroffen werden.

Impact of Pressure-Dependent Interfacial Tension and Contact Angle on Capillary Heterogeneity Trapping of CO2 in Storage Aquifers

Summary Carbon dioxide (CO2) capillary trapping increases the total amount of CO2 that can be effectively immobilized in storage aquifers. This trapping, manifesting itself as accumulated CO2 columns at a continuum scale, is because of capillary threshold effects that occur below low-permeability barriers. Considering that capillary pressure is dictated by heterogeneous pore throat size, the trapped CO2 column height and associated CO2 saturation will vary spatially within a storage aquifer. This variation will be influenced by two pressure-dependent interfacial parameters—CO2/brine interfacial tension (IFT) and CO2/brine/rock contact angle. Our objective is to understand how the pressure dependence of these two parameters affects the heterogeneity of capillary trapped CO2 at a continuum scale. Our conceptual model is a 1D two-zone system with the upper zone being a flow barrier (low permeability) and the lower zone being a flow path (high permeability). The inputs to this model include microfacies-dependent capillary pressure vs. saturation curves and permeability values. The input capillary pressure curves were collected in the literature that represents carbonate microfacies (e.g., dolograinstone) in a prevalent formation in the Permian Basin. We then used the Leverett j-function to scale the capillary pressure curve for the two zones that are assigned with the same or different microfacies. During scaling, we considered the influence of pressure on both the IFT and contact angle of CO2/brine/dolomite systems. We varied the zone permeability contrast ratio from 2 to 50. We then assumed capillary gravity equilibriums and calculated the CO2 saturation buildup corresponding to various trapped CO2 column heights. The CO2 saturation buildup is defined as the CO2 saturation in the lower layer minus that in the upper one. We found that the saturation buildup can be doubled when varying pressure in a storage aquifer, after considering pressure-dependent IFT and contact angles. Thus, assuming these two parameters to be constant across such aquifers would cause large errors in the quantification of capillary trapping of CO2. The whole study demonstrates the importance of considering pressure-dependent interfacial properties in predicting the vertical distribution of capillary trapped CO2. It has important implications in developing a better understanding of leakage risks and consequent storage safety.

A two-phase nonlinear optimization method for routing and sizing district heating systems

This paper presents a method to find the optimal topology, pipe sizing, and operational parameters of a district heating system under consideration of one design point. The current high costs of district heating systems set limits regarding the minimum heat demand density required for economic network expansions. Optimized routing with ideal pipe sizing and optimal operating parameters offers a potential for cost reduction. Therefore, this paper introduces a new two-phase method for district heating network expansion planning. This method consists of consecutive optimizations, starting with a mixed-integer linear programming followed by a nonlinear optimization. During the mixed-integer linear programming, the district heating system is optimized with continuous diameters, and the nonlinear pressure and temperature dependencies must be linearized. The resulting topology and the continuous diameters are afterward handed over to a nonlinear sparse sequential quadratic programming. The continuous diameters are discretized using a numerical continuation strategy that gradually forces the continuous diameter variables into discrete diameter choices. As a proof of concept, the district heating system for a small town with 400 consumers is optimized and analyzed. The two-phase optimization is performed in 251.68sec, and in most cases, discrete or near discrete diameters are achieved in a nonlinear continuous optimization.

New insights on the mechanism of tribochemical interaction-induced wear of H-terminated Si(110)

Reactive molecular dynamics simulations are employed to reveal the atomic-level mechanisms of tribochemical interaction-induced wear of H-terminated Si(110) in humid environment. The result shows that with interfacial water increasing, the surface wear first increases and then decreases under 2.5 GPa, while always decreases under 4.0 GPa. Four different Si atomic removal mechanisms are revealed, i.e., the stretching effect of interfacial bridge bonds, the weakening effect of H adsorption, the strain effect of O intrusion, and the pure shearing effect of a-SiO2 tip, and their occurrences show the same normal pressure and interfacial water amount dependence as the surface wear. The analysis on the prerequisite for their occurrences shows that the corresponding interfacial tribochemical interactions are first facilitated and then suppressed under 2.5 GPa, while suppressed under 4.0 GPa, which is the origin of the different normal pressure and interfacial water amount dependence of the surface wear. Moreover, it is found that a-SiO2 surface can provide H, O, or Si atoms to participate in the interfacial tribochemical interactions, and has an absolutely dominant role in the material removal of Si(110)-H compared with interfacial water, but its role is gradually suppressed by the increased interfacial water. This work sheds new and deeper lights on the mechanism for the effect of tribochemical interactions on the Si material removal in chemical mechanical polishing.

Propane-Induced Inversion of the Pressure Dependence of Highly Efficient Microemulsions: Phase Behavior and Its Prediction via HLD

Propane-Induced Inversion of the Pressure Dependence of Highly Efficient Microemulsions: Phase Behavior and Its Prediction via HLD

Volume dependence of the charge density wave phase transitions

ABSTRACT We analyse the volume dependence of the charge density wave phase transition temperature T CDW for 16 one and two dimensional materials such as the rare earth tritellurides TbTe 3 , ErTe 3 , TmTe 3 DyTe 3 , the transition metal dichalcogenide 2H-NbSe 2 , and the quasi-one dimensional conductors K 0.3 MoO 3 , NbSe 3 , ( TaSe 4 ) 2 I . The volume dependence is taken in the form of the logarithmic derivative of T CDW in function of the strain components. We point out some characteristics of this parameter. This parameter is dimensionless with an absolute value of about 10 obtained from the measurements of the thermal expansion, the longitudinal elastic constants and pressure dependence for 11 one- and two-dimensional CDW systems. In contrast a huge positive value of about 100 is found at the lower charge density wave transition in TbTe 3 , ErTe 3 , TmTe 3 and DyTe 3 .

The pressure dependence of the experimentally-determined line intensity and continuum absorption of pure CO2 in the 1.6µm region

Fourier-transform measurements of pure CO2 spectra in the 1.6 µm region covering bands from the ground state to the 30011, 30012, 30013, and 30014 states at ambient temperature and 212 K with pressures up to 1 atm have been recorded. The measured spectra have been multispectrum-fitted with the Hartmann-Tran model with first order line-mixing taken into account. In the fits, a linear decrease of the line intensities with increasing pressure was introduced. From the fitted baselines, the self-continuum, which complements the contribution of the local lines within +/− 25 cm−1, was determined for the two strongest bands, 30012–00001 and 30013–00001. The depleted intensity was found to be transferred to the continuum for both temperatures. The intensity in the continuum at 1 atm was about 1 % of the total band intensity for ambient temperature and about 3 % at 212 K. For both temperatures, the average depleted intensity/continuum area was found in excellent agreement with values estimated from the second virial coefficient. From these results, a new spectroscopic database with pure CO2 line profile parameters was produced, with systematic line intensity uncertainties well below 0.1 %.Retrieval simulations for the CO2 1.6 µm and 2 µm bands measurements, planned with the future CO2M mission, similar to the OCO mission, were carried out to assess the impact of intensity depletion and continuum. The impact of the continuum was larger than that of the depletion and larger for the 2 µm band than for the 1.6 µm band, with a substantial column error of 2 % for the 2 µm band when omitting both, depletion and continuum.The findings regarding pressure-dependent intensity and continuum may be applicable to other in-band continua showing similarity to the monomer band in shape and position. The new results may increase the knowledge on the physical nature of continua.

High-pressure elasticity of novel (VNbTaTi)C high-entropy carbides

Acoustic velocities and elasticity of high P-T synthesized new (VNbTaTi)C high-entropy carbides (HECs) are reported at high pressure using large volume press (LVP)-based ultrasonic interferometry technique. Using the finite-strain equation approach, the bulk modulus and shear rigidity, and their pressure dependences, are derived from the current experimental data, yielding B0 = 261.6(2) GPa, G0 = 191.4(3) GPa, ∂B/∂P = 4.34(18), and ∂G/∂P = 1.83(6). Interestingly, the (VNbTaTi)C HECs is more incompressible than the superhard γ-B (∼213.9 GPa), and almost as incompressible as superhard PcBN (∼254 GPa). Meanwhile, its shear rigidity (∼191.4 GPa) is comparable to the superhard B6O-B4C composite (G = 202 GPa), and as stiff as the (TiZrNbTa)C (193 ∼ 195 GPa) HECs. More strikingly, the fracture toughness is enhanced up to ∼4.6(3) MPa·m1/2, and the Vickers hardness of (VNbTaTi)C HECs is ∼22.6(2) GPa, which are significantly stronger than other high-entropy carbides. These new findings and results may be very important for its applications in extreme environments.

Thermodynamic modeling of pressure-dependent phase diagram in alkali metals Li, Na and K

The high-pressure behavior of the alkali metals has attracted much attention in both experimental and theoretical aspects. This study is focused on the thermodynamic optimization of the temperature and pressure dependence of the molar volumes, the compressibility and phase diagrams of Li, Na and K according to the CALPHAD method. The pressure-temperature phase diagrams of lithium, sodium and potassium up to 50–100 GPa were calculated using the obtained thermodynamic parameters. The available experimental data, such as extremely low melting temperatures at high pressure, pressure-induced structural transitions between simple bcc and fcc crystals and the molar volume changes with the increasing pressure, were well reproduced in our calculations. The good agreements between our calculations and the experiments assessed in the literature indicated that our thermodynamic parameters are reasonable. Our thermodynamic calculations would assist to understand the phase transitions and structural properties of alkali metals at high pressure.

Pulsed townsend electron and ion swarm parameter measurements of the trigger RPC standard mixture

The electron swarm parameters and ion drift velocities of the standard mixture R134a/iC4H10/SF6 95.2/4.5/0.3 used in trigger-purpose resistive plate chambers are examined in the pulsed Townsend experiment. Reduced electric fields up to 330Td at pressures from 400Pa to 12kPa are investigated, whereby no significant pressure dependence of the reduced swarm parameters are observed. The acquired effective ionization coefficient and the bulk drift velocity agree with predictions made using the updated R134a cross-sections from the swarm parameter simulation software Magboltz version 11.19.

Quantitative in situ Raman spectroscopy investigation on HSO4− dissociation at high pressures (up to 420 MPa) and its geological implication

Sulfate-bearing hydrothermal fluids are widespread in crustal environments, and recent papers highlight a possible important role of sulfate as an agent for mass and electron transfers in subduction zone. The geochemical characters of sulfate-bearing fluids (e.g., ability of complexing with ore-forming elements) depend largely on the dissociation behavior of HSO4−. However, the dissociation of HSO4− was only investigated at vapor saturation pressures and the pressure dependence of the dissociation behavior is thus unclear. In this study, we modified the fused silica capillary capsule (FSCC) method to explore the dissociation behavior of HSO4− quantitatively via in situ Raman spectroscopy experiments. We designed a new heating stage that can accommodate a 7 cm-long FSCC, and we show that thick-walled FSCCs with high degrees of filling can withstand pressures up to 645 MPa at temperatures to 450 °C. The sulfate concentrations in Cs2SO4–H2SO4 solutions were measured using Raman spectroscopy with increasing pressures and temperatures (P–T). The sulfate concentrations were calibrated using Cs2SO4 solutions with known concentrations, and the concentrations of HSO4− were determined by mass balance. According to our experimental results, increasing pressure increases the dissociation of HSO4− into SO42− and H+ while increasing temperature promotes ion association, which means that HSO4− dissociation is favored in high-density fluids. Comparisons between our experimental results with those of thermodynamic predictions using currently available thermodynamic properties indicate that the dissociation of HSO4− is stronger than previously thought in high-density fluids, especially at high pressures. We then optimized the thermodynamic properties of HSO4− based on our experimental results, and used them to simulate the S(VI) speciation in slab-derived fluids. Similar with our experimental results, the simulations also predict that the HSO4− will largely dissociate into SO42− and H+ in fluids with high P–T conditions, causing the SO42− as the predominant S(VI) speciation in subduction zone.

Structural stability, mechanical, and thermodynamic properties under pressure of B2-type CuM (M = Be, Al, and Zn) alloys: a DFT investigation

In this work, we systematically examined the structural stability, mechanical properties, and thermodynamic behavior of B2-type CuBe alloy, and compared the results with isostructural Cu-based alloys (CuAl and CuZn) by employing first-principles calculations in the pressure range of −22 to 100 GPa. This study revealed the stable existence of CuBe alloy at low-density expansion states (e.g. ∼ −20 GPa), indicating its superior structural stability compared to CuAl and CuZn. The pressure dependence of properties such as cell parameter a (a/a 0) and density ρ (ρ/ρ 0), elastic parameters (elastic constants C ij , bulk modulus B, shear modulus G, and Young's modulus E), deduced parameters (B/G ratio, Poisson's ratio ν, Vickers hardness, sound velocity, and Debye termperature ΘD), and thermodynamic parameters (free energy F, entropy S, and heat capacity C v) were investigated. All CuM (M = Be, Al, and Zn) alloys had more difficulty undergoing uniaxial stress than shear stress. External pressure reduced the ductility of the CuBe alloy, while excess pressure (P > 50 GPa) resulted in increased ductility, which was similar to CuAl but different from CuZn. The hardness and ΘD values demonstrated consistent variation corresponding to the ductility changes. Thermodynamic parameters were minimally affected by pressure, and the stronger interactions led to greater F in the CuBe alloy. These findings offer confidence for the future design of ordered Cu-Be alloys with exceptional properties.

Plastic deformation of dry fine-grained olivine aggregates under high pressures

Abstract This study investigates the effect of pressure on diffusion creep of dry San Carlos and synthetic (prepared by sol-gel method) olivine. We prepared dry (water content < 9 ppm wt) fine-grained (< 1 μm grain-size) olivine and deformed the samples (both San Carlos and solgel olivine in the same assembly) in the same sample assembly under high-pressure (P = 2.9–8.8 GPa) and modest temperatures (T = 980–1250 K) at a fixed strain-rate. Evolution of strength was studied using the radial X-ray diffraction from various diffraction planes. We found that San Carlos and sol-gel olivine show similar rheological behaviour (when normalized to the same grain-size). Stress estimated by the radial X-ray diffraction increases with time and initially shows similar values for all diffraction planes. In many cases, stress values start to depend on the diffraction planes in the later stage and time dependence becomes minor. The micro-structural observations show that grain-size increases during an experiment. The results are interpreted using a theory of radial X-ray diffraction and the theoretical models of diffusion and dislocation creep. We conclude that the initial stage of deformation is by diffusion creep, but deformation in the later stage is by dislocation creep. For dislocation creep, our results are in reasonable agreement with previous low temperature dislocation creep results after a correction of temperature effect. For diffusion creep, we obtain an activation volume of 7.0 ± 2.4 cm3/mol that is substantially smaller than the values reported on dislocation creep but agrees well with the results on grain-growth. By comparing the present results on dry olivine with the previous results on wet (water-saturated) olivine, we found that water enhances diffusion creep but only modestly in comparison to dislocation creep. The difference in the pressure and water content dependence between diffusion and dislocation creep has an important influence on the dominant deformation mechanisms of olivine in the upper mantle.

Investigation of cyclopentene + OH and cyclopentene thermal decomposition reactions

This study presents the first high-temperature measurements of cyclopentene+OH→k1Products reaction over 856 – 1258 K and 1.03 – 4.33 bar. The determined rate coefficients of k1 exhibited Arrhenius temperature dependence with an activation energy ∼ 3.3 kcal mol−1 and negligible pressure dependence. Rate coefficients of OH + cyclopentene are faster than OH + 1-pentene but comparable to OH + 2-pentene, highlighting the significance of allylic CH bonds in these reactions. At 1258 K, our rate coefficient is ∼ 30 % slower than the average room-temperature measurement, indicating the role of OH-addition pathways at low temperatures. Site-specific rate coefficients and branching ratios are determined, with H-abstraction at the allylic CH site accounting for ∼68 % of the reaction and alkylic CH bond contributing ∼22 %. Our measured k1 may be given as (unit: cm3molecule−1s−1):k1=1.64×10−10e(−1660T)Cyclopentene decomposition reaction (cyclopentene→k2cyclopentadiene+H2) is studied over 1186–1472 K and 1.17 – 1.38 bar. Time-resolved yields of the product, cyclopentadiene, are monitored using a sensitive UV laser diagnostic near 220 nm. Absorption cross-sections of cyclopentadiene, measured in two separate mixtures, showed weak positive temperature dependence (8.7 – 9.8 × 10−18 cm2molecule−1) over 961 – 1326 K. Our rate coefficients of k2 exhibited a positive Arrhenius temperature dependence with an activation energy of ∼ 54.7 kcal mol−1. At 1300 K, the decomposition of cyclopentene proceeds 5.5 and 28 times faster than that of cyclopentadiene and cyclopentane, respectively. Our measured k2 may be expressed as (unit: s−1):k2=2.55×1012e(−27,527.6T)The pentagonal structure of cyclopentene influences its H-abstraction and decomposition reactions distinctively. While H-abstraction by OH follows a mechanism akin to cyclohexene and linear alkenes, with comparable rate coefficients at allylic CH bonds, the penta-ring structure significantly impacts the decomposition mechanism. Cyclopentene decomposition predominantly produces cyclopentadiene and H2 in a ring-conserving manner, differing from the cleavage of allylic-alkylic CC bonds in the decompositions of 1-alkenes and cyclohexene.

Inflection Point in Pressure Dependence of Ionic Conductivity as a Fingerprint of Local Structure Formation.

In this study, we employed dielectric spectroscopy to investigate the effect of temperature and pressure on the ion dynamics of phosphonium ionic liquids (ILs) differing by the length of an alkyl chain, [P666,n][TFSI] (n = 2, 6, 8, 12). We found that both temperature and pressure dependence of dc-conductivity (σdc) determined for all examined ILs herein exhibit unique characteristics, unusual for aprotic ILs. Two regions differing by ion self-organization have been identified from the derivative analysis of σdc(T-1) data. On the other hand, isothermal measurements performed at elevated pressure revealed a unique concave-convex character of σdc(P) dependences, resulting in a clear minimum in the pressure behavior of activation volume. Such an inflection point characterizing the pressure dependence of σdc in [P666,n][TFSI] ILs can be considered an inherent feature of ion dynamics governed by structural self-assembly. Our results offer a unique perspective to link the ion mobility at various T-P conditions to the nanostructural organization of ionic systems.

Phase Transition Thermodynamics of 1,3,5-Tris-(α-naphthyl)benzene: Theory and Experiment.

1,3,5-Tris-(α-naphthyl)benzene is an organic non-electrolyte with notable stability of an amorphous phase. Its glassy and supercooled liquid states were previously studied by spectroscopic and calorimetric methods. Despite the continuing interest in its amorphous state and, particularly, vapor-deposited glasses, the thermodynamic parameters of the vaporization of 1,3,5-tris-(α-naphthyl)benzene have not been obtained yet. Likewise, the reliable evaluation of the thermodynamic parameters of fusion below the melting point, required to establish the thermodynamic state of its glass, is still an unsolved problem. In this work, the heat capacities of crystalline and liquid phases, the temperature dependence of the saturated vapor pressures, fusion and vaporization enthalpies were determined using differential and fast scanning calorimetry and were verified using the estimates based on solution calorimetry. The structural features of 1,3,5-tris-(α-naphthyl)benzene are discussed based on the computations performed and the data on the molecular refractivity. The consistency between the values obtained by independent techniques was demonstrated.

Dynamic viscosity of low GWP refrigerants in the liquid phase: An empirical equation and an artificial neural network

This study presents a simple correlation for describing the temperature and pressure dependence of the liquid dynamic viscosity of low GWP refrigerants, namely HydroFluoroOlefins (HFOs) and HydroChloroFluoroOlefins (HCFOs). The model has 3 input parameters (i.e., reduced temperature, reduced pressure, and acentric factor) and 6 coefficients which were regressed on 794 experimental data collated from the literature for 7 alternative refrigerants (i.e., R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R1224yd(Z), R1336mzz(E), and R1336mzz(Z)). Moreover, a multi-layer perceptron neural network for the liquid dynamic viscosity of the studied fluids was developed from the selected dataset. The artificial network has the same 3 input parameters of the correlation and one hidden layer with 19 neurons. The results of the proposed correlation proved that it is an accurate model for calculating the dynamic viscosity of the studied liquid refrigerants, despite its simplicity. It ensured an average absolute relative deviation of the liquid dynamic viscosity (AARD(η)) of 2.88 %, lower than that given by other literature correlations. As expected, the multi-layer perceptron neural network provided the best results for all the selected refrigerants (AARD(η) = 0.86 % for the complete dataset), proving that it can be considered a reference for the development of other models.

Sound velocities, elasticity and thermal properties of cBN composite with AlN binder at high pressure

Cubic boron nitride (cBN) has been used as a tool material for several decades due to its high hardness and thermal stability. Various binders are commonly added to cBN to synthesise cBN composites for better cutting performance. However, most studies have only investigated properties such as hardness and bulk modulus, without comprehensively studying elastic properties through experiments. In this study, the sound velocities and elastic properties of cBN with AlN binder were determined by using the ultrasonic interferometry technique. The bulk and shear moduli with their pressure dependence were determined as B0 = 351 (3) GPa, G0 = 344 (3) GPa, B0′ = 4.32 (4) and G0′ = 1.74 (2) using the finite strain equation-of-state approaches. Elasticity-related thermal properties, such as Debye temperature, Grüneisen parameter, thermal conductivity and coefficient of thermal expansion were also estimated. The results show that the elastic properties of the cBN composite with vol. 8.8% AlN-binder are comparable to the pure cBN compact. Additionally, the thermal conductivity and coefficient of thermal expansion have little effect on cBN composite with AlN binder compared to pure cBN.