Theoretical investigation on mechanical,thermal,and ultrasonic properties of epitaxial nanostructured ZrN layers growth on MgO(001)substrate

In the present study,we calculated the elastic,mechanical,and thermo-physical properties of Zirconium Nitride(ZrN)/Magnesium Oxide(MgO)(001)nanostructures in the temperature range of 50∼300 K using higher-order elastic constants.With two fundamental factors,nearest-neighbor distance and hardness parameter,in this tem-perature range,the second-and third-order elastic constants(SOECs and TOECs)are estimated using the Coulomb&Born-Mayer potential.The computed values of SOECs have been used to calculate Young’s modulus,thermal conductivity,Zener anisotropy,bulk modulus,thermal energy density,shear modulus,and Poisson’s ratio to as-sess the thermal and mechanical properties of the ZrN/MgO(001)nanostructured layer.Additionally,SOECs are used to calculate the wave velocities for shear as well as longitudinal modes of propagation along crystalline orientations<100>,<110>,and<111>in these temperature ranges.The temperature-dependent Debye average velocity,hardness,melting temperature,and ultrasonic Grüneisen parameters(UGPs)were evaluated.The frac-ture/toughness(B/G)ratio in the current investigation was greater than 1.75,indicating that the ZrN/MgO(001)nanostructured layer was ductile in this temperature range.The selected materials fully satisfied the Born me-chanical stability requirement.At this ambient temperature,it has been computed how long thermal relaxation takes to complete and how ultrasonic waves are attenuated by thermo-elastic relaxation and phonon-phonon interaction mechanisms.These results,in combination with other well-known physical properties,can be applied to the non-destructive testing of materials for various industrial applications such as microelectronic devices,optical coatings,batteries,and solar cells.

Effects of Ultrasonic Treatment on Microstructure and Mechanical Properties of Semisolid Sn-52Bi Alloy

The effects of ultrasonic vibration temperature on the microstructure of semisolid Sn-52 Bi alloy and mechanical properties were investigated. The results show that the microstructure and mechanical properties are improved obviously after the ultrasonic treatment. Nearly round and uniformly distributed primary Sn phase particles were obtained under the cavitation and acoustic streaming caused by ultrasonic treatment. The best effects of ultrasonic treatment on microstructure and mechanical properties were obtained with the ultrasonic vibration for 120 s at 140 ℃. The elongation of semisolid Sn-52 Bi alloy treated by ultrasonic vibration for 120 s at 140 ℃ was 42% and increased by 156.09% compared to conventional liquid casting Sn-52 Bi alloy without ultrasonic vibration. It is a feasible and effective method to adopt the semisolid metal forming technology assisted with ultrasonic vibration to improve the ductility of Sn-Bi alloys.

Modeling the hydration,viscosity and ultrasonic property evolution of class G cement up to 90℃ and 200 MPa by a scale factor method

A comprehensive experimental program has been performed to characterize the hydration and engineering property evolution of a class G oil well cement under various curing temperatures from 30 to 90℃.The progress of hydration was monitored by isothermal calorimetry(atmospheric pressure);the viscosity evolution was measured using a high temperature and high pressure consistometer(up to 200 MPa);the ultrasonic property development was evaluated by an ultrasonic cement analyzer(up to 100 MPa).Test results indicate that the influences of curing temperature and pressure on the hydration,viscosity and ultrasonic property development can be modeled by a scale factor method that is similar to the maturity method used in the concrete industry.However,the key parameters of the scale factor model,namely the apparent activation energy and the apparent activation volume of cement showed obvious variations with test method and curing condition.The test results indicate that the curing temperature has a stronger effect on cement hydration rate than viscosity and ultrasonic property development rate,while the curing pressure has a much stronger influence on cement slurry properties before setting(viscosity)than after setting(ultrasonic property).

Physical properties,vitrinite reflectance,and microstructure of coal,Taiyuan Formation,Qinshui Basin,China

In this study, we experimentally established the relationship between physical properties, vitrinite reflectance, and microstructure of coal, Taiyuan Formation, Qinshui Basin, China using representative coal samples collected from three different mines via the rock mechanics testing system （MTS）. We analyzed the organic macerals, vitrinite reflectance, and microstructure of 11 coal samples using petrography and scanning electron microscopy （SEM）. The experimental results suggest that （1） the elastic parameters can be described by linear equations, （2） both P- and S-wave velocities display anisotropy, （3） the anisotropy negatively correlates with vitrinite reflectance, and （4） the acoustic velocities and Young＇s modulus are negatively correlated with the volume of micropores. The derived empirical equations can be used in the forward modeling and seismic inversion of physical properties of coal for improving the coal-bed methane （CBM） reservoir characterization.

Evolution of Microstructure,Mechanical Properties and Corrosion Resistance of Ultrasonic Assisted Welded-Brazed Mg/Ti Joint

Ultrasonic vibration with different powers from 0 k W to 1.6 k W was applied during the tungsten inert gas welding-brazing of Mg/Ti.The microstructures,mechanical properties and corrosion resistance of the ultrasonic assisted tungsten inert gas（U-TIG） welded-brazed Mg/Ti joint were characterized.The results showed that,without being subjected to ultrasonic vibration,coarse columnar α-Mg grains occurred in the fusion zone of Mg/Ti joint.However,with ultrasonic power of 1.2 k W,the average grain size of columnar α-Mg grains was refined from 200 μm to about 50 μm and the tensile strength of joints increased^18% up to 228 MPa.Besides,high fraction of grain boundaries was introduced by grain refinement,contributing to improve the corrosion resistance in two ways：（i） accelerating the formation of Mg（OH）2protective layer and（ii） reducing the mismatch and disorder between Mg（OH）2 protective layer and Mg alloy surface.

Effect of trabecular bone material properties on ultrasonic backscattering signals

In this study, ultrasonic backscattering signals in cancellous bones were obtained by finite difference time domain （FDTD） simulations, and the effect of trabecular material properties on these signals was analyzed. The backscatter coefficient （BSC） and integrated backscatter coefficient （IBC） were numerically investigated for varying trabecular bone material properties, including density, Lame coefficients, viscosities, and resistance coefficients. The results show that the BSC is a complex function of trabecular bone density, and the IBC increases as density increases. The BSC and IBC increase with the first and second Lame coefficients. While not very sensitive to the second viscosity of the trabeculae, the BSC and IBC decrease as the first viscosity and resistance coefficients increase. The results demonstrate that, in addition to bone mineral density （BMD） and microarchitecture, trabecular material properties significantly influence ultrasonic backseattering signals in cancellous bones. This research furthers the understanding of ultrasonic backscattering in cancellous bones and the characterization of cancellous bone status.

Structural, optical and electrical properties of Sn_xS_y thin films grown by spray ultrasonic

Tin sulfide（Snx Sy/ thin films were prepared by a spray ultrasonic technique on glass substrate at 300℃.The influence of deposition time tD2, 4, 6, 8 and 10 min on different properties of thin films, such as（XRD）,photoluminescence（PL） and（UV） spectroscopy visible spectrum and four-point were investigated. X-ray diffraction showed that thin films crystallized in SnS2, SnS, and Sn2S3 phases, but the most prominent one is SnS_2. The results of the（UV） spectroscopy visible spectrum show that the film which was deposited at 4 min has a large transmittance of 60% in the visible region. The photoluminescence spectra exhibited the luminescent peaks in the visible region, which shows its potential application in photovoltaic devices. The electrical resistivity（ρ） values of SnxSy films have changed from 8.1×1064to 1.62Ω·cm with deposition time.

Ultrasonic investigations on elastic properties of (Bi,Pb)-Sr-Ca-Cu oxide ceramic superconductors

Ultrasonic velocities have been measured in single phase Bi_1.7 Pb_0.3Sr2CaCu2O8+x and Bi1.7Pb0.3Sr2Ca2O10+x polycrystalline samples. Anomalous changes of both longitudinal and transverse velocities were observed near 200K, which indicates that some structural phase transitio might occur. The elastic constants of these samples have been determined from the measured ultrasonic velocity data, which are much smaller than those of YBa2 Cu3 O7-y and BaTiO3, manifesting that the interlayer coupling will dramatically decrease when the c - axes of the unit cells of these perovstite-like multilayer ceramics increase. The values of Poisson ratio, however, of those ceramics are very close, implying similar interatomic bonding forces. Corrected to void-free state, the Debye temperature of these materials is estirnated as 270 ±20k. The temperature dependence of Debye temperatures for these materials is also calculated by using the same method and reported for the first time.