Density functional theory study of mechanical, thermal, and thermodynamic properties of zinc-blende CdS and CdSe.

The structural, dynamical, electro-optical, mechanical, and thermal characteristics of the newly synthesized intermetallic compounds Ru4Al3B2 and Ru9Al3B8 have been studied under ambient and elevated pressure through density functional theory (DFT). The obtained lattice parameters of the compounds are consistent with the experimental values. The metallic character of these compounds is established by the band structure and density of states (DOS). The electronic charge density distribution and bond analysis imply that Ru4Al3B2 and Ru9Al3B8 have mainly both ionic and covalent bonding. The non-negative phonon dispersion frequency of the compounds reaffirms their dynamical stability. Both compounds are tough as well as have high melting points, and hence, can be applied in harsh conditions. Mechanical properties are significantly improved under pressure. Thermal barrier coating (TBC) is a possible field of application for both compounds. The different thermal properties such as the Debye temperature (ΘD), Grüneisen parameter (γ), melting temperature (Tm), minimum thermal conductivity (Kmin) and lattice thermal conductivity (κph) of these compounds have been studied to figure out the suitable application areas in thermally demanding situations. The pressure and temperature dependent bulk modulus (B) and other thermodynamic properties have also been analyzed, which suggested that the present compounds are strong candidates for device applications at high temperature and pressure. Owing to their high optical absorptivity and reflectivity in the UV region, they are also candidates for UV-based applications. Furthermore, they also have applicability in the fields of electronics, aviation, energy storage, and supercapacitor devices for their superior electronic, thermal and mechanical properties.

A suitable material for wind turbine blades has promoted great interest in carbon-based thermoplastic polyurethane (TPU) composites as they are flexible, lightweight, and mechanically robust. However, these carbon-based fillers deteriorate the thermal and mechanical properties in the long run due to the high agglomeration of the nanoparticles. In addition to that, these fillers also increase the production cost because of the chemical treatment conducted on the fillers. Therefore, a new approach is essential for maintaining the mechanical and thermal properties without using expensive chemical treatment in a low-cost platform. In this work, we present low agglomeration with even distribution of reinforcing fillers in the TPU matrix and robust mechanical and thermal properties by incorporating TiO2 in the carbon-based TPU matrix (TiO2/MWCNT/TPU), without inclusion of costly chemical treatments. TiO2 improves morphology due to the low valency of Ti2+, which may decrease the particle size and thus, reduces agglomeration. Moreover, the enhanced morphology assists in sustaining the rigidity of its molecular structure at high temperatures. The composite also reveals excellent mechanical properties of high tensile stress (4.46 MPa), more extended elongation at break (49%), and high Young's Modulus (9.17 MPa). The thermal analysis using DMA and TGA revealed that the sample TiO2/MWCNT/TPU is a good heat insulator and has a high glass transition temperature compared to the neat TPU indicating its ability to sustain rigidity at high temperatures overall, this composite can perform in elevated weather conditions.

Structure, mechanical and thermo-physical properties of lanthanide fission product doped UO2 in U(V) state: A density functional study

Ultra-Strong, Ultra-Tough, Transparent, and Sustainable Nanocomposite Films for Plastic Substitute

Review of the high temperature mechanical and thermal properties of the steels used in cold formed steel structures – The case of the S280 Gd+Z steel

Al-based intermetallic compounds possess excellent mechanical and thermal properties, making them promising candidates for high-temperature structural applications. In this study, the structural stability, mechanical properties, and electronic characteristics of Al5TM (TM = Mo, Nb, Os, Re, Ru, Ta, Tc, Ti) intermetallic compounds were systematically investigated using first-principles calculations based on density functional theory. All alloys exhibit negative formation energy, indicating favorable thermodynamic stability. Elastic constant analysis shows that all compounds satisfy the Born stability criteria, confirming their mechanical stability. Among them, Al5Mo (205.9 GPa), Al5Nb (201.1 GPa), and Al5Ta (204.1 GPa) exhibit relatively high Young's moduli, while Al5Os, Al5Re, and Al5Ru demonstrate large bulk moduli and good ductility. The high Debye temperatures of Al5Mo (600.5 K) and Al5Nb (606.7 K) suggest excellent thermal stability at elevated temperatures. Electronic structure analysis reveals that all alloys exhibit metallic behavior with no band gap near the Fermi level. The hybridization between TM-d and Al-3p orbitals enhances the covalent bonding between Al and TM atoms. This study provides theoretical guidance for the design and application of high-performance Al-based intermetallic compounds.

Ag sinter joining technology has gained increasing attention for its excellent thermal and mechanical properties, especially for high-temperature applications. This study focuses on the lifetime prediction of a SiC power module by Ag sinter joining based on mechanical properties including tensile, fatigue, and creep properties from room temperature to 200°C, as well as thermal properties including thermal conduction and the coefficient of thermal expansion. These mechanical properties and thermal properties of sintered Ag paste were evaluated in the study and the results show that mechanical properties of sintered Ag largely depend on the test temperature. The sintered Ag paste tends to soften at high temperature, and the fracture changed from nearly brittle to totally ductile with the testing temperature increase. From the S–N curve, the fatigue is close to the Morrow equation but not the Coffin–Manson law at room temperature. The finite element simulation of the lifetime based on Morrow’s equation for the sintered Ag layer shows that there has a crack occurrence with one fourth the side length after 10,000 cycles from − 40°C to 200°C but the crack extension area is less than one tenth of the sintered Ag layer. This study will add to the understanding of the high temperature properties and high temperature reliability as well as the lifetime of Ag sinter joining in high-temperature applications.

Machine learning for predicting thermal transport properties of solids

Effects of thermal treatment on collagen present in bovine M. Semitendinosus intramuscular connective tissue. Analysis of the chemical, thermal and mechanical properties

The structural, electronic, optical and thermal properties of chalcopyrite LiAlTe2 are studied using the full potential linearized augmented plane wave (FP-LAPW) method framed within density functional theory (DFT). The Wu-Cohen generalized gradient approximation (WC-GGA) was used as exchange-correlation potential to calculate the structural properties. Furthermore, the Tran and Blaha modified Becke-Johnson (mBJ) functional was also employed to compute the electronic and optical properties in order to get best values. The structural parameters at equilibrium are in good agreement with previous experimental and theoretical calculations. The band structures and density of states are calculated and it is found that LiAlTe2 compound is a direct band gap (-) semiconductor. In addition, the optical properties such as dielectric function, refractive index, reflectivity and absorption coefficient are calculated for photon energies up to 25 eV. This study on the optical properties has also been enriched by the introduction of the analysis of birefringence and anisotropy for this material. The calculated values of all parameters are compared with the available theoretical data where a reasonable agreement has been obtained. The study of the material properties at high temperatures and pressures is very important to understand the behavior of a material in severe conditions, so the temperature and pressure dependencies of unit cell volume, bulk modulus, Debye temperature and specific heat capacities are obtained at different temperatures (0-1000 K) and pressures (0-8 GPa) using the quasi-harmonic Debye model. To our knowledge this is the first theoretical prediction of the thermal properties for LiAlTe2 compound and still awaits experimental confirmations. We have included the spin-orbit interaction (SOI) in our calculations which is known to have significant influence on the electronic and optical properties when heavy elements are present. A weak effect is observed for the studied compound. Keywords: DFT, Wien2k, Chalcopyrite, band gap, dielectric function, thermal properties.

High temperature (up to 1200 °C) thermal-mechanical stability of Si and Ni doped CrN framework coatings

This paper presents the impact of accelerated aging on selected mechanical and thermal properties and VOC emission of polypropylene composites filled with glass fiber with different fiber contents. Due to their positive properties (good thermal and mechanical properties, low weight), glass fiber reinforced thermoplastics are becoming increasingly important. Fiber reinforced thermoplastics are mainly produced by injection molding and extrusion, whereby the extrusion compounding process is primarily used to prepare fiber-filled granulates while the injection molding process is used to manufacture products. In this study, short glass fiber reinforced thermoplastics (polypropylene) are produced on a twin screw extruder. Then, tensile test specimens are produced by injection molding. The glass fiber content is between 20 and 40 wt%. In order to investigate the long-term stability, the test specimens are artificially aged in accordance with ASTM 1980. The thermal, mechanical, and emission properties were evaluated by means of differential scanning calorimetry (DSC), tensile tests, and TDS-GC-MS analysis prior to and after accelerated aging. The objective of this study was to investigate the effects of thermal aging on crystallinity and mechanical properties and on VOC emission of glass fiber reinforced isotactic polypropylene.

Production of silicon carbide reinforced molybdenum disilicide composites using high-pressure sintering

Thermal properties of carbon nanofibers enhanced lightweight cementitious composite under high temperature

Theoretical study on the mechanical and thermal properties of uranium dioxide doped with lanthanide fission products