Understanding rock resistivity is essential for interpreting subsurface resistivity structures obtained from electromagnetic surveys. We can estimate porosity or water content from resistivity using rock physics models; however, predicted results are strongly dependent on the model with the assumption of an internal pore microstructure. In this study, we evaluated the relationship between the resistivity and pore microstructure of clay-free sandstones based on digital rock physics while focusing on tortuosity. Simulation results demonstrated an increase in resistivity and its anisotropy with decreasing porosity. Tortuosity values calculated from local electric current further explain the evolution of resistivity, which suggests that smaller pore volumes (i.e., porosity) prevent pore connectivity and enhance tortuosity, resulting in higher resistivity and anisotropy. The resistivity of high-porosity data can be fitted using Archie’s equation with empirical parameters, whereas the resistivity of low-porosity data cannot. This illustrates the difficulty in applying Archie’s equation to low-porosity rocks; however, the equivalent channel model reproduced the resistivity over a wide porosity range using the calculated tortuosity. Our results confirm that tortuosity is a key factor for determining electrical properties.

The effect of carbon on the heterogeneous deformation behavior of a martensite was investigated by multiscale strain distribution analysis using the digital image correlation method. Specially, 18%Ni martensitic steels with and without carbon (0.15C steel and C-free steel, respectively) were studied. Low-magnification observation showed that in both steels, a macroscopic strain distribution was caused by the shape of the specimen. However, high-magnification observation revealed that the strain was concentrated in specific blocks in 0.15C steel, suggesting that its heterogeneous deformation behavior depends on the martensitic structure. Thus, addition of carbon in 18%Ni steel was concluded to cause preferential plastic deformation of the blocks owing to an in-lath plane slip system, which tends to promote heterogeneous deformation.

The mechanical property, macro and micro-structure of AA6181 aluminum alloys sheets during twin roll casting (TRC) process with pulse electric current (PEC) of different intensity were tested and observed. With increased PEC intensity, the effect of controlling macro-segregation of sheet was more apparent the flow and temperature field during the TRC process was substantially unchanged with the different intensity of PEC. The primary dendrite arm of Al-Mg-Si alloy was increased, but the growth of secondary dendrite arm spacing was restrained. The elongation was increased from 8.1% to 24.2% when PEC strength reaches from 100 A to 500 A. But the yield strength and tensile strength with increasing strength of PEC show a change slightly.

Cellulose nanofiber (CNF) is regarded as a new-generation reinforcement fiber with its low density and high mechanical properties. However, it has been considered that CNF could lose its outstanding properties due to carbonization. Therefore, CNF has never been consolidated with metal powders. On the other hand, titanium carbide (TiC) fiber is probably obtained by the chemical reaction between the carbonized CNF and titanium (Ti). This study evaluated the morphology transformation of CNF in Ti during consolidation. Moreover, the tensile properties of CNF-added Ti were investigated. CNF was carbonized around 350°C and micrometer-sized and round-shaped TiC crystals were precipitated. In addition, the O atom was distributed into Ti during the CNF carbonization process. Ti–CNF 3.25 wt% compact showed an ultimate tensile strength (UTS) of above 700 MPa and a good fracture elongation. It was demonstrated that the UTS of Ti–CNF 3.25 wt% compact was a higher UTS than the theoretical value estimated from the increment of 0.2% yield stress of Ti by O atoms.

Cryogenic applications require careful material selection due to severe property degradation at low temperatures. Face-centered cubic (FCC) alloys like high-manganese steel offer good low-temperature toughness but become brittle at cryogenic temperatures. This brittleness increases safety risks due to sudden, unpredictable fractures. Therefore, novel technologies are urgently needed to improve the mechanical properties of FCC alloys for cryogenic applications. This research presents a new surface-cracking process for high-manganese steels to address the degradation of mechanical properties at cryogenic temperatures. This technique involves the intentional introduction of surface micro-cracks, which significantly enhances the Charpy impact toughness of the steel at low temperatures. To observe the effect of surface cracks, specimens with varying crack densities were fabricated: 5 lines (5L) and 10 lines (10L). These were compared with a standard specimen without surface cracks (0L). Microstructural observations reveal that the dispersion of crack propagation energy by the surface micro-cracks improves Charpy impact toughness, promoting a ductile fracture mode even under cryogenic conditions.

This study investigates the effect of loading direction on the compression behaviour of extruded pure magnesium with different grain-sizes and at different strain-rate. At the same grain-size level, samples compressed at 45 degrees to the extrusion direction have lower yield stress than samples compressed parallel to the extrusion direction. However, the loading direction has a negligible effect on the dominant deformation modes in the studied conditions.

The use of COSMO-RS (COnductor-like Screening MOdel for Realistic Solvation) method was adopted in this study to efficiently identify substances that exhibit selective adsorption on chalcopyrite (CuFeS2) and enargite (Cu3AsS4). For each mineral, the changes in concentration for approximately 20 substances were examined through experiment, and their adsorption capacities were quantified using Henry’s law constants. Multiple linear regression analyses were conducted using the Henry’s law constant data as the objective variables and the σ-moments acquired from COSMOtherm as the explanatory variables. This established adsorption prediction equations specific to each mineral. Equations for both minerals exhibited a high predictive accuracy with R2 values of >0.9. Quantitative adsorption amounts were obtained by incorporating the σ-moments for 11,577 substances obtained from COSMOtherm into these equations. Further investigation was also executed by a novel concept of “Contributions,” representing the extent of contribution to adsorption, based on adsorption prediction equations and σ-moment definitions. In addition, for several selected chemicals, bubble pickup tests were performed as a fundamental evaluation of the reagents for flotation separation. It was found that PEG-8 increased the amount of chalcopyrite collected by 62% selectively and dodecane decreased the amount of enargite collected by 48%, demonstrating the effectiveness of screening based on this method. This study proposes a new screening method for flotation agent candidates based on a simple adsorption prediction formula obtained by combining adsorption experiments and numerical analysis, and demonstrates its validity.

A Cu/carbon steel multilayered sheet was quenched, and its tensile properties and electrical conductivity were evaluated. A full martensite structure was developed in the carbon steel layers in the multilayered sheet after quenching at 1063 K. The obtained Cu/martensite steel multilayered sheet exhibited a much higher ultimate tensile stress and approximately identical electrical conductivity compared to those in the Cu/carbon steel multilayered sheet without a quenching process. The decrease in the electrical conductivity during the quenching process in the multilayered sheet can be predicted from the decrease in the conductivity of the Cu layers owing to the diffusion of Fe atoms into the Cu layer. The ultimate tensile stress-electrical conductivity balance in the Cu/martensite steel multilayered sheet was 5.0 × 104 MPa%IACS, which is higher than that in conventional commercial Cu alloys. The ultimate tensile stress-total strain balance in the Cu/martensite steel multilayered sheet was significantly lower than that in each phase in the sheet. The measured ultimate tensile stress and electrical conductivity in the Cu/martensite steel multilayered sheet were approximately identical to the values estimated from the rule of mixture, using the tensile stress, electrical conductivity, and volume fraction of each component phase. This result indicates that the ultimate tensile stress and electrical conductivity of multilayered sheets can be easily controlled based on the rule of mixture.

Recently, direct recycling has gained attention as an environmentally friendly and cost-effective lithium-ion battery (LIB) recycling process. This technology focuses on recycling cathode active materials (CAMs) from spent LIBs or manufacturing scrap. In this study, we investigated the direct recycling of CAMs recovered from manufacturing scrap using a dry grinding and classification process, with dried cathode composite materials used as experimental material. In the grinding process, a jaw crusher was used for primary grinding, followed by a stirred media mill for secondary grinding. Particles under 32 µm were classified into three fraction size groups (coarse, medium, and fine) using an elbow-jet air classifier. Thermogravimetry differential thermal analysis and scanning electron microscopy confirmed the concentration of polyvinylidene difluoride and carbon powder in the fine-sized fraction. X-ray diffraction showed no degradation of crystallinity during the process. Finally, charge-discharge and cycle tests were conducted on battery cells made from two types of cathode slurry. Cathode Slurry I, prepared by mixing 10 mass% of coarse- and medium-sized fractions, exhibited almost the same battery performance as the original product. Cathode Slurry II, prepared by mixing 10 mass% of fine-sized fraction, along with a higher amount of organic matter, resulted in a higher internal resistance and a 5.3% decrease in initial battery capacity. This study demonstrated the potential for direct recycling of CAMs from manufacturing scrap using a simple grinding and classification process.