Materials Letters: X最新文献

Laser powder bed fusion (LPBF) has revolutionized many industries. In this paper, we report a new approach of LPBF for oxide ceramics with selective oxidation that reduces cracks and manufacturing defects. In this method, laser energy density was used to control the oxidation within the material article. Cuprous oxide was additively manufactured into CuO with remarkable crack reduction and improvement in microstructure. The effect of process parameters on the microstructure of Cu₂O and its oxidation behavior toward energy beam of different laser powers were analyzed. The experimental results clarified that the oxidation was increased by increasing the laser power in the presence of oxygen.

The use of engineering ceramics with intricate geometries is limited by manufacturing processes and lack ease of machinability of ceramics. Additive manufacturing of pre-ceramic polymers which are pyrolyzed into ceramics after 3D printing has recently been used to circumvent traditional manufacturing processes creating ceramics with complex geometries, however, mechanical characterization is limited. Polymer-derived ceramics and their green-body precursors are printed using digital light projection 3D printing in two orientations (0°- and 90°- to the build plate) and mechanically characterized. The results show that mechanical anisotropy exists both in the green-body polymer samples where the 0°-samples are stronger and stiffer than their 90°-counterparts and the final ceramics, where the stronger samples are fabricated at 90° despite isotropic hardness measurements. Through the manufacturing process, it was noted that samples undergoing pyrolysis built in the 90°-orientation have a pyrolysis survival rate of 94% whereas the 0°-samples showed a survival rate of 54%. The results suggest that the build-direction of 3D printed green-bodies plays a role in both material manufacturing and mechanical integrity of the final ceramic materials.

The solidification rate of materials affects the properties of the cast product and the pouring temperature also influences the freezing conditions of cast-metal alloys. The propose of this study is to evaluate the tensile strength of cast samples by using five variations of pouring temperatures through permanent molds by a gravity casting process. The results showed that the tensile strength maximum was 443 MPa at 1210 °C, the freezing range affected the tensile properties of cast samples.

Lumefantrine, exhibits poor bioavailability due to its very low solubility. A liquisolid compact of lumefantrine was prepared with mesoporous silica as a novel coating material. Lactose anhydrous and syloid 244FP were selected as carrier and coating materials respectively. Varying the carrier to coating ratio from 10 to 35, six formulations were prepared and evaluated for tests for tablets. thermal, surface characteristics, surface morphology, and surface area analysis. The tabletability of the formulation lactose to syloid 244FP ratio at 20:1 was found to be the best among all in terms of compression characteristics, faster disintegration, and enhanced dissolution. Hence it can be concluded that the use of a suitable amount of mesoporous silica in the formulation of liquisolid compact could significantly enhance the dissolution of the drug.

An effect of variation of slit widths of excitation and emission monochromators on emission intensity, peak position and asymmetric ratio of Eu³⁺ has been observed in YPO₄:Eu³⁺. Stark splitting is observed. Eu³⁺ ion occupies D_2d site symmetry in crystal lattice. However, asymmetric ratio is observed to be lesser in value ∼≤1.5. The possible explanation for low value of asymmetric ratio is explained.

Additive manufactured flexible electrodes show prospect applications in flexible electronics. However, morphological defects may affect a flexible electronic device's sensitivity, response value, reliability, etc. Therefore, accurate and efficient defect detection is still challenging, especially for mass-manufactured flexible electrodes. This paper proposed and tested a rapid morphological defects detection approach with infrared thermography technology. This approach shows advantages of high detect resolution (minimum test defect: 183.38um), good linearity (R² = 0.9887), efficiency, and nondestructive and large-scale applications, thereby achieving quality control and process evaluation in the mass additive manufacturing of flexible electrodes. Furthermore, resulting in improves the reliability and consistency of flexible electronic devices.

In general, metastable β-Ti-alloys exhibit low ductility at room temperature, which restricts its workability and critical applications. Here, we report a hierarchical microstructure tailoring strategy to achieve an excellent strength-ductility combination in Ti-4Al-5Mo-5V-5Cr-1Nb (Ti-45551) alloy. It was revealed that high density deformation twinning can be successfully introduced in primary α particles of Ti-45551 alloy through warm dynamic plastic deformation (DPD). After warm DPD process, the hierarchical microstructure was constructed in Ti-45551 alloy, including equiaxed primary α particles with high density deformation twins, β-phase matrix and finely dispersed nanoscale secondary α lamellas. Uniaxial tensile experiments have revealed that Ti-45551 alloy exhibited enhanced strength-ductility synergy with hierarchical microstructure at room temperature. This excellent combination of strength and ductility is derived from high twin density in in primary α particles and unique hierarchical microstructure. Also, this study demonstrates a feasible and low-cost route to design high performance Ti alloy.

Despite extensive studies on electrorefining to remove impurities from copper production units, bleeding electrolytes is the most popular method for controlling impurities due to low operating costs. A controlled cooled-reheat cycle was used to remove impurities in industrial electrolytes of Khatoon Abad copper company. Phase identification and physical study were done by the XRD, SEM, TEM, and FTIR techniques. The results confirmed the possibility of the removal of 23 wt% Ni, 26 wt% Sb, 2.4 wt% As and convention of 6 wt% of As⁵⁺ to As³⁺ at cooled-reheat cycle.

Hot pressing of pure Ti and cast iron under vacuum formed a ∼15 µm wide TiC-layer through the thermo-reactive diffusion process. Nanoindentation testing of the TiC-layer revealed average hardness and elastic modulus values of ∼35 GPa and ∼400 GPa, respectively. High-resolution indentation mapping indicated hardness change across the boundary with peak values observed within the TiC-layer. Solid state high temperature diffusion holds significant potential for developing uniform hard coatings on pure Ti/Ti-alloys.