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In this paper, a novel hybrid triply periodic minimal surface (TPMS) core with a nonlinear transition region was designed by combining two types of TPMS (Diamond and Schwarz P) structures using the sigmoid function. The width of the transition region was precisely regulated by adjusting the gradient control parameter r in the sigmoid function. Composite sandwich structures (CSS) were fabricated by bonding two carbon fiber reinforced polymer (CFRP) face sheets to a 3D printed polylactic acid (PLA) core. The bending performance and failure mechanisms of the CSSs with the hybrid TPMS cores were analyzed through three-point bending tests and finite element analysis (FEA). The results indicate that as r increases, the transition region of the hybrid TPMS cores becomes narrower, leading to a gradual decrease in bending strength, bending stiffness, and core shear stress. The failure process of the CSSs in the experiment aligns well with the FEA results. Through comparative analysis of the stiffness-to-weight and strength-to-weight ratios of the CSSs with the native TPMS cores, the hybrid TPMS cores with a wider transition region enhance the structural efficiency of the CSSs, while those with a narrower transition region negatively impact the performance of the CSSs. [ABSTRACT FROM AUTHOR]

A larger liquid–gas interface area during the carbonation process for preparing high-purity aragonite CaCO3 whiskers by using porous quartz stones was developed. The presence of plenty of open pores ranging from 0.02 to 0.20 mm inside the porous quartz stones could disperse CO2 gas in Ca(OH)2 suspension into tiny bubbles, with an average diameter ranging from 0.28 to 3.05 mm and a large liquid–gas interface area ranging from 3571.4 to 327.9 mm2, respectively, which could enhance the diffusion effect of CO2 molecules and the uniformity of carbonate ions in the system. Thus, a uniform and low supersaturation was obtained, improving the growth of CaCO3 whiskers. The prepared CaCO3 whiskers showed the highest purity of 99.7%. The formation mechanism of ultrahigh purity CaCO3 whiskers was also studied in detail. Then, the prepared CaCO3 whiskers were introduced into a PVC matrix to study their effect on the tensile strength of PVC, and the results showed that the tensile strength was enhanced by 46.4% with 5 wt% whiskers. This method provides an effective way to enhance the performance of inorganic crystals. [ABSTRACT FROM AUTHOR]

Abstract: Fluffy hollow carbon spheres with the diameter of 0.3–1.8 μm and shell thickness of 30–80 nm were successfully synthesized via FeCl3 catalyzed solvent-thermal reaction in a sealed autoclave at 350 °C for 3 h, with CaC2 and CCl4 as carbon sources and reactants. XRD and TEM observations verify that the fluffy hollow carbon spheres are composed of curved and disordered carbon flakes with the interlayer instance of approximate 0.35 nm. Furthermore, MCNTs with Fe–Mn–Cr nanorods encapsulated are also observed. A possible growth mechanism for the fluffy hollow carbon sphere is proposed. [Copyright &y& Elsevier]

W–Cu composites with Ag/La2O3 hybrid addition were prepared through pressure-free sintering at different sintering temperatures from 900 to 1200 °C. Microstructure, electrical conductivity and mechanical properties of W–Cu composites with additional Ag/La2O3 hybrid were analyzed. Microstructural observation showed that Ag was partially solubilized into Cu to generate Cu–Ag solid solution during the sintering, while Ag aggregation and La2O3 dispersion were found in the Cu matrix. The higher sintering temperature reduced the porosity of the sintered bulk composites. W–Cu composites with Ag/La2O3 hybrid addition possessed the higher values of electrical conductivity, hardness and strength at each sintering temperature, and the optimum sintering temperature was 1100 °C, at which Ag/La2O3 hybrid reached enhancement in properties comparing with W–Cu composites. [ABSTRACT FROM AUTHOR]