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At present, the steel industry produces a large amount of steel slag during the smelting process, which causes serious pollution to the environment and land. Therefore, new technologies must be used to deal with steel slag. In this study, the steel slag powder refined by the wet grinding technology is used as the matrix material, MgO as material additive, and the clay is used as the binder to prepare a new type of composite heat storage material. The results indicate that the mass ratio of wet grinding steel slag powder, MgO powder and clay is 6:3:1, the composite heat storage material can have a strong compressive strength of 70.9 MPa. The thermal conductivity of the heat storage material is 0.98 W/m⋅K and can reach 1.27 J/g⋅K at 720 ℃, which has good thermal conductivity and long service life. When the heat storage material rises to 900 ℃, the heat storage density can reach 905 J/g, with good heat storage performance and thermal cycle stability. The objective is to develop sustainable and low-cost thermal energy storage material for industry waste heat recovery and in renewable energy applications. At the same time, this valuable market for slag in the energy field provide a new way to directly utilize steel slag with extraordinary economic and environmental benefits. [ABSTRACT FROM AUTHOR]

In recent years, heat storage technology has attracted wide attention in the fields of renewable energy storage for its relatively high melting point, high heat storage capacity and economy, Na2CO3 and eutectic salt mixtures containing Na2CO3 are promising candidates in the field of solar energy storage. In this paper, a molecular dynamics (MD) simulation of Na2CO3 was conducted with the Born–Mayer potential function. The simulated solid–liquid phase change temperature is 1200 K, and the error is 5.4%. The heat capacity at constant pressure (Cp) is higher in liquid than in solid, the average Cp of solid is 1.45 J/g and that of liquid is 1.79 J/g, and the minimum error is 2.8%. The simulation results revealed the change rules of density and thermal expansion coefficient of Na2CO3 in the process of heating up, and these changes were analyzed by radial distribution functions (RDF) and angular distribution functions (ADF). Moreover, the RDF and ADF results show that the atomic spacing of Na2CO3 increases, the coordination number decreases, and the angle distribution between atoms becomes wider as the temperature rises. Finally, this paper examined the microscopic changes of ions during the phase transition of Na2CO3 from solid to liquid. It is concluded that the angle change of CO 3 2 − in the liquid state is more sharply. This study improves the understanding of the thermodynamic properties and local structure of Na2CO3 and provides theoretical support for Na2CO3 heat storage materials. [ABSTRACT FROM AUTHOR]

TiAl-based alloy is an excellent high-temperature structural material, but poor hot workability has been the bottleneck hindering its development. In this study, we take into account the hot workability and mechanical properties of Ti-48Al alloy through microstructure adjustment. Powder metallurgy Ti-48Al alloy prepared by vacuum sintering is used as the raw material, which has a near-γ microstructure composed of equiaxed grains. Although the composition is simple, the alloy achieves high mechanical properties after forging with 75 % deformation. Controlling the forging temperature to 1300 °C can make the microstructure transform into a duplex structure composed of γ/α2 lamellar colonies and γ equiaxed grains. As-forged alloy has an ultimate tensile strength of 650 ± 17 MPa and a yield strength of 644 ± 16 MPa at room temperature. It still maintains high strength at high temperature, with ultimate tensile strength of 684 ± 19 MPa at 500 °C, 700 ± 19 MPa at 700 °C, and 320 ± 10 MPa at 900 °C. In addition, the alloy has good ductility with elongation of 58.2% due to dynamic recrystallization at 900 °C. • Mechanical property is significantly improved by forging with simple composition. • The alloy has ultrafine equiaxed grain of 2.45 µm and lamellar spacing of 20–50 nm. • Duplex microstructure without remnant lamellae forms in PM Ti-48Al alloy. • Ti-48Al alloy exhibits great plasticity of 58.2 % at 900 °C. [ABSTRACT FROM AUTHOR]

We prepared a reduced-graphene-oxide/Cu (rGO/Cu) composite coating to suppress the total secondary electron yield by two-step electrodeposition. We found that driven by the applied electric field, copper ions can enter the interior of graphene oxide (GO) film and nucleate, while the surface is still GO. The rGO/Cu composite coating was obtained by heat treatment with a combination of hydrogen and argon. After heat treatment, XPS analysis shows that the oxygen content of rGO on the surface of the composite coating is reduced from 31.29 at.% to 11.00 at.%, and the carbon content is 85.25 at.%. Raman analysis shows that rGO is still mainly sp2 hybrid structure. The deposited copper particles sintered in the composite coating and formed Cu-O-C chemical bond. The maximum secondary electron yield (δ max) is 1.10, which is close to the δ max of rGO coating (1.09). Compared with the rGO coating, the presence of copper in the rGO/Cu composite coating slightly increases the TEY, but significantly improves the bonding strength between the coating and the substrate at high temperatures. [Display omitted] • A new method for preparing rGO/Cu composite coatings was proposed. • Copper ions enter into the GO layer and nucleate under the applied electric field. • Stable rGO/Cu coating at variable temperature was obtained on OFCU surface. • The rGO /Cu composite coating has excellent low secondary electron yield. [ABSTRACT FROM AUTHOR]