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The high temperature gas-cooled reactors (HTGRs) are the next-generation reactors with high safety, because the cores of HTGRs would not melt. But it is important to improve the oxidation resistance of the fuel in case of a huge oxygen ingress into the core to further improve the safety of HTGRs, because most of the volume of the core of the HTGRs consists of graphite. Coated fuel particles (CFPs), of which the diameter is around 1 mm, are used in HTGRs. A small sphere containing fissile materials is sealed up with ceramics coating layers to form a CFP. A mixture of CFPs and starting materials of binding material (matrix) is sintered to form fuel compact. Currently the matrix is graphite, which would easily oxidized in case of a huge oxygen ingress into the core. In this study, the development of oxidation resistant fuel compact, of which the matrix is a mixture of SiC and graphite, has been carried out. Simulated CFPs (alumina particles) and starting materials of matrix (Si powder, graphite powder and resin) were molded and hot-pressed into simulated fuel compacts. In order to maintain the structural integrity of fuel elements for HTGR under accident conditions, not only oxidation-resistant but also high-strength fuel compacts should be further developed. Hot press conditions such as pressure would be one of the factors affecting the strength of the HTGR fuel elements. In order to identify the optimal hot press conditions for preparing the high-strength fuel elements, the effect of the hot press conditions on the mechanical strength properties of the HTGR fuel elements should be evaluated quantitatively. In the present study, the response surface model, which represents the relationship between the hot press conditions and the mechanical strength properties, has been constructed by introducing statistical design of experiments (DOE) approaches, and the optimal hot press conditions were estimated by the model.

In this research, Co-30 mass% Cr alloys were fabricated by a vacuum hot-press sintering process. Different amounts of submicron cobalt and chromium (the mean grain size is 800 and 700 nm, respectively) powders were mixed by ball milling. Furthermore, this study imposed various hot-press sintering temperatures (1100, 1150, 1200 and 1250°C) and pressures (20, 35 and 50 MPa), while maintaining the sintering time at 1 h, respectively. The experimental results show that the optimum parameters of hot-press sintered Co-30 mass% Cr alloys are 1150°C at 35 MPa for 1 h. Meanwhile, the sintered density reaches 7.92 g·cm–3, the closed porosity decreases to 0.46%, and the hardness and transverse rupture strength (TRS) values increase to 77.2 HRA and 997.1 MPa, respectively. While the hot-press sintered Co-30 mass% Cr alloys at 1150°C and 20 MPa for 1 h, the electrical conductivity was slightly enhanced to 1.79 × 104 S·cm–1, and the phase transformation (FCC → HCP) of cobalt displayed a slight effect on sintering behaviors of Co-30 mass% Cr alloys. All these results confirm that the mechanical and electrical properties of Co-30 mass% Cr alloys are effectively improved by using the hot-press sintering technique.

The springback failure of ultra-high strength boron steel (22MnB5) in hot press forming (HPF) process was characterized under bending and membrane conditions. Hot press forming for U–shaped parts with ultra-high strength boron steel were experimented and simulated to study the effect of initial blank temperatures on springback failure in the automotive industry. The results specify the various preheated temperature of 22MnB5 blank effect toward springback occurrences with reference to hot press forming dies design. ANSYS Workbench was used to verify finite element (FE) simulations of the processes in order to consolidate the knowledge of springback. The validated numerical simulation model were used in analyzing the stress and strain distributions along the formed part in the FE models, it was found that the springback angle was related in averaging value throughout quenching, regardless of the forming conditions. Springback failure mainly caused dimension deviation in hot press form parts due to the impact of thermal restoring moments and quenching rate of hot press forming process.

In the present research an Al–7.7%Mn–4.9%Zr–3.2%Cu (wt%) alloy was processed by mechanical alloying (MA) followed by hot press sintering. The microstructure, phase composition, and mechanical properties of the MA granules and sintered samples were investigated. The dissolution of Mn, Zr, and Cu with further precipitation of the Al6Mn phase were observed during high-energy ball milling. In the alloy processed without stearic acid after milling for ~10 h, an Al-based solid solution with ~4.9 wt%Zr, ~3.2 wt%Cu and a ~5 wt%Mn with a grain size of ~16 nm and a microhardness of ~530 HV were observed. The addition of stearic acid facilitated Mn dissolution and precipitation of the Al6Mn phase during milling but led to the formation of the ZrH2 phase that decreased the Zr solute and the microhardness. Precipitation of the Al6Mn, L12–Al3Zr, and Al2Cu phases during annealing and sintering of the MA granules in the temperate range of 350–375 °C was observed, and an additional Al20Cu2Mn3 phase was precipitated at 400–450 °C. Hot-press sintering at 450 °C provided a low fraction of cavities of ~1.5%, the yield strength of 1100 MPa, ultimate compressive strength of 1200 MPa, strain at fracture of 0.5% at room temperature, the yield strength of 380 MPa, ultimate compressive strength of 440 MPa, and strain at fracture of 3.5% at 350 °C. The microstructural evolution during high-temperature deformation on the sample surface was studied and the differences in deformation behavior for the alloys sintered at different temperatures were discussed.

Background and Objectives: Soft‐textured wheat with low damaged starch content, low product discoloration, and varying protein strength has the potential to be suitable for making tortillas if the required flour characteristics are known and selected for. Eastern US soft winter (ESW) wheat varieties were evaluated to identify the characteristics required for making tortillas in comparison to five commercial tortilla flours (CTFs). Findings: ESW wheat flours had lower protein, damaged starch and ash contents, and polyphenol oxidase activity than CTFs and produced larger and brighter‐colored tortillas. Lactic acid solvent retention capacity (LA‐SRC) showed a strong association with tortilla quality attributes. Seven ESW wheat flours with LA‐SRC greater than 115.6% produced tortillas comparable with CTF tortillas in rollability scores. Conclusions: ESW wheat, with high protein content and strength, appears to be suitable for making tortillas. The lower damaged starch content and polyphenol oxidase activity in ESW wheat when compared with hard wheat flour would be advantageous because ESW wheat would require less water for dough preparation and would produce larger and brighter‐colored tortillas. Significance and Novelty: These results prove that the selected ESW wheat flours are desirable for making tortillas and provide guidance for selecting ESW wheat for making tortillas. [ABSTRACT FROM AUTHOR]

Magnesium alloy/PC/ABS composites were prepared by hot-press molding technology. The bonding strength is the crucial factor to influence the comprehensive performance of this composite, and it was closely related to the different processing parameters such as temperature, pressure and time. After exploring their relationship, the optimal hot-press processing condition was obtained. The micro- and nano-structure of composites also received attention. Before hot-pressed, the magnesium alloy surface was treated by micro-arc oxidation in order to construct the nano-sized pores. With the aid of scanning electron microscope (SEM) and atomic force microscope (AFM), a refined mechanical interlocking structure was observed with the formation of coordinate bonds at the interface of an alloy-polymer hybrid. The binding energy of the chemical elements at the bonding interface of the composite was also tested by X-ray photoelectron spectroscopy (XPS) and the analysis concluded that coordination bonds were formed at the bonding interface. The maximum tensile shear strength of the composite reached 9.48 MPa. [ABSTRACT FROM AUTHOR]

The evolution of various intermetallic layers and the formation of voids at the substrate/coating interface of hot-dip-aluminized (Al-9 wt% Si) hot-press-forming steel were systematically investigated using a field-emission scanning electron microscope and glow discharge optical emission spectrometer. Following austenitization at 900°C for 10 min, the substrate/coating interface of the air-cooled and quenched Al-Si coatings was characterized by the presence of Fe2SiAl2, Fe2 Al5, and a-Fe(Al) layers. The results revealed that rapid cooling/quenching effectively restricts the diffusion of Al, Si, and Fe atoms, leading to the formation of fewer Kirkendall voids within the intermetallic and a-Fe(Al) layers, with a decreased thickness of the latter. Consequently, the quenched Al-Si coating exhibited increased Vickers hardness, indicating enhanced mechanical properties due to the higher cooling rate. [ABSTRACT FROM AUTHOR]

The current practice in aluminum recycling plants is to change the waste into molten metal through the conventional recycling (CR) manufacturing process. However, the CR technique is so energy-intensive that it also poses an indirect threat to the environment. This paper presents a study on meltless direct recycling hot press forging (DR-HPF) as an alternative sustainable approach that has fewer steps with low energy consumption, as well as preventing the generation of new waste. A laboratory experiment was conducted to study the mechanical properties and surface integrity of AA7075 aluminum alloy by employing a hot press forging (HPF) process under different temperatures (380, 430, and 480 °C) and holding times (0, 60, and 120 min). It was found that as the parameter increased, there was a positive increase in ultimate tensile strength (UTS), elongation to failure (ETF), density, and microhardness. The recycled chips exhibit the best mechanical properties at the highest parameters (480 °C and 120 min), whereas the UTS = 245.62 MPa and ETF = 6.91%, while surface integrity shows that the calculated microhardness and density are 69.02 HV and 2.795 g/cm3, respectively. The UTS result shows that the highest parameters of 480 °C and 120 min are comparable with the Aerospace Specification Metals (ASM) Aluminum AA7075-O standard. This study is a guide for machinists and the manufacturing industry to increase industry sustainability, to preserve the earth for future generations.