For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiO2 membranes with heterogeneous ...structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. In the binary nanocomposites, RGO was tightly adhered to TiO2 fibers and by simply adjusting the loading of RGO, the strength and modulus of the fibrous membranes were improved. Notably, the RGO-permeated TiO2 fibers exhibited 1.41 MPa in tensile strength and 140.02 MPa in Young’s modulus, which were 705% and 343% of the original TiO2 fibers, respectively. Benefiting from the enhanced light response and the homogeneous and compact heterogeneous structure, the synthesized RGO/TiO2 membranes displayed good antibacterial performance with a photocatalytic inactivation rate of 6 log against E. coli within 60 min. This study offers a highly efficient alternative to inactivate E. coli for the synthesis of TiO2-based membranes.
To further strengthen the AlCoCrFeNi high-entropy alloy (HEA) coating prepared by high-speed laser cladding (HLC), laser remelting (LR) was chosen to reprocess it. The effects of LR on the ...topography, microstructure, growth orientation, phase distribution, and properties were investigated. It was revealed that there were a large number of liquid phase separation (LPS) zones in the HLC coating because of an ultrafast cooling rate. After LR, the LPS zones were eliminated. Compared to HLC coating, the microhardness increased from 622 HV to 762 HV, and the friction coefficient and the wear weight loss were reduced by 0.1 and 0.5 mg, respectively. In electrochemical testing, the self-corrosion potential increased by 45.9 mV and the self-corrosion current density decreased by one order of magnitude. Meanwhile, EBSD analysis indicated that the LPS zones were prone to recrystallization. The LPS zones were nickel-poor, low hardness, also BCC phase, and had a clearer (101) orientation. With the elimination of the LPS zones, the kernel average misorientation values were reduced, Taylor factor values and high angle grain boundaries were increased, and the average grain size was reduced from 2.43 μm to 2.12 μm. Eventually, for LR coatings, the combination of fine grain strengthening, solid solution strengthening, spalling reduction, and Cr element segregation resulted in better wear and corrosion resistances. The overall results show that a reasonable LR application can induce the microstructure of the HLC coating and improve its service properties.
● The AlCoCrFeNi high-entropy alloy coatings were prepared by high-speed laser cladding (HLC) and reprocessed by laser remelting (LR).● There were a large number of liquid phase separation (LPS) zones in the HLC coating. After LR, the LPS zones were replaced by fine equiaxed crystals.● The LPS zones were nickel-poor and low hardness, had a clearer (101) orientation, and tended to spall off in the wear test, causing a decrease in the overall wear resistance of the coating.● As a result of the elimination of the LPS zones, the microhardness and wear resistance of the LR coating were improved by solid solution strengthening and fine grain strengthening.● Appropriate undercooling and more high angle grain boundaries caused by LR provided a larger driving force for grain boundary segregation. The elemental content of Cr at the grain boundaries became higher, and the corrosion resistance of the LR coatings increased significantly. Display omitted
•HLC led to a large number of the LPS zones in the AlCoCrFeNi HEA coating.•LR could successfully eliminate the LPS zones.•Recrystallization made the grains of the LPS zones coarse and soft.•The microhardness and wear resistance of the coating were improved by LR.•Higher Cr content at grain boundaries boosted corrosion resistance of LR coating.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Three stages of ice crystal formation in muscle tissue in this paper were analyzed.•The working principles and equipment of ultrasound-assisted freezing technique, high-voltage electric and magnetic ...field-assisted freezing technique, and liquid nitrogen freezing technique were discussed, respectively.•The future direction of cold chain storage and transport technology were analyzed.
Low temperature environments can effectively inhibit the growth of microorganisms in raw meat products due to the reduced activity of enzymes, which is conducive to the long-term preservation of foodstuffs. At present, mainstream technologies include ultrasonic-assisted freezing, high-voltage electric and magnetic field-assisted freezing, and liquid nitrogen freezing technologies are widely used in the freezing process. In this paper, the freezing processes and devices for the fresh meat products were reviewed. The formation mechanism of ice crystals during the freezing of meat products was analyzed. The influence of the shape and size of ice crystals on their quality was studied. Also, the effect of different freezing processes and freezing device on the quality of meat products was studied. The key technologies regarding cold chain storage and transportation of meat products should move in the direction of intelligence, information, efficiency, and the unmanned. Finally, the key processes and device regarding freezing, cold chain, storage, and transportation were planned for the future development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The AlCoCrFeNi high-entropy alloy coatings were prepared by laser cladding (LC) and reprocessed by laser remelting (LR). Laser remelting caused cracks on the coating surface, but the cracks of ...boronized laser remelting (LR-B) coating were significantly suppressed. Compared to the LR coating, the microhardness of the LR-B coating increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination contributed to the transition of 25% of the BCC phase to the FCC phase. The property enhancement was mainly due to the fine grain strengthening, dislocation strengthening, and Cr2B reinforced particles as reinforced phase.
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•A trace amount of boron was doped in the protective gas during laser remelting.•The cracks of the boronized laser remelting (LR-B) coating were significantly suppressed.•With the addition of boron, the FCC phase and Cr2B were formed.•The Cr2B second-phase strengthening increased microhardness and wear resistance.•The Cr2B particles in the LR-B coating resulted in excellent corrosion resistance.
To avoid cracking of the AlCoCrFeNi high-entropy alloy (HEA) coating during laser remelting (LR), a trace amount of boron (B) was doped in the protective gas. Compared to the LR coating, the cracks of the boronized laser remelting (LR-B) coating were significantly suppressed, the microhardness increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination mainly contributed to the transition of 25 % of the BCC phase to the FCC phase, and the property enhancement was due to the fine grain strengthening, dislocation strengthening, and Cr2B reinforced particles generation. This novel finding can be applied to other BCC structure HEA coatings for macroscopic crack control and optimization of wear and corrosion resistances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiOsub.2 membranes with heterogeneous ...structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. In the binary nanocomposites, RGO was tightly adhered to TiOsub.2 fibers and by simply adjusting the loading of RGO, the strength and modulus of the fibrous membranes were improved. Notably, the RGO-permeated TiOsub.2 fibers exhibited 1.41 MPa in tensile strength and 140.02 MPa in Young’s modulus, which were 705% and 343% of the original TiOsub.2 fibers, respectively. Benefiting from the enhanced light response and the homogeneous and compact heterogeneous structure, the synthesized RGO/TiOsub.2 membranes displayed good antibacterial performance with a photocatalytic inactivation rate of 6 log against E. coli within 60 min. This study offers a highly efficient alternative to inactivate E. coli for the synthesis of TiOsub.2 -based membranes.
In this study, an AlCoCrFeNi high-entropy alloy (HEA) coating was prepared on the surface of AISI 1045 steel by high-speed laser cladding (HLC). The microstructure, phase composition, element ...distribution, microhardness, wear resistance, and corrosion resistance of the coatings were analyzed, respectively. It was found that a metallurgical bond was formed, the main microstructure were the fine columnar and equiaxed dendrites, and the phase composition of the coating was a single-phase bulk cubic-centered structure (BCC/B2). Moreover, the elements of the HLC coating were evenly distributed without obvious segregation at the macro level. Compared to conventional laser cladding (CLC), the efficiencies of cladding and processing quality were improved. The scanning speed of CLC was 7 mm/s with some pores and overburning on the surface of the coating. However, the scanning speed of HLC increased by 40 times to 300 mm/s, and the surface roughness of the HLC coating was 39.83 % lower. The dilution ratio of the HLC coatings was 4.6 %, which was 3 times lower than that of 13.4 % by CLC. It also led to a significant decrease in the grain size, element transition zone, and heat affected zone. As a result, the hardness of the coating increased by 100 HV, the friction coefficient decreased by 0.15, the wear weight loss was reduced by 9.85 %, the self-corrosion potential increased by 84 mV, and the self-corrosion current density was one order of magnitude lower. Therefore, the potential application of HLC is to effectively improve the wear and corrosion resistances of HEA coatings.
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•HLC had a scanning speed of 300 mm/s, which was about 40 times faster than CLC.•The surface roughness of the HLC coating was 39.83 % lower.•The HLC coating was denser and was also composed of a single-phase BCC/B2 structure.•The microhardness, wear and corrosion resistances of the HLC coating were enhanced.•AlCoCrFeNi HEA coating was mainly strengthened by fine grain strengthening.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
