A new reduction–diffusion method for preparing submicron-sized Sm2Fe17N3 was developed. First, submicron-sized α-Fe/Sm2O3 composite precursors with good dispersibility were prepared directly by ...ultrasonic spray pyrolysis and hydrogen reduction (USP-HR). Then, the precursor was successfully converted into Sm2Fe17N3 powder by Ca reduction–diffusion and nitridation. The results displayed that the precursor prepared by USP-HR was a monodisperse homogeneous composite of spherical particles of α-Fe and Sm2O3. α-Fe and Sm2O3 exist in an intercalated structure in the composite spherical particles. This creates conditions for the preparation of ultrafine Sm2Fe17N3 particles with uniform sizes and dispersity. The results show that Sm2Fe17N3 is a single-phase, composed of submicron-sized particles with no other impurity phases. The physical property measurement system shows that the coercivity of 0.616 ± 0.347 µm particles reaches 14.7 kOe.
•A facile method to fabricate selective copper patterns on polyethylene terephthalate surface can be achieved.•Effects of surface roughness on adhesive force, electronic and structural properties are ...investigated.•Thickness is 2.5 µm, resistivity is 2.1 × 10−6 Ω cm, adhesion is 5B.
In this work, a facile method combined with catalyst solution (mixture of AgNO3, 3-aminopropyltriethoxysilane, alcohol, SiO2 particle and deionized water) printing and electroless deposition to fabricate selective copper coating is demonstrated. The catalyst solution can write onto (polyethylene terephthalate (PET)) surface directly with good stability and resolution. The structure can catalyze plating reaction. SiO2 particle can enhance surface roughness (Sr) of catalyst coating. Effects of Sr on electronic, adhesive force and structural properties of copper coating are investigated. High Sr can facilitate the enhancement of Ag-adsorbed amount, deposition rate, adhesive force, crystallinity and electrical stability of plated coating. When the Sr is 0.78 µm, the thickness of copper coating is 2.5 µm, minimum width of copper line is 250 µm, the resistivity is 2.1 × 10−6 Ω cm, adhesion of 2.5 µm thick coating is 5B.
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In this study, new grain boundary diffusion (GBD) technology is applied to Nd-Fe-B sintered magnets with different thicknesses utilizing DyH3 nanopowder. The weight ratio is 0.25 wt.%. For ...comparison, the GBD processes include solid-liquid phase separation diffusion (SepD) and solid-liquid phase simultaneous diffusion (SimD). The magnetic properties and microstructure of GBD magnets with different thicknesses are thoroughly investigated. The comprehensive magnetic properties of SepD magnets are higher than SimD magnets. When the magnets are 8 mm thick, the SepD magnet obtains a coercivity of 18.10 kOe, which is higher than the SimD magnets (17.00 kOe). It was determined that SepD can manufacture thick magnets with excellent coercivity. In SepD magnets, the Dy element diffusion distance is deeper than in SimD magnets. For SepD magnets, there are core-shell structures formed in the surface region, while there are anti-core-shell structures that are unfavorable to magnetic properties in the surface region of the SimD magnets. The enhanced coercivity and temperature stability of the SepD magnets is primarily due to the more continuous core-shell structures produced by the deeper diffusion depth of the Dy element. This study will provide more theoretical guidance for the application of SepD in magnets with different thicknesses.
In this study, we aimed to enhance the quality of electrophoretic deposition (EPD) coatings for Nd-Fe-B grain boundary diffusion (GBD) by addressing issues related to the adhesion and densification ...of coating. We introduced a novel approach by incorporating polyvinyl pyrrolidone (PVP) into an alcohol suspension containing TbH3 nano-powders. The addition of PVP resulted in the formation of a dense coating with superior adhesion and a smooth surface. To evaluate the effectiveness of the EPD coating with PVP, we compared the EPD rate of the TbH3 nano-powders alcohol suspension with and without PVP. The EPD rate of the suspension with PVP exhibited a significant 30-fold increase compared to the suspension without PVP, indicating a substantial improvement in the electrophoretic efficiency. Based on our experimental findings, we recommend depositing the EPD coating at a voltage of 120 V and adjusting the deposition time accordingly to achieve a desired coating weight percentage of 1.0 wt% with a thickness of approximately 30 μm. Following the GBD process, the coercivity of the magnet with PVP increased from 1131 kA/m to 1896 kA/m, which improved the high-temperature stability of the magnet. Overall, our research offers a promising approach to overcome the limitations associated with EPD coatings for GBD applications, providing a potential solution for enhancing the performance and industrial viability of these coatings.
The effect of heat treatment on the microstructure and thermal stability of sintered Nd-Fe-B magnets was investigated. The results show that the microstructure of the magnets was greatly affected by ...heat treatment. The intrinsic coercivity (H cj ) was increased and the temperature coefficient of coercivity (β) was decreased by heat treatment. As the annealing temperature changes from 500°C to 770°C, H cj first increases and reaches a maximum, then starts to decrease, but β remains unchanged from 500°C to 680°C and increases rapidly when annealed over 680°C. A magnet with H cj = 30.55 kOe, β (from 20°C to 200°C) = -0.4079%°C was obtained after annealed at 620°C for 2 h. The relationship between the annealing temperature and magnetic properties was studied.
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•A facile method to fabricate high-adhesive copper coating on polyethylene terephthalate surface can be achieved.•Effects of Ag electron structure and surface topography on adhesive ...force of plated coating is investigated.•The maximum effective thickness is 3.6 μm.
Electroless plating on polymer surface is a low-cost process for surface metallization, but it exhibits low adhesive force and complex production process, which makes it difficult for practical application. We employ a facile method combined with novel catalyst solution printing and electroless plating to fabricate high-adhesion copper coating on (polyethylene terephthalate (PET). The catalyst solution is a mixture of AgNO3, PVA, KH550, alcohol and deionized water. On the one hand, hydrophilic PVA and hydrophobic KH550 condense to helical conformation catalyst solution, which could synergistically absorb Ag. On the other hand, the two phases separation structure facilitate the formation of roughness surface. As a result, the catalyst solution can form highly active polymer brush/Ag particle structure on the PET surface, and realize to modify and activate PET simultaneously. Region-selective copper coating could plate on PET surface, the maximum effective thickness is 3.6 μm, rupturework is 4.5 J/m2, adhesion is 5B, electrical resistivity is 2.3 × 10−6 Ω cm. While maintaining reliability even after over 6 times of folding test and 1000 times of bending. Our results provide the underlying insights needed to guide the design of the fabrication of metal polymer.
•Two pyridine-derived ligands were coordinated to Tb(III) and Eu(III) ions and doped into MOF micropores.•The interaction between PAA and ligands adjusted ligand triplet level, leading to intensity ...variation of RE(III) emission lines, showing a ratiometric sensing signal for PAA.•Linear calibration working curves were observed with maximum sensitivity of 8.01, response time of ∼36 s, LOD of 0.3 µM, and working region of 0–70 µM.
As an important oxidant, peracitic acid (PAA) has found wide applications in chemical engineering, agriculture, and industry, as well as public safety. Consequently, the easy-and-fast recognition for PAA is always desired. In this work, we have introduced rare earth-based probes in a microporous host bio-MOF-1, where bio-MOF-1 denotes Zn8(ad)4(BPDC)6O·2(Me2NH2)+·G, ad= adenine, BPDC=4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water. Two ligands, 2,2′-bipyrimidine (bpm) and 2,2′-bipyridine (bpy), were coordinated to RE (rare-earth) ions, Tb(III) and Eu(III). The resulting RE probes were co-doped into bio-MOF-1 micropores via ionic exchange with various relative doping levels. The resulting composite samples were characterized by SEM/EDX/elemental mapping, and their doping levels were determined by ICP analysis. The interaction between PAA and ligands (bpm and bpy) adjusted ligand triplet (T1) level, leading to intensity variation of Tb(III) and Eu(III) emission lines (increased Tb(III) emission and decreased Eu(III) emission), which was modulated as a ratiometric sensing signal for PAA. Linear calibration working curves were observed for bpm-based composite samples, with maximum sensitivity of 8.01, response time of ∼36 s, LOD of 0.3 µM, and working region of 0–70 µM.
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•Region-selective electroless copper plating on the polyethylene terephthalate sheet modified with primer can be achieved.•A certain structure of primer-modified substrate could achieve good ...wettability and high resolution simultaneously.•The plated copper coating possess high adhesion.
A easy method to prepare selective copper coating on polyethylene terephthalate (PET) surface via writing activated solution on primer-modified PET sheet combined with electroless plating is demonstrated, the effects of PET surface structure on resolution and adhesion of copper coating were investigated. Results showed that the PET sheet modified with different primer (SiO2 particles-emulsion mixed liquors) could adsorb the stannum(II) and silver ions, which used as catalyst for selective electroless copper plating. When the SiO2 content increased from 0% to 10%, average surface roughness value, Ag-adsorption capability, plated coating thickness and adhesive force of thick plated coating were enhanced, surface resistivity was decreased, but resolution of activated coating was firstly enhanced and then reduce. The average roughness value was measured to be 12 μm for PET sheet modified with 6% SiO2-primer, resulting in good wettability and high resolution simultaneously. The region-selective copper coating could plate on PET surface and through hole, leading to a high conductivity of both sides. The plated coating was a composite of continuous layer of copper and randomly scattered SiO2 particles, resulting in a better adhesion of the copper coating. The minimum width of copper line was about 250 μm and the thickness of copper coating was 2.4 μm, surface resistivity was 8.6 × 10−6 Ω cm. No matter how the region-selective plated PET sheet was compressed or stretched, even for folded sheet, conductivity and mechanical properties were not affected.
The Pr, Cu, and Pr
75
Cu
25
were deposited on the sintered NdFeB by magnetron sputtering technology, and the samples were subjected to grain boundary diffusion heat treatment. The magnetic ...properties, microstructure, temperature stability and bending strength of the magnet were analyzed. Compared with the blank magnet, the grain boundaries of the diffusion magnet increase and enhance the Nd phase and its continuum, thereby isolating the main phase grains and resulting in a stronger magnetic decoupling effect. The coercivity of Pr and Pr
75
Cu
25
diffusion magnets increased from 12.86 kOe to 14.69 kOe and 15.78 kOe, respectively, while the coercivity of diffusion Cu magnets increased from 13.38 kOe to 14.83 kOe. In the temperature range of 20 ~ 120 °C, the reversible temperature coefficients of coercivity (|
β|
) of diffusion Pr, Cu, and Pr
75
Cu
25
magnets decrease by 0.034%/°C, 0.021%/°C and 0.089%/°C, respectively. Meanwhile, the irreversible flux magnetic loss (
H
irr
) decreased by 20.96%, 0.94%, and 27.71% respectively. The average bending strength increased by 55.89 MPa, 155.65 MPa, and 130.21 MPa, respectively.
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•Three typical-structure regions formed in GBD Nd-Fe-B sintered magnets possessed remarkable different magnetic properties.•The nucleation position of reversed domain was transferred ...to the grain interior region via forming core-shell structures.•The efficiency of heavy rare earth could be further improved by forming homogeneous and complete core-shell structures.
The grain boundary diffusion (GBD) method could effectively improve the coercivity of Nd-Fe-B sintered magnets, but the uneven distribution of heave rare earth (HRE) elements would lead to the decrease of squareness factor of the demagnetization curve of the magnets, which limited the application of this method. In this paper, three typical-structure regions were summarized based on microstructure characterization, and the magnetic properties and magnetization reversal mechanism were analyzed. The differences in nucleation positions and magnetization reversal processes of the three regions were discussed, and it found that the remarkable differences among them resulted in the low squareness factor of GBD Nd-Fe-B sintered magnets. In addition, the efficiency of Tb elements could be further improved to enhance the coercivity of Nd-Fe-B sintered magnets by forming homogeneous and complete core-shell structure grains, which could strengthen the nucleation field and even transfer the nucleation position from the grain surface defect layer to the grain interior region. Our results could provide guidance and reference for further improving the permanent magnetic properties of Nd-Fe-B sintered magnets by optimized GBD method.
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