Papers by Keyword: Magnetic Powder

Abstract: For the past few years, nanocrystalline soft magnetic alloy has become hot topic in the field of strategic functional materials based on its excellent magnetic properties and advantages of energy saving, low cost, etc. With rapid innovationof various new type soft magnetic materials, FeCuNbSiB soft magnetic powder cores havebeen gradually turning into researching focusin soft magnetic material field for its excellent high frequency properties, such as high magnetic permeability (μ) and quality factor (Q), low core loss (P_c) and coercivity (H_c), etc.This paper mainly reviews the recent advances and technological achievements of FeCuNbSiB nanocrystalline soft magnetic powder cores, and also provides a brief introduction of FeCuNbSiB/Mn-Zn ferrite powder core, one new type composite magnetic powder core. Finally, future developing trend for FeCuNbSiB nanocrystalline powder cores isalso prospectedcompendiouslyin the paper.

Abstract: Recently, using ceramsite to treat wastewater has received wide attention. In this tudy, the ceramsite packing material was modified to make it more ready for bacteria attachment and improved its waste-water treatment efficiency by magnetic field. In addition, the optimal percentage of the additive was obtained through the wastewater treatment experiments in a contact aeration bioreactors. The results showed that the optimal percentage of magnetic powder, polyvinyl alcohol, amylum, sodium bicarbonate, and expanded perlite was 7%, 3%, 2%, 5% and 10% respectively. And the performance of the modified ceramsite in the contact aeration bioreactors was compared with the packing which without magnetic powder, polyvinyl alcohol and amylum showed that the modified ceramsitethe had obviously advantages in terms of time it took for the reactors to attain the stable treatment, organic reduction rate and water retention.

Abstract: Recently, using biological ceramsite to treat wastewater has received wide attention. In this study, use of fly ash, cement, calcium oxide, gypsum, expanded perlite as main components, magnetic powder and sodium bicarbonate as complex additive and sodium silicate solution as binder, a novel biological ceramsite was developed by steam curing method. Density, piled density, apparent density and void fraction of the biological ceramsite were tested. The optimal percentage of main components was obtained through the orthogonal experiments. In addition, the main affecting factors were also analyzed on the properties of the biological ceramsite. The results showed that the optimal percentage of magnetic powder, sodium bicarbonate, cement and expanded perlite was 10%, 10%, 10% and 5% respectively.The analysis of the results disclosed that the affecting factors of the density, the piled density, the apparent density and the void fraction were the expanded perlite, magnetic powder, cement (and magnetic powder), sodium bicarbonate, respectively.

Abstract: the effect of pH shock on the magnetic micro-aerobic activated sludge system used to deal with low load glucose wastewater was studied. After pH shocking under the condition of pH=6.0 and 9.0 for 15 days, COD_Cr removal efficiency of the reactor with magnetic powder was higher than that of the reactor without magnetic powder, and remained above 80% in the 5 days recovery experiment at pH=7.5, while about 50% of the reactor without magnetic powder. SVI in the reactor with magnetic powder was lower than that of the reactor without magnetic powder after pH shocking, and after the 5 days' recovery experiments, SVI of the sludge with magnetic powder could recovered to the original value, but the indicators of the sludge without magnetic powder could not recovered to the original value.

Abstract: In current paper, ballasted flocculation as a simulated Actiflo and Sirofloc process with coagulant, micro-sand (MS)/magnetic powder (MP) and PAM was optimized using single-factor and orthogonal experimental method for eutrophic landscape water treatment. A flocculation index instrument was also used to indicate the flocs property. It was determined that the optimum removal rate of turbidity, UV₂₅₄, COD_Mn and total phosphorus, with 96.11%, 34.63%, 57.88% and 55.32%, respectively were achieved under MP ballasted flocculation with PAM added 2 minutes after initial mixing. Additionally, MS/MP ballasted flocculation with or without PAM could not significantly increase the velocity of flocs formation, but the flocs size could be increased observably by MP ballasted flocculation regardless of PAM.

Abstract: A micromachining technique has been developed for the fabrication of microscale polymer-bonded magnet. Two types of lithographically defined molds, photoresist mold and electroplated metal mold, were introduced. Photoresist mold is convenient, while electroplated metal mold can be fabricated on the glass or steel substrate which can bear much more compression. NdFeB films of thickness between 50 and 500 µm were prepared by micro-patterning of composites containing 83-95wt% of commercial NdFeB powder after curing at the room temperature. Magnetic properties mainly depend on the types and percentage of volume loading of magnetic powder. Coercivity of 772.4kA/m (9.70kOe), remanence of 275.1mT (2.751kG), and energy product of 22.6kJ/m³ (2.8MGOe) have been achieved. This easily developed magnet could be a promising candidate for applications in magnetic microelectromechanical systems (MEMS).

Abstract: Calciothermic reduction-diffusion (CRD) method was employed to prepare the Sm2Fe17 powder. By using CRD method, single-phase Sm2Fe17 powders were successfully made and no α-Fe phase detected. And Subsequent suitable nitrogenation treatment after CRD process enabled us to obtain Sm2Fe17Nx magnetic powders. However, the magnetic performance of the powders was below expectation due to their large particle size. Further study on effective milling process is needed.

Abstract: In first part of the report motion of magnetic powder materials in a vertical or inclined pipe are investigated. Mathematical models are analyzed, taking into account intensity of a pulse electromagnetic field, parameters of a powder and its interaction with the surface of the pipe and air. Experimental device, including control and measure system with the analysis of parameters by computer, is described. Second part of the report investigates a motion of non-magnetic materials. For this reason an additional magnetic container with open surface is used. After an impulse action the container stops before bound. Non-magnetic materials continue flying motion. In third part of the report the authors investigate motion excitation with impulse generator for plane vibrotransporters. It is shown that this excitation is very stable, because after impulse action the mechanical system continues vibration with a non-periodical motion and stops waiting for next impulse.

Abstract: Nd, Ce and Pr in ER-magnets are very active and easy react with oxygen and other oxidizing substance [1]. So this paper deals with the formation of some organic films on the Nd8Fe80B6Co6 magnetic powders. Then the belt of the alloy was made in a melt-spun furnace and then heat-treated at certain temperature. After that the magnetic powders were prepared by special crashing techniques. Epoxy resin and titanate were chosen as coat materials. The test showed that the epoxy-titanate coating material has the lowest weight increase in the exposure of oxidation atmosphere. Effects of the coat materials on the properties of bonded alloy were also investigated. The magnetic properties of the alloy with epoxy-titanate coating material were similar to one without coat.

Abstract: Effect of washing step in R-D process on the structure and magnetic properties of Nd-Fe-B powder fabricated by the process using a spray-dried precursor was investigated. Although the powder washed in water contained much more residual CaO than that washed in dilute acetic acid, magnetic properties of the former were much better than those of the latter due to less removal of Nd-rich phase. In the powder washed in water Nd2Fe14B particles were enclosed with thin layer of Nd-rich phase, and each particle consisted of one or more subgrains of the size 50 ~ 100 nm or more. Milling the powder before water washing was effective to remove more CaO, thereby increased the remanence of the powder.