Failure analysis of Sm2Co17 type permanent magnet for high temperature
With the increasing using temperature, the magnetic performance of high temperature stable Sm2Co17 type permanent magnet will be decreased. In order to explore the effect of the high temperature on microstructure of the alloy, the differential thermal analysis (DTA) was made and three distinct phase transformation temperature 254 °C, 342 °C and 540 °C were obtained. Then X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray energy dispersive spectrometer equipped (EDS) were used to analyze the phase information, microstructure and composition of the samples treated at the above temperatures. The results suggested that the oxidation and precipitation of Cu and Fe are the key reason to result in the failure of the material, which provides an important reference for the research of the magnet.
Temperature dependence of coercivity and magnetization reversal mechanism in Sm(Co/sub bal/Fe/sub 0.1/Cu/sub y/Zr/sub 0.04/)/sub 7.0/ magnets
The temperature dependence of coercivity in Sm(Co/sub bal/Fe/sub 0.1/Cu/sub y/Zr/sub 0.04/)/sub 7.0/ magnets with y=0 to 0.20 has been systematically studied. Two models are discussed with respect to the temperature dependence of coercivity. One model considers only domain wall (DW) pinning and explains the "abnormal" behavior as a temperature-induced transition from a repulsive DW pinning to an attractive one. The other model assumes a combination of pinning and nucleation of DWs in magnetically isolated 2:17 cells. In this model, the cell-boundary pinning of DWs takes place in the alloys with low Cu content at temperatures below the Curie temperature of 1:5 phase. Nucleation controls the magnetization reversal in the case of complete magnetic isolation of the 2:17 cells. This condition is expected to be fulfilled at any temperature above RT in the Cu-rich magnets, and only above Curie temperature of the 1:5 phase in the alloys with lower Cu content.
Comparison between Two Chemicals for Reducing Scale Formation in Reverse Osmosis Systems
In this present research was transacted with the calcium carbonate scale inhibition on the membrane surface of the reverse osmosis desalination system. Influence of changing feed solution flow rate (10-25)l/h, pH of the feed solution (6-10) on the recovery ,penetrate flow rate and total dissolved solid in (RO) system by using solution of calcium carbonate as feed solution was investigated, furthermore the effect of adding two types of scale inhibitor ,zinc chloride and polyamino polyether methylene phosphonate with difference concentration (2-8)mg/l for zinc chloride and (8-15) mg/l for polyamino polyether methylene phosphonate was calculated. The results showed that the permeate rate increases as the feed flow rate augmentation ,while it reducing with time, the total dissolved solids decreases as the feed flow rate increases while it increases with time and recovery rate decreases as the feed flow rate increases and it also decreases with time. It was concluded that the permeate rate decreases as the feed solution pH value increases and it cause high scale forming thus decrease the permeate TDS.By adding the scale inhibitor, it was found that the permeate rate and recovery rates increases as the concentration of inhibitor increases while the total dissolved solids decreases in the permeate with increasing the concentration of both inhibitors .It was discovered that Polyamino polyether methylene phosphonate more sturdy than zinc chloride as scale inhibitor for reverse osmosis desalination system in all concentrations was studied in this article.