Isothermal oxidation behavior of FeCo–2V intermetallic alloy

Isothermal oxidation behavior and the nature of oxide layer formed during oxidation of FeCo–2V alloy were characterized in the temperature range of 500–600 °C. Oxidation kinetics of the alloy follows a parabolic rate law. SEM and XRD studies indicate the formation of an iron rich outer oxide layer and an inner solute rich layer containing cobalt and vanadium rich oxides. The oxidation mechanism of the FeCo–2V alloy is similar to that of low alloy steels. During the initial stages, preferential oxidation of iron and cobalt occurs at the alloy surface and leads to the formation of a solute rich inner layer. Continued oxidation occurs through oxidation of iron and cobalt at the outer layer and internal oxidation of inner layer. The iron rich oxide layer formed at the surface on oxidation of FeCo alloy is semi-conducting in nature and may not provide the necessary insulating barrier required at the surface to minimize eddy current losses during A.C. applications.     

An EPR investigation of electrospun polyaniline-polyethylene oxide blends

The EPR magnetic susceptibility behavior of the camphorsulfonic acid doped polyaniline (PANCSA) blends with polyethylene oxide (PEO) is reported in fibers and films. In particular, EPR investigations on electrospun (PANCSA)_0.72(PEO)_0.28 nanofibers, cast films of (PANCSA)_0.72(PEO)_0.28 and cast films of (PANCSA) were performed to investigate differences in the mesoscopic disorder as induced by the process of electrospinning. The changes observed in the Pauli susceptibility, EPR lineshape, EPR linewidth, and dc conductivity are interpreted as due to increased chain alignment in the fibers compared with the cast films.     

Study of magnetic field assisted mechanochemical polishing process for inner surface of Si3N4 ceramic components: Finishing characteristics under wet finishing using distilled water

This study discusses the finishing characteristics of a magnetic field assisted mechanochemical polishing process using Cr₂O₃ abrasive mixed with magnetic particles in the case of wet finishing using distilled water, which was proposed for internal finishing of Si₃N₄ fine ceramic tubes. It was clarified that a highly accurate finishing can be achieved more efficiently in the case of wet finishing using distilled water compared with dry finishing. Moreover, those conditions necessary to achieve high efficiency finishing are discussed.     

基于三维有限元动态模拟圆柱形表面腐蚀缺陷漏磁场

根据电磁场有限元分析的基础理论，对储罐底板圆柱形表面腐蚀缺陷，应用ANSYS三维有限元静态分析了圆柱形表面腐蚀缺陷漏磁场，得到了圆柱形表面腐蚀缺陷漏磁场的空间分布。在一定条件下，静态模拟的缺陷漏磁场受励磁结构中永磁铁磁场的影响较大，造成在永磁铁附近漏磁场分布的畸变。而动态模拟下得到的漏磁场只在缺陷附近有明显的变化，缺陷漏磁场受励磁结构中永磁铁磁场的影响很小，有利于对腐蚀缺陷的分析。     

CNG储气瓶的金属磁记忆检测

使用金属磁记忆检测方法和超声方法对在役的七组公交车CNG高压储气瓶组进行了检测,并对比分析了两种方法的检测结果。结果表明,金属磁记忆方法检测到的可疑区域涵盖了超声检测到的缺陷区域,因此用磁记忆方法检测高压储气瓶,有较高的可靠性和高效性。     

Numerical modelling and implementation of ferrite cored eddy current probes

This paper focuses on the development of a magnetic moment method of calculating vector field quantities for a highly permeable ferrite cored eddy current probe. Basis functions are used in this method to replace the scattered field caused by the probe core in accordance with the surface equivalence theorem. These functions are further developed and tested for accuracy and convergence. An efficient material profile equation, independent of probe coil and basis function properties, is also designed and verified. Collocation point selection and optimisation is finally undertaken leading to the accurate determination of probe source coil impedance. The accuracy of calculation is verified using an industry standard finite element solver.     

Behavior of residual carbon in Sm(Co, Fe, Cu, Zr)z permanent magnets

When sintered Sm(Co, Fe, Cu, Zr)_z permanent magnets are prepared by metal injection molding, some organic binders are added in alloy powder, which leads to much residual carbon in the magnets. The residual carbon decreases magnetic properties and destroys the microstructure of the magnets. In this paper, the behavior of carbon in Sm(Co, Fe, Cu, Zr)_z permanent magnets has been studied. The results indicate that Sm(Co, Fe, Cu, Zr)_z magnets can keep excellent magnetic properties when the carbon content is below 0.1 wt.%: Br ≥ 10 kGs, H_cj ≥ 22 kOe, BH_max ≥ 25 MGOe. When the carbon content is above 0.1 wt.%, Br, H_cj and BH_max decrease with increasing carbon content evidently. Carbon consumes Zr content and forms ZrC, which reduces the volume fraction of the lamella and Sm(Co, Cu)₅ phases. Thus, the cell size increases and the cellular microstructure deteriorates. When the carbon content reaches 0.43 wt.%, there is not enough Sm(Co, Cu)₅ phase to form a uniform cellular microstructure. Br, H_cj and BH_max are approximate to zero. Since carbon has little influence on the content of Sm₂(Co, Fe)₁₇ phase, Ms can keep a high value (≥100 emu/g). ZrC has high melting point (3420 °C) and acts as dispersion particle in the magnets, which prevents the grains of SEM structure growing and reduces the liquid content of green compacts during sintering. Therefore, the density of the magnets decreases.     

复杂环境下磁悬浮转子噪声和振动的测试与分析

介绍了磁力轴承的特点,阐述了B＆K振动噪声测试仪的测试要求,以及所有的测试状态和测试方法。接着对噪声测量结果和振动测量结果进行了总结和分析。这对于研究磁力轴承的噪声、振动以及转子的临界转速有一定的参考意义。     

基于MC9S12DP256的汽车ABS数据采集系统设计

设计了基于MC9S12DP256单片机的汽车ABS数据采集系统;详细介绍了该系统的硬件电路以及系统软件设计.大量的ABS实车实验证明:该数据采集系统工作性能良好,可靠性高.采集数据的精度完全可以满足汽车ABS系统的要求.     

Fast chemical vapor deposition of microcrystalline silicon by applying magnetic field to hollow electrode enhanced radio frequency glow plasma

Fast chemical vapor deposition of microcrystalline silicon by applying magnetic field to hollow electrode enhanced radio frequency (rf) glow plasma has been investigated. We have already developed a plasma generation technique called hollow electrode enhanced rf glow plasma transportation (HEEPT). In this study, we equipped a HEEPT system with a hollow cylinder shaped permanent magnet around an orifice prepared at the center of the counter electrode. The plasma was characterized by plasma emission spectroscopy. Silicon thin films were deposited on a glass substrate. It was found that increasing the magnetic flux density resulted in increasing plasma emission intensity, film deposition rate, and crystallinity. The maximum deposition rate of 6.9 nm/s was achieved with high crystallinity and photo-sensitivity at a plasma excitation frequency of 13.56 MHz, a substrate temperature of 300 °C and a magnetic flux density of 75 mT. Our results indicate that the magnetic field is effective in promoting fast chemical vapor deposition of microcrystalline silicon thin films with photo-sensitivity using the HEEPT technique. We consider that the effectiveness is due to a decrease of electron temperature caused by drift motion of electrons in the magnetic field inside the orifice.