Influences of magnetic treatment on microstructure densification of diamond saw segments

The heated test pieces were treated with alternating magnetic field by self-made experimental facility firstly. And influences of magnetic treatment on microstructure densification of Diamond Saw Segments were studied through hardness testing, ultrasonic testing, metallurgical structure and fracture pattern analysis by comparative method. The mechanism of magnetic treatment is analyzed and discussed in the end. The results show that the hardness of test pieces after magnetized are harder than before, that HRB hardness is improved by 3.58 on average. The sound path and amplitude of echo wave both decrease in test pieces after magnetized. The relative pad value of echo wave is regularly related with the microstructure densification, what is profound to further establish the regularity studying the degree of matrices densification using ultrasonic testing. The pores become few and pore shape gradually spheroidizing with the magnetic treatment, and matrices are more homogeneous and compact than the without by metallographic microscope. The degree of matrices densification is further improved after magnetized. The average crystal grain size is finer than the without, and the reason of grain refining is that densification of diamond saw blade improved. Magnetic treatment can act as one kind of effective technique to improve the microstructure densification of diamond saw segments.     

低频脉冲磁场处理Co_(68.15)Fe_(4.35)Si_(12.5)B_(15)的穆斯堡尔谱研究

用低频脉冲磁场处理非晶合金Co68.15Fe4.35Si12.5B15,用穆斯堡尔谱结合透射电镜对处理前后的试样进行了微结构分析。结果表明,在低频脉冲磁场处理下,非晶合金Co68.15Fe4.35Si12.5B15发生了纳米晶化,晶化析出相为体心立方α-Fe(Si),析出量为2.743%~23.960%,晶粒尺寸约2~10 nm,且晶化量与磁场强度和脉冲频率均有关系。     

纳米磁性流体密封承压能力的回归分析

纳米磁性流体密封的应用中最关键的问题是密封能力的确定，其影响因素很多，如纳米磁性流体本身的性质、磁板结构、负载运行过程等，其中磁板结构的设计对密封能力有着决定性的影响。作者从磁板结构的分析出发，通过回归计算研究了典型磁板结构的参数对密封能力的影响规律，得出了回归公式，并进行了密封实验。实验研究表明，所得回归经验公式能较真实的反映密封性能，在考虑一定裕度的情况下，可以用公式指导纳米磁性流体密封装置的设计。     

炮口感应装定系统发送线圈仿真设计

利用有限元分析软件ANSYS,对发送线圈的磁场分布进行了重新分析和计算,并结合炮口感应系统的具体要求,提出了一种适合于引信炮口感应装定系统的磁场均匀度计算的新方法。研究了此方法在发送线圈磁场分布的分析中所带来的独特优点,设计出磁场均匀度更高的发送线圈,有效地提高了感应装定的可靠性,为感应装定系统的设计提供了理论依据。     

Effect of austenitization heat treatment on the magnetic properties of Fe-40wt % Ni-2wt % Mn alloy

The effect of austenitization heat treatment on magnetic properties was examined by means of M6ssbauer spectroscopy on an Fe-40wt%Ni-2wt%Mn alloy. The morphology of the alloy was obtained by using scanning electron microscopy （SEM） under different heat treatment conditions. The magnetic behavior of the non heat-treated alloy is ferromagnetic. A mixed magnetic structure including both paramagnetic and ferromagnetic states was obtained at 800℃ after 6 and 12 h heat treatments. In addition, the magnetic structure of the heat-treated alloy at 1150~C for 12 h was ferromagnetic. With the volume fraction changing, the effective hyperfine field of the ferromagnetic austenite phase and isomery shift values were also determined by Mtssbauer spectroscopy.     

9SiCr磁场等温贝氏体研究

本文研究了磁场对9SiCr贝氏体相变,组织及性能的影响,结果发现:磁场确实能够加速贝氏体相变,并使贝氏体形核核心增多,贝氏体片变窄,且经磁场处理的试块,其机械性能较高,工件的使用寿命提高。     

高梯度强磁场聚氧集氮机理与实验方案研究

开发空气中氧氮资源,以提高能源利用率．从氧氮磁性差异入手,采用高梯度强磁场进行氧氮分离．提出了一套磁场梯度聚氧集氮实验方案,探讨了磁路设计的主要性能参数,进行了聚氧集氮磁性材料和最佳氧浓度范围的选择．     

高梯度强磁场聚氧集氮机理与实验方案研究

开发空气中氧氮资源，以提高能源利用率．从氧氮磁性差异入手，采用高梯度强磁场进行氧氮分离．提出了一套磁场梯度聚氧集氮实验方案，探讨了磁路设计的主要性能参数，进行了聚氧集氮磁性材料和最佳氧浓度范围的选择．     

永磁直线伺服电机的磁场分析及优化设计

介绍了一种圆筒型永磁直线伺服电机,电机次级采用轴向磁通结构,初级采用无铁心空心式绕组设计,完全消除了传统有铁心永磁电机固有齿槽效应所引起的推力波动问题.该结构电机的输出推力稳定性主要与电机气隙磁场分布的正弦程度有关,提高气隙磁场分布的正弦性是改善电机伺服性能的重点.通过对电机磁场进行有限元分析,研究了电机次级永磁体宽度和半径2个主要尺寸对气隙磁场分布的影响,并给出了这2个主要尺寸的最佳取值.经过优化设计,电机的气隙磁场分布得到了改善,磁场谐波分量大大降低,输出推力更加稳定,伺服性能得以提高.     

汽轮发电机转子绕组匝间短路的故障原因与磁场分析

阐述了汽轮发电机转子的一般结构和转子绕组匝间短路的原因,主要对转子绕组匝间短路的磁场进行了数学分析,得出转子匝间短路时磁场信号的故障特征,为信号的后续处理提供了良好的依据.     

Experiments and analysis for rheological properties of MRF

The work principle of flat-plate structure under shearing mode is expounded based on a vertical type rheometer for MRF which combined data acquisition with treatment and result display.The formula to calculate shearing stress is deduced.Based on different recipe for MRF,experiments under different working gap length were done by altering the intensity of magnetic field.The rheological model for MRF was established and the relationships between shearing stress,viscosity and magnetic field intensity were deduced.Experiments indicate that MRF has the flowing characters:with an increase of the magnetic induction and the nominal shear rate,the shear stress of MRF increases.However,as the working gap decreases,the shear stress increases.MRF has shear thinning property under magnetic field.     

环带磁场在磁流变抛光技术中的应用

磁流变抛光是获得光滑光学表面的理想工艺之一.为了获得一种可用于磁流变抛光中的环形磁场,设计了一种新型的环带式磁场结构,并对其进行模拟与分析,利用该磁场结构构造了一种面接触式的磁流变抛光设备.实际测量证明该磁场结构可形成满足磁流变抛光要求的高梯度磁场.将环形磁极浸入磁流变抛光液中,可使其形成圆环状的Bingham凸起;利用它对K9玻璃进行抛光,可使其表面粗糙度达到约为1 nm的水平.     

磁声耦合防蜡技术研究与现场应用

油井结蜡造成抽油杆超负荷运行,影响到抽油杆的使用寿命,由于结蜡严重而引起的油井作业在维护性作业中所占比例也较高.在室内实验条件下对延长油田的含蜡原油分别进行变频、变功率的磁场、超声波以及二者耦合处理,实验证实,在参数为超声波功率20W、频率20kHz以及磁场功率800W、频率2kHz的耦合处理后,原油降粘效果最好;含蜡量减少,原有粗大的蜡晶结构被破坏.现场应用表明,在相同的工况条件下,安装了防蜡器的油井耗电量减少4.62％,产量有所增加、抽油机载荷下降5％,平均检泵周期延长2倍以上,防蝽效果明显.     

物理扰动对针状焦组织结构的影响

以煤焦油沥青为原料,在磁场诱导和超声波空化条件下制备针状焦,并通过扫描电镜SEM和X射线衍射XRD分析了外界物理扰动对针状焦组织结构的影响。结果表明,磁场诱导和超声波空化均能有效地提高针状焦的有序度、石墨化度和结晶度。与超声波空化相比,磁场诱导对针状焦的影响更大,磁场诱导作用下制备的针状焦经过高温煅烧后,其石墨化度达到45.35%。     

同轴等大方形线圈的互感系数

根据方形线圈的磁场分布公式,通过数值计算,得到了两个长度为2l、相互距离为d的同轴等大方形线圈的互感磁通量与电流、长度和相互距离之间的数值关系,并利用绘图软件Origin7.5强大的线性回归和曲线拟合功能,给出了两个同轴等大方形线圈的互感系数的近似解析式.计算结果表明,互感系数由方形线圈的长度和相互距离决定,而与电流无关.     

超磁致伸缩致动器结构设计与静态特性实验

对超磁致伸缩致动器的结构如驱动磁场、偏置磁场、预压结构、水冷机构等进行设计,利用致动器加工实物,完成致动器的静态特性实验,获得不同预压力和驱动磁场强度下的致动器输出位移曲线,并得到了最优参数。     

真空磁过滤系统的磁场模拟

利用ANSYS9.0有限元分析软件对弯曲磁过滤器的磁场进行数值模拟,计算线圈个数与扫描磁场对过滤磁场的影响,并将数值模拟数据与试验数据做了对比分析.结果表明,实验实测与有限元分析基本一致,模拟结果为磁过滤装置的设计提供了比较准确的数据资料.     

Effect of Electromagnetic Compound Treatment on Microstructure and Performance of Cemented Carbide

In order to study the effect of electromagnetic compound treatment on the mechanical property, cutting performance and microstructure of cemented carbide, the samples were treated by a self-made electromagnetic compound treatment device with different magnetic field strength(H=1, 1.25 and 1.5 T). The electromagnetic compound treatment method was proposed to couple pulsed magnetic field and pulsed current. The results show that after the pulsed magnetic field treatment, the values of the transverse rupture strength of the samples were respectively reduced by 21%, 20.6% and 20.1%; the cutting performance was decreased by about 4.5%, which means the tool life was decreased. After the electromagnetic compound treatment, the values of the transverse rupture strength of the rectangular samples were respectively increased by 8%, 8.6% and 9.5%, and the tool life was increased by 4.2%, 7% and 10.3%. After the electromagnetic compound treatment, the pulse current provided the driving force for dislocation motion. A strong pulse current driving force is more likely to make the dislocation multiply and slip. A high density dislocation cell is formed within the material, so the mechanical properties were significantly increased.     

基于空间频率评价磁流变抛光非球面中频误差

基于空间频率的概念,提出磁流变抛光非球面表面波像差的相移评价算法,根据位相与表面高度差之间的关系,计算出元件表面上各点的实际高度差.通过规划表面残余误差与抛光工艺参数之间的关系,确定能够有效消除表面残余误差的磁流变抛光工艺规范,制造成功在20 mm通光口径内面形精度达到20 nmRMS(均方根值)的非球面曲面.该方法克服了传统评价方法的局限性,为深入开展纳米精度磁流变抛光技术提供有力的技术储备.     

SF_6 旋弧灭弧室结构与驱弧磁场大小关系

ＳＦ６旋弧灭弧室利用电弧在磁场中快速旋转而熄弧，了解磁场的大小分布情况十分重要，因此采用向量磁位法对复杂结构下灭弧室磁场分布进行计算，同时也分析了铁磁物的存在对磁场分布的影响．