Magnetically Addressable Shape‐Memory and Stiffening in a Composite Elastomer

With a specific stimulus, shape‐memory materials can assume a temporary shape and subsequently recover their original shape, a functionality that renders them relevant for applications in fields such as biomedicine, aerospace, and wearable electronics. Shape‐memory in polymers and composites is usually achieved by exploiting a thermal transition to program a temporary shape and subsequently recover the original shape. This may be problematic for heat‐sensitive environments, and when rapid and uniform heating is required. In this work, a soft magnetic shape‐memory composite is produced by encasing liquid droplets of magneto‐rheological fluid into a poly(dimethylsiloxane) matrix. Under the influence of a magnetic field, this material undergoes an exceptional stiffening transition, with an almost 30‐fold increase in shear modulus. Exploiting this transition, fast and fully reversible magnetic shape‐memory is demonstrated in three ways, by embossing, by simple shear, and by unconstrained 3D deformation. Using advanced synchrotron X‐ray tomography techniques, the internal structure of the material is revealed, which can be correlated with the composite stiffening and shape‐memory mechanism. This material concept, based on a simple emulsion process, can be extended to different fluids and elastomers, and can be manufactured with a wide range of methods.     

Cellulose‐Based Microparticles for Magnetically Controlled Optical Modulation and Sensing

Responsive materials with birefringent optical properties have been exploited for the manipulation of light in several modern electronic devices. While electrical fields are often utilized to achieve optical modulation, magnetic stimuli may offer an enticing complementary approach for controlling and manipulating light remotely. Here, the synthesis and characterization of magnetically responsive birefringent microparticles with unusual magneto‐optical properties are reported. These functional microparticles are prepared via a microfluidic emulsification process, in which water‐based droplets are generated in a flow‐focusing device and stretched into anisotropic shapes before conversion into particles via photopolymerization. Birefringence properties are achieved by aligning cellulose nanocrystals within the microparticles during droplet stretching, whereas magnetic responsiveness results from the addition of superparamagnetic nanoparticles to the initial droplet template. When suspended in a fluid, the microparticles can be controllably manipulated via an external magnetic field to result in unique magneto‐optical coupling effects. Using a remotely actuated magnetic field coupled to a polarized optical microscope, these microparticles can be employed to convert magnetic into optical signals or to estimate the viscosity of the suspending fluid through magnetically driven microrheology.     

Tunable Magnetism in Nanoporous CuNi Alloys by Reversible Voltage‐Driven Element‐Selective Redox Processes

Voltage‐driven manipulation of magnetism in electrodeposited 200 nm thick nanoporous single‐phase solid solution Cu₂₀Ni₈₀ (at%) alloy films (with sub 10 nm pore size) is accomplished by controlled reduction‐oxidation (i.e., redox) processes in a protic solvent, namely 1 m NaOH aqueous solution. Owing to the selectivity of the electrochemical processes, the oxidation of the CuNi film mainly occurs on the Cu counterpart of the solid solution, resulting in a Ni‐enriched alloy. As a consequence, the magnetic moment at saturation significantly increases (up to 33% enhancement with respect to the as‐prepared sample), while only slight changes in coercivity are observed. Conversely, the reduction process brings Cu back to its metallic state and, remarkably, it becomes alloyed to Ni again. The reported phenomenon is fully reversible, thus allowing for the precise adjustment of the magnetic properties of this system through the sign and amplitude of the applied voltage.     

井下液体流速检测仪的研制

介绍了一种井下低流速液体流速检测仪的研制 ,阐述了利用 2DCM硅磁敏二极管和波纹管制造井下液体低流速传感器的设计原理与结构 ,提出了用XTR10 4补偿电路和智能化检测系统的方案 ,实验结果表明 ,该项技术方案是可行的     

实用新型光纤磁场强度传感器

在高压电气系统中 ,磁场的检测是非常重要的。新型实用光纤磁场传感器应用了现代光通信系统中的新型磁光晶体、准直器、带尾纤的半导体激光器、耦合器等多项技术 ,使传感器不仅结构紧凑 ,而且具有良好的抗震性能和测量准确度     

非晶态合金材料磁敏特性及应用的研究

本文论述了非晶态合金材料的磁学性能与磁敏功能,并在此基础上对非晶态合金传感器的开发应用进行了分析研究。     

钕掺杂对TbFeCo薄膜磁光性能的影响

采用射频磁控溅射方法制备了非晶磁光 ,并在TbFeCo中引入Nd ,以提高薄膜的本征克尔角。测试了薄膜的磁光性能 ,研究了薄膜成分对其磁光性能的影响。结果表明 ,在TbFeCo薄膜中掺入一定量的Nd ,可显著提高薄膜的磁光性能 ,薄膜的磁光克尔 (Kerr)角可达 0 47°,矫顽力可达 3 .4× 10 5A·m- 1 。但Nd的掺入量过高 ,反而使薄膜的磁光性能恶化     

稀土超磁致伸缩电机及其应用

稀土超磁致伸缩电机在大应变、强力和高功率密度及高精度、快速响应以及高可靠性等方面有着其它电机无法比拟的优点。介绍了这种电机的结构原理、性能特点及其典型应用事例。文中还就稀土超磁致伸缩材料及其驱动器件的市场应用前景进行了展望。     

磁处理降低钢铁材料中残余应力的研究现状及展望

磁处理是一种降低钢铁材料中残余应力的新方法,具有高效、灵活、效果明显而又无不利组织转变等优点,有望能得到广泛应用.综述了近年来磁处理降低残余应力方法的研究现状,并对国内外的最新研究成果进行了简要的介绍与评述,在此基础上,对磁处理方法的发展进行了展望.     

小功率永磁同步发电机设计特点

在分析了小功率永磁同步发电机结构基础上阐述了该种电机的设计特点 ,并设计研制了样机 ,以此验证了设计方法的正确性