Advanced Materials Research Vol. 1052

Abstract: The Ni-Fe-La-P rare earth alloys of glass fiber were prepared. Rare earth element lanthanum (La) was first introduced into glass fiber by electroless plating, in order to improve and adjust the chemical, physical properties and microstructure of alloy coatings. The application of rare earth element La in electroless plating was explored. The results showed that an appropriate amount of rare earth element La could improve the stability of the chemical plating solution and reduce the temperature of electroless plating by 6 °C ~ 20 °C. The rare earth element La not only could make the morphology of alloy coatings compacted, smooth and uniform, but also could greatly improve the contents of Fe, Ni and could tremendously reduce the content of P in the alloy coatings of glass fiber. The conductivity and magnetic properties of the alloy coatings could be increased by rare earth element La. In the preparation of the Ni-Fe-La-P electroless alloys of glass fiber, the optimal content of La₂O₃ was 1.2 g·L^-1. Rare earth element La could promote the transition of alloy coatings from amorphous state to rystal state, improve the electromagnetic performances of alloy coatings and enhance the electromagnetic wave absorbing properties of alloy coatings.

Abstract: Solution-based nickel (Ni)-induced crystallization (S-MIC) of amorphous silicon (a-Si) films has been studied with a two-step annealing process. We especially introduced Ethyl cellulose (EC) into the Ni-salt solution, so the viscous Ni-salt solution can be uniformly spin-coated on the a-Si film prepared by plasma enhanced chemical vapor deposition (PECVD). The annealing temperature can be first set from room temperature (RT) to 400°C and kept at 400°C for 2 h in nitrogen ambience. And then, it is increased from 500°C to 550°C and kept for several hours in the following annealing. The correlations among crystallization, the concentrations of Ni-salt solution and annealing conditions can be discussed. The experimental results show that with the help of the two-step annealing, the a-Si films can be crystallized at a low temperature of 500°C. The crystalline fraction gets up to 81.2% after annealing at 520°C for 2 h and the grain size of the polycrystalline Si film is approximately 0.2 μm. Energy dispersive spectroscopy (EDS) analysis shows that very little Ni metal atoms reside in the crystallized Si film for S-MIC.

Abstract: By using a SPS-30 spark plasma sintering pressing sintering furnace, the Cu-50Mo-WC composites were prepared with four different WC content by spark plasma sintering method (SPS). The wear behavior of the Cu-50Mo-WC composite pin against the QCr0. 5 bronze disc was examined on a pin-on-disc tribotester. The worn surface morphologies of the composite were observed by a scanning electron microscope (SEM). The wear mechanism was investigated briefly.The results show that the WC particles improve the hardness and wear resistance of the composites. The main wear mechanism of the composites is of adhesive wear and abrasive wear. When addition of 1% WC content, the optimal comprehensive properties of the composite is obtained.

Abstract: The four different contents of (Cu/50W)- TiC composites were prepared by spark plasma sintering method. The density, relative density, micro-hardness and conductivity were determined, respectively. The microstructure of the composite was analyzed by SEM. The wear resistance was investigated by a QG-700 atmosphere and high temperature friction and wear tester. The results show that, when the content of TiC is 3%, the optimum comprehensive properties of the (Cu/50W)-3TiC composite are obtained. The density, micuo-hardness and conductivity of the composites are 98.7%, 113HV10 and 61.4%IACS, respectively. The wear mechanisms of the (Cu/50W)- TiC composites are mainly of micro-cutting wear and adhesive wear.

Abstract: In this study, the brand name 35CS300 and 50CS400 electromagnetic steel with tensile and high cycle fatigue properties were investigated. The specimens were prepared in rolling and transverse directions. In the first, the material basic properties were built from tensile test. The high cycle fatigue was performed under stress ratio 0.1 and two sampling direction. The tensile result showed that the specimens in rolling direction (L) are slight greater than in transverse direction (T). About the fatigue test results, the 35CS300 and 50CS400 sampling direction had less effect in fatigue limit. The fracture mechanism was showed that 35CS300 has void and brush like pull out under ductile failure. But the results showed in the 50CS400 specimens had splitting fracture surface with brittle fractograph. The electromagnetic steel surface of the insulating layer under dynamic fatigue loading would cause fragmentation; if the electromagnetic steel for long-term use will reduce the efficiency.

Abstract: This paper investigates the dynamic characteristics of parabolic film slider bearing operating with ferrofluids. Comparing with the slider bearing of an inclined plane film, the parabolic film slider bearing operating with ferrofluids in the presence of external magnetic fields provide higher better dynamic stiffness and damping performances.

Abstract: Temperature can significantly affect the performance of a viscoelastic dielectric elastomer (DE). In the current study, we use a thermodynamic model to characterize the influence of temperature on the viscoelastic electromechanical response undergoing a constant electric load by taking into account the temperature dependent elastic modus and dielectric constant. Due to the significant viscoelasticity in the dielectric elastomer, DE membrane creeps in time and the inelastic stretch of DE is smaller than that of the total stretch. The results show that the total stretch of the viscoelastic electromechanical deformation increases with the increasing temperature until suffering electromechanical instability at a high temperature; the actuation performance is dominated by the moduli of the elastomer. This may be used to guide the design of dielectric elastomer actuators undergoing temperature variation.

Abstract: The dielectric strength of halogen-free glass-reinforced polyamides, including PA6, PA66, PA66/6T and PPA has been evaluated in severe conditions i.e. 120°C and 140°C according to IEC60243-1. A few halogenated grades have been evaluated as well for comparison purposes. The influence of the type of flame retardant is discussed, and results in terms of dielectric strength retention at high temperature are compared with electrical Relative Thermal Index RTI and the compound melting temperature.

Abstract: The magnetoelectric (ME) effect induced in a multiferroic composite is potentially a key to improve the performance of the nanoread head in the future magnetic recording device. In this paper, the analysis of the 1-dimensional (1D) L-T mode model containing sandwiched structures of Terfenol-D/Lead zirconate titanate (PZT)/Terfenol-D nanomultiferroic composites is performed. The magnetostriction process is described using the 1D standard square law. The magnetoelectric coupling is then investigated. The piezoelectric response on the applied dc magnetic field and PZT to Terfenol-D thickness (t_p:t_m) ratio, is determined. The optimal electric field and potential across the PZT layer are achieved at 1.3:1 thickness ratio. The result agrees well with the associated magnetic field-induced strain profile. The peak ME coefficient is found at 1.37:1 thickness ratio.

Abstract: Three half-metallic ferromagnets with NaCl structure, X₄CS₃ (X = Mg, Ca and Sr) are investigated by the first principle calculations based on the density functional theory in thegeneralized gradient approximation. Non-spin and spin polarized calculations are done to obtain the lattice constants, the equilibrium cell volumes, the stable energies and the magnetic moments of X₄CS₃, and band structure and density of states for X₄CS₃ at high pressure are calculated. From the calculations it has been found that X₄CS₃ is stable in the FM state. The corresponding lattice constants and the equilibrium cell volumes in FM are greater than that in NM. The magnetic moment of X₄CS₃ decrease as pressure increases, and a second order magnetic phase transition of Sr₄CS₃ from FM to NM state at pressure of 140GPa, but a second order magnetic phase transitions of Mg₄CS₃ and Ca₄CS₃ have not been found. According to the band and the density of states, as the pressure increases the half-metallic nature of X₄CS₃ destroyed.