三自由度并联平台机构运动性质研究

针对目前国际上广泛研究的３－ＲＰＳ平台机构的运动性质作出分析、讨论了基面上一在转副共面或共面汇交等不同情况下的运动性质，以及该类机构在不面位形下运动性质的变化，从理论上深入地讨论了反螺旋力线矢与允许运动的关系。     

小角X光散射法测定环型聚苯乙烯无扰分子尺寸

本文采用小角Ｘ光散射技术测定了环型聚苯乙烯在θ溶剂中无扰分子尺寸；得到了分子尺寸与分子量关系的数学表达式，分析了链刚性对分子尺寸的影响，并将实验结果与相应的线型聚苯乙烯进行了对比。     

Effect of heat treatment on microstructure and properties of hot-extruded nickel-aluminum bronze

The effect of heat treatment on the microstructure and properties of a hot-extruded nickel-aluminum bronze was investigated. Experimental materials were heat treated through different processes, including quenching, normalizing, aging and annealing, and their microstructure, corrosion resistance and mechanical properties were characterized. It is found that quenching causes all β phase transformed into β phase, however, normalizing causes β phase transformed into β α and κ phases. When the quenched sample is aged, fine phase is precipitated from the as-quenched microstructure of β＇ phase. Annealing causes the transformation of β into a and κ phases. The results of mechanical property tests show that quenching, normalizing and aging improve the tensile strength and hardness of the experimental material, with a corresponding fall in elongation. Annealing raises the elongation but reduces the tensile strength and hardness. Furthermore, corrosion resistance of nickel-aluminum bronze ranks from worse to better in the following order： aged, quenched, normalized, hot-extruded and annealed. However, with the exposure time of corrosion test increasing, the difference of average corrosion rate between those nickel-aluminum bronzes tums small.     

Microstructure and mechanical properties of high strength as—cast Ti—15—3 alloy

The effects of heat treatment and solidification cooling rate on the microstructure and mechanical properties of as-cast Ti-15-3 alloy prepared by induction skull melting method were investigated.Results show that the microstructure of as-cast Ti-15-3 alloy changes from the features of simplified and larger size of beta grains to finer grain size with increasing solidification cooling rate.After solution treatment and different ageing treatment,alpha phase precipitates in grains interior as well as in grain boundaries.Due to the modification of the precipitate phase,the tensile stength and elongation of the alloy are improved simultaneously.A good combination of the values of 1.406GPa of σb and 4.5% of δ was obtained,which will be satisfied the use of this kind of alloy in critical areas.     

Structure and electronic properties of SiC thin-films deposited by RF magnetron sputtering

SiC thin-films were prepared by RF-magnetron sputtering technique(RMS) with the target of single crystalline SiC and then annealed. The surface morphology of thin-films was characterized by AFM. The result shows that the surface of the thin-films is smooth and compact; XRD analysis reveals that the thin-films are amorphous. The thickness, square-resistance and curves of resistance—temperature were measured. The results show that the curves of lnR versus 1/kT both before and after annealing satisfy the expression of lnR∝△W/kT, where ?W is electron excitation energy in the range of 0.014 2-0.018 5 eV, and it has a trend of increasing when the temperature is increased. After synthetical analysis we get the conclusion that the electronic mechanism of the thin-films is short distance transition between the localized states in the temperature range of 25-250 ℃. The resistivity is in the range of 2.4×10-3-4.4×10-3 Ω·cm and it has the same trend as electron excitation energy when annealing temperature is increased, which further confirms the electronic mechanism of thin-films and the trend of electron excitation energy versus annealing temperature.     

Magnetic and mechanical properties of FeSi alloys with high Si content

The chemical vapor（CVD） deposition-diffusion method was applied to prepare FeSi alloys with high silicon content up to 6.5%. In spite of various deposition and post-annealing, the sample remains α-Fe bcc structure. The cross section of the composition was analyzed to evaluate the Si content and distribution before and after annealing. The results show that the soft magnetic properties are improved by increasing the silicon content. For the samples containing about 6.5% Si, the coercivity decreases to 60 from 237.3 A/m of the original. It is also obtained that, in addition to the Si content, Si distribution has a large influence on the core loss due to the effect of resistivity. The micro-hardnesses were also evaluated along the cross-section after various annealings.     

Preparation and properties of PAn/ATTP/PE conductive composites

Polyaniline/Attapugite/PE（PAn-ATTP/PE）composites containing particles with core-shell structure were obtained via the two-step blending processs. The experimental condition is as follows： Organo-attapulgite and PAn was obtained by modifying attapulgite with laury benzenesulfonic acid sodium salt and, then added to PE. The electrical conductivity, structure and properties of the composites were studied. Under the function of shear stress, core-shell structure particles with ATTP as the core and PAn as the shell were formed in the composites. The structure of PAn-ATTP/PE composites were characterized by FTIR,XRD,SEM, etc, respectively. The effects of concentration of doping agent on the conductivity and mechanical property of the composites were investigated. The mechanical properties and impact fracture surface of the ternary composites were studied by means of the tensile tester, SEM, etc. The results show that polyaniline encapsulated ATTP enhances the strength of the PE. And the conductivity of PAn-ATTP/PE composites of is improved effectively when polyaniline encapsulated ATTP is added. The composite have good conductivity when 10% polyaniline encapsulated ATTP is added.