青铜峡3~#机组水轮机转轮室的更新改造

本文就水轮机转轮室的更新改造工作,从准备、旧件拆除、新件组装调整、试运等方面进行了较为详细的介绍,并且从中总结出经验和教训.     

Controllable degradation of biomedical magnesium by chromium and oxygen dual ion implantation

The surface stability of biodegradable magnesium is crucial to tissue growth on implants in the initial healing stage. Inspired by the design principle of biomedical stainless steels, we implant chromium as a passive element into pure magnesium to alter the surface biodegradation behavior. However, because Cr exists in the metallic state in the implanted layer to induce the galvanic effect, excessively fast degradation is observed. Ensuing implantation of oxygen produces a thicker surface oxidized layer composed of chromium oxide, which successfully retards the surface degradation of pure magnesium. The dual implantation process offers a promising means to improve the initial surface stability of Mg in the physiological environment.     

Novel thermoelectric materials based on boron-doped silicon microchannel plates

The thermoelectric properties of boron-doped silicon microchannel plates (MCPs) were investigated. The samples were prepared by photo-assisted electrochemical etching (PAECE). The Seebeck coefficient and electrical resistivity at room temperature (25 °C) were measured to determine the thermoelectric properties of the samples. In order to decrease the very high resistivity, boron doping was introduced and by modulating the doping time, a series of samples with different resistivity as well as Seebeck coefficient were obtained. Boron doping changed the electrical resistivity of the samples from 1.5 × 10⁵ Ω cm to 5.8 × 10⁻³ Ω cm, and the absolute Seebeck coefficient deteriorated relatively slightly from 674 μV/K to 159 μV/K. According to the Seebeck coefficient and electrical conductivity, the power factor was calculated and a peak value of 4.7 × 10⁻¹ mW m⁻¹ K⁻² was obtained. The results indicate that silicon MCPs doped with boron are promising silicon-based thermoelectric materials.     

Effects of BiAlO3 on structure and electrical properties of K0.5Na0.5NbO3-LiSbO3 lead-free piezoceramics

(1−x)(0.948 K_0.5Na_0.5NbO₃-0.052LiSbO₃)-xBiAlO₃ (KNNLS-xBA) lead-free piezoceramics were synthesized by conventional solid state reaction method. The compositional dependence of phase structure and electrical properties of the ceramics was systemically studied. XRD patterns revealed that all the ceramic samples possessed pure perovskite structure. In addition, polymorphic phase transition (PPT) for the ceramics with BA doping could not be observed in the measuring range from room temperature to 500 °C. Within the studied range of BA addition, the ceramics with x = 0.002 represented a relatively desirable balance between the degradation of the piezoelectric properties, improvement in temperature stability and mechanical quality factor. It was found that the KNNLS-0.002BA ceramics exhibited optimum overall properties (d₃₃ = 233 pC/N, k_p = 35%, tanδ = 0.047, P_r = 27.3 μC/cm², Q_m = 56 and T_c = 349 °C), suggesting that this material should be a promising lead-free piezoelectric candidate for piezoelectric applications.     

Fabrication,properties, and cytocompatibility of ZrC film on electropolished NiTi shape memory alloy

The microstructural characteristics, mechanical properties, and cytocompatibility of ZrC films deposited on electropolished NiTi shape memory alloy (SMA) by magnetron sputtering are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), nanoindentation, and MTT test. The deposition rate of the ZrC film is smaller than the pure Zr film. Although ZrC is the only phase in the film, the pure ZrC film with small oxygen content is non-stoichiometric. The hardness and modulus increase initially with larger nanoindentation depths, reach maximum values, and then gradually decrease afterwards as a result of the composite effects of the ZrC film and NiTi substrate. Deposition of the ZrC film promotes proliferation of fibroblasts revealing enhanced cytocompatibility compared to uncoated NiTi.     

聚吡咯/La0.3Ca0.7Ni0.25Co0.75O3复合材料的制备、表征及性能

用甘氨酸-硝酸盐燃烧法和溶液原位合成法分别制备了钙钛矿型氧化物La0.3Ca0.7Ni0.25Co0.75 O3粉末及其吡咯相对质量分数为60%和80%的聚吡咯/钙钛矿复合微粒PPY/La0.3Ca0.7Ni0.25Co0.75O3.用X射线衍射(XRD)、红外光谱(FTIR)对材料进行了表征.并用循环伏安曲线对复合材...