高压抗噪声干扰MOS栅驱动电路的设计

设计了一种高压抗噪声干扰MOS栅驱动电路,能有效抑制开关转换过程中产生的dv/dt噪声,消除高压电路工作过程中可能出现的误触发,提高系统的稳定性和可靠性.采用共模反馈从而使电路结构简单,同时采用窄脉冲触发式控制降低了功耗.本电路可以集成在高压集成电路(HVIC)中.采用某公司高压600V0.5μm BCD工艺模型,通过Cadence仿真验证表明:本电路可有效滤除dv/dt噪声,被消除的dv/dt噪声最高可以达到60V/ns,同时被消除的失调噪声可以达到20%,保证了高压栅驱动电路稳定、可靠地工作.     

镁合金微弧氧化Y2O3-ZrO2-MgO膜制备及性能

在K2ZrF6-Y(NO3)3-NaAlO2电解液中采用微弧氧化技术在AZ91D镁合金表面制备了Y2O3-ZrO2-MgO复合膜层(Al-Zr-Y膜).运用电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)和电化学分析与高温氧化等方法研究了Al-Zr-Y膜的组成与结构、耐腐蚀性及热稳定性.结果表明:Al-Zr-Y膜主要由Y2O3,ZrO2,MgO和Al2O3等物相组成,与Na2SiO3-(NaPO3)6电解液中的膜层(Si-P膜)相比,Al-Zr-Y膜的厚度较小,但膜层的致密性较好、表面粗糙度小;腐蚀电流密度较小、开路电位较正、极化阻抗较高;在5%NaCl溶液中的腐蚀速率低于Si-P膜,约为AZ91D镁合金的1%.Al-Zr-Y膜层比普通Si-P膜层具有更好的抗高温氧化性能和耐热冲击性能.     

弱溶剂墨水打印涂层用粘合剂的制备及应用研究

以甲基丙烯酸甲酯、丙烯酸丁酯等为原料,采用乳液聚合法合成了弱溶剂墨水打印涂层用粘合剂.考察了交联剂种类及用量、致孔剂用量、单体质量比对吸墨性能及其它应用性能的影响.研究表明,当w(交联剂二乙烯基苯)=4%,w(致孔剂乙酸乙酯)=30%,m(硬单体甲基丙烯酸甲酯)∶m(软单体丙烯酸丁酯)=1∶2时,合成的粘合剂具有较好的应用性能.     

溶胶-凝胶法制备有机/无机杂化材料及其在光固化涂料中的应用

以正硅酸乙酯、3-缩水甘油醚氧基丙基三甲氧基硅烷为原料,氨水为催化剂,用溶胶-凝胶法制备了纳米级有机/无机杂化材料。考察了催化剂用量对该纳米杂化材料粒径大小的影响,结果表明,随着催化剂用量的增加,粒径越来越大。将不同量的有机/无机杂化材料加入光固化涂料中制备了杂化涂料,研究了固化膜的形态、力学性能及漆膜的性能。结果表明:杂化材料可以改善UV固化膜的硬度、附着力和抗冲性能。     

基于变频调速的智能恒压供气系统

根据空压机电机变频控制节能的基本原理,提出了采用STC89C52单片机进行变频调速控制而设计的变频调速恒压供气系统,该系统以单片机作为中心控制单元,可根据管网用气量的变化实现空压机组的自动切换或变频调速,控制方便、灵活,可以大幅度地节能。     

真空直流溅射镀膜的条件分析

由真空直流溅射镀膜所得到的样品表面薄膜质量受到镀膜条件的影响,这些条件包括镀膜的氛围和直流电压,其中的惰性气体如氢气的气压控制是致关重要的,这2个参量对离子流的影响是很明显的。在试验中,对离子流与这2个参量的关系进行了定量分析,从而确定出镀膜条件的影响规律,找到最佳的镀膜条件。我们还采用了在样品表面加圆柱环的方法来控制等离子流溅射方向从而使镀膜均匀。     

Analysis of residual stress distri bution along interface asperity of thermal barrier coating system on macro curved surface

Based on the study of the radial residual stress distribution on the macro curved interfaces of thermal barrier coating system(TBCs) for the hollow curved substrate structures,the hollow four-concentric-circle model was developed.And the concentric-circle model with a fine scaled sinusoidal interface was proposed to describe the stresses distribution on the rough interface of TBCs with macro curved geometry.The influences of the geometric and thermophysical parameters were discussed by the developed mode...     

A comparative study of four modified Al coatings on Ni3Al-based single crystal superalloy

Four modified Al diffusion coatings (Al, Cr? Al, Al?Si and Cr? Al ? Si coatings) were prepared on Ni3Al based single crystal superalloy IC20. The oxidation tests were carried out at 1 150 °C for up to 100 h. Cyclic hot corrosion tests were carried out at 950 °C for 50 h. The results indicate that the oxidation and corrosion resistance s of IC20 alloy are improved significantly by the coatings, and both oxidation and hot corrosion resistances of the four coatings are rated in the order (from worst to best) of Cr ? Al, Al, Cr ? Al ? Si, Al? Si coatings. It is found that the degradations of Al and Cr ? Al coatings are very quick due to the serious inter-diffusion between the coatings and substrates. The inter-diffusion between Si-containing coatings and substrates is reduced since Si effe ctively retards the outward diffusion of Mo. The weak effects of Cr and benefit effects of Si to the oxidation and hot corrosion resistance were discussed. The hot corrosion degradation mechanism of superalloy IC20 was analyzed.     

Effects of surface modification on isothermal oxidation behavior of HVOF-sprayed NiCrAlY coatings

NiCrAlY coatings were deposited on Ni-based superalloy by high-velocity oxygen-fuel spraying (HVOF). Surface modification by means of grit-blasted, shot-peened and ground methods was used in order to study the effect of surface conditions on the isothermal oxidation behavior of HVOF-sprayed NiCrAlY coatings at 1050 ℃. The results showed that surface modification had an obvious effect on the isothermal oxidation behavior of the coatings. There was a large decrease in growth rate compared with the as-sprayed coating. The scale formed on the grit-blasted and shot-peened coatings was a mixture of Al₂O₃ and NiCr₂O₄, while the oxide formed on the ground coating was composed mainly of Al2O3. After surface modification, the content of NiCr₂O₄ spinels decreased compared with the as-sprayed coating.     

金融危机背景下包头市稀土产业可持续发展现状及对策研究

在金融危机持续蔓延的现实背景下,针对包头市稀土产业的发展现状、经济运行数据、竞争格局等方面进行分析,对未来稀土产业可持续发展的整体环境及趋势进行探讨和研究,指出了制约包头市稀土产业发展的瓶颈问题,提出了包头市稀土产业可持续发展的一些新的思路、目标和具体措施。