共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
汽油中的硫、磷、铅、锰、硅等微量杂质会严重影响电喷发动机系统中氧传感器的氧敏效应,是使氧传感器失效的主要原因之一。分析了这些杂质对氧传感器响应特性的影响以及损坏氧传感器的主要原因。研究发现:硫和锰会与氧传感器中的多孔铂电极发生反应,降低电极活性而恶化由稀至浓响应速度。铅会与铂电极形成低共熔物,延长氧传感器的响应时间。而硅和磷的作用主要在于对多孔电极层和保护层的严重堵塞。 相似文献
3.
基于Delany-Bazley-Miki多孔介质声学模型,运用COMSOL有限元软件计算了泡沫铝阻性消声器的传递损失,研究和分析了消声器内部穿孔管穿孔率、壁厚、孔径以及泡沫铝吸声材料厚度、流阻率、空气背衬等结构参数对其消声性能的影响。结果表明传递损失随结构参数的变化基本呈现周期性规律,其中穿孔管穿孔率较小时消声性能较差,泡沫铝材料厚度在不同频段时对其传递损失的影响不同。 相似文献
4.
5.
两种消声器的消声性能测定及分析 总被引:2,自引:0,他引:2
研究了多孔金属功能材料---泡沫铝制成的两种结构的消声器,进行了消声性能对比测试,结果表明,泡沫在消除空气动力噪声方面具有优越的性能。 相似文献
6.
ZrO2氧传感器多孔铂电极热处理工艺 总被引:1,自引:1,他引:1
多孔铂电极作为ZrO2氧传感器的重要组成部分,主要起催化、导电作用,对氧传感器的氧敏性能影响较大.通过对多孔铂电极进行不同形式的高温热处理,发现适当热处理后电极电导率发生变化,电极多孔性能得到明显改善,响应性能得到很大程度提升.讨论了高温处理后电极各种性能改善的原因. 相似文献
7.
《仪表技术与传感器》2020,(1)
为了快速便捷地检测水环境中的铅,设计了以MSP430单片机为控制核心的便携式电化学分析仪。基于三电极体系,使用多孔g-氮化碳(g-C_3N_4)修饰玻碳电极,实现了用线性扫描伏安法检测溶液中的铅离子,并将检测的结果传输到上位机。实验结果显示,以多孔g-C_3N_4为传感材料增加了工作电极对铅离子的敏感度,可检测浓度低至1×10~(-6)mol/L的铅离子溶液,检测结果与CHI666e电化学工作站表现一致。 相似文献
8.
9.
10.
金属纤维多孔材料是一种重要的纤维类多孔材料,具有优异的吸声性能。对金属纤维多孔材料的制备工艺进行了介绍,综述了金属纤维多孔材料的吸声理论模型以及试验研究的现状。针对单层金属纤维,依据理论与试验研究结果,详细探讨了不同结构的金属纤维多孔材料的特性参数(包括纤维丝径、孔隙率和平均孔径等)、装配参数(主要指背后空气层厚度)、梯度特性以及外部环境对材料吸声性能的影响。探讨了金属纤维复合结构的吸声性能以及金属纤维多孔材料吸声性能的优化现状。最后阐述了金属纤维多孔材料在声学领域的工程应用,并对金属纤维多孔材料的后续研究工作进行了展望。 相似文献
11.
12.
13.
提出一种具有定向孔隙多孔储油介质的制备方法,该方法以聚四氟乙烯(PTFE)粉末作为基材,苯甲酸作为造孔剂,通过模压、涂覆高温密封胶和真空烧结得到具有定向孔隙的多孔介质。分析模压压力和造孔剂质量分数对多孔介质的硬度、密度、孔隙率、储油率和油保持率等性能的影响。试验结果表明,制备压力与多孔介质的硬度和干密度分别呈线性正效应关系和负效应关系,对孔隙率、储油率和油保持率的影响不显著。造孔剂质量分数与多孔介质的硬度和密度呈线性负效应关系,与孔隙率呈线性正效应关系;造孔剂质量分数越大,甩油初始渗油速率也越大,但对最终油保持率的影响并不显著。多孔介质内部孔隙具有溶洞型的纤维化组织结构,内部孔隙相互贯通,且具有良好的定向性。 相似文献
14.
Li X Bian W Li D Lian Q Jin Z 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2011,225(3):315-323
The tissue engineering scaffolds with three-dimensional porous structure are regarded to be beneficial to facilitate a sufficient supply of nutrients and enable cell ingrowth in bone reconstruction. However, the pores in scaffolds tend to be blocked by the cell ingrowth and result in a restraint of nutrient supply in the further side of the scaffold. An indirect approach of combining the rapid prototyping and gel-casting technique is introduced in this study to fabricate beta-tricalcium phosphate (beta-TCP) scaffolds which not only have interconnected porous structure, but also have a microchannel network inside. The scaffold was designed with customized geometry that matches the defect area, and a double-scale (micropores-microchannel) porous structure inside that is beneficial for cell ingrowth. The scaffolds fabricated have an open, uniform, and interconnected porous architecture with a pore size of 200-400 microm, and posses an internal channel network with a diameter of 600 microm. The porosity was controllable. The compressive yield strength was 4.5 MPa with a porosity of 70 per cent. X-ray diffraction analysis shows that these fabrication processes do not change the crystal structure and chemical composition of beta-TCP. With this technique, it was also possible to fabricate porous scaffolds with desired pore size, porosity, and microchannel, as well as customized geometries by other bioceramics. 相似文献
15.
16.
多孔铂电极的活性对氧传感器的使用性能起着决定作用,通过电化学循环伏安测试(CV)和扫描电镜分析,研究了YSZ(氧化钇稳定的氧化锆)粉末对铂浆法制得的多孔铂电极活性的影响,其中,以循环伏安测试中的电流密度来表征多孔铂电极的活性.结果表明:随着铂浆中YSZ粉末的含量升高,所制得的多孔铂电极孔隙率和电化学反应活性明显升高,这可能是由于YSZ粉末的加入提高了多孔铂电极O2(g),Pt/YSZ体系的三相界面面积造成的. 相似文献
17.
Estimation of the connectivity of a synthetic porous medium 总被引:2,自引:2,他引:0
18.
19.
激光加工多孔端面机械密封的参数研究 总被引:1,自引:0,他引:1
建立了激光加工多孔端面机械密封的流体动力学分析模型。根据基本假设,一个孔栏上的液膜压力分布可表征整个密封面上的液膜压力。将参数进行无量纲化,采用有限差分法对激光加工多孔端面机械密封进行了参数研究,并利用MATLAB计算机软件得到了无量纲液膜压力的三雏分布规律。由计算分析可知,液膜平均压力随着液体粘度和转速的增加、液膜厚度的减小而增大;随着流体压力的增大,微孔产生的动压效应减弱。另外,微孔密度和微孔深径比的对液膜平均压力有很大影响,对其进行优化,可使平均液膜压力达到最大。 相似文献
20.
Micro Electrical Discharge Machining Deposition in Air for Fabrication of Micro Spiral Structures 总被引:2,自引:0,他引:2
Micro electrical discharge machining(EDM) deposition process is a new micro machining method for fabrication of metal micro structures. In this process, the high level of tool electrode wear is used to achieve the metal material deposition. Up to now, the studies of micro EDM deposition process focused mainly on the researches of deposition process, namely the effects of discharge parameters in deposition process on the deposition rate or deposition quality. The research of the formation of micro structures with different discharge energy density still lacks. With proper conditions and only by the z-axis feeding in vertical direction, a novel shape of micro spiral structure can be deposited, with 0.11 mm in wire diameter, 0.20 mm in outside diameter, and 3.78 mm in height. Then some new deposition strategies including angular deposition and against the gravity deposition were also successful. In order to find the forming mechanism of the spiral structures, the numerical simulation of the transient temperature distribution on the discharge point was conducted by using the finite-element method(FEM). The results show that there are two major factors lead to the forming of the spiral structures. One is the different material removal form of tool electrode according with the discharge energy density, the other is the influenced degree of the movement of the removed material particles in the discharge gap. The more the energy density in single discharge is, the smaller the mass of the removed material particles is, and the easier the movements of which will be changed to form an order tendency. The fine texture characteristics of the deposited micro spiral structures were analyzed by the energy spectrum analysis and the metaliographic analysis. It shows that the components of the deposited material are almost the same as those of the tool electrode. Moreover the deposited material has the brass metallic luster in the longitudinal profile and has compact bonding with the base material. This research is useful to understand the micro-process of micro EDM deposition better and helpful to increase the controllability of the new EDM method for fabrication of micro structures. 相似文献