NiO基厚膜NO_2传感器的研制

文中分别以化学沉淀法、柠檬酸法和均相沉淀法制备了NiO纳米材料,通过XRD方法对所制备材料的晶体结构进行分析表征.并以上述不同方法制备的NiO为基体材料,Cr2O3、WO_3为掺杂剂制作了电导型厚膜NO_2气体传感器.研究了工作温度、掺杂剂等对器件气敏性能的影响.结果表明:掺杂WO_3的NiO基厚膜传感器对NO_2有较高的灵敏度、良好的选择性及响应特性,并且对器件的敏感机理做了初步的分析.     

NASICON基NO_2气体传感器

文中介绍了一种管式结构的固体电解质NO_2气体传感器.该传感器是用溶胶–凝胶法制备的NASICON(钠离子导体) 为导电层材料,利用化学沉淀法制备的NiO和贵金属Au作为敏感电极材料制得的.文中研究了不同敏感电极材料对气体传感器性能的影响.以NiO+Au 作为敏感电极材料的传感器具有较大的灵敏度,当工作温度在300 ℃时,对浓度为(5～200)×10-6的NO_2表现出了良好的气敏性能,传感器的灵敏度大于70 mV/decade.     

一种基于纳米SnO2材料的CO气敏器件的研制

介绍了纳米ＳｎＯ２－ＰｄＯ混合材料及其ＣＯ气敏器件的制备过程,并对该敏感器件的敏感特性进行了测试和分析,结果表明,由纳米材料制备的敏感器件对ＣＯ的敏感特性大大提高。     

氨气泄漏检测材料的研究

简述了氯气等制冷工业中的化学气体的性质与检测方法。详细研究了ＷＯ３系半导体氨敏材料及元件的敏感特性,对Ｉｎ２Ｏ３,ＳｎＯ２等半导体氨敏材料也进行了探讨。     

用于海洛因检测的低浓度乙酸敏感元件制备和敏感性能研究

文中通过对海洛因毒品的特性分析,提出了采用氧化传感器检测低浓度乙酸气体,间接检测海洛因毒品的技术方案,并对ZnFe2O4、ZnGa2O4气敏材料的制备和气敏性能进行了研究,认为Sb掺杂ZnFe2O4敏感材料适合于乙酸传感器,用于海洛因毒品的检测。     

三氧化钨的矿气气敏传感器的研究

以钨丝为原料,用气相法制备纳米WO3气敏材料,以WO3为基材,制备了矿气气敏传感器.气敏性能测试表明,在2.5V加热电压下,该法制备出的传感器元件对5000ppm的矿气,灵敏度达2.6.分析后认为制备的材料大小分布呈连续性,晶粒间的体缺陷是增加元件对矿气灵敏度的主要原因.     

薄膜型钯-铬合金氢气传感器技术研究

文中介绍了采用Pd-Cr合金作为氢敏材料,利用MEMS加工技术制备薄膜型氢气传感器.测试了传感器对0～4％浓度范围氢气的敏感特性,结果显示,传感器对0～4％氢气浓度具有良好的线性输出特性,并表现出较高的响应灵敏度和较好的响应重复性.     

掺杂ZnO臭氧敏感特性研究

通过主体材料ＺｎＯ掺入多种掺杂剂对Ｏ３气敏特性影响的研究,得到了对Ｏ３敏感的较佳材料,用该材料制作 成的气敏传感器对Ｏ３具有较高的灵敏度、较低秘较好的响应恢复特性。     

Zn掺杂对SnO_2棒状晶湿敏陶瓷湿敏特性影响研究

采用共沉淀法制备出SnO_2棒状晶湿敏粉体,分析了Zn掺杂对材料湿敏性能的影响,研究了材料的复阻抗特性和频率特性。实验结果表明,Zn的添加量对材料的微结构和湿敏特性都具有较大影响。适当的Zn掺杂可使材料具有棒状晶粒的微结构和较好的湿敏性能,频率特性表明该材料具有较好的频率响应。     

纳米结构金属氧化物气敏材料的研究进展

具有纳米结构的金属氧化物由于纳米效应表现出了非常优异的气敏性能;以维度为线索,简要综述了零维、一维、二维和三维纳米结构金属氧化物气敏材料的制备方法和不同结构对其气敏性能的影响,最后指出了未来该领域的研究和发展方向。     

Tribological behavior of sintered tin bronze with additions of alumina and nickel oxide

The tribological characteristics of sintered tin bronze with additions of oxides of aluminum and nickel have been studied. The addition of ultrafine particles of alumina or the mixture of alumina and nickel oxide to sintered tin bronze reduces the coefficient of friction, the temperature in the friction zone and the volume wear rate of the rubbing surfaces. The average coefficient of friction of the material does not change substantially over time. During wear, the chipping of oxide microparticles was observed, which led to a change in the roughness of the working surfaces. The presence of Motor Life Professional additive in oil reduces coefficient of friction, the temperature in the friction zone, and the volume wear rate of rubbing surfaces.     

铝合金脉冲换向氧化着色工艺

介绍在１５％的硫酸加硫酸镍电解液中,采用脉冲换向ＬＦ５铝材进行氧化着色工艺,所获得的氧化膜性能,成膜速度,着色效果均明显估于脉冲非换向氧化着色工艺。     

High‐temperature oxidation of nickel and chromium studied with an in‐situ environmental scanning electron microscope

Investigations of the morphology of metal oxide scales formed at high temperatures in oxidative environments are usually undertaken after exposure of the samples is completed. In this study, an environmental scanning electron microscope (ESEM) was used as a tool for the in‐situ observation of oxide scale formation. Pure nickel and chromium samples were oxidized at a temperature of 973 K in either pure oxygen or water vapour at a pressure of 667 Pa. The evolution of an oxide scale was followed in‐situ for up to 3 h. The morphology of the developing oxide scales was found to be a function of the metal substrate and the gaseous species. The growth mechanisms of the different metal oxide scales are reviewed and related to the analysed in‐situ images. Emphasis is placed on the relationship between oxidation mechanism and scale morphology. Nickel is seen to oxidise by outward diffusion of nickel probably on oxide grain boundaries when exposed to oxygen. Water vapour changes the scale morphology and a duplex‐type scale arises due to preferential overgrowth. The scale which develops due to chromium oxidation in oxygen is a fine‐grained, thin, and dense layer. In contrast, water vapour leads to whisker growth on chromium and an open, felt‐like structure forms. The applicability of the ESEM to the study of such systems is demonstrated, and its limitations are outlined. The results are encouraging examples of the possibilities which the in‐situ ESEM technique possesses.     

Wear mechanisms in electroless nickel coatings

Electroless nickel coatings are susceptible to severe adhesive wear against plain carbon steel under dry sliding contact, because the low interfacial and high surface free energies of this material combination produce highly compatible surfaces. Controlled heat treatment eliminates severe wear by inducing crystallization of amorphous nickel to Ni₃P, which is incompatible with steel. Electroplating the counterface with chromium also eliminates severe adhesive wear owing to the efficient barrier properties of its surface oxide but a stainless steel counterface exacerbates the problem because of its single-phase microstructure and the low durability of its oxide film. The reciprocating diamond scratch test gives a different ranking order of wear rate from the Falex, pin-on-flat and Taber tests, because of its dependence on fracture toughness as the dominant material parameter rather than adhesive transfer. Wear mechanisms observed in the investigation include adhesive transfer, oxidation, three-body abrasion, micromachining, plastic deformation and delamination. In general, no correlation is found between wear rate and hardness; this is primarily because of changes in the mechanism of wear effected by processing, counterface materials or sliding conditions.     

The fretting wear of Ti-6Al-4v and aged inconel 718 at elevated temperatures

The fretting wear of Ti-6Al-4V and Inconel 718 was investigated with a sphere-on-flat configuration. The spherical surface was 100 mm in radius and in all tests was made of the same material as the flat. The normal load was 2.75 N and the frequency of the tangential movement was 50 Hz. Two amplitudes of slip were used, 10 and 40 μm. Tests were conducted in air at temperatures up to 600 °C for the titanium alloy and up to 540 °C for the nickel alloy. High temperature strain gauges enabled a continuous record of the tangential stress to be made and subsequent calculation of the coefficient of friction. Wear was assessed from measurement of the scar volume. At 280 and 540 °C at an amplitude of 40 μm the coefficient of friction and wear rate decreased to a low value on the nickel alloy. This only occurred at 540 °C for the lower amplitude of slip. Low friction and wear are associated with the formation of a “glaze” oxide, which requires a larger slip amplitude at lower temperatures for its formation.The titanium alloy generally exhibited higher coefficients of friction which continued to increase at 10⁶ cycles, although wear rates at 200 °C and above were comparable with those on the nickel alloy. “Glaze” oxide begins to form at 200 °C and is well developed at 400 °C. At 600 °C breakdown occurs owing to local creep of the substrate.     

The application of scanning transmission electron microscopy (STEM) to the study of thin anodic films on nickel and nickel-molybdenum alloys

Anodized thin-film samples of nickel, molybedenum and a nickel-13 w/o molybdenum alloy have been analysed by scanning transmission electron microscopy, using selected area diffraction, microdiffraction and X-ray micro-analysis. Thin-film samples were obtained by ion thinning with argon and by electropolishing in acetic acid-perchloric acid. Electropolishing is the preferred technique for these studies, producing a surface with roughness on a scale of 1 nm. The anodized films on nickel and nickel 13 w/o molybdenum alloy exhibit a rugosity with a ‘particle’ size of 3 nm. The crystal structure of the films is similar to f.c.c. nickel oxide. Molybdenum enrichment was detected in the anodized alloy surfaces but there is no electron diffraction evidence for a crystalline molybdenum oxide. The electron diffraction pattern from anodized pure molybdenum suggests that the surface film is amorphous.     

Interface wear reactions between nickel and a nickel-33 at. % chromium alloy in a simulated face seal

The wear tracks of a nickel specimen mated against a nickel-33 at. % chromium alloy in a simulated face seal have been characterized by optical and scanning electron microscopy. Both surfaces showed a smeared layered appearance, with smooth-bottomed holes present. A layer of alloy material was transferred to the nickel, but no nickel was transferred to the alloy. Observations of a cross section through the nickel specimen revealed that the alloy layer covering the surface was highly plastically deformed. The layer of nickel in contact with the alloy layer had a fine grain size, showing that frictional heating had induced recrystallization in the nickel, although not in the alloy layer.     

镍钛合金双层波纹石墨复合垫片的设计与参数优化

针对反应釜的高腐蚀性、恒温以及多振动等工况,设计一种新型镍钛合金双层波纹石墨复合垫片,其骨架材料为镍钛合金,结构为双层式波纹结构,在双层骨架的内外侧填充石墨层。选取波纹数、骨架厚度和波纹幅值等参数进行正交优化设计,采用ANSYS软件模拟该垫片在一定波纹数(4～6个)、骨架厚度(0.3～0.5 mm)和波纹幅值(0.3～0.5 mm)时的变形特征。结果表明:新型垫片的最佳回弹率为93.84%,对应的波纹数、骨架厚度和波纹幅值为5个、0.5 mm和0.3 mm。与不锈钢双层波纹石墨复合垫片和不锈钢单层波纹石墨复合垫片对比表明:镍钛合金双层波纹石墨复合垫片具有最好的回弹性能。     

基于不同磨料的氮化硅陶瓷球精研工艺研究

为探究磨料对氮化硅陶瓷球精研加工的影响,从而提高氮化硅陶瓷球的表面质量和材料去除率,以基液种类、磨料种类和研磨盘转速为主要影响因素设计正交试验,并分析各因素对表面粗糙度Ra的影响程度。以表面粗糙度Ra和材料去除率为评价指标,通过单因素试验优化研磨参数。根据正交试验结果,得到精研加工过程中各影响因素对于表面粗糙度Ra的影响程度,从大到小排列依次为:磨料种类>基液种类>研磨盘转速。综合考虑陶瓷球精研加工的要求,确定最佳的研磨参数组合为:煤油基液、碳化硅磨料以及150 r/min的研磨盘转速。在金刚石、碳化硅、氮化硼、氧化铬和氧化铁这5种磨料中,氧化铁磨料修复粗研过后的氮化硅陶瓷球表面缺陷的效果最好。     

Zn_2SnO_4气敏材料的共沉淀法制备及其氧化物掺杂改性

新型复合材料Zn_2SnO_4具有良好的气敏性,文献鲜有报道Zn_2SnO_4材料的制备以及氧化物掺杂改性;因此采用液相共沉淀法制备了Zn_2SnO_4粉体材料,利用X射线衍射仪(XRD)对合成的材料的结构进行了表征;通过固相反应制备了MnO_2,Li_2O掺杂的Zn_2SnO_4粉体,对旁热式气敏元件的性能进行了测试.实验发现Zn_2SnO_4是一种性能优良的酒敏材料,氧化物掺杂剂MnO_2和Li_2O的加入明显提高了材料对乙醇气体的灵敏度和选择性,质量百分含量为0.5%的Li_2O的掺杂量可以使元件对于体积分数为50×10-6的乙醇气体灵敏度达到150.