A Novel Electrochemical Oxygen Sensor for Determination of Ultra-low Oxygen Contents in Molten Metal

A novel electrochemical oxygen sensor has been developed by using Laβ-Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor hot also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of Laβ-Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both Laβ-Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for Laβ-Al2O3 oxygen sensor was discussed too.

Self-Healing,Self-Adhesive and Stable Organohydrogel-Based Stretchable Oxygen Sensor with High Performance at Room Temperature

With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-healable,self-adhesive,and room-temperature oxygen sensor with excellent repeatability,a full concentration detection range(0-100%),low theoretical limit of detection(5.7 ppm),high sensitivity(0.2%/ppm),good linearity,excellent temperature,and humidity tolerances is fabricated by using polyacrylamide-chitosan(PAM-CS)double network(DN)organohydrogel as a novel transducing material.The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy.Compared with the pristine hydrogel,the DN organohydrogel displays greatly enhanced mechanical strength,moisture retention,freezing resistance,and sensitivity to oxygen.Notably,applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor.Furthermore,the response to the same concentration of oxygen before and after self-healing is basically the same.Importantly,we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments.The organohydrogel oxygen sensor is used to monitor human respiration in real-time,verifying the feasibility of its practical application.This work provides ideas for fabricating more stretchable,self-healable,self-adhesive,and high-performance gas sensors using ion-conducting organohydrogels.

Real Time Dynamic Study of Amperometric Exhaust Oxygen Sensors

Previously,we had identified the various dynamic mechanisms of a wide range air to fuel ratio sensor operated in the engine exhaust by using the transfer function approach.In this study,we utilized these results to model the real time sensor response to an engine exhaust excursion.In the fitting,we identified a new dynamic mechanism,which was not detected in the previous transfer function study.This new dynamic occurred at the stoichiometric point when the engine changed from rich to lean.This new mechanism involved the depletion of the adsorbed fuel species on the electrode surface by an oxidation process. The dynamics of this effect depends on the ratio of the diffusion flux of the sensor-coating layer to the total adsorbed gas species on the electrode surface.The smaller the ratio is,the slower the dynamic mechanism will be.

Research on Oxygen Sensor for Metallurgical Process

A new technique for manufacture of the oxygen sensor used formetallurgical process has been developed. The powder of MgO-PSZ was prepared by coprecipitation. The MgO-PSZ tube was prepared by powder injection molding (PIM). The final sintered tube was assembled into oxygen cell, then tested in laboratory and on RH vessel. The results showed that the thermal shock resistance of MgO-PSZ matrix is strong enough for determining the active oxygen concentration in steel melt. The reproducibility of the EMF measurement is very good. The structure of the tube has been analysed by means of SEM and XRD. In addition, the characteristics such as the density and phase ratio in the product were compared with that of Shijiazhuang Maple Wood Sensor Company′s product.

Dissolved oxygen sensor based on sol-gel matrix doped with tris(2,2'-bipyridine)ruthenium dichloride

To establish a immobilization method of oxygen sensitive dye, a dissolved oxygen sensor based on a sol-gel matrix doped with ruthenium complex ([Ru(bpy)3]2+) as the oxygen-sensitive material is reported. The results indicate that the I0 /I100 value of the [Ru(bpy)3]2+-doped in tetraethylorthosilane (TEOS) composite films are estimated to be 10.6, where I0 and I100 correspond to the detected fluorescence intensities in pure nitrogen saturated water and pure oxygen saturated water, respectively. Also, the Stern-Volmer plot shows a very good linearity at low dissolved oxygen concentrations. The response time of the composite films is 5 s upon switching from nitrogen saturated water to oxygen saturated water and 10 s from oxygen saturated water to nitrogen saturated water. The dissolved oxygen sensors based on the ruthenium complex/TEOS composite films exhibit greater sensitivity, stability and faster response time as compared to the existing ones. Furthermore, the thin films possess greatly minimized dye leaching effect.

Sintering Caβ″/β/α-Al_2O_3 High Temperature Oxygen Sensor

An extended-life and ultra-low oxygen sensor has been fabricated by using polycrystalline Caβ″/β/α-Al2O3 as a solid electrolyte. Five reference electrodes CaO+O2, Caβ″/β/α-Al2O3 (powder)+O2,Cr+Cr2O3, Nb+NbO and Mo+MoO2 were tested in order to select a better reference electrode for this sensor. The limit of determining oxygen activity and the extended-life of the sensor were also tested in this study.

Solid Reference Electrode of Metallurgical Oxygen Sensor

The thermal equilibrium state of the reference electrode was investigated. The results show that the temperature difference between the inside and the outside of zirconia tube was very small and the Seebeck effect can be ignored after the sensor was dipped into liquid steel for more than 2 s. A special sensor was designed to test the relation between the EMF （electromotive force） of sensor and the thermal equilibrium state of the reference electrode. Based on these results, it is suggested that the peak in EMF curve was caused by the change of oxygen potential in reference electrode before the thermal equilibrium was reached. If NiO was added by 2%-5% to the Cr/Cr2O3 reference electrode, the peak in EMF curve could be eliminated.

The performance of Pt/air oxygen sensors in stagnant Pb-Bi eutectic at high temperatures

Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic(LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor and another one from Karlsruher Institute of Technology(KIT) were tested in stagnant oxygen-saturated liquid LBE.Calibrations showed that the trend and values of corrected electromotive force(EMF) of the self-developed sensor, with a bias voltage of 20 mV, were consistent with theoretical results above 425℃, and similar results were obtained in cross-calibration test with EMF value of KIT sensor as reference. In stability test at 450℃ for 100 hours, the KIT sensor performed better than the self-developed one, which showed signal fluctuations.Both sensors exhibited quick response to temperature variations in the responsiveness test.

Effect of ZrO_2 (9mol% Y_2O_3) coating thickness on the electronic conductivity of Mg-PSZ oxygen sensors

The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2 (9mol% Y2O3) slurry and then co-firing at 1750°C for 8 h. The double-cell method was employed to measure the electronic conductivity parameter and exam the reproducibility of the coated Mg- PSZ tube. The experimental results indicate that the good thermal shock resistance of the Mg-PSZ tube can be retained when the coating thickness is not more than 3.4 μm. The ZrO2 (9mol% Y2O3) coating reduces the electronic conductivity parameter remarka- bly, probably due to the lower electronic conductivity of Y2O,-stabilized ZrO2 than that of MgO-stabilized ZrO2. Moreover, the ZrO2 (9mol% Y2O3) coating can improve the reproducibility and accuracy of the Mg-PSZ tube significantly in the low oxygen measure- ment. The smooth surface feature and lower electronic conductivity of the coated Mg-PSZ tube should be responsible for this im- provement.

Properties of Zirconia Material as Oxygen Sensor

The properties and applications of ZrO2-Y2O3 material used as oxygen sensor were studied.Oxygensensors are studied by X-ray diffraction technique,microstructure determination and thermal shock resistancetest,and are tested on the spot.Oxygen sensors made from the sintered dense ZrO2 stabilized by Y2O3 can beused to measure the oxygen concentration in molten steel at 1600℃.The data obtained are stable and reliable,and the thermal shock resistance is high.The oxygen concentration is measured at（1～150）×10-4% with re-sponse time of 2～3s.

Preparation and Properties of Sensing Membrane for Fiber Optic Oxygen Sensor

Four sensing membranes based on fluorescence quenching were prepared by sol-gel method and CA membrane method, and the Ru(Ⅱ) complexes, Ru( bpy)3 Cl2 and Ru(phen)3 Cl2 , were used as the indicators . The results indicate that the volume fraction of oxygen o2 have a linear relationship in large scale with tan0/tanfor all of the sensing membranes. They have super properties such as excellent limit of detection ,fast response time and good reproducibility. The stability of the sensing membranes made by sol-gel method is better than those by CA membranes, but the uniformity of the latter is better than that of the former.

Preparation and Characterization of Zireonia Oxygen Sensors

A thimble zirconia oxygen sensor was prepared with YSZ.The surfaces of the Pt electrode, electrolyte and their interface were observed with a scanning electron microscope(SEM).The sensor was examined with engine bench test to evaluate the essential performance.The basic function such as electromotive force output and response time was discussed.The oscillograph trace was also obtained and analyzed with four different frequencies.The experimental results reveal that the oxygen sensor has high performances meeting the demands of practical applications..

Preparation and Properties of Modified Sol-Gel Sensing Membrane for Fiber Optic Oxygen Sensor

Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.

Preparation and analysis of zirconia oxygen sensors

Thimble zirconia oxygen sensors were prepared with yttria stabilized zirconia(YSZ). The surfaces of the electrode, electrolyte and their interface were observed by scanning electron microscope(SEM). The sensor was examined with engine bench test to evaluate the essential performance. The results show that the oxygen sensor has good performance, which can meet the demand of practical applications. Chemical equilibrium theory was introduced to explain electromotive force of the sensors and the influence of temperature on the signals. The educed theoretical model of electromotive force agrees well with testing results.

APPLICATI0N OF POSITRON ANNIHILATION TECHNIQUE TO ZrO_2 OXYGEN SENSOR

In the paper, the authors analyse the rela-tionship between the electrical conductivity σ ofZrO2 and the content of doped stabilizing agent bythe Positron Annihilation Technique, and explain thechange tendency of σ with the content of stabilizingagent. The research shows that "number of effectivevacancy" in material is a decisive factor causingchange of σ.

Optical Oxygen Sensors With Improved Lifetime Incorporating Titania Beads and Polydimethylsiloxane Coatings

The use of optical sensors for oxygen measurement is becoming more important because of their capability for low-cost and direct measurement,but as yet,little has been reported about their long-term performance.Phosphorescent sensors based on platinum octaethylporphyrin(PtOEP)embedded in polymer matrices tend to degrade with time.To reduce the rate of degradation,sensor films were fabricated and then coated with a layer of polydimethylsiloxane(PDMS)and tested in a six-month study.The PDMS-coated sensors showed an average degradation rate of〜0.073%/day,compared to〜0.18%/day for uncoated sensors.Titania beads were also incorporated into the films to increase light scattering and improve the response;these beads compensated to some degree for the absorption due to the PDMS films.The films with titania beads improved the response significantly(about 40%)compared to the films without titania beads.Incorporation of titania beads also moderately improved the aging characteristics.

Limiting current oxygen sensor based on Y,In co-doped SrTiO_(3)as a dense diffusion barrier layer

A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).

A Phase Shift Demodulation Technique： Verification and Application in Fluorescence Phase Based Oxygen Sensors

基于能够测量 0.03 阶段度的减法，在正弦曲线之间的限制表明的一种阶段移动解调技术在这份报纸被介绍。一个自我获得模块和实际 subtracter 扮演阶段移动解调系统的内核部分。在不同阶段的电的信号被用来验证系统的性能。另外，新设计光来源，激光纤维微分来源(LFDS ) ，能够产生微型阶段被用来进一步验证系统可靠性。在电的信号的 0.99997 的 R 平方和在 LFDS 的 0.99877 的 R 平方被完成，并且 0.03 度测量限制在实验被认识到。而且，阶段移动解调系统被用于荧光阶段认识到基础的基于的氧传感器工作。试验性的结果揭示那一次好重复并且更好，比 0.02% 氧集中测量，精确性被认识到。另外，阶段移动解调系统能对另外的应用程序容易综合。

Piezoresistive effect in MoO3 nanobelts and its application in strain-enhanced oxygen sensors

有不同性质的 MoO3 nanobelts (NB ) 经由物理蒸汽免职(PVD ) 被综合了方法。NB 的结晶的结构和形态学被 X 光检查衍射，传播电子显微镜学和扫描电子显微镜学描绘。电的大小被执行，在 MoO3 的深刻 piezoresistive 效果试验性地学习了并且验证。影响计量器因素的因素例如 NB 尺寸，做的集中和空气作文，被讨论并且分析。煤气的察觉到性能也在设备被测试，由把紧张用于煤气的传感器，它的察觉到的表演能有效地被调节并且提高，这被表明。这研究在 MoO3 NB 和另外的电子调整测量负担得起更好的设备性能和更宽广的材料功能的这效果能借助于被结合的通用机制的第一幅插图提供重要 piezoresistivity 的第一示范。