摘要:
A process for applying materials to a carrier, for which the material is atomized just prior to applying it by compressed air that is supplied separately. The process is particularly suited for the application of electrically conductive material to carriers of ceramics materials.
摘要:
A layer system (11, 12) and a process for producing such a layer system is proposed which serves, in particular, to produce exhaust gas sensors. The modified layer system according to the invention advantageously contains very finely dispersed and highly reactive mixed oxides of alkali metals and at least trivalent elements on or in the porous covering layer (12), which mixed oxides exhibit an improved gettering action with respect to all the contaminants from the exhaust gas. Exhaust gas sensors having a layer system according to the invention are largely insensitive to contaminants from the exhaust gas.
摘要:
An electrochemical measurement sensor for determining the oxygen content in gases, in particular in exhaust gases from internal combustion engines, having a solid electrolyte of stabilized zirconium dioxide and/or other oxygen ion-conductive oxides and at least one electrode on the side of the solid electrolyte exposed to the gas which is to be measured, is proposed, the electrode or electrodes containing, if desired, a ceramic support structure, and the electrode or electrodes exposed to the gas, which is to be measured, being covered by a porous ceramic protective layer of an Al.sub.2 O.sub.3 and/or Mg spinel (MgO.Al.sub.2 O.sub.3) matrix with preferably metastable ZrO.sub.2 particles incorporated therein.The use of an Al.sub.2 O.sub.3 ZrO.sub.2 mixed oxide, which is preferably obtained by coprecipitation or by combination of suspensions of separately precipitated components or by spray-calcination of a combined solution of salts of the components and which may, if desired, contain a stabilizer for the ZrO.sub.2, such as, for example, Y.sub.2 O.sub.3, for forming the protective layer makes it possible, surprisingly, to form a firmly adhering, sintering-on protective layer which has a relatively narrow pore size distribution and which allows the best possible gas access to the outer electrode of the measurement sensor. The use of the Al.sub.2 O.sub.3 /ZrO.sub.2 mixed-oxide powder also achieves very extensive balancing of the hitherto observed mismatch of mechanical stresses and layer strengths on the one hand and the desired porosity and sensor control position on the other hand.
摘要:
A PTC temperature sensor, in particular for use in the exhaust gas system of internal combustion engines, has a sensing element including a PTC resistor connected to conductor webs disposed in a housing. The PTC resistor and the conductor webs are composed of a homogeneous material to form a PTC resistor track. The temperature sensing element is formed from a laminated composite of ceramic films in which the PTC resistor track is hermetically encapsulated with respect to the gas being measured and the ambient air.
摘要:
A sensor element for limiting current sensors for determination of the .lambda.-value of gas mixtures is proposed, which has at least one outer pumping electrode and one inner pumping electrode, on a solid electrolyte in platelet or foil form, conducting O.sup.2- ions, of which the inner pumping electrode is arranged in a diffusion channel for the measuring gas. It consists of a porous three-dimensional precious metal electrode having a supporting structure, the thickness of which electrode corresponds to the height of the diffusion channel. Characteristic of the inner pumping electrode is a greatly improved load-bearing capacity in comparison with electrodes of sheet-like design, whereby the service life of the sensor element is increased. A further advantage of the three-dimensional design of the inner pumping electrode is that it takes on a supporting function during lamination in the production of the sensor element by ceramic foil and screen printing techniques.
摘要:
The part of the distributor electrode in the breakdown region has a resistance of at least 400 ohms per millimeter. The total resistance of the electrode is in the range of between 0.5 and 1.0 kilo-ohms. The material is a mixture of a resistive ceramic material and a finely dispersed additive of metallic conductivity. Arrangements for creating surface discharge gaps thereby slowing down the sparking process and decreasing interference are also illustrated.
摘要:
To improve current loading of the electrodes and thus improve the start-up operation of an electrochemical system which includes a solid electrolyte body, particularly at temperatures in the order of about 300.degree. C., the solid electrolyte body and the electrode layer thereover has an intermediate coating of fully stabilized zirconium dioxide applied; for example partially stabilized zirconium dioxide is fully stabilized in its surface region by yttrium or ytterbium oxide. This intermediate layer, while improving the current carrying capability of electrodes applied thereover, additionally prevents the occurrence of damage to the microstructure of partially stabilized solid electrolyte ceramic, particularly under changeable temperature loading, so that, if the solid electrolyte body essentially entirely consists of partially stabilized ceramic, the additional fully stabilized coating or surface zone can also be provided where the solid electrolyte body does not carry an electrode layer. The fully stabilized coating or layer - which may be a surface zone of the partially stabilized body - can be obtained by coating the partially stabilized body with a stabilization oxide which, in a heat treatment, is then diffused into the surface zone; or an aqueous suspension of about 92 mol-% ZrO.sub.2 and 8 mol-% Y.sub.2 O.sub.3 or 8 mol-% Yb.sub.2 O.sub.3 can be applied, by spraying, dipping, or the like; up to 3% (by weight) of sinter-active Al.sub.2 O.sub.3 is preferably added in order to improve sintering activity of the layer, over which, where desired, an electrode layer or a composite cermet electrode layer can be applied.
摘要翻译:为了改善电极的电流负载,从而改善包括固体电解质体的电化学系统的启动操作,特别是在约300℃左右的温度下,固体电解质体和其上的电极层具有 施加完全稳定的二氧化锆的中间涂层; 例如部分稳定的二氧化锆通过钇或氧化镱在其表面区域中完全稳定。 该中间层在提高其上施加的电极的载流能力的同时,另外防止了对部分稳定的固体电解质陶瓷的微结构的损害,特别是在可变温度负载下的发生,使得如果固体电解质体基本上完全由部分 也可以在固体电解质体不携带电极层的情况下提供额外的完全稳定的涂层或表面区域。 完全稳定的涂层或层 - 其可以是部分稳定体的表面区域 - 可以通过用稳定化氧化物涂覆部分稳定的体来获得,其在热处理中然后扩散到表面区域中; 或者通过喷涂,浸渍等可以施加约92mol%ZrO 2和8mol%Y 2 O 3或8mol%Yb 2 O 3的水悬浮液; 为了提高层的烧结活性,优选添加高达3重量%的烧结活性Al 2 O 3,根据需要,可以在其上施加电极层或复合金属陶瓷电极层。
摘要:
To increase the response speed and sensitivity, while providing higher output voltages and permitting higher loading of the electrodes of gas sensors, particularly exhaust gas sensors to determine the transition of exhaust gases from internal combustion engines between reducing and oxidizing state, the sintering activity of the electrode which, typically, a cermet electrode, is selected to be less than that of the solid electrolyte body so that the resulting pore structure will be more open than that of the solid electrolyte body. The electrodes, essentially, consist of finely divided ceramic material, such as zirconium oxide, and finely divided electron conductive material such as platinum. On the pre-sintered solid electrolyte body, a mixture of the ceramic and the electron conductive material is applied in which the ceramic of the lattice support structure for the cermet electrode is less sinter-active than the ceramic of the solid electrolyte body, resulting in the improved pore structure of the cermet electrode layer.
摘要:
To facilitate mass production and permit ready introduction of a substance which provides an oxygen partial pressure reference level, for example the oxygen in ambient air, an elongated plane flat plate-like solid electrolyte body is provided with electrodes thereon, and one of the electrodes is covered by a trough-like cover element to form the reference electrode, the space beneath the trough-like element and the electrode itself being available for the substance which may, but need not be, the oxygen of air, and may be a solid material providing a reference oxygen partial pressure level. The cover plate may, itself, be made of solid electrolyte material and may form a portion of another sensing element, so that a plurality of sensing elements can be superimposed in sandwich-like fashion. A heater element can be applied to a flat plate element of the assembly where desired. The sensors can operate in the potentiometric or polarographic mode.
摘要:
To decrease the quantity of catalytically active noble metal used in a Cermet (ceramic-metal) electrode, particularly one containing platinum, the electrode has a non-uniform noble metal concentration, with respect to its cross section, so that the outer region thereof consists essentially only of ceramic material, protecting the softer noble metal which is subject to erosion, and permitting a higher concentration of noble metal close to the solid electrolyte body where it is most needed. This type of electrode can be applied, for example, by concurrent spraying of an aqueous suspension of noble metal-and-ceramic from one nozzle, and a suspension of only ceramic from another nozzle, and varying the throughput through the two nozzles, first only spraying the metal-ceramic mixture and then starting the ceramic-only suspension while decreasing the mixture suspension until only ceramic material is sprayed; in accordance with another method, the solid electrolyte body can, for example, be dipped in sequential suspensions or have sequential suspensions applied thereto by dripping-on, painting-on, or the like. The electrode and the solid electrolyte body, for example zirconium dioxide, are then sintered.