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.
摘要:
To increase the sensitivity of internal combustion engine exhaust gas sensors, which provide a voltage jump output upon transition of the composition of the exhaust between reducing and oxidizing state, and to maintain the porosity of a platinum, or platinum metal alloy layer forming an electrode on a body of zirconium dioxide, the electrode or electrode layer has dispersed therein an oxide or a carbide of a metal which impedes or inhibits recrystallization at the temperatures to which the sensor is exposed, for example 1000.degree. C., typically zirconium, titanium, tantalum, niobium, aluminum or thorium oxide, or titanium or tantalum carbide, applied, for example, by sequential vaporization of platinum or a platinum metal alloy and the respective metal forming the oxide, in an atmosphere containing residual oxygen, and then oxidizing the remaining metal being applied; or by simultaneous application of a carbide and platinum, for example during simultaneous cathodic atomization, or electron beam vaporization of the respective materials, to form a porous electrode layer of about 2-3 .mu.m thickness, containing approximately 5-40 mol-% of the recrystallization-inhibiting material and having a square resistance not exceeding 20 ohm-square resistance.
摘要:
A device for cleaning gas mixtures that contain particles, in particular for cleaning soot-laden exhaust gases of internal combustion engines, is described in which the device is embodied as a filter that has a porous surface of a sintered-metal-containing filter-supporting material that is exposed to the gas mixture to be cleaned. The sintered-metal-containing filter-supporting material has a catalytically active material component.
摘要:
A method is described for producing a ceramic powder, in which at least one ceramic base powder or ceramic slurry is subject to a heat treatment for generating an intermediate product from which the ceramic powder is produced. The ceramic base powder, the ceramic slurry, or an optionally added additive is transformed in the heat treatment such that gas components are essentially avoided in the ceramic powder or such that gases released from the ceramic base powder or from the ceramic slurry adjust a partial pressure in the ceramic powder.
摘要:
An insulation layer of a heating device for a sensor for determination of oxygen concentration in gas mixtures, in particular exhaust gasses of an internal combustion engine, is produced by applying a silicate-free insulation base material consisting only of barium oxide and/or strontium oxide with aluminum oxide to coat the heating device (50) and then heating the heating device with the insulation base material applied to it to temperatures of about 1350° to 1600° C. to form the insulation layer (60) by sintering. The sensor includes a Nernst measuring cell provided with a first electrode (16) and a second electrode (18) arranged in a solid electrolyte (20). The insulation layer (60) is arranged between the solid electrolyte (20) and the heating device (50).
摘要:
An arrangement of a sensor element of an electrochemical measuring sensor in a metallic housing is proposed, wherein the sensor element (13) in the form of a tube closed at one end rests with a metallic sealing ring (18) on a seal seat (16) implemented on the housing. The seal seat (16) is designed as a raised circular ring surface having a radius (r), with the sealing ring (18) orienting itself tangentially with respect to the radius (r).
摘要:
Proposed is an electrochemical measuring instrument (10) for determining the oxygen content in gas mixtures, in particular exhaust gases from combustion engines, with a sensor element (14) that is installed potential-free in a metal casing (11). The sensor element (14) has an oxygen ion conducting solid electrolyte body (23) in the shape of a tube closed on one side, with electrodes (25, 26) and connections (27, 28), and is fitted inside the casing (11) with a metal sealing ring (20). The connection (27) which runs along the outer surface of solid electrolyte body (23) is covered with an electrically insulating layer (21), at least in the area surrounding sealing ring (20). In addition, a ductile cover layer (31) that spans solid electrolyte body (23) is applied over insulating layer (21) in the area surrounding sealing ring (20), with which the sensor element (14) rests on sealing ring (20).
摘要:
The electrochemical sensor for determination of an oxygen content of exhaust gases, includes a probe element including a tube made from a raw material mixture consisting essentially of an ionically conductive solid electrolyte; an outer electrode located on the outer surface of the tube; a substantially pore-free conductor strip layer located on the outer surface, connected to the outer electrode, and extending toward the open end, the conductor strip layer having a portion in close proximity to the tube open end; and a substantially pore-free cover layer hermetically covering at least the portion of the pore-free conductor strip layer in close proximity to the open end of the tube, the cover layer being made from a cover layer material including the ionically conductive solid electrolyte. The cover layer material advantageously a sintering activity which is at least equal to that of the raw material mixture from which the tube is made. The conductor strip layer consists essentially of a ceramic supporting framework and an electron-conducting material. The ceramic ceramic binder has at least the same sintering activity as the cover layer material.
摘要:
An electrical-discharge electrode, in particular a spark-plug electrode, having a main electrode body made of metal, the main electrode body, in particular at least its tip, is provided with an intermetallic phase composed of nickel aluminides, and a method of producing this electrical-discharge electrode.
摘要:
A method is disclosed for the protection of catalytic converters for exhaust gas purification by measuring the temperature with a heat tone sensor suitable particularly for the implementation of the method, wherein a heat tone sensor composed of at least two NTC or PTC resistors and provided with a coating of a catalytically active material on the sensor in the region of at least one of these resistors is arranged ahead of the catalytic converter in the exhaust gas stream or a part thereof, with the catalytically active material initiating the same exothermal reactions as they take place in the catalytic converter employed for the exhaust gas purification. If the resistor is overheated due to an overly intensive exothermal reaction, resulting in a change in resistance, the heat tone sensor detects the drop in the throughput rate of the catalytic converter.