Abstract: A probe for measuring oxygen potential, especially to determine the carboransfer properties of a furnace atmosphere containing the gases H.sub.2, CO, and CH.sub.4, with the probe having an oxygen ion conducting, solid measuring electrolyte with a contact electrode in the furnace atmosphere and a contact electrode in a reference medium that has a known oxygen concentration. To improve the accuracy of the measurement, an oxygen ion conductive compensation electrolyte in the form of a detachable solid body is connected between the contact electrode in the furnace atmosphere and the solid measuring electrolyte.

Abstract: A method and device for control of the carbon level of a gas mixture reacting in a heat treatment furnace, which gas mixture arises by means of the introduction of a fuel containing hydrocarbon into the furnace chamber, the reaction products of which are not in a state of water-gas equilibrium and not in a state of methane gas equilibrium and which gas mixture has an excess of methane. The controlled condition is determined by a first measurement device from the portion of the gas component CO which is present in the furnace chamber as a first measured value, and by a second measurement device from the electrical voltage of an oxygen-ion-conducting solid body electrolyte as a second measured value and by a third measurement device from the furnace chamber temperature as the third measured value. A regulating member is controlled as a result to automatically change the quantity flow of the supply to the furnace chamber until correspondence of the measured carbon level with its desired value exists.

Abstract: A method for gas carburization of workpieces made of steel in a furnace chamber, by which in the initial phase of the treatment more carbon than desired is released or dissolved in the workpiece surface and in the final phase of the treatment is decarburized to the desired edge carbon content by change of the quantity flow of the decarburizing gas. The decarburizing process is performed by exclusive introduction of a hydrogen-free, oxygen-containing decarburization gas in the furnace chamber.