Abstract: The present invention relates to an absorption gas analyzer for measuring a concentration of at least a component gas in a sample gas. The absorption gas analyzer comprises a main absorption cell for containing the sample gas for measurement therein. At least a narrow band emitter emits electromagnetic radiation in at least a predetermined narrow wavelength band which is transmitted through the main absorption cell. A reflecting device is disposed for reflecting the electromagnetic radiation after transmission through the main absorption cell such that the electromagnetic radiation is transmitted again therethrough. At least a detector detect the electromagnetic radiation and provide at least an intensity signal in dependence upon the concentration of the at least a component gas. The absorption gas analyzer enables simultaneous determination of concentration of a plurality of individual component gases with a high level of accuracy.

Abstract: Disclosed is a process for manufacturing a corrosion resistant iron-alloy, powered metal or sintered carbide component. In a first step, the component is subjected to an initial thermochemical treatment preferably consisting of nitriding, in a closed furnace in order to form onto the surface of the component a nitrogen diffusion zone followed by the superficial layer consisting of .gamma.' and .epsilon. nitride layers. In a second step, an aqueous solution comprising oxygen, carbon, nitrogen and sulfur is introduced into the furnace for a period of time sufficient to allow transformation of the .epsilon. nitride layer into a porous layer of ferrous oxide(s). This process is particularly efficient and permits to produce a superficial porous ferrous oxide layer thicker than 2 .mu.m onto a nitride steel component.