L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des

Yannick Rancon

Philippe Queille

Eric L Duchateau

Frederic Rotman

Michel Olivier

Didier Domergue

Tom Nilsson

A plant for generating a nitrogen-based gas is provided. The plant includes a source of impure nitrogen under pressure containing a residual oxygen concentration; a main gas conduit; a catalytic deoxygenation reactor; a secondary gas line connected to a source of a secondary reducing gas at one end thereof and to the main gas conduit at a point situated upstream of the catalytic deoxygenation reactor at another end thereof; and a device for removing water vapor present in a gas. The source of impure nitrogen is connected to the catalytic deoxygenation reactor via the main gas conduit. The main gas conduit between the source of impure nitrogen and the point where the secondary gas line is connected is devoid of any flow control device.

Process and plant for generating nitrogen for heat treatment

A process for generating a nitrogen-based gas, comprising the steps of: (i) combining a secondary reducing gas including at least one reducing gas with a primary nitrogen gas including 0.5-5% by volume of oxygen, the combining of the secondary gas being performed according to an uncontrolled all-or-nothing method; (ii) reacting the primary gas and the secondary gas in a catalytic deoxygenation reactor so as to obtain a nitrogen-based reaction gas which includes water vapor; and (iii) removing at least a part of the water vapor present in the nitrogen-based reaction gas by cooling the reaction gas under pressure to induce formation of a liquid phase and then extracting the liquid phase from the reaction gas under pressure to obtain a purified reaction gas.

Process for generating nitrogen for heat treatment

The thermal treatment atmosphere is obtained by catalytic reaction of an impure mixture of nitrogen, advantageously obtained by permeation or adsorption, and hydrocarbon, the catalytic reaction being carried out at a temperature between 400.degree. and 900.degree. C., typically between 500.degree. and 800.degree. C., with a noble metal base catalyst, typically platinum or palladium on alumina support. The reaction may be carried out in a reactor placed inside or outside the furnace.

Process of the production of an atmosphere for the thermal treatment of

Metallization of ceramics of the type comprising depositing a metallic paste based on molybdenum and/or tungsten and manganese on a ceramic substrate and effecting the sintering of the paste in an atmosphere having a predetermiend oxido-reduction potential, with a rise in and a maintenance of a temperature between 1300.degree. C. and 1600.degree. C., then cooling to ambient temperature, with production of an atmosphere by the addition to a pure neutral gas of a quantity of additional oxygen and a quantity of hydrogen at least sufficient to subsequently obtain by catalytic reaction the desired content of water vapour and contingently the excess content of hydrogen.

Process for the metallization of ceramics and apparatus for carrying out

The invention concerns the production of ceramic-metal multilayer components comrising effecting, after making up in the crude state, in particular by metallization and stacking of pre-cut raw ceramic bands, a simultaneous firing operation, termed cofiring, on the components under an atmosphere based on hydrogen or nitrogen or a mixture of hydrogen and nitrogen, having a regulated water vapor content at a temperature of first of all between 800.degree. C. and 1800.degree. C., and more precisely either at a moderately high temperature plateau between 800.degree. C. and 1300.degree. C. for certain ceramic materials such as codierite and metallic materials such as copper and nickel, or at a temperature plateau between about 1400.degree. C. and 1800.degree. C. for refractory materials such as tungsten, molybdenum, alumina, according to which the atmosphere having a water vapor content is obtained by addition to a vector gas at (13) and (14) of a quantity of additional oxygen (15), and a quantity of additional hydrogen at (14) sufficient to obtain by hydrogen-oxidation reaction the predetermined water vapor content, and determining these quantities of addition of oxygen and the contingent addition of hydrogen so that said water vapor content is, in the course of the cofiring, that which is the most appropriate for the different stages of said cofiring.

Process for producing ceramic-metal multilayer components and apparatus

Heat treating metals by continuous longitudinal passage of metallic pieces in an elongated treating zone under controlled atmosphere having a high temperature upstream end where the controlled atmosphere comprises nitrogen and reducing chemical substances, such as hydrogen, possibly carbon monoxide, and a downstream cooling end under an atmosphere essentially formed by introducing nitrogen. In the high temperature upstream end, the nitrogen which constitutes the atmosphere is supplied by introducing nitrogen with a residual oxygen content not exceeding 5%, the reducing chemical substances being present at any moment in amounts at least sufficient to eliminate oxygen introduced with nitrogen. The nitrogen introduced in the downstream cooling end is substantially free of oxygen. Application of the process to the annealing of metallic pieces.

Process for heat treating metals in a continuous oven under controlled

Process for thermal treatment of metals by passage of metallic pieces into an elongated zone under a controlled atmosphere, having an upstream section at an elevated temperature, where the controlled atmosphere comprises nitrogen and reductive chemicals, particularly hydrogen, possibly carbon monoxide; and a downstream section at a lower temperature under a controlled atmosphere. The invention is characterized by the fact that in the upstream section at an elevated temperature, the atmosphere comprises nitrogen having a residual content of oxygen between 0.5% and 5% produced by separation of air using permeation or adsorption techniques. The reductive chemicals are present at all times in a content at least sufficient to eliminate the oxygen admitted with the nitrogen. The controlled atmosphere in the section downstream from the elongated thermal treatment zone is formed by admission of a gaseous flow taken from the upstream section at an elevated temperature and transferred directly into the downstream section at a lower temperature.

Process for thermal treatment of metals

The invention concerns glass-metal sealing comprising effecting on a metallic piece, in particular an alloy based on iron and nickel or iron, nickel and cobalt, first of all a decarburization under an atmosphere, at a temperature of between 950.degree. C. and 1,150.degree. C., formed by hydrogen (10 to 99%), water vapor (1 to 8%), with a ratio hydrogen/water vapor higher than five, the possible remainder being nitrogen, then an oxidation under an atmosphere formed by an inert vector gas such as nitrogen, either at a temperature of 600.degree. C. to 800.degree. C. and with a water vapor content of 8% to 2%; or at a temperature of 900.degree. C. to 1,100.degree. C. and with a water vapor content of 4% to 0.5%; then establishing the connection. The gas mixture for a treatment atmosphere is obtained by mixing nitrogen and hydrogen conducted through pipes (13, 14), to which oxygen is added through a pipe (15) upstream of a catalytic chamber (11) permitting the elimination of the oxygen and the production of a content of water vapor.

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Velizy, France

Yannick Rancon