Abstract: The present invention discloses a novel, moisture-free atmosphere for brazing carbon steels that provides good braze flow and brazed joint quality with minimum or no formation of soot on brazed joints. According to the present invention, carbon steels are brazed in continuous furnaces using a moisture-free atmosphere containing a mixture of three gases including nitrogen, hydrogen, and carbon dioxide. The key features of the invention involve (1) formation of moisture, which is needed to facilitate braze flow and to minimize formation of soot on brazed joints, in-situ in the heating zone of the furnace by the reaction between hydrogen and carbon dioxide and (2) reduction in the overall amount of a reducing gas required for brazing carbon steels by keeping moisture out of the cooling zone.

Abstract: A process for producing low-cost atmospheres suitable for annealing, brazing, and sintering ferrous and non-ferrous metals and alloys, neutral hardening low, medium, and high carbon steels, sintering ceramic powders, and sealing glass to metal from non-cryogenically produced nitrogen containing up to 5% residual oxygen is disclosed. According to the process, suitable atmospheres are produced by 1) pre-heating the non-cryogenically produced nitrogen stream containing residual oxygen to a desired temperature, 2) mixing it with more than a stoichiometric amount a hydrocarbon gas, 3) passing it through a reactor packed with a platinum group of metal catalyst to reduce the residual oxygen to very low levels and convert it to a mixture of moisture and carbon dioxide, and 4) introducing the reactor effluent stream into the heating zone of a furnace and converting in-situ a portion of both moisture and carbon dioxide with a hydrocarbon gas to a mixture of carbon monoxide and hydrogen.

Abstract: A process for producing low-cost atmospheres suitable for decarburize annealing carbon steels from non-cryogenically generated nitrogen containing up to 1.54 residual oxygen by catalytically deoxygenating a non-cryogenically generated nitrogen stream at low temperatures with a hydrocarbon gas and mixing the deoxygenated stream with an economical amount of hydrogen prior to introduction into the furnace for annealing. The process includes the use of 1) hydrocarbon gas to convert residual oxygen to a mixture of carbon dioxide and moisture at low temperatures and 2) mixing the deoxygenated stream with a sufficient amount of hydrogen to maintain a pH.sub.2 /pH.sub.2 O ratio of at least 2 in the furnace.

Abstract: A process for generating in-situ low cost atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering metal and ceramic powders in a continuous furnace from non-cryogenically produced nitrogen containing up to 5% residual oxygen is presented. The disclosed process involves mixing nitrogen gas containing residual oxygen with a pre-determined amount of a reducing gas such as hydrogen, a hydrocarbon, or a mixture thereof, feeding the gaseous mixture through a non-conventional device into the hot zone of a continuous heat treating furnace, converting residual oxygen to an acceptable form such as moisture, a mixture of moisture and carbon dioxide, or a mixture of moisture, hydrogen, carbon monoxide and carbon dioxide, and using the resultant gaseous mixture for annealing and heat treating metals and alloys, brazing metals and ceramics, sintering metal and ceramic powders, and sealing glass to metals.

Abstract: An improved method for producing substantially moisture- and oxygen-free, nitrogen-hydrogen atmospheres suitable for annealing, hardening, brazing, and sintering ferrous and non-ferrous metals and alloys is disclosed. According to the disclosed method, suitable nitrogen-hydrogen atmosphere is produced by 1) generating a nitrogen stream containing about 0.1 to 5% residual oxygen by a known non-cryogenic air separation technique, 2) mixing it with a pre-determined but more than stoichiometric amount of hydrogen required to convert residual oxygen to moisture, 3) converting residual oxygen to moisture by reaction with hydrogen in a catalytic reactor, 4) cooling the reactor effluent stream, and 5) removing moisture from it in a regenerative sorbent dryer.

Abstract: A process for generating in-situ low-cost atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals, sealing glass to metals, and sintering metal and ceramic powders in a continuous furnace from non-cryogenically produced nitrogen containing up to 5% residual oxygen is presented. The disclosed process involves mixing nitrogen gas containing residual oxygen with a predetermined amount of a hydrocarbon gas, feeding the gaseous mixture through a nonconventional device into the hot zone of a continuous heat treating furnace, converting residual oxygen to an acceptable form such as a mixture of moisture and carbon dioxide, a mixture of moisture, hydrogen, carbon monoxide, and carbon dioxide, or a mixture of carbon monoxide, moisture, and hydrogen, and using the resultant gaseous mixture for annealing and heat treating metals and alloys, brazing metals, sintering metal and ceramic powders, and sealing glass to metals.

Abstract: An improved process for deoxygenating non-cryogenically produced nitrogen with a hydrocarbon is disclosed. According to the process, non-cryogenically produced nitrogen stream containing residual oxygen impurity is 1) pre-heated, 2) mixed with a hydrocarbon, and 3) passed through a reactor packed with a platinum group of metal catalyst to reduce oxygen to very low levels by converting it to a mixture of carbon dioxide and moisture. The reactor effluent stream is optionally treated downstream to produce a nitrogen stream substantially free of moisture and carbon dioxide. The key features of the disclosed process include 1) pre-heating non-cryogenically produced nitrogen containing residual oxygen to a certain minimum temperature, 2) adding more than stoichiometric amount of a hydrocarbon to the pre-heated nitrogen stream, and 3) using a platinum group of metal catalyst to initiate and sustain the reaction between oxygen and hydrocarbon.

Abstract: An improved process for producing nitrogen-based atmospheres suitable for annealing ferrous metals and alloys, brazing metals, sintering metal and ceramic powders, and sealing glass to metals from non-cryogenically generated nitrogen is presented. These atmospheres are produced by 1) humidifying non-cryogenically generated nitrogen containing less than 5.0 vol. % residual oxygen, 2) mixing it with a specified amount of a hydrocarbon gas, 3) feeding the gaseous mixture into the heating zone of a furnace through a diffuser, and 4) converting in-situ the residual oxygen and moisture present in it to a mixture of carbon dioxide, carbon monoxide, moisture, and/or hydrogen. The key features of the present invention include a) humidifying the feed gas prior to introducing it into the heating zone of a furnace operated above about 800.degree. C.

Abstract: A process for producing low-cost atmospheres suitable for annealing, brazing, and sintering non-ferrous metals and alloys from non-cryogenically produced nitrogen containing up to 5%, residual oxygen is disclosed. According to the process, suitable atmospheres are produced by 1) pre-heating the non-cryogenically produced nitrogen stream containing residual oxygen to a desired temperature, 2) mixing it with more than a stoichiometric amount a hydrocarbon gas, 3) passing it through a reactor packed with a platinum group of metal catalyst to reduce the residual oxygen to very low levels and convert it to a mixture of moisture and carbon dioxide, and 4) using the reactor effluent stream for annealing, brazing, and sintering non-ferrous metals and alloys in a furnace.

Abstract: A process for generating in-situ low-cost atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering metal and ceramic powders in a continuous furnace from non-cryogenically produced nitrogen containing up to 5% residual oxygen is presented. The disclosed process involves mixing nitrogen gas containing residual oxygen with a pre-determined amount of a reducing gas such as hydrogen, a hydrocarbon, or a mixture thereof, feeding the gaseous mixture through a non-conventional device into the hot zone of a continuous heat treating furnace, converting residual oxygen to an acceptable form such as moisture, a mixture of moisture and carbon dioxide, or a mixture of moisture, hydrogen, carbon monoxide and carbon dioxide, and using the resultant gaseous mixture for annealing and heat treating metals and alloys, brazing metals and ceramics, sintering metal and ceramic powders, and sealing glass to metals.

Abstract: A process for producing low-cost furnace atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering non-ferrous metal and ceramic powders from non-cryogenically produced nitrogen containing from 0.05 to 5.0% residual oxygen is presented. The disclosed process involves 1) mixing non-cryogenically produced nitrogen with a predetermined amount of dissociated ammonia, 2) passing the mixture through a low-pressure drop catalytic reactor, 3) converting the residual oxygen to an acceptable form such as moisture and reducing the residual oxygen level to below about 10 ppm, and 4) using the resultant gaseous mixture for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering non-ferrous metal and ceramic powders.

Abstract: An integrated two-step process for producing low-cost atmospheres suitable for annealing ferrous and non-ferrous metals and alloys, brazing metals, sealing glass to metals, and sintering metal and ceramic powders in continuous furnaces from non-cryogenically produced nitrogen containing up to 3% residual oxygen is disclosed. The residual oxygen present in non-cryogenically produced nitrogen is converted to moisture by mixing it hydrogen and passing the mixture through a reactor packed with a platinum group catalyst in the first step of the process. The reactor effluent stream containing a mixture of nitrogen, unreacted hydrogen, and moisture is mixed with a predetermined amount of a hydrocarbon gas and introduced into the heating zone of a continuous furnace in the second step of the process to 1) convert moisture to a mixture of carbon monoxide and hydrogen by reaction with the hydrocarbon gas via water gas shift reaction and 2) produce atmospheres in-situ suitable for heat treating.

Abstract: A process for generating in-situ low-cost atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals, sealing glass to metals, and sintering metal and ceramic powders in a continuous furnace from non-cryogenically produced nitrogen containing up to 5% residual oxygen is presented. The disclosed process involves mixing nitrogen gas containing residual oxygen with a predetermined amount of a hydrocarbon gas, feeding the gaseous mixture through a nonconventional device into the hot zone of a continuous heat treating furnace, converting residual oxygen to an acceptable form such as a mixture of moisture and carbon dioxide, a mixture of moisture, hydrogen, carbon monoxide, and carbon dioxide, or a mixture of carbon monoxide, moisture, and hydrogen, and using the resultant gaseous mixture for annealing and heat treating metals and alloys, brazing metals, sintering metal and ceramic powders, and sealing glass to metals.

Abstract: An improved process for producing high-moisture containing nitrogen-based atmospheres suitable for oxide and decarburize annealing of carbon steels from non-cryogenically generated nitrogen is presented. These nitrogen-based atmospheres are produced by 1) mixing non-cryogenically generated nitrogen containing less than 5.0 vol. % residual oxygen with a specified amount of hydrogen, 2) humidifying the gaseous feed mixture, 3) feeding the gaseous mixture into the heating zone of a furnace through a diffuser, and 4) converting in-situ the residual oxygen present in it to moisture. According to the present invention, the total amount of hydrogen required for producing suitable atmospheres can be minimized by simultaneously humidifying the feed gas and controlling the residual oxygen level in it. The key features of the present invention include a) humidifying the feed gas prior to introducing it into the heating zone of a furnace operated above about 600.degree. C.

Abstract: A process for generating in-situ low-cost atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering metal and ceramic powders in a continuous furnace from non-cryogenically produced nitrogen containing up to 5% residual oxygen is presented. The disclosed process involves mixing nitrogen gas containing residual oxygen with a pre-determined amount of a reducing gas such as hydrogen, a hydrocarbon, or a mixture thereof, feeding the gaseous mixture through a non-conventional device into the hot zone of a continuous heat treating furnace, converting residual oxygen to an acceptable form such as moisture, a mixture of moisture and carbon dioxide, or a mixture of moisture, hydrogen, carbon monoxide and carbon dioxide, and using the resultant gaseous mixture for annealing and heat treating metals and alloys, brazing metals and ceramics, sintering metal and ceramic powders, and sealing glass to metals.