Abstract: An apparatus includes a first enclosure, a first door, at least one first valve, at least one inlet diffuser and at least one substrate holder. The first enclosure has a first opening. The first door is configured to seal the first opening. The first valve is coupled to the first enclosure. The inlet diffuser is coupled to the first valve and configured to provide a first gas with a temperature substantially higher than a temperature of an environment around the first enclosure. Each substrate holder disposed within the first enclosure supports at least one substrate.

Abstract: A manufacturing apparatus for a semiconductor includes a reaction chamber into which a wafer is introduced, gas supply unit for supplying a gas to the reaction chamber, gas exhaust unit for exhausting the gas from the reaction chamber, a holder for holding the wafer at an outer circumferential part of the wafer, a first heater for heating the wafer from below, a reflector provided above the holder, and a drive mechanism for driving the reflector.

Abstract: A device for the levitated guidance of web-shaped material, particularly metal strips, with at least one first radial fan and with at least one flow channel system that is assigned to the at least one first radial fan provides that the at least one first radial fan generates a fluid flow that is transported through the at least one flow channel system to the surface of the web-shaped material for the levitated guidance thereof. The device is characterized in that at least one additional radial fan for increasing the pressure in the fluid flow is arranged in the at least one flow channel system downstream of the at least one first radial fan referred to the fluid flow direction.

Abstract: In a deposited-film formation apparatus or process having the means or steps of evacuating the inside of an inside-evacuatable chamber through an evacuation piping by an evacuation means, feeding a material gas into the chamber while evacuating the inside of the chamber, and applying a high-frequency power to form a deposited film on a substrate disposed inside the chamber, a leak is detected on the basis of a measured value of a temperature sensor which detects the heat of reaction that is generated when the material gas fed into the chamber reacts with oxygen contained in air having entered from the outside, so as to be able to stop the material gas feeding. In deposited-film formation apparatus or processes making use of spontaneously ignitable gases, the leak can quickly be detected when air enters the chamber because of any unexpected accident such as a break of piping.

Abstract: A pipe for feeding a gas into an oven, a furnaces, or the like (such as a CVI/CVD oven), and in particular into a reaction chamber structure inside the oven, is provided with a gastight tubular sealing device extending radially outward of the pipe and defining a path that is practically gastight, through which there extends the feed pipe. The tubular sealing device is preferably at least partially flexible in the transverse direction and/or the axial direction so as to accommodate positioning defects between a location situated in the reaction chamber and a location where the gas feed pipe penetrates the oven (which defects may be due, for example, to asymmetrical thermal expansion/contraction).

Abstract: Apparatus and operating methods are provided for controlled atmosphere furnace systems. In one possible embodiment, hydrogen is injected from a hydrogen source to an enclosure. The hydrogen is circulated within the enclosure from a gas inlet to a gas outlet. A temperature is raised within the enclosure to a predetermined threshold. Hydrogen is pumped from the gas outlet to the gas inlet with an electrochemical hydrogen pump. The electrochemical hydrogen pump has a first electrode in fluid communication with the gas outlet, and a second electrode in fluid communication with the gas inlet. An electrical potential is provided between the first and second electrodes, wherein the first electrode has a higher electrical potential with respect to zero than the second electrode. Various methods, features and system configurations are discussed.

Abstract: A method for heat treating at least one workpiece, such as a coated turbine engine component, is provided. The method comprises the steps of cleaning a furnace to be used during the heat treating method, which cleaning method comprising injecting a gas at a workpiece center location and applying heat, and diffusion heat treating the at least one workpiece in a gas atmosphere with the gas being injected at the workpiece center location. After the diffusion heat treatment step, the coated workpiece(s) may be subjected to a surface finishing operation such as a peening operation.

Abstract: A diffuser (24) for an annealing furnace has a plurality of radially extending generally and vertically oriented vanes (40) for radially directing furnace gases. The vanes have top edges (42) defining a generally planar support and the top edges of the vanes have a notch (38) therein for receiving a conduit (34) preferably ring shaped that extend substantially around a center portion of the diffuser plate. The conduit (34) is connected to an inlet (32) for receiving enriching gases and exit ports (50) circumferentially space about said conduit (34) passing the enriching gases into the diffuser (24) to be mixed with ambient furnace gases.

Abstract: Pottery wares are fired in a saggar in an electric kiln, whereby effects such as reduction firing and soda firing may be obtained.

Abstract: A firing container for silicon nitride ceramics, which is a hermetically sealed container having a gas inlet and a gas outlet, characterized in that the interior of the hermetically sealed container is partitioned by a gas supply chamber partition plate into a gas supply chamber communicating with the gas inlet, and a firing chamber to accommodate an object to be heat-treated and communicating with the gas outlet, and the gas supply chamber partition plate has vent holes selectively formed in the vicinity of its periphery.

Abstract: A convection oven with laminar airflow and/or moisture injection. A radial airflow fan is used to provide a circulating airflow that is substantially even and substantially turbulence free. The circulating airflow is provided to an oven chamber via a plurality of egress ports that rim a divider wall disposed between the oven chamber and a fan chamber. The airflow interleaves with a plurality of pans in the oven chamber to provide a laminar airflow. Moisture is injected into the circulating airflow either upstream of the fan or by flashing water onto the hot blades of the fan from either the low pressure side or the high pressure side of the fan.

Abstract: In a firing furnace of plasma display panel, gas distribution piping and gas exhaust piping each have a circular cross section and a uniform diameter along the longitudinal direction of those pipings. The gas distribution piping has a plurality of circular openings formed in a side face thereof and the openings are constructed such that the opening becomes larger in a stepwise fashion in a direction from both end portions to the central portion of the gas distribution piping. Furthermore, the gas exhaust piping has a plurality of elliptic openings formed in a side face thereof and the openings are constructed such that the opening becomes larger in a stepwise fashion in a direction from both end portions to the central portion of the gas exhaust piping.

Abstract: The present invention relates generally to a heat treatment system and method for heat-treating an object to be treated. Particularly, the invention relates to a heat treatment system wherein an object to be treated is carried in a reaction vessel, which has been pressure-reduced to a predetermined degree of vacuum and the interior of which is heated to a predetermined process temperature, and a process gas is supplied into the reaction vessel via a gas feed passage to process the object.

Abstract: The present invention provides an injector robot for replacing a gas injector in a running furnace, which is still running and without any cooling and reheating action. According to the present invention, the injector robot is arranged and mounted upon a boat elevator, which is originally used to transport a boat with wafers into the furnace. The replacement of the gas injector could be executed precisely and safely by the assistant means and will not affect the predetermined procedure of the furnace.

Abstract: A thermal processing unit of the present invention includes: a reaction container which an object to be processed is conveyed into and from; a process-gas introducing part for introducing a process gas into the reaction container; a replacement-gas introducing part for introducing a replacement gas into the reaction container, the replacement-gas introducing part being independent of the process-gas introducing part; and a discharging part for discharging a gas in the reaction container. A controlling part is connected to the process-gas introducing part, the replacement-gas introducing part and the discharging part.

Abstract: The aim of the invention is the simple and economical production of a hydrogen-rich process gas from water vapour and hydrogen, whereby the proportion of water vapour to hydrogen may be precisely controllable and reproducible. Said aim is achieved, with a method and device for the production of a process gas for the treatment of substrates, in particular semiconductor substrates, in which the oxygen for formation of a process gas, comprising water vapour and hydrogen, is burnt in a hydrogen-rich environment in a combustion chamber.

Abstract: A thermal processing unit of the present invention includes: a reaction container which an object to be processed is conveyed into and from; a process-gas introducing part for introducing a process gas into the reaction container; a replacement-gas introducing part for introducing a replacement gas into the reaction container, the replacement-gas introducing part being independent of the process-gas introducing part; and a discharging part for discharging a gas in the reaction container. A controlling part is connected to the process-gas introducing part, the replacement-gas introducing part and the discharging part.

Abstract: The invention relates to an arrangement and method for heating gases in a gas circulation duct in connection with continuously operated sintering. In the sintering furnace, hot gas is fed in from above the belt in order to sinter the material located on the belt, and part of the gas circulation duct is formed as a burning zone, a burner ring, where the gas is heated. The burner ring comprises at least one burner unit directed inwardly from the circumference of the gas circulation duct.

Abstract: This invention provides a heat treatment equipment for an object to be treated capable of removing the desorption gas effectively, and of ensuring the equality of the temperature in the plane of the object to be treated by controlling preferably the turbulent airflow inside the heat treatment chamber. More specifically, this invention provides a heat treatment equipment for an object to be treated comprising a heat treatment chamber 104 having an opening and closing shutter 110 for carrying the object to be treated on the side thereof, an exhaust air way 113 formed along the periphery of the heat treatment chamber 104 including the opening and closing shutter 110 and an exhaust hole 101 for exhausting in the heat treatment chamber 104 from the exhaust air way 113 through the opening and closing shutter 110.

Abstract: The present invention relates generally to a heat treatment system and method for heat-treating an object to be treated. Particularly, the invention relates to a heat treatment system wherein an object to be treated is carried in a reaction vessel, which has been pressure-reduced to a predetermined degree of vacuum and the interior of which is heated to a predetermined process temperature, and a process gas is supplied into the reaction vessel via a gas feed passage to process the object.

Abstract: A thermal treatment furnace is described in which gas leakage does not occur during thermal treatment at a high temperature. A thermal treatment furnace having a reaction tube is provided with an opening at one end and a flange surrounding the opening and covered by a cap abutting on the reaction tube at the flange to cover the opening. The flange is provided with a feature which introduces an inert gas to provide back pressure into the joint portion between the flange and the cap, thus preventing reaction gas from leaking to the outside of the furnace through the gap between the flange and the cap. The flange may be further modified to discharge gas under back pressure from between the joint surfaces of the flange and the cap to prevent the inert gas from affecting the reaction in the tube.

Abstract: A wafer treatment apparatus includes a wafer heating device having a wafer-load region at an upper portion, a shower head opposing the wafer-load region for ejecting/directing a source gas toward the wafer surface, and a reflecting apparatus positioned between the shower head and the heating device for reflecting thermal energy radiated from the heating device back toward the wafer-load region. The reflecting apparatus includes a reflector positioned above and opposing the wafer-load region, and a supporter for supporting the reflector. The reflector may have a flattened reflecting surface facing toward the wafer-load region, or may be a semi-spherical type reflector having a concave mirror facing toward the wafer-load region. The reflector can be controlled to move vertically relative to the wafer.

Abstract: This invention provides a heat treatment equipment for an object to be treated capable of removing the desorption gas effectively, and of ensuring the equality of the temperature in the plane of the object to be treated by controlling preferably the turbulent airflow inside the heat treatment chamber. More specifically, this invention provides a heat treatment equipment for an object to be treated comprising a heat treatment chamber 104 having an opening and closing shutter 110 for carrying the object to be treated on the side thereof, an exhaust air way 113 formed along the periphery of the heat treatment chamber 104 including the opening and closing shutter 110 and exhaust hole 101 for exhausting in the heat treatment chamber 104 from the exhaust air way 113 through the opening and closing shutter 110.

Abstract: A wafer treatment apparatus includes a wafer heating device having a wafer-load region at an upper portion, a shower head opposing the wafer-load region for ejecting/directing a source gas toward the wafer surface, and a reflecting apparatus positioned between the shower head and the heating device for reflecting thermal energy radiated from the heating device back toward the wafer-load region. The reflecting apparatus includes a reflector positioned above and opposing the wafer-load region, and a supporter for supporting the reflector. The reflector may have a flattened reflecting surface facing toward the wafer-load region, or may be a semi-spherical type reflector having a concave mirror facing toward the wafer-load region. The reflector can be controlled to move vertically relative to the wafer.

Abstract: A method and implementing system is provided in which a gas, such as oxygen, is injected on to area of a circuit board to which an electronic component is being mounted. The injected gas causes a formation of a coating or surface alloy layer such as tin-oxide, on the solder joint. The coating causes the solder bead or joint to have a higher surface tension and a higher reflow temperature. In an exemplary double-sided double-pass assembly operation, circuit boards pass through a soldering oven on a first pass to attach components to a first side, and then the board is inverted and passed through the oven on a second pass while components are mounted on the opposite side of the board. During the second pass, a gas injection device is aimed at the component-to-board connection points on the inverted side of the board which were soldered on the first pass. The gas is injected at the point in the soldering reflow oven at which the temperature begins to exceed the solder reflow temperature.

Abstract: The present invention is an apparatus for operating heat processing to a substrate, and comprises a heating plate to mount and heat the substrate thereon, a supporting member to support a lower surface of a periphery of the heating plate, and a supporter to support the supporting member. The supporting member has a stepped portion to surround an outer peripheral surface of the heating plate. The supporting member is fixed to the supporter by a fixing member penetrating through the stepped portion in a vertical direction. The fixing member is provided between an inner peripheral surface of the stepped portion and the outer peripheral surface of the heating plate.

Abstract: A furnace includes a core tube that has an elongate boundary wall and is configured to accommodate wafers for processing the wafers in a treatment atmosphere. The furnace includes a cooling chamber defined between the elongate boundary wall and an outer casing of the furnace, wherein the outer casing includes a heating element and has first lateral, circumferentially spaced openings in proximity of a first end of the outer casing and second lateral, circumferentially spaced openings in proximity of a second end of the outer casing. Cooling gas is supplied through one of the first and second lateral, circumferentially spaced openings to a region of one end of the cooling chamber and provides for a cooling atmosphere. The cooling gas is guided along the cooling chamber with a uniform distribution of flow and discharged through one of the first and second lateral, circumferentially spaced openings from a region of an opposite end of the cooling chamber.

Abstract: A thermal treatment furnace is described in which gas leakage does not occur during thermal treatment at a high temperature. A thermal treatment furnace having a reaction tube is provided with an opening at one end and a flange surrounding the opening and covered by a cap abutting on the reaction tube at the flange to cover the opening. The flange is provided with a feature which introduces an inert gas to provide back pressure into the joint portion between the flange and the cap, thus preventing reaction gas from leaking to the outside of the furnace through the gap between the flange and the cap. The flange may be further modified to discharge gas under back pressure from between the joint surfaces of the flange and the cap to prevent the inert gas from affecting the reaction in the tube.

Abstract: The process for manufacturing an electronic circuit includes disposing an electronic device on a circuit substrate and hot melting a solder formed on the electronic device or the circuit substrate to bond the electronic device and the circuit substrate. The process includes the steps of feeding a liquid onto lands on the circuit substrate, aligning and mounting the electronic device on the lands, placing the circuit substrate in a treating vessel and heating the circuit substrate. The heating step includes controlling a pressure of an atmosphere in the treating vessel, hot-melting the solder to prevent at least a portion of the liquid from evaporating until the electronic device and the circuit substrate are bonded and to permit the liquid to evaporate after the electronic device and the circuit substrate are bonded.

Abstract: An apparatus and system for its use for a continuous production on an alkali metal, preferably sodium metal, by a reduction of the metal hydroxide with methane or natural gas as a reductant.

Abstract: A hot plate unit includes a cover. The cover includes an inner wall and an outlet. There is provided immediately under the outlet a plate having a ventilation hole. The distance between the plate and a main surface is identical to the distance between the main surface and the internal wall face. The hot plate unit has an displacement control valve for restricting displacement at a level in the range from at least 0.1 L/min to at most 1 L/min.

Abstract: A method for producing a lightweight aggregate by treating flyash and sewage sludge. The flyash and sewage sludge are mixed together and agglomerated into pellets. The pelletized agglomerate is fed into a rotary kiln in a direction that is co-current with the flow of fuel and air through the kiln. The rotary kiln includes at least one port air zone near the infeed end of the rotary kiln to introduce port air beneath the bed of pelletized agglomerate feed stock flowing through the rotary kiln. The introduction of port air beneath the material bed causes the volatized combustible matter to burn in the bed of material, which oxidizes the outer shell of the pelletized agglomerate. As the pelletized agglomerate continues to travel through the rotary kiln, bloating occurs within the interior of the material and results in the formation of the lightweight aggregate material.

Abstract: An SOI substrate having on the surface thereof a single crystal silicon film formed on an insulator is heat-treated in a hydrogen-containing reducing atmosphere in order to smooth the surface and reduce the boron concentration without damaging the film thickness uniformity in a single wafer and among different wafers. The method is characterized in that the single crystal silicon film is arranged opposite to a member of non-oxidized silicon for heat treatment.

Abstract: A novel rapid thermal process (RTP) barrel reactor processes a larger batch of semiconductor substrates than was previously possible. The RTP barrel reactor is characterized by a short process cycle time in comparison to the same process cycle time in a conventional CVD barrel reactor. A rapid heat-up of the substrates is one of the keys to the shorter process cycle times of the RTP barrel reactor. The RTP barrel reactor utilizes a radiant heat source in combination with a heat controller that includes an open-loop controller for heat-up and a closed-loop controller for deposition as well as a new energy stabilizer to achieve heating a larger energy stabilizer and volume to a uniform processing temperature in times characteristic of RTP reactors.

Abstract: A horizontal-type silicon-nitride furnace (HOSINF) having two tubes is provided. The HOSINF includes an outer tube and an inner tube. One end of the outer tube is coupled to a pump. The other end of the outer tube can be well sealed by a door through a flange. The inner tube is located inside the outer tube. The inner tube has a closed end and an opened end, in which the opened end is near to the door, and the closed end is near to the pump. The inner tube includes a first gas inlet and a second gas inlet. Desired reaction gases are flushed into the inner tube from the first inlet and the second inlet. The inner tube surrounds a paddle carrying several wafers, on which a silicon nitride layer is to be formed. The paddle is mounted on the door. A heater is located on a side periphery of the outer tube.

Abstract: Method and apparatus for maintaining even heat distribution to each of the tubes contained in a down-fired induced draft furnace by eliminating external atmosphere disturbances such as wind from influencing furnace operation. The top of the furnace is isolated from receiving ambient air except through a central path which controls both rate and direction of air flow.

Abstract: A closed-loop control system controls introduction of either water or hydrogen into a furnace region where a part is subjected to an elevated temperature to accomplish a heat treatment process. The heat treatment process causes the part to participate in reduction and/or oxidation reactions which remain in balance at the elevated temperature so long as a hydrogen/water ratio set point is maintained. The system includes an oxygen probe in communication with the furnace region for providing (i) an oxygen output indicative of sensed oxygen concentration within furnace region, and (ii) a temperature output indicative of temperature therein. A controller determines from the oxygen output and temperature output, a measured ratio of hydrogen to water within the furnace region and compares the measured ratio with the hydrogen/water ratio set point, and provides a correction signal output in accordance with a determined difference between the measured ratio and the ratio set point.

Abstract: A furnace having a molten material holding tank with sidewall and a tuckstone or other structure above the sidewall upper end leaving a gap, or joint, therebetween. A deflector, or diverter, is provided at the upper end of the sidewall to deflect cooling air directed on the tank sidewall away from the joint and to create a pressure differential between the interior and exterior of the tank thereby reducing air infiltration into the tank through the joint.

Abstract: An improved apparatus is provided for adjusting a gas injector of a furnace in connection with oxidation, diffusion and heat treating in semiconductor processing. The apparatus includes a reaction tube for serving as a reaction chamber and heat sink. The gas injector is coupled to the reaction tube on one end and includes openings on the other end for passing source gas. An elongated open tube is secured to the gas injector and has its axis superimposed approximately on the axis of the gas injector.

Abstract: A substrate heat treatment apparatus includes a heat treatment furnace of a flat configuration, and having a cavity in which a substrate is accommodated. The heat treatment furnace includes a gas supply unit at one side end face, an opening for communication between the cavity and the outside world, and a gas discharge unit in the vicinity of the opening for discharging gas from the cavity at the other side end face. The heat treatment furnace further includes a cover for shutting the opening allowing opening/closing thereof. In the gas exhaust unit, an exhaust chamber is formed on the other side end face along the opening with a partition wall between the opening and the exhaust chamber. An exhaust portion is formed in communication with the outside world in the exhaust chamber.

Abstract: Carbothermally reduce a metal oxide to its corresponding metal nitride or metal carbide powder in a vertical gravity flow reactor by adding precursor pellets containing the metal oxide, a thermally decomposed binder material and carbon or a source of carbon directly to a heated reaction zone within the reactor. The pellets form a pellet bed, the top of which must be maintained within the heated reaction zone. The binder material is a blend of wheat and corn starches, optionally in conjunction with another binder such as melamine. The binder material thermally decomposes to a carbonaceous residue which functions both as an additional source of carbon and as a binder for the precursor pellets. The reactor may be modified by adding an internal vent line to remove volatile materials from the heated reaction zone before they have an opportunity to condense on internal reactor surfaces.

Abstract: An apparatus and method suitable for the continuous curing of pasted battery plates. The apparatus includes a hydroset oven having an atmospherically controlled hydroset chamber in which a continuous transport conveyor is mounted. Pasted plates are automatically loaded onto the transport conveyor and moved continuously through the hydroset chamber. Plenums are positioned in the hydroset oven chamber adjacent to the transport conveyor to direct temperature and humidity controlled air over the battery plates to affect hydrosetting. Additional hydroset ovens may be provided depending on the quantity of battery plates being processed. The apparatus also includes a drying oven containing a continuous transport conveyor. The drying oven is arranged in series with the hydroset oven to receive the hydroset battery plates and dry them in a continuous process.

Abstract: An apparatus for vitrifying a soot preform from which an optical fiber is produced by drawing, is composed of a main vacuum chamber 20 in which a muffle tube 70 for vitrifying the soot preform PF is located, and an auxiliary vacuum chamber 30 mounted on the main vacuum chamber 20 and communicated therewith through a passage, and a gate valve 60 for opening and closing the passage. The muffle tube 70 has a inner surface covered with silicon carbide layer 70a.

Abstract: A food conditioning chest has a generally rectangular tub supported in the housing to define an upwardly opening food well for supporting foodstuffs. Louvered openings are formed in opposite end walls and the front wall and the rear wall of the tub. A return duct communicates with the food well through the openings formed in the end walls and transports return air to an intake chamber formed beneath the tub floor. An intake duct extends from the intake chamber and communicates with the food well through the openings formed in the front wall and the rear wall. A centrifugal fan positioned in the intake chamber circulates air from the return duct and the intake duct. As the air flows through the intake chamber, it passes over at least one heating element which heats the air to a desired temperature.

Abstract: A vertical resistive combustion furnace having a vertically oriented combustion zone in which first and second coaxially aligned tubes depend. The first tube is open at one end and closed at the other. The second tube is open at one end and partially closed at the other end and is mounted within and spaced from the first tube with the space between the coaxial tubes defining a passage for combustion products produced from a sample of material to be analyzed, disposed in said second tube. The combustion products pass upwardly in the channel through the combustion zone of the furnace so that the combustion products are hot when they exit the furnace for analysis.

Abstract: A combustion chamber includes an inner cylindrical member concentrically mounted within an outer cylindrical member with a cylindrical space therebetween. The outer cylindrical member is enclosed at one end and both cylindrical members are open at an opposite end for access to the combustion area. The by-products of combustion are withdrawn from the inner cylindrical member at the closed end of the outer cylindrical member such that they reverse direction and circulate through the hot zone of the furnace in the cylindrical space. In a preferred embodiment of the invention, a porous ceramic plug which supports and spaces the tubes in concentric relationship at the one end and captures particulate by-products of the combustion holding them in the hot zone for complete combustion.

Abstract: Disclosed is a quartz tube for a furnace for processing semiconductor wafers. The furnace comprises:an elongated hollow body having opposed first and second ends and a longitudinal axis;an injector opening being formed in the first end, the injector opening including sidewalls which are spaced to slidably receive an elongated gas injector assembly through the opening; andan alignment jig received within the hollow body inwardly adjacent the first end and injector opening, the alignment jig including support means for engaging and aligning a gas injector with the injector opening to support a gas injector to emit gas substantially along the longitudinal tube body axis.

Abstract: An apparatus for maintaining a crystal at a precisely controlled operating temperature over extended periods of time without significant thermal degradation of the crystal. The apparatus has thermally conducting walls. The walls define an inner hermetically sealed chamber for the crystal. Input and output windows are hermetically sealed to the input and output ends of the chamber. The inner surfaces of these windows are maintained at the operating temperature of the crystal to prevent fogging of the windows. Flexible thermal conducting layers are used between the crystal surfaces and the walls of the chamber to achieve uniform and continuous thermal contact therebetween, without mechanical stress to the crystal. The structure provides fast thermal response, controlled temperature in the crystal interaction region and stability of operation over extended periods of time. In one preferred embodiment, the crystal is held in suspended position within the chamber between a pair of spring-loaded plungers.

Abstract: Reversing the flow of conventional furnace/retort systems prevents damaging exhaust gases from entering the furnace while still maintaining a gas flow through the retort. The gases exit the retort into a treatment system; preventing contamination of any apparatus and the escape of any hazardous gases.

Abstract: A two-stage gas distribution nozzle for a muffle furnace includes an inner pipe with spaced apertures for feeding gas at spaced intervals to an outer pipe enclosing the inner pipe. The outer pipe includes spaced apertures facing in a direction such that the jets of gas from the inner pipe impinge on a wall of the outer pipe opposite the outer pipe apertures. The gas in the outer pipe is at lower pressure than the gas in the inner pipe and is more uniformly distributed along the length of the outer pipe to provide more uniform flow to the ambient atmosphere in the muffle.