The Boc Group, Inc.

Other

Paul Francis Stratton

Mircea S Stanescu

Shuen-Cheng Hwang

Neeraj Saxena

Edward K Chang

Colin John Precious

David Geoffrey Groome

Keith Bennett

John B Boodey

Robert G Bowes

This invention is directed to a gas curtain assembly which comprises at least one structure of substantially vertical tubes on both sides of and supporting a vertical tube, forming an interconnected frame comprising at least one row of apertures for gas or fluid to pass through and forming a curtain of gas or fluid under the vertical portion of the assembly.

Gas curtain assemby for muffled continuous furnaces

An article of titanium or a titanium-based alloy, or of zirconium or a zirconium-based alloy is case hardened by heat treatment for at least 12 hours at one or more temperatures in the range of 850&#xb0; C. to 900&#xb0; C. and at a pressure in the order of atmospheric pressure in an oxygen diffusion atmosphere. The oxygen diffusion atmosphere comprises a carrier gas such as argon which does not react chemically with the article the said temperature range and molecular oxygen. The concentration of oxygen as the oxygen diffusion atmosphere is in the range of 10 volumes per million to 400 volumes per million.

Thermal Treatment Method

A hot object is quenched after heat treatment. A hot gas stream having at least 20% by volume of hydrogen is taken from for example a carburising chamber of a furnace. The gas is cooled by passage through a heat exchanger, and is compressed in a compressor. The compressor has an aftercooler (not shown) to remove heat of compression from the gas. The cooled, compressed gas flows through nozzles into a quenching chamber. The gas leaves the nozzles at a velocity of at least 50 m/s and impinges upon the hot metal object so as to effect its quenching.

Quenching method and apparatus

Objects formed of engineering and tool steels are quenched from above 850&deg; C. by immersion in an aqueous suspension of inorganic particles. The greater the proportion of particles, the slower the quench. The suspension may be saturated with carbon dioxide.

Quenching method

A method for quenching a heated metallic object includes discharging a plurality of discrete gas streams from a plurality of nozzle outlets so that the gas streams impinge substantially uniformly over the outer surface of the object, the distance between each nozzle outlet and the outer surface of the object against which the associated gas stream impinges is less than or equal to half the diameter of the nozzle outlet.

Quenching heated metallic objects

A brazing method for joining to or more pieces of metal together includes running a molten brazing solder into a space between the pieces, heating at least the adjacent surfaces of the pieces to be joined to brazing temperature in a reducing atmosphere and preheating at least the adjacent surfaces to about 600&deg; C. in an oxidizing atmosphere prior to said heating to the brazing temperature.

Furnace brazing

A furnace, for instance a reflow soldering oven, in which oxygen concentration is either directly or inferentially sensed within central processing and either one or both of the inlet and outlet sections of the furnace. Signals generated by these sensors are processed in a PID controller to generate a control signal to control the flow rate of inerting gas into the central processing section, thereby to at least inhibit ingress of air into the central processing section. The PID controller is programmed such that its integral error term is set equal to a time average of the oxygen concentrations of the central processing section less an oxygen concentration set point desired for the central processing section. The proportional and differential error terms are set equal to a time average of the concentrations of the central processing section and one or both of the inlet and outlet sections of the furnace less the oxygen concentration set point.

Furnace having regulated flow rate of inerting gas

Apparatus and method of induction heating wherein the heating operation is conducted in a low oxygen-containing atmosphere by the introduction of an inert gas alone or in combination with an oxygen-reacting gas through the ends of the induction coil housing or through removable covers enclosing the spaces between spaced apart housings.

Induction heating in low oxygen-containing atmosphere

A method of depositing a solid substance on the surface of the substrate in which the solid substance is dissolved in a solvent to create a first solution. The solid substance is less freely divided prior to dissolution than when deposited on the substrate and the deposition density of the solid substance on the substrate is regulated at least in part by solid substance concentration. The solid substance is insoluble in a liquified gas and the first solution is soluble in the liquified gas. The solvent also is capable of depressing the freezing point of the liquified gas upon expansion of the liquified gas. The first solution is dissolved in the liquified gas to create a second solution having a sufficient concentration of the solvent relative to the liquified gas that solidification of the liquified gas is substantially prevented upon the expansion thereof. Preferably, this concentration of solvent is a minimum to prevent overuse of environmentally hazardous solvents. The solution is sprayed against the substrate so that a portion of the liquified gas flashes into a vapor and the second solution containing a remaining portion of the liquified gas contacts and thereby coats the surface substrate. The remaining portion of the liquified gas is evaporated along with the solvent, so that the solid substance remains as a deposit on the substrate. The method has particular application to making very free depositions such as are required in the electronics industry to coat contacts of printed circuit boards with flux prior to soldering.

Method of depositing solid substance on a substrate

Ferrous metal is treated by austenitic nitro-carburizing in a heat treatment furnace. A suitable atmosphere is created by admitting to the furnace nitrogen; ammonia; and a liquid or vaporous organic compound of carbon, hydrogen and oxygen. The atmosphere is maintained at a temperature in the range 690.degree. to 750.degree. C. The organic compound is typically methanol and the atmosphere typically comprises nitrogen, carbon monoxide, hydrogen and free ammonia as well as small amounts of methane, carbon dioxide and water vapor. After being removed from the furnace, the ferrous metal is quenched. It has an outer surface layer of white, scuff-resistant, epsilon compound and an inner carbo-nitrided case containing austenitic and martensitic zone. The ferrous metal may then be treated to convert austenite to martensite or lower bainite.

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Huddersfield, United Kingdom

Paul Francis Stratton