Abstract: A method for manufacturing an optical element out of glass comprises placing a blank made of glass on an annular contact face of a supporting body having a hollow cross section. The blank is heated on the supporting body in a cavity of a protective cap that is arranged in a furnace cavity, such that a temperature gradient is established in the blank in such a way that the blank is cooler inside than on an outside region. The blank is press molded to form the optical element.

Abstract: A pusher furnace includes furnace sections having respective susceptors, a slide rail extending through the furnace sections for sliding pusher plates thereon and an alignment assembly for aligning the susceptors and slide rails of adjacent furnace sections. A support structure spaces the susceptors from insulation therebelow to protect the insulation from degradation from contact with the susceptors. The susceptors are slidably mounted on the support structure to accommodate thermal expansion and shrinkage of the susceptor. The upstream end of the slide rails have beveled upper edges to help prevent the pusher plates from catching thereon. The upstream ends are also laterally tapered to reduce the degree of force encountered should a pusher plate catch thereon. Adjacent insulation members have expansion joints filled with a refractory felt. The susceptors slidably and sealingly engage exhaust ports to allow for thermal expansion and shrinkage of the susceptor without damaging the exhaust port.

Abstract: A heating furnace for heating a porous preform made of fine particles of highly pure quartz glass for an optical fiber, which furnace comprises a cylindrical furnace body, a heater installed in said furnace body and a muffle tube installed inside said heater to separate a heating atmosphere from said heater, wherein said muffle tube is made of highly pure carbon and coated with a gas impermeable carbon, which furnace prevents contamination of the preform with impurities and has long life.

Abstract: Vertically oriented thermal processor, also known as a vertical diffusion furnace for the processing of silicon or gallium arsenide wafers or substrates including a vertically positionable furnace assembly, and a quartz bell-jar shaped element which positions coaxially over and about another quartz bell jar like vertically positionable process tube forming a dual wall contamination barrier. The furnace and the process tube bell jar can be moved up and down pneumatically as a unit or independently of one another during processing modes. Pneumatic cylinders provide for the lifting of the furnace element away from the wafers to ramp temperatures downwardly at an accelerated rate. An overhead track positions for accelerated removal of the furnace and process tube to the exterior of the cabinet without disconnection of electrical, pneumatic or gas connections for maintenance or component changeout.

Abstract: In an installation including a heating furnace in the rolling mill and a continuous casting apparatus, there is provided a transportable temperature holding chamber for the castings which are cut to length, in which chamber the castings are transported in groups from the continuous casting apparatus to the heating furnace, and are stored temporarily in the buffer mode. That makes it possible to save energy and to improve the quality of the steels.

Abstract: A cantilever tube for carrying loaded wafer boats into a diffusion furnace and confining flow of gas through the wafers includes an elongated slot extending from an open end of the tube to a predetermined region in which the wafer boats are positioned, the wafer boats abutting each other and forming a sealing cover for the elongated slot. A narrow boat carrier supported on a carriage system extends through the elongated slot and carries a wafer boat loaded with wafers into the open end and to the predetermined region in the cantilever tube without allowing either the carrier, or the wafer boat, or the wafers to touch the cantilever tube. The carrier lowers the boat onto the bottom inner surface of the tube, causing the boat to cover a portion of the elongated slot. The procedure is repeated for subsequent wafer boats, each of which abuts the previous one, to effectively close and seal the elongated slot when all of the wafer boats are positioned inside the cantilever tube.

Abstract: A process for making stacked high voltage rectifiers includes initially doping a plurality of silicon wafers with paint-on dopants applied with an applicator that is gradually moved from the center to the outer edge of each wafer while the wafer is peripherally supported and rotated sufficiently slowly to prevent spin-off and runover of each dopant onto the reverse side of the wafer. The dopants are driven in by heating in a diffusion furnace. The same slow rotation and moving applicator technique then is used to coat only the N-doped side of the wafer with a paint-on noble metal dopant. The noble metal is driven in using a diffusion furnace at a temperature that is selected in accordance with the measured reverse recovery time of the wafer prior to noble metal diffusion.The wafers are silver coated and stacked, and a compression jig is used to exert compressive force on the stack while it is heated in an alloying furnace to a temperature sufficiently high to cause "wetting" of the silver.

Abstract: A cantilever diffusion tube apparatus includes a quartz cantilever tube having a support end clamped to a laterally movable carriage mechanism and an outer end portion containing a plurality of spaced semiconductor wafers. The cantilever tube is coaxially aligned with a diffusion tube of a diffusion furnace. The support end of the cantilever tube is sealed by a door plate through which a gas tube extends. The wafers are loaded into the cantilever tube through a window opening. The carriage then moves the cantilever tube and wafers therein into the diffusion tube. Reactant gases are caused to flow into the cantilever tube, between the heated wafers therein, and out of the cantilever tube. Then purging gas is caused to flow through the cantilever tube and wafers therein.

Abstract: Floatable tube sheets are provided for use in a reformer furnace or the like wherein a plurality of vertically oriented catalyst tubes are disposed in the fire box with the upper tube ends extending through the fire box roof. The tube sheets are located proximate apertures or channels in the roof through which the upper tube ends protrude and provide a seal to substantially minimize air leakage through the roof. At the same time, the tube sheet plates permit vertical expansion and contraction of the tubes. The tube sheet plates themselves are moveably mounted to the roof so that they can float vertically upwardly and downwardly through a limited distance so as to compensate for tube movement in those instances in which the tubes become bent or bowed during operation. At least a pair of contiguous tube sheet plates surround each tube to facilitate easy tube sheet removal without resulting in attendant removal of any neighboring tubes or, in some instances, furnace shutoff.

Abstract: Disclosed is a continuous atmosphere controlled furnace for aluminum brazing and other purposes. A plurality of pots are suspended from a circular roof rotatable in a horizontal plane and arranged in a circle having a center on the axis of rotation of the roof. Each pot comprises a body having an open top and a cover capable of closing the open top of the body. The open top of each pot projects above the roof and that portion of each pot which contains the material to be heated extends downwardly below the roof. The material to be heated is supported on a hanger depending from the cover of each pot and the cover is lowered to place the material in the pot and close the pot. The furnace further includes an atmosphere gas distributor having its center on the axis of rotation of the roof and connected to the pots by gas supply and exhaust ducts. A method of supplying atmosphere gas through the pots is also described.

Abstract: A muffle seal for a high temperature furnace in which a quartz or similar muffle is attached to an associated metal structure to provide substantial sealing of gas in the muffle even at extremely high operating temperatures. As employed in a multi-zone furnace having a high temperature quartz muffle section and a lower temperature metal muffle section joined thereto via a gas or gas and heat barrier, the quartz muffle is joined to the barrier by a peripheral chamber provided around the end of the quartz muffle confronting the barrier, the chamber being sealed to surfaces of the muffle and the barrier by porous gaskets. A sealing gas is introduced at above atmospheric pressure to the peripheral chamber, the gas being controllably transmitted through the porous gaskets to provide isolation against leakage of gas within the quartz muffle. The novel seal can also be employed to join quartz and metal muffle sections without a barrier therebetween.