Abstract: A monitoring system for a furnace, such as one in which ceramic welding is practiced, where the temperature often exceeds 2000° F., allows substantially distortion-free, real time, monitoring. In order to monitor the furnace, a fluid cooled lance designed to be held by an operator outside the furnace has a camera (e.g. microcamera, endoscope or boroscope) mounted at the free end of the lance. An electrical connection is provided between the camera and a portable control unit mounted exteriorly of the furnace. A stationary video monitor and recorder may be mounted in the control unit, and a portable real time video monitor is mounted on the operator's headgear so that it may be seen by the operator when manipulating the lance. The lance is cooled by a water jacket having an inlet and outlet at the end of the lance exterior of the furnace, and the water jacket substantially surrounds the camera.

Abstract: A self-fusing alloy thermal spray coating or a vitreous ceramic coating is fused to a complicated metal shape or convoluted metal surface, such as a waterwall panel having a plurality of tubes interconnected by a plurality of membranes, without significant warpage or adverse change in the microstructure of the material forming the panel. The coating is first applied to the panel and then is heated to a liquidus temperature (typically between about 1000.degree.-2200.degree. F.), by induction at a frequency of greater than about 25 kHz, so as to effect fusing. An inductive coil assembly for this purpose comprises a copper tubular combined electrical current conductor and conduit for circulating cooling water having a first closed end and a second end connectable to a source of cooling fluid and a source of electricity. At least one, and preferably a plurality, of copper noses extend outwardly from the combined conductor and conduit and both conduct electricity and circulate cooling fluid.

Abstract: A powder mixture for use in ceramic welding repair of a refractory material containing alumina includes refractory particles including alumina; at least 5% by weight of a metallic combustible which is at least 30% aluminum; and from 3 to 10% by weight of an additive which is at least one material selected from the group consisting of aluminum fluoride, barium sulfate, cerium oxide, and calcium fluoride. A process for repairing a refractory material which contains alumina includes providing the above powder mixture; and projecting the powder mixture against a surface of the refractory material in the presence of gaseous oxygen so that the combustible particles and the gaseous oxygen react and release the heat of reaction against the surface and form a coherent refractory mass.