Abstract: An improved salt and method of using such salt for conditioning scale on strip or sheet metal surfaces is provided. In more particular aspects, the invention provides an improved salt of alkali metal hydroxides and alkali metal nitrates which are used in their fused anhydrous form to condition scale on metal strip or sheet. The salt preferably contains from about 40% to about 70% potassium hydroxide, from about 20% to about 55% sodium hydroxide, and from about 2% to about 30% of an alkali metal nitrate. The salt is especially adapted to be sprayed onto a moving strip or sheet of metal as it passes a spray station, although it can also be used in conventional salt bath applications in which the salt is maintained in a fused condition in a tank, and the sheet, strip, bar, tubing or other form to be treated is immersed in the fused salt bath.

Abstract: A system for descaling a strip of metal includes a nozzle assembly mounted within a spray box for spraying descaling product on the strip. The nozzle assembly includes a spray chamber; nozzles mounted directly to the spray chamber; and a heater for heating the chamber, the descaling product in the chamber, and the nozzles by conduction through the chamber. The nozzles are oriented to direct the descaling product in a spray against the upper and lower surfaces of the metal strip for an amount and a time sufficient to descale the metal strip. The nozzle assembly is attached to the spray box and can be easily removed therefrom for inspection.

Abstract: A system for descaling a strip of metal includes a nozzle assembly mounted within a spray box for spraying descaling product on the strip. The nozzle assembly includes a spray chamber; nozzles mounted directly to the spray chamber; and a heater for heating the chamber, the descaling product in the chamber, and the nozzles by conduction through the chamber. The nozzles are oriented to direct the descaling product in a spray against the upper and lower surfaces of the metal strip for an amount and a time sufficient to descale the metal strip. The nozzle assembly is attached to the spray box and can be easily removed therefrom for inspection.

Abstract: An improved salt and method for descaling and deglassing metals, especially metal forgings and even more specifically, titanium forgings wherein glass has been utilized as a forging lubricant, is provided. A composition of the salt has at least one alkali metal hydroxide, at least one alkali metal nitrate and at least one alkali metal or alkaline earth metal fluoride. Preferably, the salt includes from about 60-75% sodium hydroxide, from about 15-25% potassium hydroxide, from about 3-6% sodium fluoride, and from about 5-10% sodium nitrate. The specific preferred composition is one which contains about 67.5% sodium hydroxide, about 18% potassium hydroxide, about 4.5% sodium fluoride and about 10% sodium nitrate.

Abstract: A method of removing Cr.sup.+6 from a solution is provided. In removing the Cr.sup.+6, an effective amount of an alkali metal dithionite is added to the solution to reduce substantially all of the Cr.sup.+6 to Cr.sup.+3. A soluble material is provided in the solution which will form a precipitate. Further, the soluble material is selected such that it will coprecipitate and tie up any dissolved or colloidal Cr.sup.+3 formed as a result of the reduction of the Cr.sup.+6. In one embodiment, the solution is alkaline and preferably, the pH of the solution is reduced sufficiently such that the soluble material will quickly precipitate and form the coprecipitate material with the Cr.sup.+3. Thereafter, the solution is filtered to remove the coprecipitated material from the solution and thereby form a supernatant solution suitable for waste discharge which has substantially lowered chromium values. The precipitate has the Cr.sup.+3 tied up in an insoluble non-leachable form.

Abstract: A method and apparatus for improved settling and handling of sludge in a fused salt bath for treating materials is provided. The apparatus includes a tank divided into a work zone and a salt processing zone, with the salt processing zone having a salt recovery section and a salt heating section. A pumping device is provided which together with adjustable gate means, generate a relatively quiescent flow in the work zone allowing sludge to settle, and a relatively turbulent flow in the salt processing zone and especially the salt heating section, to keep the sludge in suspension.

Abstract: A method and composition for stopping-off nitrogen and/or carbon diffusion into metal surfaces. The composition, which is a mixture of a refractory material selected from the group of zirconium and aluminosilicate, sodium silicofluoride and sodium silicate, is coated onto the metal surface where diffusion is to be prevented. The mixture is cured and the metal part is subjected to elevated temperatures for carburizing, nitriding, or carbonitriding. The coating prevents nitrogen and/or carbon diffusion at the coated area. After treatment the coating is removed.

Abstract: A method and composition for stopping-off nitrogen and/or carbon diffusion into metal surfaces. The composition, which is a mixture of a refractory material selected from the group of zirconium and aluminosilicate, sodium silicofluoride and sodium silicate, is coated onto the metal surface where diffusion is to be prevented. The mixture is cured and the metal part is subjected to elevated temperatures for carburizing, nitriding, or carbonitriding. The coating prevents nitrogen and/or carbon diffusion at the coated area. After treatment the coating is removed.

Abstract: According to the present invention a saturated aqueous solution comprising at least one alkali metal hydroxide and at least one alkali metal nitrate is provided which can be spray added to a fused anhydrous bath which contains alkali metal materials.

Abstract: A heating assembly for a fused bath is disclosed. The assembly includes a heating element within a tube. Also, disposed within the tube is a first thermocouple. A second thermocouple is positioned in the bath outside the tube. Control means are connected to the heating elements and thermocouples so that the heating of the bath is performed responsive to the temperature sensed by the second thermocouple; but, if the first thermocouple detects heat in the tube greater than a given value it will interrupt the heating operation to prevent damage to the heating elements due to over-heating.

Abstract: A ferrous metal product to be cleaned is immersed in an oxidizing molten salt bath forming a conditioned scale on the surface of the metal. The conditioned scale is subsequently removed from the metal surface by immersing the metal product in an aqueous caustic bath containing alkali metal hydroxide with alkali gluconate and triethanolamine serving as sequestering agents. The caustic bath may optionally include a brightening catalyst or ethylenediamine-tetracetic acid.