Abstract: Hardening protection compositions based on substances which form boron glass for partial carburization of metallic components, which contain magnesium-silicon compounds as an additive. These hardening protection compositions can be used very advantageously in processes for the partial carburization of metallic components and in particular are outstandingly suitable for vacuum carburization.

Abstract: A boronizing agent in the form of a paste for the production of boride layers on metallic workpieces. The boronizing agent contains boron-releasing substances, activating substances and the remainder of inert, refractory extenders together with water and optionally auxiliaries required for paste formulation. It contains as additives: (a) calcium carbonate and/or lithium carbonate; (b) at least one compound from the group of alkali metal and alkaline earth metal nitrites; (c) at least one compound from the group of water soluble alkali metal and alkaline earth metal borates.

Abstract: A boronizing agent in the form of a paste for the production of boride layers on metallic workpieces. The boronizing agent contains boron-releasing substances, activating substances and the remainder of inert, refractory extenders together with water and optionally auxiliaries required for paste formulation.

Abstract: Hardening protection compositions based on substances which form boron glass for partial carburization of metallic components, which contain magnesium-silicon compounds as an additive. These hardening protection compositions can be used very advantageously in processes for the partial carburization of metallic components and in particular are outstandingly suitable for vacuum carburization.

Abstract: A boriding agent for generating boride layers on metallic workpieces, containing boron-releasing substances, activating substances and, in the remainder, refractory, inert extender. The activating substance is a combination of 1 to 5 wt. % potassium tetrafluoroborate and 5 to 40 wt. % calcium fluoride, relative to the total quantity of the boriding agent. With this boriding agent it is possible for single-phase, Fe2B-containing boride layers to be generated on workpieces made of ferrous materials. The agent results in lower emissions of fluorine and fluoride.

Abstract: In order to recover in an environmentally sound and economic manner used hardening shop salts which contain nitrate-nitrite, the salts, comminuted to particle sizes of from 1 to 50 mm, are dissolved in a mixture of nitric acid and hydrogen peroxide without nitrogen oxides arising, and, by evaporation and cooling, potassium nitrate, sodium chloride, and sodium nitrate are obtained sequentially by fractional crystallization.

Abstract: The process for environmentally acceptable and economical recovery of chloride salts from hardening-shop used salts utilizing the steps of leaching of the used salt, detoxification of the cyanide and selective crystallization of the individual chloride salts. The process is characterized in that all the chloride salts that are present in the hardening-shop used salt are recovered in pure form.