Process for direct nitriding of metals of low melting point
OwnerDominique Dubots, Pierre Faureinventors
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Abstract
Process for direct nitriding of metals of relatively low melting point with the aid of a nitrogen-containing gas, in which a powder of at least one of the metals is mixed with a refractory powder, the mixture is heated under an atmosphere of nitrogen-containing gas at atmospheric pressure until the start of a rapid and exothermic nitriding reaction, and this reaction, which proceeds at a temperature generally higher than that of the melting point of the metals without apparent melting being observed, is allowed to proceed until all of the metals have been consumed, in order to obtain a highly porous solid mass which is easy to grind and is based on metal nitrides or metal oxynitrides.
Claims9
A process for mass producing products based on metallic nitride or oxynitride, said process comprising the steps of:
- (a) mixing a metallic powder comprising at least one metal with a refractory powder infusible and inert with respect to said metallic powder in operating conditions of said process to obtain a bulk mixture, the metallic powder content of said bulk mixture not exceeding 66.67% of said bulk mixture;
- (b) heating said bulk mixture in a furnace under a flow of nitrogen-containing gas at approximately atmospheric pressure until a rapid and exothermic nitriding reaction of said metal begins;
- (c) controlling a nitriding temperature of said nitriding reaction at which said metallic powder melts at least partially by means of said flow of nitrogen-containing gas so as to self-maintain said nitriding reaction until said powder is completely nitrided and to avoid any apparent trace of melting in said bulk mixture;
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- (d) obtaining said products in the form of a highly porous bulk solid which is easy to grind and which is capable of being melted.
Dependencies are inferred from the claim text.