Molten-salt bath for nitriding mechanical parts made of steel, and implementation method

US9611534B2 · kind B2 · utility

Assignee

• H.E.F. · FR

Inventors

• Herve Chavanne · St-Estève, FR
• Philippe Maurin-Perrier · Saint-Marcellin-en-Forez, FR

Key dates

• Filing date: Mar 7, 2012
• Grant date: Apr 4, 2017
• Expiry date: May 25, 2033

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C8/56
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A molten-salt bath for nitriding mechanical steel parts, essentially consisting of the following (the contents being expressed in wt %): 25 to 60 wt % of alkali-metal chlorides; 10 to 40 wt % of alkali-metal carbonates; 20 to 50 wt % of alkali-metal cyanates; and a maximum of 3 wt % of cyanide ions (formed during the use of the bath), wherein the total of the contents is 100 wt %. Preferably, the bath contains: 25 to 30 wt % of sodium cyanate; 25 to 30 wt % of sodium carbonate and lithium carbonate; 40 to 50 wt % of potassium chlorides; and a maximum of 3 wt % of cyanide ions (formed during the use of the bath), the total of the contents being 100 wt %.