Ecologically friendly thermo-chemical treatment of steel products

The Department of Heat Treatment of the Institute of Precision Mechanics in Warsaw has developed an ecologically friendly thermo-chemical treatment of tooling, meeting the current requirements of its manufacturers.

The developed technological process named Nitrooxidation AG is a modification of an earlier technology of gaseous oxynitriding, developed by IMP, consisting of the subjection of steel products to the action of an atmosphere generated from a mixture of ammonia and water vapour at temperatures within the range of 500÷600°C and implemented widely, especially in the case of tools made from high speed steel. Both oxynitriding, as well as Nitrooxidation AG cause the formation of diffusion layers on the surface of tooling manufactured from high speed steel. These are composed of an oxide zone and a deeper zone enriched by nitrogen, resulting in an extension of tool life by the enhancement of their wear resistance, as well as resistance to corrosive environment. At the same time, the exterior oxide zone gives the tool surface an aesthetic dark colouring.

One of the most important features of the Nitrooxidation AG process in comparison with earlier used technologies is the separation of the nitriding phase from that of oxidation in water vapour in a way which eliminates the formation of ammonia water in effluent gases which in the nitrooxidation process caused pollution of the natural environment. In the nitrooxidation ag process, effluent gases emitted to the atmosphere contain neutral components, i.e. nitrogen, water vapour and carbon dioxide.

Nitrooxidation ag processes are conducted in GOAT-700 pit type furnaces, manufactured by IMP. The GOAT-700 furnaces are of modern design with the application of fibrous thermoinsulating materials, they are also equipped with microprocess temperature control, as well as a process control system.

The technology „Ecologically friendly thermo-chemical treatment of steel products” was awarded with GOLD MEDAL on on 54th World Exhibition of Innovation, Research and New Technologies, Brussels-Eureka 2005, Brussels 19.11.2005.