Surfaces with optimal friction and fatigue properties of nitrided/nitrocarburized components (SurfNit)

Important results from the project

The purpose of the project was to investigate possibilities of developing and tailoring nitride processes for surfaces with high strength and friction and wear characteristics for components such as gears and pistons (heavy loaded). This has been evaluated in tribological tests, where the impact of steel grade, origin surface and process parameters has been studied. Tests were seizure test, reciprocating sliding wear test, fretting test and scratch test. A new method for improved process control during nitrocarburizing showed possibilities for improved control and regulation.

Expected long term effects

The project has shown that with the new nitrocarburizing process it is possible to regulate the composition of the compound layer and facilitate a more stable process. The results indicate that seizure can be a major contributory factor regarding the advantages of nitriding processes. Nitriding processes have a comparatively low environmental impact and are an interesting alternative to case hardening.

Approach and implementation

To evaluate friction and wear performance properties selection of test method is highly dependent on the application. It was found that no single standard tribological test method can solely replicate practical knowledge of actual components, thus several tests in combination are necessary. These must be customized depending on the application. The experiments with improved process control were carried out in a lab furnace. Attempts were also made in an industrial furnace, but then the impact of the previous process was too great. Thus this requires additional work.