The Si-B-C-N films, prepared by magnetron sputtering, are very attractive due to their very high hardness (above 50 Gpa), temperature resistance and wide band gap. The composition of the films prepared under different conditions was determined using standard and resonance RBS (light element determination) and ERDA techniques. Correlation between sample preparation condition and film composition and its (mechanical) properties was found. This work is done in collaboration with University of West Bohemia. We collaborate with Sulzer Innotec, Switzerland on industry application of hard coating.