Microstructure and Mechanical Properties of Cr-W-B-N Coating Deposited by DC Reactive Magnetron Co-Sputtering
Nanocomposite Cr-W-B-N coatings with various tungsten contents were synthesized on silicon wafer substrates. The used technique is a DC reactive magnetron co-sputtering deposition equipped with a Cr-B alloy target with 20 at.% B and a W target in a mixed argon/nitrogen plasma atmosphere. Composition and microstructure of the obtained coatings were investigated using X-ray diffraction, X-ray Photoelectron Spectroscope and transmission electron microscope while the micro-hardness was measured using a depth-sensing nano-indenter. The results have shown that the microstructure and the mechanical properties of Cr-W-B-N coatings were strongly dependent on either the tungsten content or the volume fraction of W-N crystalline phases. It was observed that the micro-hardness of Cr-W-B-N coatings is lower than that of Cr-B-N coating as the tungsten content is less than 24 at.% and the volume fraction of W-N crystalline phases is lower than 37 vol.%. As the tungsten content further increased to 30 at.% and the volume fraction of W-N crystalline phases increased to 55 vol.%, the micro-hardness of Cr-W-B-N coating was found enhanced to 19 GPa and higher than Cr-B-N film. It was also obtained that the volume fraction of Cr-N crystalline phases is inversely proportional to the volume fraction of W-N crystalline phases.