Tracks: High Power Impulse Magnetron Sputtering (HIPIMS), High Power Impulse Magnetron Sputtering (HIPIMS), High Power Impulse Magnetron Sputtering (HIPIMS)
A novel CrAlYBCN/AlSiCN coating has been devised for the improved wear resistance and high temperature stability of tools for cutting applications. The as-deposited coating contained CrAlN and disordered carbon phases as detected by Raman spectroscopy. With hardness values of 3550 HK; the coating could be classified as superhard. Rockwell indentation showed class 0-1 adhesion and scratch test critical loads were 43 N on high speed steel substrates. Isothermal annealing and thermogravimetric analysis of the coating indicated high temperature stability up to 900˚C. Temperatures of 600 °C and above resulted in a surface reconstruction that smoothed the coating due to the diffusion of carbon. A thin oxide layer supported by weak oxide Raman peaks and only 9% oxygen inclusion at 800˚C observed by EDX. In pin-on-disk tests with an Al2O3 ball counterpart at room temperature, the wear track contained predominantly a CrAlN phase similar to the as-deposited coating. Wear tracks produced at 200˚C contained a Cr2O3 build-up layer resulting in an improvement in wear rate by an order of magnitude to 4x10-16 m3N-1m-1 compared to room temperature. Raman of the wear tracks at both temperatures indicated graphitisation of carbon in the coating which would improve wear resistance by acting as a solid lubricant.