Development of zirconium and boron containing coatings for the application on aluminium diecasting tools by means of MO–PACVD

Abstract

In this study Zr(B, C) and Zr(B, C, N) coatings were synthesized by means of DC-pulse-PACVD for applications in aluminium diecasting. In order to assess their ability to withstand the complex and severe loads arising from the diecasting process, the influence of the process parameters gas pressure, process gas composition and voltage on the layer properties was investigated. The layers were examined by light and scanning electron microscopy (SEM). Compositional analysis was performed by XRD, EDS, WDS and SIMS. The hardness and adhesion of the layers has been determined as well as the resistance to erosion and to alternating temperature loads. It is shown theat the composition of the coatings can be varied over a wide range via the process parameters. While the concentration of zirconium as well as of boron remains almost constant over a wide range of deposition parameters, carbon and nitrogen are found to substitute each other. Carbon-rich coatings exhibit hardness values of up to 2300 HK0.01, whereas nitrogen-rich coatings prove to be resistant to alternating temperature loading and to erosion in aluminium melt.