Effect of substrate bias voltage on the composition, microstructure and mechanical properties of W-B-C coatings

• Published in: Applied surface science 2020-10, Vol.528, p.146966, Article 146966
• Main Authors: Mirzaei, S., Alishahi, M., Souček, P., Buršíková, V., Zábranský, L., Gröner, L., Burmeister, F., Blug, B., Daum, Ph, Mikšová, R., Vašina, P.
• Format: Article
• Language: English
• Subjects: Fracture resistance; Magnetron sputtering; Protective coatings; Substrate bias; W-B-C alloys
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146966

[Display omitted] •Hard and fracture resistance W-B-C coatings were deposited by magnetron sputtering.•The effect of bias voltage on the microstructure and mechanical properties was studied.•Chemical composition was influenced by increasing the bias voltage, mainly due to re-sputtering.•The maximum changes in the hardness was occurred at bias voltages above −125 V. Commercial ceramic protective coatings usually exhibit high hardness, but low ductility impairs their performance and application-oriented properties. Accordingly, a state-of-the-art magnetron sputtered W-B-C coating can be a promising coating for the tooling industry due to its hard yet tough characteristics. In the present study, we have employed substrate biasing to enhance the delivered energy to the growing film and have investigated the effect of bias voltage on the structural and mechanical behavior of W-B-C coatings. The investigations revealed that increasing the substrate bias voltage enhanced the re-sputtering of B and C atoms and subsequently varied the chemical composition of the coatings and significantly decreased the growth rate. It also enhanced the crystallinity of the coatings. We demonstrate how the bias voltage led to an unusual transition from a featureless to a columnar microstructure. Furthermore, it was observed that as the substrate bias voltage increased from 0 V to −125 V, the compositional and structural changes resulted in a slight decrease of the hardness, while a further increase in the bias voltage to −200 V enhanced the hardness. This increase was attributed to the suppression of dislocation movement and grain boundary deformation processes by solute segregation and by lattice defects.