Deposition of TiB 2 onto X40 CrMoV 5-1-1 steel substrates by DC magnetron sputtering

Abstract

Titanium diboride (TiB 2) films are being investigated due to their promising uses not only in electronic devices but also for mechanical purposes. Its excellent corrosion resistance and chemical stability, as well as high hardness and wear resistance, makes TiB 2 particularly suitable for aluminium processing (e.g. extrusion, die-casting and machining). In the present work, TiB 2 coatings were produced by non-reactive DC magnetron sputtering from a TiB 2 target on a tool steel substrate (AISI H13 premium/EN X40 CrMoV 5-1-1). Substrates similar to those frequently found on the aluminium injection industry were produced by vacuum quenching and tempering. The deposition parameters, namely the target/substrate distance, discharge current and substrate bias, were varied in order to obtain crystalline and well-structured films, suiting the substrate composition and microstructure. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy/EDS. A deposition rate of 23 nm/min was obtained for 0.85 A cathode current intensity and 70 mm substrate–magnetron distance. For positively biased substrates, all films are dense, without a columnar structure and show a (0 0 1) texture. For negatively biased substrates, there are less surface heating effects due to a much lower electron current through the substrate, and an ordered structure appears only at −150 V.