Boron phosphide films prepared by PECVD have been characterised as a function of phosphine flow rate during deposition. The films were characterised by x-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), Nano-indentation and Scanning electron microscopy. The effect of phosphine flow rate during deposition on the dispersive, polar and acid-base components of the surface energy of the films was investigated. The components of the surface energy were determined by the Owens-Wendt (OW) and the Van-Oss-Chaudhry-Good (VOCG) methods. Both the Lifshitz-Van der Waaals dispersive interaction and the electron donor/electron acceptor acid-base components were found to depend on the phosphine flow rate during film preparation. Our results indicate the potential of Boron Phosphide films for tribological and engineering applications beyond their current application as protective coatings for soft infra-red transmitting substrates.
The corrosion susceptibility of Boron phosphide films prepared by PECVD, was studied in saturated saline solution as a function of phosphine flow rate during deposition. The chemical composition of the Boron phosphide films was determined by x-ray photoelectron spectroscopy (XPS) analysis. The investigation involved open circuit potential measurements (OCP) over several hours, potentiodynamic polarisation and electrochemical impedance Spectroscopy (EIS) measurements. The corrosion rate of the Boron Phosphide films was found to vary with changes in the phosphine flow rate during deposition. The results of our investigation also showed that Boron phosphide coated stainless steel plates had superior corrosion resistance, when compared to bare uncoated stainless steel plates. This opens up the potential for the application of Boron Phosphide films as a protective coating to improve the corrosion resistance of metals and alloys for various engineering applications.