Fracture and yield behaviour of wear and erosion resistant boron phosphide coatings for aerospace and automotive applications

Purpose: The investigation of mechanical properties of boron phosphide thin film coatings prepared by PECVD. Design/methodology/approach: The hardness of the films was determined by nanoindentation. The fracture toughness was measured by Vickers indentation and the yield strength of the films on ZnS and <100> silicon substrate was measured by a simplified form of the spherical cavity model. Findings: The measured mechanical properties indicate that boron phosphide coatings have potential engineering applications beyond protecting infrared substrates from sand erosion in aerospace environments. Research limitations/implications: Their mechanical properties are comparable to those of DLC and Si-DLC films, in addition to their superior corrosion and sand abrasion resistance. Practical implications: Originality/value: Experimental data on the mechanical properties of boron phosphide coatings that indicate their surface protection promise in engineering applications.