Optimisation of the high velocity oxygen fuel (HVOF) parameters to produce effective corrosion control coatings on AZ91 magnesium alloy

High velocity oxygen-fuel (HVOF) thermal spraying was used to fabricate Al and metal matrix composite (Al/SiCp) coatings on the Mg alloy AZ91 surface in order to investigate their efficacy as corrosion-control coatings. The corrosion behaviour of the coated specimens was evaluated by electrochemical methods and Taguchi design of experiments (DOE) methodology was used to analyse the relationship between the spraying conditions and the corrosion behaviour. Based on the above, optimum HVOF conditions were proposed where the number of layers and the spraying distance seemed to be the key parameters to obtain thick and compact coatings leading to effective corrosion control coatings.