Hardness, adhesion index and microstructure of PEEK coating on Al or Fe substrate by LVOF flame spray

Low velocity oxy-fuel (LVOF) flame spraying technique was employed to deposit poly-ether-ether-ketone (PEEK) powder onto the low carbon steel (Fe) or aluminum (Al) substrate. The adhesion index, micro-hardness and morphological properties were studied. The effects of interfacial roughness, substrate preheating, spray distance and magnetic field on the adhesion, hardness and morphological results were of our main interest. The results indicated that the optimum process conditions (smooth top-surface with high adhesion index and hardness) for thermal spray coating of PEEK on Fe or Al substrate were achieved at the substrate preheating temperature of 200 °C and with the spray distance of 100 mm. The adhesion index was increased with the increase in interfacial roughness. The hardness and adhesion index of the PEEK coating on Fe substrate increased with the application of magnetic field due to the increase in the degree of crystallinity of the PEEK under magnetic field. The recommended flux density under the experimental conditions was 17 mT.