Effect of heat treatments on the mechanical and tribological properties of electrodeposited Fe–W/Al2O3 composites

Abstract

In this study, the influence of heat treatment on the mechanical and tribological properties of electrodeposited Fe–W/Al2O3 composite coatings is studied. The properties of the as-deposited and annealed composites are compared with those of electrodeposited hard chromium coatings. The amorphous structure of the Fe–W matrix transforms into a mixed amorphous-crystalline structure upon annealing at 600 °C for 1 h. The observed microstructural transformations result in a substantial increase of both the hardness and the reduced Young's modulus of the Fe–W/Al2O3 composite coatings, reaching values of 16.3 GPa and 191.7 GPa, respectively. The results on the wear resistance studied under dry friction using ball-on-disc sliding tests show that a low wear rate is obtained for both as-deposited and annealed composite coatings, i.e. ~1.5 × 10−6 mm3/Nm. In contrast, the heat treatments are detrimental for both the hardness and wear resistance of hard chromium coatings. As a consequence, the mechanical and wear properties of the electrodeposited Fe–W/Al2O3 composite coatings, especially after annealing, are superior to the properties of hard chromium coatings. Hence, Fe–W/Al2O3 composite coatings can be considered as a valid and sustainable alternative to hard chromium coatings, particularly in applications where these materials may be exposed to high temperatures.