Fabrication and Properties of Super-hydrophobic Composite Coatings

Composite coatings of double-layered Al2O3/PTFE and single-layered Al2O3-PTFE were prepared via atmospheric plasma spraying (APS) process. The morphology, phase composition, roughness, hardness, hydrophobic property and wear resistance of the composite coatings were characterized by scanning electron microscope (SEM), 3D topography tester, micro-hardness tester, contact angle tes-ter and friction and wear tester respectively. The influence of Al2O3 bond coat, Al2O3 hard particle filling and different process parameters on the hydrophobic property and wear resistance of the composite coatings were assessed. Results show that the wear resistance of the single PTFE coating were improved significantly by inducing Al2O3 ceramic as a bond coat or as hard particle filling phase into the composite coatings; The wear resistance property of Al2O3-PTFE composite coatings was superior to that of the Al2O3/PTFE composite coatings, correspondingly the wear rate of which was 2.84×10-5 mm3/N•m and 9.97×10-5 mm3/N•m respectively, the friction coefficient is 0.51 and 0.38 respectively; While the surface of the two composite coatings showed good hydrophobic properties with static contact angle of 155.4° and 148.9° respectively, which may be attributed to the compacted micro-nano convex structure on the rough surface and the synergistic effect of fluoride with low surface energy distributed on the composite coating surface. After the friction and wear test, the surface structure of the two composite coatings was damaged, hence the hydrophobicity of the coatings degraded, even so, the Al2O3/PTFE composite coating still exhibits super-hydrophobicity. © All right reserved.