Erosion behavior of hydrophobic polytetrafluoroethylene (PTFE) coatings with different thicknesses

Abstract

The main purpose of the study is to explore the usage of polytetrafluoroethylene (PTFE) coatings to enhance slurry erosion (SE) resistance of hydro-machinery components. Although PTFE doesn't have enough hardness, however its hydrophobicity and good impact strength make it an interesting material to evaluate whether these properties could help in developing SE resistance in the parent hydro-machinery materials. Polytetrafluoroethylene (PTFE) is one of the leading materials for developing hydrophobic surfaces, which has numerous desirable properties like low friction coefficient, chemically neutral, and considerable thermal firmness. Therefore, in the present study, hydrophobic coatings of PTFE having three different thicknesses were produced (by sintering process) on a hydro-machinery steel SS410. The effect of thickness of hydrophobic coatings on the SE was analysed by conducting SE tests on the coated and uncoated steel SS410 with different combinations of operating parameters; namely average erodent particle size, slurry concentration, impingement angle and impact velocity. A relative study of different thickness of PTFE coatings vis-à-vis the bare steel SS410 was also conducted with respect to hydrophobicity. PTFE coating with minimum thickness showed the lowest erosion rate as compared to its counterparts. Moreover, the PTFE coating with minimum thickness showed superhydrophobic behavior with a contact angle of 159°, which might have also imparted the best SE resistance. With regard to SE of all the candidate materials, impact velocity was found to be the most influencing operating parameter.