Performance evaluation of centrifugal pumps after surface treatment on impeller material

In this study, the pump and the impellers of the pump were produced from a three-dimensional printer (3D printer) working with the additive manufacturing method, which has a more affordable production cost compared to its counterparts. The low efficiency in energy consumption of pumps used in the market poses a problem in this period when the world's energy needs are high. The effect of the hydrophobic feature on the surface after the coating on the pump impellers on the pump performance has been experimentally investigated in this study. In addition, the surface roughness and tensile strength of the pump parts produced by 3D printers were examined. Transparent epoxy coating, TiO2 and SiO2 nanoparticle added epoxy coatings in different mass ratios (%3, %7.5, %10) were applied to the pump impellers produced from polyethylene terephthalate glycol (PETG) raw material. The surfaces of the parts produced from PETG raw material have a contact angle of 70° and are hydrophilic. The epoxy coating with a hydrophobic contact angle of 110° between the coated surfaces, with %7.5 by mass SiO2 added, gave the best results. When the roughness analysis of the impeller surfaces made of PETG raw material coated with epoxy with massive %7.5 SiO2 additive was performed, the Ra value of the uncoated surface was reduced to 8.5 µm and the Ra value of 0.5 µm after coating, and the roughness on the part surfaces was improved. In the tensile test, the tensile strength of the uncoated material was 48MPa. After coating, this value was increased to 57MPa, increasing the tensile strength of the material. Three different pump impeller types were produced. After the epoxy coating of %7.5 by mass of SiO2 on the pump impeller surfaces, they have a hydrophobic surface. Pump performance was measured in the prepared pump performance test setup. As a result of the experiments, it has been proven that the flow rate of the pump, the pump head and the efficiency of the pump increase in impellers with hydrophobic surfaces. In addition, although there are geometrical differences in the pump impellers, it has been experimentally proven that the efficiency of the impellers increases when the surface of the impellers is turned to the hydrophobic surface. Keywords: Hydrophobic surface, Centrifugal pump, Pump impeller, SiO2 coating, Pump efficiency, PETG.