Effect of fuel pressure, feed rate, and spray distance on cavitation erosion of Rodojet sprayed Al2O3+50%TiO2 coated AISI410 steel

Cavitation erosion is one of the major concerns of wear in hydro-machinery. The ensuing damage can be mitigated by using protective coatings, prepared with ceramic materials like Al2O3 and TiO2. Hence, in this research work, Al2O3+50%TiO2 coatings developed using automated and cheaper Rodojet thermal spray process on hydro-machinery AISI410 steel have been explored with regard to cavitation erosion (CE). Coatings with variation in process parameters namely fuel pressure, feed rate, and spray distance have been prepared to analyze their effect on CE and mechanical properties. An indigenously fabricated high velocity water jet cavitation erosion test rig was used for CE analysis. CE of bare AISI410 steel was also analyzed with variation in erosion parameters namely velocity and stand-off distance. The results indicate that CE of AISI410 steel was observed to be maximum for maximum velocity of 35 m/s and intermediate stand-off distance as 10 cm, owing to the maximum bubble density with higher velocity and bursting of majority of bubbles near to the target surface due to intermediate stand-off distance. Further, CE of Rodojet sprayed Al2O3+50%TiO2 coatings were found to be lower as compared to AIS410 steel. Coating parameters with minimum pressure of O-2 and acetylene as 1.25 and 2 bar, respectively, minimum feed rate as 740 cm/min, and maximum spray distance as 23 cm were found to be optimum for maximum CE resistance, owing to the higher resistance provided to the cavitation shock wave, by the spongy, porous and thick coating with lower microhardness and fracture toughness values. Roughening of splat surface, single and overlapped CE pits were observed to be the possible mechanism behind the erosion of the Rodojet sprayed Al2O3+50%TiO2 coatings.

Automated summary

Research on cavitation erosion of hydro-machinery revealed the importance of protective coatings with Al2O3 and TiO2 materials, where the coating parameters play a crucial role in resisting cavitation damage. Comparing the cavitation erosion of bare AISI410 steel with coated surfaces, it was found that the coatings provide higher resistance to cavitation erosion.