Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

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• 作者：R. K. Kumar ; M. Kamaraj ; S. Seetharamu ; T. Pramod…
• 刊名：Journal of Thermal Spray Technology
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：25
• 期：6
• 页码：1217-1230
• 全文大小：5,002 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Surfaces and Interfaces and Thin Films
  Tribology, Corrosion and Coatings
  Materials Science
  Characterization and Evaluation Materials
  Operating Procedures and Materials Treatment
  Analytical Chemistry
  
• 出版者：Springer Boston
• ISSN：1544-1016
• 卷排序：25

文摘

The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.Keywordscavitation erosionHVOF/HVAF coatingporositysurface topography