Cavitation erosion characteristics and mechanisms of hydraulic turbine substrates and their coatings
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View abstract on PubMed
Summary
This summary is machine-generated.The Laser-Clad (LC) coating demonstrated superior cavitation erosion resistance compared to thermal spray coatings and the S135 stainless-steel substrate. High hardness alone does not guarantee performance, as pores and defects significantly influence failure mechanisms.
Area Of Science
- Materials Science
- Surface Engineering
- Tribology
Background
- Cavitation erosion poses a significant threat to the longevity of components in hydraulic machinery.
- 06Cr13Ni5Mo (S135) stainless steel is susceptible to cavitation damage, necessitating protective coatings.
- Understanding coating performance and failure mechanisms is crucial for material selection.
Purpose Of The Study
- To systematically investigate the cavitation erosion resistance of S135 stainless steel and four different coatings.
- To analyze the failure mechanisms of the coatings under ultrasonic cavitation conditions.
- To compare the effectiveness of HVOF-WC10Co4Cr, HVOF-Cr3C237WC18, HVAF-WC10Co4Cr, and Laser-Clad (LC) coatings.
Main Methods
- Ultrasonic cavitation testing was employed to assess weight loss and surface roughness changes.
- Microstructural analysis was implicitly used to understand failure mechanisms.
- Comparative analysis of four distinct coating types against a stainless-steel substrate.
Main Results
- The Laser-Clad (LC) coating exhibited the best performance, with the lowest weight loss and minimal roughness increase.
- HVOF-WC10Co4Cr showed the poorest resistance, despite high microhardness, indicating hardness is not the sole determinant.
- Thermal spray coatings failed via crack propagation from pores along inter-splat boundaries; HVAF-WC10Co4Cr showed improved resistance due to lower porosity.
- The LC coating's lamellar structure confined damage, but process defects led to localized delamination and pit formation.
Conclusions
- The Laser-Clad coating offers superior cavitation erosion resistance for S135 stainless steel.
- Coating porosity and internal defects significantly impact cavitation erosion resistance.
- Failure mechanisms vary with coating type, involving fatigue crack initiation at pores and propagation along boundaries or through-thickness defects.
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