World Geothermal Congress 2020+1
March - October, 2021

Friction and Wear Behaviour of Surface Coatings for Geothermal Applications


[University of Iceland, Iceland]

The global chase for renewable and green energy has led to an increased requirement in geothermal power generation. In such regard, one of the key elements for higher well output and increased efficiency of geothermal turbines and equipment during production is the reduction in mechanical energy loss. The reliability of mechanical systems owing to tribological properties of materials alleviates the negative impact of energy loss from friction and wear. Though desirable friction provides traction to support the motion of mechanical components, when in excess it can lead to unsteady vibrations causing fatigue, cracks, and wear. These damages give rise to production losses through complete loss of component functionality due to changes in the material property. Such tribological issues are observed in entire regions of geothermal power generation cycles; specific problem areas include wellheads, valves, pumps, and the steam turbines. To address these issues, several studies have focused on the development of coating materials as protection against such damages. This study aims to investigate the tribological properties of coatings deposited on substrates that are representatives of geothermal plant components. For this reason, dry sliding experiments were performed on Cermet coated and uncoated flat stainless steel substrates against a tungsten carbide (WC) ball. HVOF coated steels performed much better than bulk 304L and 630 stainless steel substrates. The coatings had a lower coefficient of friction and wear volume. This is due to the coating abrasive resistant microstructure and the dominance of coating-to-metal (WC) contact during the experimental conditions. Microscopic examinations of the wear tracks identified abrasion as the wear mechanism in the stainless steels. The wear track of the coatings showed thin material removal and splat formation for the highly worn-out coating.

        Topic: Corrosion and Scaling Paper Number: 27069

         Session 28C: Corrosion and Scaling 1 -- Coating Developments [Tuesday 15th June 2021, 12:00 am] (UTC-8)
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