Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Experimental Investigation of HVOF and Polymeric Coatings for Turbine Blade Protection
Submission Author:
Fernando Moreira Bordin , SC
Co-Authors:
Fabio Antonio Xavier, Carlos Enrique Niño, Rodrigo Bastos Fernandes, Leandro Luiz Silva, Waldson Bezerra, Fernando Moreira Bordin, Erick Cardoso Costa, Miguel Barcelos, Beatriz Santos
Presenter: Fabio Antonio Xavier
doi://10.26678/ABCM.COBEM2023.COB2023-1754
Abstract
Hydroelectric power plant maintenance is a very costly and time-consuming activity, especially when the main cause of turbine blade wear is the severe abrasion caused by a large amount of abrasive sediment. Abrasion-resistant coatings are used to mitigate this problem. However, the limited time for turbine maintenance, associated with many turbines, confined space, and health and safety concerns, limits the methods of coating application. This study presents a comparison between two popular coating application methods: thermal spray by high-velocity oxygen fuel (HVOF) and polymeric application by trowel/brush. The objective is to evaluate the performance of commercial coating materials, which are largely used for abrasion and cavitation wear of turbine blades, under a dry sand/rubber wheel abrasion apparatus, following ASTM G65. The coating materials were evaluated in terms of wear resistance and behavior, versus the estimated application time, to compare the time-effectiveness of commercial coatings. The coatings were applied onto AISI 316L stainless steel samples, with a minimum thickness of 300 µm (HVOF coatings) and 600 µm (polymeric coatings). The coating materials were characterized in terms of overall thickness, hardness by macro and microindentation, and subsurface morphology: phases and chemical elements. The experiments were performed in a dry sand/rubber wheel abrasometer, using Procedure D with a maximum number of revolutions equal to 6000, a loading of 45 N applied by a cantilever loading system. A load cell, supervised by a microcontroller, was fixed to the specimen fixture, to calibrate the static load onto the workpiece, and to closely follow the normal force behavior during the experiments. The results were evaluated in terms of wear rate behavior (adjusted volume loss divided by time) of each measuring interval, followed by the cavity profile and normal force signals, along with the estimated application time. There is a significant advantage for the HVOF coated specimen in terms of wear resistance. However, the health, safety, and lower necessary time to apply polymeric coating may justify the increasing interest in this type of coating material, ultimately leaving the decision of the most time-effective coating material to the end-user.
Keywords
hydroeletric power plant, abrasion resistant coatings, ASTM G65, wear behavior, performance evaluation
