Development and validation of coupled erosion-corrosion model for wear resistant steels in environments with varying pH

    
    Erosion and corrosion are two of the most common causes of metal wear. Erosion is the result of impingement of a high-velocity gas or liquid on a surface, while corrosion is due to oxidative or chemical reactions of the metal surface with its environment. In many applications, the combined effect of both erosion and corrosion can become significant, leading to accelerated metal wear.
    
    In order to accurately predict the combined effect of erosion-corrosion on a given material or component, it is necessary to develop and validate a coupled erosion-corrosion model. In the past, several researchers have attempted to develop such models, but the amount of experimental and theoretical work required for each case is often considerable. Recently, researchers have focused on developing a generic erosion-corrosion model that can be applied to a range of materials in environments with varying pH.
    
    This paper presents the development of a coupled erosion-corrosion model, which is specifically designed to predict the wear rate of wear resistant steels in environments with varying pH. The model combines two fundamental theories, the erosion-corrosion theory and the electrochemistry of corrosion theory. The model incorporates both corrosion and erosion mechanisms in a single framework and is validated with experimental data.
    
    The model consists of three main components: the erosion balance equation, the corrosion balance equation and the pH-dependent kinetics equation. The erosion balance equation describes the mass loss due to the impingement of a high velocity gas or liquid on the material’s surface. The corrosion balance equation describes the local galvanic current sections, while the pH-dependent kinetics equation describes the rate of corrosion as a function of pH.
    
    The proposed model was validated using experimental results from several long-term tests conducted at KNPM, Rome. The tests consisted of erosion-corrosion of a series of 9Cr-1Mo steel in aqueous media with pH ranging from 1-14. The experimental results show good agreement with the predictive model. Both the erosion and corrosion processes were found to be significant contributors to the overall wear process.
    
    The results also highlighted that the corrosion process was more significant than the erosion as the pH increased. This result is in agreement with previous studies, which indicate that the corrosion processes become increasingly dominant in both acidic and basic aqueous solutions.
    
    The findings from this study provide a better understanding of the erosion-corrosion processes for wear resistant steels in environments with varying pH. The model is a useful tool for corrosion engineers who need to accurately predict wear rates and failure times for components in corrosive environments. Additionally, the findings can be used to help optimize coating and treatment processes in order to maximize component life.

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