# Electrochemical Surface Modification of Laser Cladded Ni-Based Single Crystal Superalloy in NaNO3 Solution

## TL;DR

This paper explores using electrochemical dissolution to achieve smooth surfaces in laser-repaired Ni-based single-crystal superalloys.

## Contribution

The study demonstrates electrochemical dissolution as a promising method for shape accuracy in laser-clad superalloys.

## Key findings

- Dendritic and interdendritic regions in the substrate dissolved at different rates, causing a rough surface.
- Dendritic and interdendritic regions in the cladding structure dissolved simultaneously, resulting in a smooth surface.
- Phase dissolution preferences explain the difference in surface quality between substrate and cladding.

## Abstract

Since mechanical processing can introduce stress in the sample, electrochemical dissolution has been utilized to attain shape accuracy in certain materials. However, this technique is rarely applied to laser-repaired Ni-based single-crystal superalloys. In this work, the transpassive dissolution behaviors of an additive manufacturing-repaired Ni-based single crystal superalloy in a 10% NaNO3 solution were investigated by comparison with the substrate. A significant disparity in dissolution rates was found between the dendritic and interdendritic regions of the substrate, resulting in a rough surface. Conversely, the dissolution of the dendritic and interdendritic regions in the cladding structure occurred nearly simultaneously, leading to a high-quality, smooth surface. This behavior was attributed to the differences in phase dissolution preferences between the substrate and the cladding structure. It indicates that electrochemical dissolution is a promising method for achieving shape accuracy in laser-clad Ni-based single-crystal superalloys.