Institute of Fundamental Technological Research

This study investigates the use of high-frequency eddy current testing (ECT) to assess the structural integrity of aluminide coatings on MAR-M247 nickel superalloy under simulated fatigue conditions. Aluminide coatings, deposited via chemical vapor deposition at thicknesses of 20 µm and 40 µm, were tested using custom-designed probes optimized for defect detection. Results demonstrate that substrate grain structure and coating thickness significantly influence coating durability, with fine-grain substrates exhibiting the least resistance changes and greatest fatigue tolerance. Eddy current signal variations correlated with microstructural changes, enabling detection of damage otherwise invisible to traditional methods. These findings establish ECT as a precise, non-destructive approach for monitoring aluminide coatings in critical applications.

Nickel alloys, Aluminide coating, Non-destructive testing, Eddy current testing

This study investigates the use of eddy current testing (ECT) as a non-destructive technique to evaluate the thickness and structural variations of non-magnetic aluminide coatings on MAR-M247 nickel-based superalloy. Coatings with thicknesses of 20 μm and 40 μm were applied to substrates exhibiting fine, coarse, and columnar grain structures. Using sensors of different geometries, impedance measurements were performed within a frequency range of 11.5 MHz to 12.5 MHz. Results demonstrated the designed sensor’s superior sensitivity, with the highest values of absolute resistance difference significantly exceeding the threshold for reliable distinction due to coating thicknesses or grain structures. The study highlights the impact of eddy current penetration depth and edge effects on the measurement accuracy, emphasizing the need for optimized sensor design and frequency selection. Findings confirm the efficacy of ECT in differentiating coatings of varying thicknesses and substrate structures, offering a reliable tool for quality control in high-temperature applications.

Aluminide coating, Eddy current testing, Non-destructive testing, Nickel alloys

A method for the nanoidentation of resistance coatings 1–100 nm thick and intended for use in microelectromechanical systems is proposed on the basis of atomic-force microscopy (AFM). The elastic moduli of the coatings are determined using three models of contact: the Hertz model, the Johnson–Kendall–Roberts model and the Makushkin model, with and without allowance for the influence of a solid substrate