Effect of Pt on Stress Rupture Properties of Pt-Modified Nickel Aluminide Coatings at 1100 °C

TL;DR

This paper investigates how adding platinum affects the durability of high-temperature coatings used in superalloys.

Contribution

The study reveals that higher platinum content in PtAl coatings reduces their stress rupture life at high temperatures.

Findings

Higher Pt content in PtAl coatings significantly decreases stress rupture life at 1100 °C/100 MPa.

Cracks near the substrate in high-Pt coatings accelerate fracture failure.

Increased coating thickness from Pt is not the main cause of reduced durability.

Abstract

Platinum plays a crucial role in the superior high-temperature oxidation resistance of Pt-modified nickel aluminide (PtAl) coatings. However, PtAl coatings usually serve in thermo-mechanical coupling environments. To investigate whether Pt contributes to the high-temperature mechanical properties of PtAl coating, stress rupture tests under 1100 °C/100 MPa were performed on PtAl coatings with varying Pt contents. The different coatings were obtained by changing the thickness of the electroplated Pt layer, followed by a diffusion heat treatment and the aluminizing process in the present work. The results of the stress rupture tests indicated that an increasing Pt content resulted in a significant decrease in the stress rupture life of PtAl-coated superalloys under 1100 °C/100 MPa. Theoretical calculations and microstructural analysis suggested that an increased coating thickness due to the Pt content is not the main reason for this decline. It was found that the cracks generated close to the substrate in high-Pt-coated superalloys accelerated the fracture failure.

Figures