A Probabilistic Method for Estimating the Influence of Corrosion on the CuAlNi Shape Memory Alloy in Different Marine Environments

Špiro Ivošević,Peter Majerič,Gyöngyi Vastag,Nataša Kovač,Rebeka Rudolf

doi:10.3390/cryst11030274

Špiro Ivošević, Peter Majerič + Show 3 more

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https://doi.org/10.3390/cryst11030274

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Abstract

This paper gives an approach to the probabilistic percent corrosion depth estimation model for the CuAlNi Shape Memory Alloy (SMA) in different marine environments. Real testing was performed for validation of the theoretical model, where CuAlNi SMAs were exposed to 6 and 12 months in different seawater environments. Focus Ion Beam (FIB) analysis was used to measure the real corrosion depth on the surfaces of tested samples. A statistical approach to the investigation of the corrosion rate of CuAlNi SMA is given, where the corrosion rate is observed as a continuous random variable described by a linear corrosion model, with the assumption that corrosion starts immediately upon alloy surfaces being exposed to the influences of the marine environment. The three best-fitted two-parameter distributions for estimating the cumulative density function and the probability density function of the random variable were obtained by applying adequate statistical tests. Furthermore, using EDX analyses, we identified the chemical composition of the corroded materials, and with the help of Principal Component Analyses, we determined which corrosion environment had the most dominant influence on the corrosion process. The research results indicated that the changeable environment in the tides had a more heterogenic chemical content, which accelerated the corrosion rate.

Highlights

In the last century, special attention was focused on smart materials based on the research of alloys, polymers, ceramics, composites, and hybrid systems, the most significant discoveries are related to Shape Memory Alloys (SMA)
Considering the basic mechanical, chemical, and characteristics of alloys, as well as their characteristic shape memory, they have a wide variety of applications for engineering and technical applications, such in medicine, aerospace, vibration control, biomechanics, automotive, marine, robotic and different domestic applications
In order to determine corrosion rate and changes in chemical composition on the surface of CuAlNi SMA samples, 2 databases were used for the verification of research results

Summary

Introduction

In the last century, special attention was focused on smart materials based on the research of alloys, polymers, ceramics, composites, and hybrid systems, the most significant discoveries are related to Shape Memory Alloys (SMA). Considering the basic mechanical, chemical, and characteristics of alloys, as well as their characteristic shape memory, they have a wide variety of applications for engineering and technical applications, such in medicine, aerospace, vibration control, biomechanics, automotive, marine, robotic and different domestic applications. SMAs were applicable for blood clot filters, orthodontic corrections in biomedicine [5], eyeglass frames, antennas of mobile phones, bra underwires for domestic application, fluid connectors, coupling and thermal actuators, fire safety valves, and electric circuit breakers in industrial applications [6], pipe and tube couplings in the aircraft industry, sensors and thermal or electrical actuators in automobiles and connectors in robotic arms [6]

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