Hot Corrosion Studies of Gas Turbine Alloy Materials PhD

Cranfield University

This is a self-funded PhD position to work with Dr Adnan Syed in the Surface Engineering and Precision Centre. The PhD project will focus studying high temperature corrosion mechanisms in details to identify the material degradation and coatings applications details in extreme environments. A novel techniques/method will be developed with focus on better prediction and more accurate measurement of high temperature corrosion rate involving mathematical models validated through simulation, experiments and analysis.

Gas Turbines are used as a multipurpose power source in various applications like aviation, power generation, shipping and oil & gas industry. Gas turbines typically operate at very high temperatures. The material advancements and use of latest cooling mechanisms have led to even greater operating temperatures in modern Gas Turbines. During the operation of gas turbines, such high temperatures are coupled with the impurities or ash compounds like Sulphur, halides, sodium and vanadium. In certain cases, these contaminants may be consumed from the operating environment as in the case of NaCl, marine atmosphere plays the part while the industrial environment can be attributed to the presence of Sulphur. These factors introduce the requirement for giving focused and increased attention to hot corrosion phenomenon. Contrary to oxidation, hot corrosion can result in erratically rapid material loss, compromising the loadcarrying capacity of the GT components and ultimately leading to catastrophic failure. The lack of ability of early detection and timely prevention of hot corrosion has resulted in many engine failures leading to accidents with even loss of precious lives.

The combustion chamber and the turbine sections of the gas turbine are most prone to high temperature environmental attack because of having the highest temperature in the Gas Turbine. Metals and alloys experience increased oxidation rate when a thin fused salt film covers their surfaces in an environment having oxidizing gas with elevated temperatures. This phenomenon is known as ''Hot Corrosion'', also called high-temperature corrosion. In other words, the formation of a permeable non-protective oxide film at metal or alloy surface having sulphides in the substrate and lacking the involvement of aqueous electrolytes.

You will investigate various alloys types and corrosion testing methods to determine a suitable alloy and coating system The project includes a detailed literature survey leads to the development of a test matrix, includes test conditions, type of alloys used including bare or coated alloys. The project includes testing the material in the facility available at Cranfield’s high temperature corrosion laboratory. A detailed analytical phase. for better understanding of the microstructure, requires working on the advanced microscopy tools such as SEM/EDX, FIB and TEM. Also use dimensional metrology for metal loss evaluation. Thermodynamics calculations using FactSage software will also be used.

The candidate will be based at the Surface Engineering and Manufacturing Centre, which provides state-of-the-art equipment for the testing, analysis and characterisation of materials, of exposed corroded materials. The Centre also houses sold network with aerospace sector which help the students in the result discussions This is a self-funded PhD open to UK, EU and international applicants.

Research carried out during this PhD project will lead to better understanding of hot corrosion that will eventually:

Enable early failure identification.
Enable material selection criteria for alloys and coatings systems.
Increase alloys and coating material knowledge of performance in extreme environment.
Improve gas turbine material outcome.