The first jet engine is believed to have been developed in the 1930s, during the second world war. Having gone through countless iterations, this invention was regarded as one of the biggest breakthroughs in aviation history. Since then, there have been major advancements in the aviation industry, including the development of the ramjet and scramjet. However, despite the advancements that have been made to jet engines in recent years, there are still a number of problems that occur.
Keep reading to find out how the development of thermal barrier coatings for gas turbine engine applications has helped to overcome these problems.
Without the proper care and maintenance, jet engines can be subject to severe component damage, which can ultimately decrease the lifespan of the engine. Some of the most common problems with gas turbine engines include:
Corrosion can be caused by a number of external factors. However, one of the most common causes of aircraft corrosion is moisture. If an aircraft has an increased standstill time, it can allow condensation to form within the engine. When left for extended periods of time, condensation can lead to corrosion on the surface of metal components. It has been proven that this type of corrosion is particularly prevalent in aircrafts that operate in humid environments.
Sulfidation is the most common form of corrosion found on aircraft engine blades. When the aircraft fuel is burned at a high temperature, sodium sulphate gas is released into the air. Sodium sulphate gas attacks any nearby metal components, including the blades of the engine. If the engine components are not regularly cleaned, sulfidation can cause severe corrosion. When this happens, large blisters form on the surface of the metal, indicating that component failure is imminent.
Thermal fatigue is often caused by simply starting up and shutting down the engine. This process of hot and cold thermal cycling puts pressure on turbine components, and causes small defects to form. As each turbine blade can only experience a certain number of hot thermal cycles, it is important that the temperature of the engine and quality of the blade are carefully monitored. If precautions are not taken, thermal fatigue can escalate to complete engine failure.
To avoid any of these problems leading to component replacement, a number of aircraft manufacturers are now using thermal barrier coatings. Depending on the component requirements, there are a number of thermal barrier options which can be used to significantly extend the lifespan of aircraft engines.
High velocity oxygen fuel involves fuel and oxygen being fed into a combustion chamber. Through continuous combustion, a hot gas is produced which exits through a converging-diverging nozzle. A powder feedstock is injected into the jet stream, creating a spray. This is directed towards the component, where it forms a thermal barrier coating. Suitable for components in high temperature environments, this process is ideal for protecting jet engine blades.
Plasma coating utilises a high-density arc current between cathode and anode to form plasma. Properties of the plasma stream can be controlled by cathode nozzle arrangement and electric arc settings, producing a coating with tailored microstructural properties. From corrosion resistance to oxidation resistance, this form of thermal barrier coating can be used to meet a variety of jet engine requirements.
Combustion coating is the process of combining a gaseous fuel and oxygen to create a flame. The coating material is fed continuously into the middle of this flame, ready to be applied to the surface of the component. Through rapid cooling, this forms a thermal barrier coating, which is capable of restoring dimensions to damaged aircraft components.
EP Coatings specialises in thermal barrier coatings for gas turbine applications. Through our state-of-the-art manufacturing facilities, we have the ability to produce bespoke coating solutions for aviation customers. From corrosion resistance to temperature protection, we work closely with our customers, to make sure we understand the exact requirements of their components.
If you would like to find out more about our thermal barrier coating solutions, get in touch.