International passenger air travel is rising and aircraft manufacturers are finding it difficult to cope with the demand. There was a record backlog of over 14,000 units at the end of 2017 and the whole industry is expecting to see revenues increase by 4.8%.
This news is beneficial to plating suppliers as aircrafts have a large amount of plated components, both for replacement parts and in manufacturing.
However, similar to several other resource-heavy industries, the aerospace sector is facing a high amount of pressure to become more friendly to the environment. This has resulted in the industry working to reduce emissions and mitigate the use and production of materials that are hazardous.
The key focus for airlines is to reduce emissions by increasing fuel efficiency as these are a main contributor to greenhouse gases. This can be achieved in two ways: by making the aircraft smaller and by maximizing the efficiency of the engine itself. Each of these methods affect the materials utilized on the aircraft, along with plated components.
Increasing Efficiency of Aircraft
When considering the weight of a complete aircraft in comparison to the weight of a single plated component, it might seem absurd to argue that thinner platings can make a difference.
However, there are many plated components where taking fractions of microns from the plating thickness of each component adds up. As long as the lifetime of the part remains unaffected, it is better to create the thinnest coating possible.
When increasing the efficiency of the engine, heat is a critical element. More mileage is achieved from each gallon of fuel when the engine runs at the greatest heat.
The challenge for aircraft engineers is the extent of heat that the engine can cope with until the components start to fail. In the context of plated parts, it is important to consider the amount of heat that the component can withstand before the plating fails and the underlying metal begins to corrode.
Cutting Hazardous Waste
In the past, the aerospace industry has heavily relied on cadmium plating to decrease corrosion. However, cadmium is very toxic and is now subjected to harsh environmental controls. For example, cadmium compounds are listed as substances of very high concern for REACH regulations in the EU.
Therefore, alternative plating materials that can cope with high temperatures and mitigate corrosion are necessary to replace the widespread use of cadmium.
Zn-Ni is Replacing Cadmium as a Viable Plating Material
Zinc-Nickel has performed to a high standard in aircraft applications and is quickly becoming a credible alternative to cadmium. Zn-Ni creates a thin and constant layer across the coated surface at the crystal structure level.
As such, complicated or inconsistent surfaces can be simply plated with a high quality and smooth finish. This naturally even and thin finish maximizes the wear resistance of the part, which is critical when transporting parts – particularly in aircraft where any errors can cause catastrophe.
One of the most positive characteristics of Zn-Ni is that it limits the impact of thermal stress on components. As detailed earlier, the components being able to run safely at high temperatures increases fuel efficiency. Tests have demonstrated that Zn-Ni coated parts enable corrosion resistance at temperatures of up to 200 °C.
Using XRF to Measure Zn-Ni Thickness in a Production Environment
When used in an aircraft application, the Zn-Ni layer must be exactly the correct composition and thickness to guard the underlying substrate, and keep the total weight down at the same time. Deposited zinc-nickel thicknesses are within the micron and sub-micron level for each layer.
X-ray fluorescence (XRF) analysis is the optimal way to discover the thickness and composition of these layers, as it is quick, accurate and non-harmful. For the most accurate readings, XRF equipment must be used in combination with the correct type of detector. Nickel and Zinc are very close to one another on the X-ray results spectrum.
Therefore, certain XRF analyzers may struggle to understand the differences between the two peaks. A better resolution is achievable with equipment that contains a silicon drift detector (SDD), enabling improved accuracy.
This information has been sourced, reviewed and adapted from materials provided by Hitachi High-Tech Analytical Science.
For more information on this source, please visit Hitachi High-Tech Analytical Science.