Development of an advanced ultrasonic technique for interior inspection of HVOF (High Velocity Oxygen Fuel) coated landing gear tubes
Customer name :
NRC
Completion date : 04/2021 à 10/2024
In brief
Environmental constraints are forcing the replacement of hard chromium in several sectors, notably aerospace. As a result, carbide-based coatings applied by thermal spraying are becoming the norm for landing gear wear parts. However, this technology does not lend itself well to hollow, deep and small-diameter components, due to the physical limitations of the process and the size of the equipment.
As part of this project, CTA has developed an advanced inspection technique adapted to the inside inspection of tubes coated with HVOF (High Velocity Oxygen Fuel). This inspection technique is aimed in particular at hollow components, notably landing gear components. Its performance has been evaluated using samples containing artificial defects, demonstrating its effectiveness in detecting the latter.
Project summary
HVOF technology applied to the internal surface of tubular components must achieve a quality comparable to that of external coatings, making it essential to use non-destructive testing (NDT) techniques to verify integrity, combining speed, ease of industrial deployment, high probability of detection and reduced operator dependency.
In this project, CTA developed an inspection technique for cylindrical parts coated with HVOF (WC-Co-Cr) thermal spray on their internal surfaces. The technique was optimized using simulations and validated experimentally. It can detect cracks in the coating and base metal, as well as areas of poor adhesion and coating delamination. In addition, CTA has designed a mechanical system to automate the inspection process and make it more efficient.
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CTA's role
CTA has developed an inspection system optimized for the internal inspection of tubular components coated with HVOF on their inner surface. This technology could be particularly useful for NRC's aerospace partners, especially for the inspection of landing gear components.
Results
- For plates, all EDM notches, representing cracks, were detected with the developed technique, whether they were located in the coating or in the substrate. Concerning the poor adhesion areas, large defects were clearly identified, but the sensitivity was lower for smaller defects.
- For tubes, the technique enabled clear detection of almost all flat-bottomed holes. Notches, whatever their orientation, were also accurately identified, demonstrating the good sensitivity of the method. The images obtained showed a good signal-to-noise ratio and satisfactory defect visibility.