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7301 |
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Cold spraying onto notched surfaces: Scanning acoustic microscopy as a tool for evaluation of the interface quality |
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Martin Koller / Czech Academy of Sciences, Czech Republic Hanus Seiner / Czech Academy of Sciences, Czech Republic Michaela Janovska/ Institute of Thermomechanics of the Czech Academy of Sciences, Czech Republic Martin Sevcik/ Institute of Thermomechanics of the Czech Academy of Sciences, Czech Republic Jan Cizek/ Institute of Plasma Physics of the Czech Academy of Sciences, Czech Republic Jan Kondas/ Impact Innovations GmbH, Germany Reeti Singh/ Impact Innovations GmbH, Germany |
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Scanning acoustic microscopy (SAM) technique was used for studying the character and quality of interface of cold sprayed Fe coatings deposited onto Al-based substrates with machined notches. For that, two different substrates were used, 10-mm cold-rolled 99.5% Al and 5-mm cold sprayed coating deposited from 99.99% Al powder. Two notch geometries were machined into the substrates: square-shaped (1 mm depth, 1 mm width) and trapezoid-shaped (1 mm depth, 1 mm width at the bottom and 2 mm width at the surface). The Fe coating was applied using the 5/11 high-pressure cold spray system (Impact Innovations, Germany) using nitrogen. From each sample, 0.5-mm thick plates were cut vertically across the notches and the SAM measurements were performed on ~5x5 mm2 areas around them. At each measurement point, an ultrasonic wave with 30 MHz nominal frequency was focused on the top surface of the plate and the reflected signal was detected. By comparing the received echoes, the distributions of the wave velocity and the wave attenuation were obtained. The ultrasonic waves in the coatings are much more attenuated above the edges of the notches, corresponding to the areas at which the Fe coatings were not deposited perpendicularly, showing the reduced bonding quality when compared to the perpendicular deposition. The study has demonstrated that SAM method can be used to qualitatively assess the bonding quality of CS coatings in depth. |