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Ceramic automotive valves - chances and limitations on nondestructive testing

: Netzelmann, U.; Reiter, H.; Shi, Y.; Wang, J.; Maisl, M.; Diederichs, R.

Diederichs, R.:
NDTnet '97 Archive. CD-ROM : The Online Journal of Nondestructive Testing & Ultrasonics
Herford: NDT Internet Publishing, 1997
6 S. : Ill., Lit.
Fraunhofer IZFP ()

Automotive valves made out of silicon nitride were investigated by various nondestructive testing techniques. Fluorescent dye penetrant testing was used to detect surface defects. High frequency ultrasound (80 MHz) was employed to test the valve head and valve shaft regions for volume defects. Defects with dimensions down to 50 mu m could be detected in the shaft. Leaky Rayleigh waves were used to find surface defects in the valve seat and at the surface of the shaft. Digital radiography was used to test the head region in a partly automated way. X-ray computed tomography in its 2D and 3D implementations could detect defects in the shaft, in the notch area and in the transition area between head and shaft, offering good spatial resolution and characterization. Resonant testing is a very fast testing technique, but probably not able to detect very small single defects.