Papers by Keyword: Impulse Excitation Technique IET

Abstract: In order to obtain a protection against temperature and stress induced detrimental rumpling of the metal surface of turbine blades, thin ceramic coatings are suggested. As a cheap and fast method for the fabrication of a ceramic zirconia coating, electrophoretic deposition on a Ni based superalloy is described. Crack free, 0.15 mm thick coatings with homogenous morphology were obtained. The Young’s modulus and the damping property of the ceramic coating, derived from the impulse excitation technique, are investigated as a function of the temperature up to 1000°C.

Abstract: The Impulse Excitation Technique (IET) is a non-destructive technique for evaluation of the elastic and damping properties of materials. This technique is based on the mechanical excitation of a solid body by means of a light impact. For isotropic, homogeneous materials of simple geometry (prismatic or cylindrical bars), the resonant frequency of the free vibration provides information about the elastic properties of the materials. Moreover, the amplitude decay of the free vibration is related to the damping or internal friction of the material. At present, IET is a well-established non-destructive technique for the calculation of elastic moduli and internal friction in monolithic, isotropic materials. Standard procedures are described in ASTM E 1876-99 and DIN ENV 843-2. IET can also be performed at high temperature (HT-IET) using a dedicated experimental setup in a furnace and constitutes a valuable tool in the field of mechanical spectroscopy. In the present work, the most recent advances in high temperature characterization using IET at K.U. Leuven are presented: the deformation behaviour of WC-Co hard metals, softening phenomena in TiB2, relaxation mechanisms in ZrO2 composites and “in-situ” monitoring of the damage evolution in uniaxially pressed metallic green compacts during delubrication.