Nondestructive Evaluation Methods for Composites: Ultrasonic Measurements and Image Analysis Application on Testing in Extreme Conditions

Abstract

This article deals with nondestructive testing methods such are ultrasonic measurements and image analysis as applied to the thermal stability testing of materials. Image analysis is also used to determine damage to the surface during the cavitation resistance testing. Possibilities of the used nondestructive methods and results of their application are discussed on the basis of the obtained results for low cement, high alumina castables.

Anisotropy analysis of low cement concrete by ultrasonic measurements and image analysis

“…Image analysis was realized by Image Pro Plus Program for the surface degradation study [25]. By this way, monitoring of surface defects level was possible by taking and analysing photographs of samples surface areas before and during the thermal shock [2,10,12,[26][27][28][29][30][31]. Anisotropy of samples surface is based on determination of differences between damaged and undamaged areas.…”

“…The highest dissipation of ultrasonic velocities in three directions and therefore the largest material inhomogeneity and anisotropy inside the material before and during the thermal shock was observed in the samples sintered at 1300 ºC. However, these samples exhibited the greatest stability during the thermal shock, since they withstood 110 cycles of thermal shock without hazardous cracks [10,12,26,27,29,30]. Samples sintered at 1300 °C exhibited polynomial dependences of fifth order during the thermal shock.…”

“…The UPVT method has been considered in detail in Refs. [10,12,26,27,29,30]. Briefly, pulses of longitudinal elastic stress waves are generated by an electro-acoustical transducer that is held in direct contact with the surface of the sample under test.…”