THE INFLUENCE OF TRANSMISSION DIRECTION AND THE NATURAL FREQUENCY OF TRANSDUCERS DURING THE TESTING OF SILICA REFRACTORY BRICKS BY THE ULTRASONIC PULSE METHOD
Evaluating the quality of refractory materials is one of the important stages of production before these materials are handed over to the customer. One of the required parameters is to evaluate ultrasonic pulse velocity, as determined by measurements performed via the ultrasonic pulse method. Are presents findings on the influence of the direction of transmission and the natural frequency of transducers on ultrasonic pulse method measurements of silica refractory bricks. The findings reveal that the measurement requirements specified in standards for other building materials cannot be fully applied in the case of silica refractory bricks, and the assumption that ultrasonic pulse velocity increases with shorter measuring bases is not confirmed. The highest ultrasonic pulse velocities were measured during transmission across the width of the product, while the lowest velocities were measured over the thickness of the sample. In order to evaluate the quality of silica refractory bricks, it is necessary to unambiguously determine a uniform measuring base for transmission so as to ensure the reproducibility of the measurements performed by different laboratories.