The evaluation of mechanical properties is essential to the performance guarantee of the material. However, this process is very complex for ceramic materials due to the variety of defects of such material. The aim of this work was to investigate the use of ultrasonic velocity measurements to the determination of mechanical properties in ceramic composites. To accomplish this, seven batches of alumina/zirconia, alumina/spinel and alumina/zirconia/spinel refractories were grinded, uniaxially pressed at 100 MPa and sintered at 1550 oC. The evaluation of ultrasonic pulse velocity (UPV) was performed in commercial equipment with a transducer of 5 MHz. The results showed that the addition of zirconia and spinel to the alumina matrix increased the compression resistance of the matrix in 75%. Furthermore, exponential equations relating mechanical properties and UPV were found and it was observed the existence of an intrinsic relation between these parameters.

Keywords: Alumina, Composite, UPV, Spinel, Zirconia.