ACOUSTIC DISPLAY OF PROPERTIES POSSESSED BY POROUS TITANIUM

Abstract

The production process is to be controlled at each stage using nondestructive methods as one of the indispensable conditions for imparting the optimal structure to a powder material and promoting its high mechanical properties. Acoustic methods are believed to be promising in this respect. The parameters of acoustic fields are influenced by many factors associated with the formation of the structure and properties of a powder material. An urgent task is to improve acoustic methods for the identification and practical use of this influence. Using a model material as an example, the capabilities of a nondestructive acoustic method relying on joint measurements of the propagation velocities of longitudinal, transverse, and rod elastic waves are shown in studying the patterns peculiar to the structurization of the powder material at the molding and sintering stages. The following problems that can be solved using this method are considered and experimentally confirmed: identify how the properties of the initial powders influence the characteristics of the final material, monitor the processes of compaction and contact formation in the material, and identify the features of these processes that are manifested in the uneven distribution of properties over the material, the presence of elastic aftereffect, and staging. Additional criteria are proposed to increase the reliability and information content of the results. An analysis of the experimental data show that the propagation velocities of bulk and rod elastic waves in different ways reflect the features of the compaction and contact formation of powder materials. The differences are explained by the peculiarities of acoustic fields in the formation of various types of elastic waves.