Elastic and anelastic properties of SiC/Si ecoceramics

The paper represents an acoustic investigation of elastic and anelastic properties of a new class of materials produced with natural (wood) products—biomorphic SiC/Si (bio-SiC/Si) ceramics. Specimens were fabricated by melt Si infiltration in a carbon bio-matrix after the wood (white eucalyptus) templates pyrolysis. It has been found that there exist, at least, two mechanisms that influence the elastic and anelastic properties of bio-SiC/Si. The first one is adsorption and/or desorption of air molecules (presumably because of the pores and residual carbon). The second one is associated with a microplastic deformation that is due to dislocations or any other structural entities which can oscillate under ultrasonic stresses and, in this way, increase both the damping and non-linear anelastic strain. The eucalyptus carbon bio-matrix has also been studied.