Sintering and mechanical properties of β‐SiC powder obtained from waste tires

Plasma synthesized SiC powder obtained from quartz and carbonaceous residue of waste tires was successfully sintered at 1925 ℃ by pressureless liquid-phase method using yttria and alumina as sintering aids (T-SiC). Comparison with sintered SiC obtained from commercial powder (C-SiC) put in evidence of similar sintered density (98%T.D.), but much finer microstructure of T-SiC than that of C-SiC. T-SiC also showed higher flexural strength than C-SiC both at room temperature (508 vs. 458 MPa) and at 1500 ℃ (280 vs. 171 MPa). Difference in liquid phase was responsible for the differences in hardness and fracture toughness. The high value of the Young's modulus of T-SiC (427 MPa) confirmed the high degree of sinterability of this powder and that it can be a promising candidate for structural applications with high added value. © 2016, The Author(s)

Lamb waves monitoring of the thermomechanical aging effects in ceramic coatings

International audienceCeramic coatings are mainly used to protect underlying alloy structures, and cover a wide range of thermomechanical and electrochemical applications, especially in the energy management and related industries. The work described in this paper focuses on the use of the Acoustic Emission (AE) technique to produce a permanent Structural Health Monitoring (SHM) of various coating systems subject to thermal cycling conditions. SHM generally refers to those methods that provide the ability to detect and interpret adverse changes in a structure in order to improve their reliability. The AE consists of elastic wave that propagates in the material carrying the information of occurred and latent defects. Since the challenge in designing such a method is knowing what changes to look for and how to identify them, the emphasis in this particular paper is placed on the cumulative frequency analysis of such AE waves and their potential for determining damage to coatings prior to their final breakdow