Stress measurements in ZrB2–SiC composites using Raman spectroscopy and neutron diffraction

Two-phase zirconium boride thin film obtained by ultra-short pulsed laser ablation of a ZrB12 target

“…Up to now there are no experimental data to confirm the theoretical calculation of the vibrational properties of ZrB 2 [19]. Watts et al [20] indicate that this metal boride is only weakly Raman active and exhibits two Raman bands, which are very difficult to be separated from the background [19,20]. On the contrary, Raman spectroscopy has been used to characterize boron compound with MB 12 stoichiometry, showing that the presence of structural imperfection leads to numerous detectable Raman peaks, in the region where only Raman inactive vibrations are expected [15,21,22].…”

“…7(b)). Since ZrB 2 is weakly Raman active [20], this finding suggests that nanoparticles, with a different composition with respect to microparticles, could be composed of zirconium diboride. The broad band between 1200 and 1600 cm −1 is the well known amorphous carbon Raman band, probably due to some organic contamination.…”

Graphene NanoPlatelets reinforced tantalum carbide consolidated by spark plasma sintering

“…Silicon carbide particles have been shown to improve hardness and strength of ZrB 2 however toughness often remains unchanged. The difference in the coefficient of thermal expansion (CTE) between SiC and ZrB 2 has been shown to generate residual stresses [36]. The size of the starting ZrB 2 and SiC powders has also been shown to have an effect on properties.…”

2D Raman mapping and thermal residual stresses in SiC grains of ZrB2–SiC ceramic composites

“…They can play an important role in either enhancing the functional properties of materials and devices, if properly designed, or simply degrading their performances [1][2][3]. If the composites consist of two different phases, for example ZrB 2 and SiC in ZrB 2 -SiC particulate composites, then, upon cooling from the high sintering temperature, due to thermal expansion and elastic mismatch of the properties of the two phases, the thermal residual stresses occur at a temperature called the "joining temperature" [4]. A number of theoretical calculations have been developed to estimate the thermal residual stresses.…”

“…Many experimental techniques, such as X-ray [4], neutron diffraction [4,11], hole drilling [1,12], ultrasonics [1,13], and micro-Raman spectroscopy [4,11,[14][15][16], have been used for measuring thermal residual stresses in composites [1,13]. One of the techniques, so called piezospectroscopy, based on shift of the Raman active peaks as a function of either applied or residual stresses, exploits the relation between the characteristic frequencies of the atomic vibrations of materials and applied or residual stresses [17][18][19].…”