O.N. Grigoriev et al./Composites: Part B 37(2006)530-54 a) 1234 5 0.5mm (e)p 6 吕2 Fig. 4. Morphology of surface of double layer ceramic (a) and the curve of its scan by laser beam(b), the signal of photodiode versus the press applied to the sample double layer ceramic (c). ceramics, which depends on the structure and its physical state, zero represents the conditionally chosen origin of stresses including stresses or strains counting off. The vertical lines represent the conditionally Reflection of linearly polarized radiation from the sample drawn borders between the structurally different zones results the elliptically polarized light. The parameters of this including a porous one, near layers boundary, that was created ellipticity are defined by internal stresses or caused by external due to chemical interaction of layer components during loading. Both PM and P carry out dynamic analysis of sintering. The obtained curve of the stress distribution near polarization state of the light. The intensity of a circular boundary qualitatively fits more complex distribution than we component of elliptically polarized light is proportional to expected for simple case of two-layer configuration value of elastic stresses or deformations. Anisotropy of An Signal of the photodiode was calibrated against the pressure n-y is connected with stresses or deformations by ratio: applied to sample at the same conditions, at which the stresses An=T(ox-Oy) and An=p(Er-Ey), where T and p are- were registered. Using such calibration curve(Fig. 4c)the piezooptic and elastooptic coe fficients accordingly for each numerical magnitude of stresses was obtained for entire scan structural component of a material Results presented in Fig 4 show that the maximum stress drop For example, Fig. 4 shows the results of quantitati near boundary of layers is about 200 MP measurements carried out on a sample of Sic and Sic+ 20%TiB2 two-layered ceramics. The powders Sic and TiB2 3.2.2. Strength of laminates with the diameter of 5-10 um were taken to fabricate a sample Our studies have shown that in the composites containing The rectangular bar with the sizes 5x5X8 mm was cut out and the a-SiCMs Powders(the composites 1 and 2, Table 3)both polished for measurements types of layers(SiC and TiB 2) have a low porosity, which are Fig. 4b shows stresses registered at the scanning of a sample formed during sintering(Fig. 5a). Low relaxation ability of by the laser beam(=0.63 um and a diameter 50 um) along an such structures results in microcracking of composites with axis x according to Fig. 3. The horizontal line passing through types of fracture described in [11]ceramics, which depends on the structure and its physical state, including stresses or strains. Reflection of linearly polarized radiation from the sample results the elliptically polarized light. The parameters of this ellipticity are defined by internal stresses or caused by external loading. Both PM and P carry out dynamic analysis of polarization state of the light. The intensity of a circular component of elliptically polarized light is proportional to value of elastic stresses or deformations. Anisotropy of DnZ nxKny is connected with stresses or deformations by ratio: DnZp(sxKsy) and DnZp(3xK3y), where p and p are— piezooptic and elastooptic coefficients accordingly for each structural component of a material. For example, Fig. 4 shows the results of quantitative measurements carried out on a sample of SiC and SiCC 20%TiB2 two-layered ceramics. The powders SiC and TiB2 with the diameter of 5–10 mm were taken to fabricate a sample. The rectangular bar with the sizes 5!5!8 mm was cut out and polished for measurements. Fig. 4b shows stresses registered at the scanning of a sample by the laser beam (lZ0.63 mm and a diameter 50 mm) along an axis x according to Fig. 3. The horizontal line passing through zero represents the conditionally chosen origin of stresses counting off. The vertical lines represent the conditionally drawn borders between the structurally different zones, including a porous one, near layer’s boundary, that was created due to chemical interaction of layer components during sintering. The obtained curve of the stress distribution near boundary qualitatively fits more complex distribution than we expected for simple case of two-layer configuration. Signal of the photodiode was calibrated against the pressure applied to sample at the same conditions, at which the stresses were registered. Using such calibration curve (Fig. 4c) the numerical magnitude of stresses was obtained for entire scan. Results presented in Fig. 4 show that the maximum stress drop near boundary of layers is about 200 MPa. 3.2.2. Strength of laminates Our studies have shown that in the composites containing the a-SiCM5 powders (the composites 1 and 2, Table 3) both types of layers (SiC and TiB2) have a low porosity, which are formed during sintering (Fig. 5a). Low relaxation ability of such structures results in microcracking of composites with types of fracture described in [11]. Fig. 4. Morphology of surface of double layer ceramic (a) and the curve of its scan by laser beam (b), the signal of photodiode versus the press applied to the sample of double layer ceramic (c). 534 O.N. Grigoriev et al. / Composites: Part B 37 (2006) 530–541