Structure, physicomechanical properties, and special features of failure of hot-pressed boron carbide base ceramics

Structure and Properties of B4C - SiC Composites

“…In conclusion we can note that the new technological procedures employed to prepare the composite powders as well use of the reaction interaction of the starting components during hot pressing enabled us to prepare composites with mechanical properties superior to those reported in the literature [3,4]. The value of K Ic of the B 4 C − 20% SiC composite [3], prepared by hot pressing, is 4.9 MPa ⋅ m 1/2 and those of the B 4 C − 10 mass% SiC and B 4 C − 20 mass% SiC composites obtained by reaction sintering under hot pressing conditions are 5.0 and 5.25 MPa ⋅ m 1/2 , and their bending strength is 400 and 510 MPa, respectively [4].…”

“…This facilitates crack propagation along the grain boundaries. Table 1 shows the values of HM and K Ic of hot-pressed B 4 We measured also the bending strength of specimens B 4 C − SiC of standard shape made with a press unit with induction heating: From the data given above we see that by using the differences in the composition and morphology of the powder mixtures and the different mechanisms of formation of B 4 C − SiC composite during hot pressing we can control the structure and phase formation processes which are responsible for the properties of the resulting composite. The mean grain size of the main phase B 4 C was about 5 µm and the size of the microvoids was 1-2 µm in hot-pressed composite prepared from B 4 C − SiC composite powder.…”

“…The value of K Ic of the B 4 C − 20% SiC composite [3], prepared by hot pressing, is 4.9 MPa ⋅ m 1/2 and those of the B 4 C − 10 mass% SiC and B 4 C − 20 mass% SiC composites obtained by reaction sintering under hot pressing conditions are 5.0 and 5.25 MPa ⋅ m 1/2 , and their bending strength is 400 and 510 MPa, respectively [4].…”

“…The initial boron carbide powder contained free carbon (up to 3 mass%). A study of the structure of the initial B 4 Si powder showed that the particles of the powder obtained by the interaction of amorphous boron with finely dispersed silicon powder below the silicon melting point, were friable agglomerates tenths of a micrometer in size while the single-crystal grains constituting them were of submicron size. The agglomerates disappeared after milling for 10 min.…”

“…The strength and cracking resistance of the ceramic can be increased by introducing tough, brittle, or filamentary second-phase components into the matrix to form a heterogeneous structure. Compounds containing silicon are among the most effective second-phase additives, according to the data of [1][2][3][4]. The most pronounced effect is observed when high-strength materials are made of composite powders or materials such that they or their dissociation products interact with boron carbide at consolidation temperatures, thus activating consolidation processes.…”