Fabrication of textured B4C ceramics with oriented tubal pores by strong magnetic field-assisted colloidal processing.

Highly structure-controlled B 4 C ceramics were prepared via strong magnetic field-assisted slip casting of a slurry, containing B 4 C base particles and pore-forming agents with a fiber shape. To achieve gas release at a lower porosity for maintaining its mechanical strength, these B 4 C ceramics had a structure in which a large number of oriented tubal pores were dispersed in a crystallographically-aligned and dense B 4 C matrix phase. The B 4 C microstructure, such as structuration and orientation degree distributions of the B 4 C grains and tubal pores, was characterized by SEM observation, EBSD analysis, and X-ray CT. Among the investigations, it was found that the oxidic impurities, as an inhibitor of sintering, which existed on the B 4 C surface, can be removed by ethylation and azeotropy due to an ethanol treatment followed by vacuum drying. Thus, an ethanol treatment of a green compact before sintering was significantly effective for the fabrication of the B 4 C ceramics, including the microstructure that coexisted with a dense matrix phase with tubal pores. The resultant ceramic specimens showed the remarkable three-point bending strength of 459−554 MPa, which is two times higher when compared to conventional B 4 C pellets with a similar porosity. [ABSTRACT FROM AUTHOR]