Effect of sintering temperature and compaction pressure on the microstructure and mechanical strength of B4C supports for ceramic membrane filtration

The effect of sintering temperature and compaction pressure—used as a model for extrusion pressure—on the microstructure and mechanical strength of porous B 4 C supports for ceramic membrane filtration was investigated using extrudates prepared from a mixture of super-coarse (∼22–59 μm) and ultrafine (∼0.3–0.6 μm) powders. Total porosity (∼44 %) and mechanical reliability (Weibull moduli 4.1–4.3) were largely unaffected by sintering temperature (1900–2100 °C), but complete recrystallisation of ultrafine particles at 2100 °C was essential to optimise the macropore size–strength combination (∼3.5 μm–26.4 MPa, 14.8 μm–30.6 MPa, and 17.6 μm–49.2 MPa at 1900, 2000, and 2100 °C, respectively). Comparison with earlier supports highlighted the key role of extrusion pressure, and complementary experiments showed that increasing compaction pressure significantly enhanced sinterability, yet supports pre-compacted at 300 MPa and sintered at 2100 °C still retained high porosity (∼31 %) and large macropores (∼9.3 μm), together with outstanding strength (∼130.2 MPa). Finally, practical guidelines are proposed for optimising the processing of porous B 4 C supports and other ceramic supports for filtration applications.