Ca3Co4O9 with B4C additions in different proportions (0, 0.10, 0.25, 0.5, and 0.75 wt.%) have been fabricated using the classical solid-state method. Powder XRD patterns displayed that phase is major one all samples. Microstructural observations showed has superficially oxidized, producing liquid B2O3 during sintering, reacting grains to produce bridges between them. In spite of increase porosi...