Ablation resistance of HfC(Si, O)-HfB2(Si, O) composites fabricated by one-step reactive spark plasma sintering

•Dense HfC(Si, O)-HfB2(Si, O) composites are fabricated to enhance ablation resistance of HfC.•The composite is composed of HfC(Si, O), HfB2(Si, O), O-doped SiC, and free carbon.•The dense oxide layer contains Si-doped and (Si, B)-codoped HfO2, and HfB2 matrix grains.•The HS15 composite sample exhibits a better ablation resistance.