Effect of boron carbide reinforcments on the PEO process of B4C/Al matrix composite.

Plasma electrolytic oxidation (PEO) is an effective way to improve the thermal control property and service lifetime of the B 4 C/aluminum matrix composites (B 4 C/AMC) used in nuclear power field. The evolution process of B 4 C particles during the growth of PEO film was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) morphology observation, secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) chemical composition analysis. The results show that the B 4 C particles keep intact status but inhibit spark discharge in the initial oxidation stage, and then a few B 4 C particles are partly oxidized to small size and mixed into the film. After that, plenty of B 4 C particles are oxidized to B 2 O 3 and solid C which escapes from the film as carbon oxide gas under strong spark discharge. The B 4 C particles disrupt the continuity of the film due to lack of sparking on their surface at the early stage of oxidation, but the film compactness is improved with decreasing B 4 C particles in the film under high oxidation voltage. [Display omitted] • B 4 C particles keep intact status but delay spark discharge in the initial oxidation stage. • B 4 C particles disrupt the continuity of the film due to lack of sparking on their surface. • B 4 C particles are oxidized to B 2 O 3 and solid C which escapes from the film as carbon oxide gas under strong spark discharge. • Film compactness is gradually improved with decreasing B 4 C particles in the film under high oxidation voltage. [ABSTRACT FROM AUTHOR]