Plasma assisted pyrolysis for processing of composite ceramic coatings based on silazane precursor and TiB2 filler applied onto a sintered steel

Abstract

In this work, silazane-based polymer coating loaded with reactive TiB2 filler was applied onto a sintered steel substrate. Two thermal processing routes were investigated for the conversion of the precursor and filler into a composite ceramic coating: conventional pyrolysis (CP) and plasma-assisted pyrolysis (PAP), both performed at nitrogen atmosphere. The sample substrate and coatings were characterized by optical and scanning electron microscopy, energy-dispersive spectrum, X-ray diffraction, and glow discharge optical emission spectroscopy. Microstructural analysis revealed a denser ceramic composite coating with an improved conversion of TiB2 filler when the pyrolysis process was assisted by plasma. Interdiffusion between the steel substrate and filled PDC coating leads to the formation of new phases in the coating, which in contrast, were not observed when the process was performed by conventional pyrolysis.