A new method of obtaining hydrosilylation-derived polysilazane-based SiCN(O) coatings on Crofer 22 APU steel deposited by dip-coating: Comprehensive structural, microstructural, and chemical studies

• Thickness of the coatings depends on the crosslinking time of the synthesized system. • SiCN(O) coatings on Crofer 22 APU steel contain Si-N, Si-C, Si-O, and M−O bonds. • SIMS depth profiles show diffusion of Mn and Cr into the SiCN(O) coating. • MnCr 2 O 4 -based inclusions are present on the layer-substrate interface. This study focuses on the optimization of polysilazane-based SiCN(O) coatings on Crofer 22 APU steel obtained by dip-coating. Single- and double-layered coatings were investigated. SEM analysis of the cross-sections showed that the thickness of the coatings depends on the crosslinking time, and the number of deposited layers. FTIR spectroscopy revealed the presence of Si–N, Si–C, as well as Si–O and M−O bonds, which suggests that the coatings contain oxygen, hence, they are referred to as SiCN(O) coatings. The ToF-SIMS analysis showed the local increase in the concentration of metals on the coating-substrate interface, and, in the case of the double-layered coating, on the layer-layer interface. Raman Confocal Imaging of the cross-sections displayed the presence of the free carbon phase, amorphous silica, as well as inclusions made of the MnCr 2 O 4 spinel found on the coating-substrate interface. The double-layered coating was further investigated by TEM, which revealed an intralayer based on the Mn-Cr spinel located between the SiCN(O)-based layers, and inclusions located on the coating-substrate interface. The stoichiometry of the spinels building the intralayer and the inclusions was confirmed to be MnCr 2 O 4 by electron diffraction supplemented by EDS microanalysis. The coatings’ elastic modulus was measured by PF QNM.