Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Plasma-assisted and furnace pyrolyzed polysilazane-based CrSiCN composite coating system – a comparison
Submission Author:
Daniel Auri Schaefer , SC
Co-Authors:
Daniel Auri Schaefer, Tatiana Bendo, Aloisio Nelmo Klein
Presenter: Daniel Auri Schaefer
doi://10.26678/ABCM.COBEM2023.COB2023-0155
Abstract
Steel components exposed to reactive and corrosive environments such as high temperature oxidation, acidic corrosion, degrade or fail quickly leading to enormous economic loss. Common solution to this problem is either using expensive alloys or replacing corroded parts frequently. Alternatively, applying appropriate coating offers promising way to protect metallic substrate from corrosion and extended their service life. Recently polymer derived ceramics (PDCs) have gained greater attention due to its properties like easy application on substrates of any shape, low temperature processing and the potential to tailor the properties via microstructure and composition design. Further, these compounds, in polymeric and ceramic states, possess outstanding protective properties that are necessary for environmental barrier applications. In this work, polysilazane–based polymer coating loaded with reactive Cr filler was applied by spray coating on a sintered steel substrate and subsequently pyrolyzed. Plasma assisted pyrolysis (PAP) and furnace pyrolysis (FP) were investigated as processing routes for the conversion of the precursor and filler into a composite ceramic coating. The samples substrate and resulting layer system were characterized by optical and scanning electron microscopy, energy-dispersive spectrum and X-ray diffraction. During pyrolysis a functionally intermediate layer consisting of a mixed Fe-Cr metal carbide and nitride is formed by reaction with the precursor elements, substrate and pyrolysis atmosphere. The X-ray diffractograms exhibited the formation of a mixed hexagonal β-Cr2N and cubic CrN phases, with higher intensity peaks related to the cubic phase at the conventional process and the major presence of hexagonal phase at the PAP process, involved by an amorphous SiCN matrix. The pyrolysis of a coating containing 55 % vol. of active filler allowed the development of coatings with up to 20 µm of thickness. The interaction of reactive plasma atmosphere with polymeric ceramic precursor and Cr reactive filler led to formation of an adherent and dense coating. A dense diffusion layer is visible at the coating–steel interface, indicating good bonding. After PAP this diffusion layer becomes thicker, and lower porosity within the coating is observed.
Keywords
Polymer-derived Ceramic, Plasma Assisted Pyrolysis, Cr-Si-C-N coating, ceramic coating
