Aerosol deposition of Ti3SiC2-MAX-Phase coatings

For the present study on aerosol deposition, the Ti3SiC2 MAX-phase was chosen as model system due to the availability of commercial powder and property data. The as-received powder was milled to different nominal sizes. For revealing details on coating formation and possible bonding mechanisms, aerosol deposition experiments were performed for different particle size batches and process gas pressures. Microstructural analyses reveal, that coating formation preferably occurs for particle sizes smaller two microns. Using such small particle sizes, crack-free, dense layers can be obtained. The individual deposition efficiencies for the different particle sizes, particularly the critical size below which deposition gets prominent, vary with process gas flows and associated pressures. Detailed microstructural analyses of coatings by high resolution scanning electron microscopy reveal plastic deformation and fracture, both attributing to shape adaption to previous spray layers and probably bonding. In correlation to coating thickness or deposition efficiencies, respective results give indications for possible bonding mechanisms and a tentative window of aerosol deposition for Ti3SiC2 MAX-phases as spray material.