Coatings are mainly applied on surfaces for decorative, protective, or functional purposes, but in most cases it is a combination of these. The term “functional coatings” describes systems which possess, besides the classical properties of a coating (i.e., decoration and protection), an additional functionality. This additional functionality may be diverse, and depend upon the actual application of a coated substrate. There are different methods to apply functional coatings. Chemical vapour deposition is one of the widely used method to apply thin film and functional coatings to different substrates.
In detail, it is a process where one or more volatile precursors are transported via the vapour phase to the reaction chamber, where they decompose on a heated substrate to create high quality, high-performance solid material from a gaseous phase.
Typical CVD process consist of steps given below.
1. Evaporation and transport of reagents (i.e. precursors) in the bulk gas flow region into the reactor;
2. Gas phase reactions of precursors in the reaction zone to produce reactive intermediates and gaseous by-products;
3. Mass transport of reactants to the substrate surface;
4. Adsorption of the reactants on the substrate surface;
5. Surface diffusion to growth sites, nucleation and surface chemical reactions leading to film formation;
6. Desorption and mass transport of remaining fragments of the decomposition away from the reaction zone.
Chemical vapor deposition (CVD) is widely used in different fields of materials-processing such as semiconductor industry, production of synthetic diamonds, oxidation resistant aluminide coatings. Current and main focus of our coating and heat treatment research group is application of aluminide coatings for gas turbine blades made of Ni base superalloys.
Each experimental work in IMER research group is supported by computer simulations. Currently THERMOCALC, DICTRA, TC PRISMA AND JMAT PRO software exist in our laboratory. Mechanical, kinetic, thermodynamic simulations are performed by using these software. Some of these simulations are listed below:
- Phase Diagrams
- Property Diagrams
- Diffusion Simulations
- Precipitate Kinetics
- TTT and CCT Dİagrams
- Heat Treatment Simulations
- Stress-Strain Analysis
- Creep and more…