The cold spray technique is a new coating technology that is based on the high velocity impinging of small solid particle on the substrate. This technique allows to produce coatings and thick deposit with less heat influence. Cold-sprayed coating indicates brittle fracture that a crack is propagated in particle interface. It is important to understand and control the microstructure. This study evaluates the microstructure and heat treatment behavior of the cold-sprayed copper coatings by SEM and EBSD (Electron Back-Scatter Diffraction) method. CI (Confident Index)and IQ (Image Quality) values of EBSD method was applied to the evaluation of crystal structure and grain boundary structures. It was found that cold-sprayed coating annealing does not complete with standard annealing conditions such as applied to the bulk material. As-sprayed coating consists of fine grains. The grains are surrounded by irregular atomic arrangement region and amorphous phase. Grain boundary and particle to particle interface are inhomogeneous. Since this irregular interface structure role diffusion barrier, heat treatment effects of cold-sprayed coatings are different from bulk materials. Moreover, it is considered that structure is possible cause of brittle fracture.
Thermal Barrier Coating (TBC) is applied to gas turbine. The TBC is removed and re-coated by thermal spray when it is repaired periodically. If the Yttria Stabilized Zirconia (YSZ) can be re-coated by thermal spray after removing the top coating by using an environment-friendly water jet treatment to repair TBC, it can become very useful repairing method. In order to re-coat the YSZ on the bond coating by thermal spray after removing only the top coating of TBC, we compared the validity of water jet treatment with that of blast treatment. The results are as follows. (1) The surface roughnesses of the bond coatings after removing only the top coating both by water jet treatment and blast treatment are the range of the roughness that can get good adhesive strength. (2) Water jet treatment has more properties than blast treatment in the case of the working time and the influence on the environment. (3) From the above things, water jet treatment is effective to re-coat the top coating by thermal spray.