High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

Abstract

Thermal barrier coating systems are usually build-up with bond coats to ensure a good adhesion of the ceramic top coat and to protect the substrate against oxidation and corrosion. Such system is often subjected to complex thermo-mechanical loading. Because of the very different damage processes encountered during service operations, a simplified system was investigated by removing the bond-coat. Recently adhesion bond strength was enhanced using laser surface texturing of the substrate in thermal spraying processes. Atmospheric plasma spray yttria-stabilized-zirconia thermal barrier coating system was deposited on the Ni-based AM1 single crystalline superalloy without bond coat. Adhesion bond strength was already increased compared to conventional processing method. Top coat durability was evaluated at high temperature and damage mechanisms were studied. Isothermal and cyclic oxidation tests showed durability of 1000 h and 400 cycles at 1100°C. The oxidation mechanisms at the substrate/top coat interface changed due to fast solidification during the laser texturing process. Then, TBC system was studied under high temperature mechanical solicitation in tension creep. The textured interfaces were not damaged after 1% creep strain while top-coat/substrate interfacial cracking was observed for grit-blasted specimens. Moreover, no preferential crack development in the substrate was observed. Patterns provided an enhanced adhesion by changing the stress distribution near the interface.

Bonding strength and thermal shock resistance of a novel bilayer (c‐AlPO4‐SiCw‐mullite)/SiC coated carbon fiber reinforced CMCs

“…However, the bonding strength between mullite, SiC w ‐mullite, c ‐AlPO 4 ‐SiC w ‐mullite outer coatings and SiC–C/SiC composites substrate is 2.41, 4.31, and 7.38 MPa, respectively. From the above results, we can draw the following conclusions that the bonding strength of the coating prepared by novel sol‐gel method combined with air spraying is lower than that of CVD method due to the sintering densification process of the coating is not completed, and it will become better as the densification process proceeds . In addition, the SiC whiskers in mullite coating are oxidized into molten SiO 2 on the surface during the sintering process.…”

“…From the above results, we can draw the following conclusions that the bonding strength of the coating prepared by novel sol-gel method combined with air spraying is lower than that of CVD method due to the sintering densification process of the coating is not completed, and it will become better as the densification process proceeds. 37 In addition, the SiC whiskers in mullite coating are oxidized into molten SiO 2 on the surface during the sintering process. As a result, the bonding strength of the coating is improved.…”

Effect of Laser Surface Texturing on Coating Adherence and Tribological Properties of CuNiIn and MoS2 Coating

“…High temperature durability of bond coatless thermal barrier coating system on single crystal Ni-based AM1 single crystal alloy is improved after laser texturing [20]. Laser texturing with groves in stainless steel increased the adhesion strength of atmospheric plasma sprayed molybdenum coating by 49.7% as compared to grit blasted surface [21].Surface texturing of triangular pattern was created by LST on die steel (50Cr) substrate.…”

Influence of Bondcoat Topography on the Properties of Suspension Sprayed YSZ Thermal Barrier Coatings

“…Additionally, laser-based processes offer attractive perspectives in terms of industrial scalability, processing times, and process environment variables. Laser ablation, as surface preparation was applied by different authors in order to improve the coatings adhesion or to produce tailored surface topographies, respectively [16][17][18]. A well-established laser technique able to produce periodical structures in the micro-and sub-micrometer range is direct laser interference patterning (DLIP) [19][20][21].…”