Effect of Coating Pre-Treatment on Surface Recrystallization of DD6 Single Crystal

Abstract

Thermal barrier coatings (TBCs) are widely used to protect high-temperature components against harsh environments, such as extremely high temperatures. In this work, a second generation Ni-based single crystal superalloy (DD6) was treated in two ways: (1) via simple surface sandblasting under different pressures with no additional coating, and (2) through simple surface sandblasting under different pressures and then by applying NiCoCrAlYHf (HY5) coatings. The effects of pre-treatment (sandblasting) and the HY5 coating on the surface recrystallization of the alloy were thoroughly investigated. According to the results, both sandblasting pressure and the presence or absence of a coating significantly influence surface recrystallization. In particular, the critical sandblasting pressure for recrystallization increased the maximum recrystallization depth in both the coated and uncoated samples. Meanwhile, the recrystallization depth of the alloy with a coating was reduced compared to that without a coating. In addition, the number of recrystallized cells in the coated alloy was decreased, which indicated that the HY5 coating effectively reduced the degree of recrystallization.

Surface Engineering of Metals: Techniques, Characterizations and Applications

“…Additionally, research has focused on improving the adhesion and cohesion of wearresistant coatings to ensure their durability under high-stress conditions [80,81]. Techniques such as surface pretreatments, interlayer materials, and optimized deposition processes have been investigated to enhance the bonding strength between the coating and the substrate [82][83][84]. For example, the use of intermediate layers such as titanium nitride (TiN) or chromium nitride (CrN) has shown improved adhesion, leading to enhanced wear resistance and an extended component lifespan [85][86][87].…”

“…Furthermore, the application of single crystal coatings has gained attention in recent years [83]. Single crystal coatings offer superior mechanical properties compared to their polycrystalline counterparts, thanks to their high crystalline order and absence of grain boundaries.…”

Lattice Rotation and Deformation Mechanisms under Tensile Loading in a Single-Crystal Superalloy with [001] Misorientation

“…Compared to equiaxed crystal cast superalloys, this significantly increases their thermal strength and resistance to thermal corrosion [ 3 , 4 , 5 ]. In addition, high-pressure turbine blades made from single-crystal superalloys are equipped with complex cooling systems and thermal barrier coatings to further enhance their high-temperature resistance [ 6 , 7 , 8 , 9 ].…”