April_AMP_Digital

iTSSe TSS A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 0 5 1 iTSSe TSS SIMULATION OF THERMAL SRPAY COATING ON 3D OBJECTS: NUMERICAL SCHEME AND AERONAUTIC TEST CASE T. Van Hoof, G. Fradet, F. Pichot, S. Selezneff, and N. Poletz A novel numerical methodology is proposed to simulate thermal spray coating process on 3D objects with a focus on the prediction of the footprint shape and thickness. Themeth- od is based on the level set approach to capture the evolution of the deposited layer interface during the coating process. The shadowing effects that strongly affect the final footprint on 3Dobjects are considered. Themethod allows for the impo- sition of complex source trajectory and orientation evolution which are requested to tailor the final footprint on complex 3D objects. The capabilities and limitations of the proposed nu- merical tools are assessed using an aeronautic test case: the thermal spray coating of a part of aircraft engine (seal teeth). (Fig. 1) MECHANICAL PROPERTIES AND THERMAL SHOCK RESISTANCE OF 8YSZ-AL 2 O 3 COMPOSITE COATINGS WITH DIFFERENT THICKNESSES Fazhang Lu, Wenzhi Huang, and Haitao Liu The mechanical properties and thermal shock resis- tance of plasma-sprayed 8YSZ-Al 2 O 3 composite coatings with different thicknesses have been analyzed. At a thickness of 330 μm, the Young’s modulus of the coating surface increased from 96.54 to 121.39 GPa and the surface hardness increased from 6.63 to 9.14 GPa when the Al 2 O 3 content was varied from 10 to 40 wt.%. Adding more alumina in the coating resulted in a change in the coating surface residual stress from tensile (48.8 MPa) to compressive (−115.9 MPa), while the thermal shock resistance at 1100°C decreased from 162 to 56 cycles. Moreover, at given Al 2 O 3 content, the thermal shock resistance of the coating decreased drastically when its thickness was increased, which can be attributed to the enhanced Young’s modulus and hardness near the bond coat/ceramic coating interface. An increase in the ceramic thickness resulted in a sig- nificant stress gradient as well as strain energy in the direction of the coating thickness, bringing about high thermal stress during thermal shock testing. The horizontal crack propaga- tion caused by thermal stress in the interface area could be the main reason for coating failure. (Fig. 2) T he Journal of Thermal Spray Technology (JTST), the official journal of the ASM Thermal Spray Society, publishes contributions on all aspects—fundamental and practical—of thermal spray science, including process- es, feedstock manufacture, testing, and characterization. As the primary vehicle for thermal spray information transfer, its mission is to synergize the rapidly advancing ther- mal spray industry and related industries by presenting re- search and development efforts leading to advancements in implementable engineering applications of the technology. Articles from the December and February issues, as selected by JTST Editor-in-Chief Armelle Vardelle, are highlighted here. In addition to the print publication, JTST is available online through springerlink.com . For more information, visit asmint- ernational.org/tss. Fig. 1— Micrograph cross section of seal teeth after coating. Fig. 2 — Typical photographs of (a) 330-μm coating; (b) 590-μm coating; and (c) 870-μm coating with 20 wt.% Al 2 O 3 content after bonding strength testing. 17 JTST HIGHLIGHTS