November/December AMP_Digital

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 | N O V E M B E R / D E C E M B E R 2 0 1 8 4 6 iTSSe TSS iTSSe TSS T he Journal of Thermal Spray Technology (JTST), the official journal of the ASM Thermal Spray Society, publishes contributions on all aspects—fundamental and prac- tical—of thermal spray science, including processes, feedstock manufacture, testing, and char- acterization. As the primary ve- hicle for thermal spray information transfer, its mission is to synergize the rapidly advancing thermal spray industry and related industries by presenting research and development ef- forts leading to advancements in implementable engineering applications of the technology. Articles from the August and October issues, as selected by JTST Editor-in-Chief Armelle Var- delle, are highlighted here. In addition to the print publication, JTST is available online through springerlink.com . For more information, visit asminternational.org/tss. JTST HIGHLIGHTS PREDICTION OF COATING PROPERTIES OF THERMALLY SPRAYED WC–Co ON COMPLEX GEOMETRIES Vasileios Katranidis, Spyros Kamnis, and Sai Gu This work outlines the development of an analytical software tool that enables the prediction of various coating properties on any given sprayable geometry. The prediction is achieved by analyzing the input computer-aided design geom- etry and by correlating the resulting kinematic conditions with experimental measurements. The results of the developed tool have been validated experimentally using HVOF-sprayed WC-17Co coatings. Specifically, coating thickness, microhard- ness, WC vol%and specific sliding wear rate are examined and their values are predicted for the case of the external spray of a rotor-like model (Fig. 1). MICROSTRUCTURE AND THERMOPHYSICAL PROPERTIES OF SrZrO 3 THERMAL BARRIER COATING PREPARED BY SOLUTION PRECURSOR PLASMA SPRAY Wen Ma, Xinhui Li, Xiangfeng Meng, Yannan Xue, Yu Bai, Weidong Chen, and Hongying Dong Strontium zirconate (SrZrO 3 ) thermal barrier coatings were deposited by solution precursor plasma spray (SPPS) using an aqueous precursor solution. The phase transition of the SrZrO 3 coating and the influence of the aging time at 1400°C on the microstructure, phase stability, thermal expansion coefficient, and thermal conductivity of the coating were investigated. The unique features of SPPS coatings, such as interpass boundary (IPB) structures, nano- and micrometer porosity, and through-thickness vertical cracks, were clearly observed in the coatings. The vertical cracks remained substantially unchanged while the IPB structures gradually diminishedwithprolongedheat treatment time. The t -ZrO 2 developed in the coatings transformed completely to m -ZrO 2 phase after heat treatment for 100 h. Meanwhile, the SrZrO 3 phase in the coatings exhibited good phase stability upon heat treatment. Three phase transitions in the SrZrO 3 coatings were revealed by thermal expansion measurements. The thermal conductivity of the as-sprayed SrZrO 3 coatingwas ~1.25Wm −1 K −1 at 1000°C and remained stable after heat treat- ment at 1400°C for 360 h, revealing good sintering resistance (Fig. 2). 12 Fig. 1 — Rotor-like geometry and the vertical rotation axis passing through the center of mass. Fig. 2 — Schematic of the SPPS process.