July/August_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 | J U L Y / A U G U S T 2 0 2 0 6 6 iTSSe TSS iTSSe TSS ELECTRICAL CONDUCTIVITY OF METAL- POLYMER COLD SPRAY COMPOSITE COATINGS ONTO CARBON FIBER- REINFORCED POLYMER Vincent Bortolussi, Bruno Figliuzzi, François Willot, Matthieu Faessel, and Michel Jeandin Cold spray is a promising process to coat polymers and carbon fiber-reinforced polymer (CFRP). The choice of the metal-polymer couple of materials, however, has a strong in- fluence on coating buildup and properties. This article shows that spraying mixtures of copper and polymer particles lead to composite coating. The polymer promotes coating build- up onto CFRP to the expense of the electrical conductivity of the coating as a result of its insulating properties. The article investigates the influence of the coating microstructure on electrical conductivity. Various copper powders, with different morphologies, particle sizes, and oxygen contents were mixed with a polyaryl-ether-ether-ketone (PEEK) powder. Cold spray of these powders resulted in composite coatings, and the mi- crostructures and electrical properties of such coatings as a function of powder characteristics and spraying parameters is studied. A morphological model of the coating microstructure was developed to reproduce numerically microstructures in 3D. The conductivity of the coatingswasmeasured experimen- tally for various copper powders. (Fig. 3) at a fast enough rate, that the CaCO 3 phase would melt before undergoing total thermal degradation. Sprayable mussel and oyster shell powder was manufactured by crushing and mill- ing. A range of plasma spray parameters incorporating a wide operating window of plasma power and gas velocity were trialed. Coatings were initially formed from both powders un- der all plasma spray conditions used. However, the samples degraded into powdery debris with time due to the reaction of CaO with water in the air to form Ca(OH) 2 . No evidence of CaCO 3 meltingwas found, indicating that it was not possible to form a coating by thermal spraying. FABRICATION OF TIO 2 -SRCO 3 COMPOSITE COATINGS BY SUSPENSION PLASMA SPRAYING: MICROSTRUCTURE AND ENHANCED VISIBLE LIGHT PHOTOCATALYTIC PERFORMANCES Mengjiao Zhai, Yi Liu, Jing Huang, Wenjia Hou, Songze Wu, Botao Zhang, and Hua Li A novel TiO 2 -SrCO 3 co-catalyst with a porous structure was fabricated by suspension plasma spraying. SrTiO 3 as re- vealed by high-resolution TEM was formed by the chemical reaction of TiO 2 with SrCO 3 during the high-temperature plas- ma spraying. A narrow band gap (2.58 eV) and reduction in the recombination speed of photoinduced carriers of the coatings were detected by UV–visible diffuse reflectance spectrometry and fluorescence spectrometry, respectively. The enhanced visible light-driven photodegradation properties of the coat- ings resulted in promoted degradation of methylene blue. The composite coatings also demonstrated significantly pro- nounced bactericidal activities against the Gram-negative bac- terium Escherichia coli than the pure TiO 2 coatings, achieving a killing rate of over 99.7%. The results give insights on the po- tential to fabricate large-scale nano-TiO 2 -based porous photo- catalytic coatings by suspension plasma spraying for versatile environmental applications. (Fig. 4) Fig. 3 — SEM view of spherical copper powders. 1 PLASMA SPRAYING OF CACO 3 COATINGS FROM OYSTER AND MUSSEL SHELL S. Matthews and A. Asadov Theaimof this researchwas toestablishwhether the shell of green-lipped mussels and Pacific oysters could be plasma sprayed to promote and accelerate the establishment of filter feeder colonies. While CaCO 3 degrades before melting under equilibriumconditions, the hypothesis considered in this work was that the high-temperature, highly nonequilibrium condi- tions experienced by powders during plasma spraying may be sufficient to impart enough thermal energy into the powder, Fig. 4 — The inactivation efficiency of E. coli by different samples: (A) blank; (B) substrate; (C) TiO 2 coating fabricated under the plasma powder of 30 kW; and (D) TiO 2 -SrCO 3 coating fabricated under the plasma powder of 30 kW. JTST HIGHLIGHTS 16