In this work, an artificial neural network (ANN) model was developed to investigate the application of Cr 3 C 2 -25NiCr coatings by HVOF spraying and predict the resulting properties based on flow rates, stand-off distance, and other parameters. HVOF coatings were sprayed and tests were conducted to generate data for training, validating, and testing the model. The model was trained with an R-value of 0.99965 to predict the relationship between spray parameters and coating properties including hardness, porosity, and wear rate. The reliability and accuracy of the model was subsequently verified using independent test sets.

In this work, binder-free Co 3 O 4 films with in-situ oxygen vacancies are deposited in a one-step process by solution precursor plasma spraying (SPPS). It is believed to the first time Co 3 O 4 layers composed of hexagonal flakes were synthesized through the SPPS route. Specific capacitances up to 1700 F/g were obtained at a scan rate of 5 mV/sec, almost 97% of which was retained after 13,000 cycles at 20 mV/sec. This supercapacitor-like performance is attributed to the synergistic effects of a binder-free composition with in-situ oxygen vacancies and porous nanostructures.

The results accumulated up to now by a number of research works tend to show that a single metal oxide semiconductor (MOS) cannot achieve the multiple objective required to make an efficient photocatalytic system, which includes not only the light response, but also the photochemical stability and the avoidance of the recombination of photogenerated electron/hole pairs. Mixing different MOS is considered a promising strategy as it induces beneficial synergistic effects. In this work, we have developed an original method to prepare compositionally graded films that are active in photodegradation applications. The selected compositionally graded films are the CuO-ZnO and CeO 2 -ZnO pairs that were deposited via the Solution Precursor Plasma Spray (SPPS) process. Various composition gradients were achieved using different modes of injection of the precursor solutions, generating distinct “film configurations”. We characterized the resultant films by SEM and XRD. We determined the corresponding optical bandgap energies through UV-Vis adsorption spectrometry. Then we evaluated the photocatalytic performances of these CuO-ZnO and CeO 2 -ZnO films through the photodegradation of aqueous solutions of the Orange II dye. The CeO 2 -ZnO-M films proved capable of degrading almost entirely the Orange II dye within 2 hours, under UV light. Finally, we discuss the correlation between the various film configurations and their photodegradation efficiency. This exploratory work tackles the relatively novel field represented by the use of compositionally graded oxide films for enhanced photochemical reactivity and stresses the effectiveness and versatility of the SPPS technique for the preparation of a large variety of photocatalytic films.

Binary spinel-type metal oxides (AB 2 O 4 ) semiconductors, including ferrites (AFe 2 O 4 ), are attractive photocatalysts thanks to their excellent visible light response and good photochemical activity and stability for the photodegradation of organic pollutants. Currently, their synthesis proceeds via conventional chemical routes that follow rather tedious protocols and the final preparations consist in nano-powders, a form that is not exempt of EHS (Environment, health and safety) risks along their handling. From an industry perspective, it is desirable to dispose of an efficient and preferably simple synthesis route capable to produce photocatalytic preparations in a non-dispersible form, for instance in the form of robust films attached on solid substrates. We report herein a single-step method based on the Solution Precursor Plasma Spray (SPPS) process that enables the preparation of promisingly active ferrite-based photocatalytic films, namely CuFe 2 O 4 and ZnFe 2 O 4 . We have investigated various types of precursor solutions, including the atomic A/Fe ratios, solvent type and solute concentration, and studied the evolution of the phase composition of the resultant CuFe 2 O 4 and ZnFe 2 O 4 films by XRD. The corresponding surface morphologies and energy bandgaps were also studied by SEM and UV-Vis spectroscopy, respectively. Then the photocatalytic activities of the selective ferrite films were evaluated through the degradation of aqueous solutions of the Orange II dye under different light irradiations. The results of the overall work also revealed that SPPS process represents a fast, one-step, versatile alternative compared to conventional multi-step processes, which is suitable for preparing complex composition metal oxide film-formed photocatalyst.

Effect of plasma spraying parameter on the strain of plasma sprayed YSZ coatings is investigated by changing the spraying power and spraying distance. The porosity is measured through using image processing method. The strain of coatings is calculated and characterized through using the digital image correlation (DIC) software system. It can be found that the porosity of YSZ coatings increases with the increment of spraying distance and the decrement of spraying power. The strain on the far field of the cracking tip shows a fluctuation tendency when the tensile forces increase. The slope of strain-force is related with the coating porosity. DIC method can be used to characterize the coating deformation in 2-dimension.