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Abstract During the fabrication of functional high-endothermic-enthalpy graphite/SiO 2 composite coating, the oxidation and vaporization of raw materials have become serious issues in hyperthermal preparation environment. In this study, these issues were addressed through densification and modification of the feedstock powder. Then, the corresponding coating was prepared by optimized plasma-spraying parameters. By investigating the modified feedstock powder and the resulting splats and coatings by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy, we realized an optimized composite feedstock powder preparation process and an ideal coating structure. The compactness of the powder reached its optimum after treating at 1400 °C for 2 h. After heat treatment densification and Ni shell covering processes, the modified powder exhibited good oxidation resistance, vaporization resistance, and spreading performance during plasma spraying. Thus, a pure and dense composite coating was prepared. Positive laser resistance performance was observed during the initial laser ablation test, which proved that this modified graphite/SiO 2 coating has good application potential in the laser protection field. Moreover, this study provides an experimental basis and a feasible method for difficult-to-spray composite coatings' preparation, such as graphite/SiO 2 composite. [ABSTRACT FROM AUTHOR]

Perovskite La 1− x Sr x TiO 3+ δ oxide is used in various industrial applications because of its excellent physical and chemical properties, which beneficially affects the lifetime and performance of electronic and optical devices. This study illustrates the effects of the spray parameters on particles molten state, microstructure, and optical reflectivity from room temperature up to 1000 °C of single-phase La 1− x Sr x TiO 3+ δ ( x = 0.1) coating deposited by atmospheric plasma spraying technique. The phase structure and surface morphology of the coating were examined using X-ray diffraction and scanning electron microscopy analysis, respectively, whereas the optical property coating was characterized by UV–visible–near infrared spectroscopy. Results show that plasma spray parameters significantly influenced the microstructure and optical performance of the La 1− x Sr x TiO 3+ δ coating, and oxygen deficiency during spraying considerably reduced the coating reflectivity. A high-reflectivity coating can be prepared by adopting optimized plasma spraying parameters and subsequent heat treatment. [ABSTRACT FROM AUTHOR]

With the development of laser technology, laser-related materials have been widely studied. Both laser stealth coatings and laser protective coatings are currently the focus of attention. However, less research has been done on laser stealth and protective integrated coatings. In this paper, plasma-sprayed Y 2 O 3 –Ti 3 AlC 2 coatings were prepared with low-power (LP) and high-power (HP) parameters, and their laser stealth and laser protection properties were characterized. The LP coating and HP coating appeared to have lower reflectivity at 1064 nm because a low-reflectivity second phase and many loose flocs on the surface are introduced, which indicates excellent laser stealth performance. When irradiated by a laser, the LP coating exhibited excellent laser protection ability, and its reflectivity increased after irradiation because Ti 3 AlC 2 oxidized and decomposed and densely arranged small particles formed on the surface. The LP coating perfectly protected the 500-W laser irradiation for 20 s. In addition, the laser damage threshold of the LP coating was 5.599 s at 1000-W laser irradiation, which indicates that the LP Y 2 O 3 –Ti 3 AlC 2 coating is a potential material with laser stealth and laser protection integration. [ABSTRACT FROM AUTHOR]

Metal materials have been used as thin films in many optical applications because of its excellent high reflectivity in the near-infrared range. However, studies on thick metal coatings deposited by plasma spraying have rarely been conducted. The current study investigates the relationship between optical property and microstructure for different metal plasma-sprayed coatings (Al, Cu, and Ag) and discusses the corresponding mechanical properties. The phase structure and surface morphology of as-sprayed powders and corresponding coatings were examined by X-ray diffraction and scanning electron microscopy, respectively. The optical and mechanical properties were characterized by UV–visible-near infrared spectroscopy, Multi-Specimen machine testing and Vickers microhardness testing. Results indicate that the optical behavior of metal plasma-sprayed coatings is related to their phase structure, splat microstructure, and surface roughness. Optimization of powders in molten state and the surface microstructure is proposed as an effective method to improve the optical property of these coatings. The molten state and low porosity also help to improve the mechanical properties of the coating materials. [ABSTRACT FROM AUTHOR]

With the repaid development of laser manufacturing industry, laser protection for optical components, especially high power continuous laser, has been a major concern. Optical coatings should have a good anti-laser ablation property. However, the high-power laser ablation behavior of plasma-sprayed Ta 2 O 5 coatings is rarely investigated. In this paper, tantalum oxide coatings were prepared by plasma spraying technique and irradiated using continuous laser with 1070 nm wavelength. The phase structure, ablation surface morphology and reflectivity of the coating were characterized by XRD, SEM, and UV–Visible-near Infrared Spectroscopy. During laser irradiation, the tantalum oxide coatings experience three stages: coating oxidation, micro-cracks occurrence and mechanical failure. A finite-element simulation was also conducted to explore the change of temperature field during irradiation. The simulation results show that the change of reflectivity of tantalum oxide coating during laser irradiation is of great benefit in improving its laser protection ability. [ABSTRACT FROM AUTHOR]

The microstructure of thermal spray powders plays a significant role in the application performance of thermal protection coatings deposited by air plasma spraying. Based on the design of the spray powder structure, the YSZ@Cu core-shell structure powders have the potential to be a thermal conduction anisotropy material for thermal protection coating, owing to the special alternate-layered structure formed during plasma spraying. To study the mechanism of the thermal conduction anisotropy of YSZ/Cu composite coatings, the YSZ coatings, YSZ@Cu coatings and YSZ-Cu coatings were fabricated by YSZ powders, YSZ@Cu core-shell structure powders and YSZ-Cu mechanical mixture powders, respectively. There were YSZ vertical thermal insulation layer and Cu horizontal thermal condition layer in the YSZ@Cu coatings, which provides a structural basis for the realization of thermal conduction anisotropy. Compared with the YSZ-Cu coatings, the temperature difference between the back-surface center area and the edge area of the YSZ@Cu coatings is significantly reduced by approximately 37%, which is attributed to the synergistic effect of alternate-layered comprising the YSZ layer and the high thermal conductivity Cu layer. YSZ@Cu coatings can effectively prevent the rapid rise in local temperature by the analysis of finite-element simulation, which is beneficial for prolonging the service life of the thermal protection coating in a non-uniform temperature field. • To reveal thermal conduction anisotropy, YSZ@Cu core-shell structure powder was used to fabricate composite coatings by APS. • The YSZ@Cu coating has an alternate-layered structure including horizontal thermal conduction and vertical thermal isolation layer. • Based on experimental analysis, the novel YSZ@Cu coating make surface temperature difference reduce by approximately 37%. [ABSTRACT FROM AUTHOR]