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Owing to the light weight and high energy, the "All-aluminum engine" can reduce fuel consumption and pollutant emissions, showing a great significance in saving resources and protecting the environment, and becoming a research hotspot. However, the aluminum alloy cylinder liners have difficulty withstanding extremely harsh working conditions, such as strong friction and wear, making the engine extremely easy to damage. In this work, Al-25Si wear-resistant coating was deposited by inner hole supersonic plasma spraying technique to improve the wear resistance of the aluminum alloy cylinder liner. The microstructure, phase composition, mechanical properties and tribological properties were tested by SEM, XRD, tribological machine, etc. The results indicated that the coating exhibited an excellent bonding strength of 44.1 MPa, and the average hardness and average friction coefficient of the coating are 267.09 ± 14.85 HV0.2, and 0.20, respectively. The total wear amount, the wear scar width and the wear scar depth of the coating are 2.77 × 10−3 mm3, 654.3 μm and 8.95 μm, respectively, which showed that the coating can significantly improve the tribological properties of the "All-aluminum engine". The wear mechanism of the coating was mainly interpreted by furrow cutting, extrusion and spalling in two-body abrasive wear, three-body abrasive wear and a small amount of oxidative wear. [ABSTRACT FROM AUTHOR]

Three contents of zinc oxide (2 wt %, 4 wt % and 6 wt %) were added into raw BaTiO 3 powders. The maximum relative permittivity value (ε r ) is in the range 230–406 and the dielectric loss (tanδ) varies between 0.18 and 0.09 for all ZnO modified BaTiO 3 coatings for frequency1 kHz at ambient temperature. The reasons for enhancing the relative permittivity are attributed to the elimination of micro-cracks and pores. The detail discussion was conducted on the characteristics morphologies (cross section, fracture surface and spreading behavior of BaTiO 3 +xwt. % ZnO composite powders) and phase. With the analysis, the addition of ZnO leads to the improvement in the melting state and increment in amorphous phase. Zn existed in the form of secondary phase (ZnO) and substitution in the BaTiO 3 lattice. The enhancement in structure and dielectric performance is highly discussed based on the phase equilibria and chemical defect. [ABSTRACT FROM AUTHOR]

In order to prepare the PbTiO3 coating with high density and excellent piezoelectric properties on all kinds shape surface, the PbTiO3 coating was prepared by supersonic plasma spraying. The microstructure and mechanical properties were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectrograph (XPS). The dielectric constant and dissipation constant of the PbTiO3 coating were tested. The results show that the coating has a single ferroelectric phase with perovskite structure, and its surface is smooth and dense. In the course of spraying, about 50% PbTiO3 is decomposed into PbO and TiO2 at high temperature. The ferroelectric hysteresis is weak and the ferroelectric hysteresis loop is not completely closed, which indicates that the defects, such as pores and cracks, exist in the coating. Although the defects are inevitable, the PbTiO3 coating with ferroelectric and piezoelectric properties is successfully prepared. [ABSTRACT FROM AUTHOR]

This paper studied the microstructures and dielectric properties of PZT coatings prepared by supersonic plasma spraying. Samples of the PZT coatings were evaluated by various techniques. The phases and microstructures of the coatings were investigated by XRD, SEM, and TEM, respectively. The results showed that the coatings deposited on steel substrate had a dense microstructure, and there was no phase transformation during spraying. Additionally, the Curie temperature of the PZT coatings was about 370 °C by the investigation of dielectric constant. [ABSTRACT FROM AUTHOR]

This study investigated the potential effect of vacuum annealing on the microstructure and hot salt corrosion behavior of CoNiCrAlY/YSZ/LaMgAl11O19 (LMA) double-ceramic coatings. A hot-salt corrosion test revealed that sprayed coatings exhibited an unsatisfactory anti-corrosion performance, and the LMA layer underwent severe fracture and corrosion degradation. Vacuum annealing induced a prominent recrystallization of the amorphous phase in LMA layer, triggering severe volume shrinkage and microcrack initiation. The recrystallization and volume shrinkage of the LMA layer were aggravated by an increase in the annealing temperature. The annealed coating with a higher fraction of the LaMA phase showed superior resistance to hot-salt corrosion. However, the salt mixture diffused simultaneously along the microcracks and eventually eroded into the YSZ layer. These results confirmed that vacuum annealing significantly enhanced the hot-salt corrosion resistance of the LMA layer. However, it deteriorated the barrier effect of the salt mixture through microcrack formation. [ABSTRACT FROM AUTHOR]

Using the supersonic plasma spraying (SPS) technique, the preparation of a NiCrBSi (Ni60) coating was achieved by adding nano TiO2 in Ni60 coating with WC ceramic particles. Ni60-TiO2 (Ni60T) and Ni60-TiO2/WC coating (Ni60TW) were successfully prepared. Results show that of the three, Ni60T had the best densification, the porosity of the Ni60T coating exhibited the best value of 1.3%, and also has a stronger hardness value of 890 HV. At the same time, the coating corrosion resistance, wear coefficient, and the wear morphology of Ni60T are superior to Ni60 and Ni60TW coatings. It is added TiO2 and ceramic WC(Co) in Ni-based spraying powder. The main purpose is for the nanoparticles to achieve the effect of refining the grain, which can greatly improve the coating's hardness and toughness. [ABSTRACT FROM AUTHOR]

Obtaining excellent mechanical properties and high electrical conductivity for ceramic/metal composites is of great significance. In this study, the Ti 3 SiC 2 /Cu composite coatings (20 wt% and 50 wt% Ti 3 SiC 2) were prepared by plasma spraying with the agglomerated Ti 3 SiC 2 /Cu powders. The effects of Ti 3 SiC 2 content on the microstructure, mechanical properties, electrical conductivity and tribological properties of the coatings were analyzed. The results showed that besides the primary compound region, the diffusion and decomposition zones also coexisted within the coatings. The 20 wt% Ti 3 SiC 2 /Cu composite coating showed a denser microstructure with the highest microhardness of 224 HV 0.1 , whereas higher fracture toughness was obtained for the 50 wt% Ti 3 SiC 2 /Cu coating (1.26 MPa•m1/2). Moreover, the 20 wt% and 50 wt% Ti 3 SiC 2 /Cu composite coatings had considerably high electrical conductivity, with the values of 7.9 × 106 S/m and 4.3 × 106 S/m, respectively. Compared to dry friction, the friction coefficient of the coating increased under current-carrying condition, and the wear of the tribo-pairs was accelerated. Generally, the main wear mechanisms of the 50 wt% Ti 3 SiC 2 /Cu composite coating under dry friction and current-carrying conditions are the adhesion wear, abrasive wear and fatigue wear. • Ti 3 SiC 2 /Cu composite coatings were prepared by supersonic plasma spraying. • Effects of Ti 3 SiC 2 content on the coating microstructure and properties were investigated. • Friction and wear properties of the 50 wt% Ti 3 SiC 2 /Cu composite coating under current-carrying condition were analyzed. [ABSTRACT FROM AUTHOR]