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The microstructure and bonding strength of plasma sprayed coating are highly dependent on flattening and solidification behavior of in-flight droplets. In the present study, the flattening and solidification behavior of subsonic/supersonic droplets after impacting on a flat substrate was comparatively studied. Results show that a dimensionless Somerfeld number (K) of flattening droplets can be used as the splashing threshold. Due to the extremely rapid spreading and solidification of supersonic-droplet, some large-sized bubbles and grains that usually formed at the bottom of flattened subsonic-droplet were effectively restrained, leading to the improvement of splat/substrate micro-shear strength. The effect of grain size and growth feature on the macro-bonding property was further elaborated. It was found that the simultaneous increase of both velocity and temperature of in-flight droplets was an effective approach for the improvement of bonding strength of as-sprayed coating.

In the present work, one new technique named as supersonic suspension plasma spraying (SSPS) is employed to fabricate high-performance yttria-stabilized zirconia (YSZ) based thermal barrier coatings (TBCs). The typical microstructures, such as vertical-cracked and columnar-structured coatings, were tailored by controlling the key spray parameters. The process-microstructure-property relationship of SPPS-coating was investigated. It was found that the deposition rate was significantly improved by reducing the stand-off distance or increasing the solid content and spray power. The columnar-structured coating exhibited the longest thermal cycling life at 1300 °C, which was approximately 7 times longer than that of coating with wide vertical cracks. Both the simulation and experimental results showed that the failure of SPPS-coating occurred near the top coat/bond coat interface. However, the failure modes were largely dependent on its microstructure. For the coating with wide vertical cracks, the oxidation of bond coat was the main reason that caused its spallation, while the failure of columnar-structured coating was attributed to the accumulation of sintering stress.

Spinel LiCo x Mn 2− x O 4 powder was synthesized by sol–gel method. The influence of Co content on the structure and electrochemical properties was investigated by XRD, SEM and charge–discharge experiments. The results show that, with the increase of cobalt content, the initial discharge special capacity of LiCo x Mn 2− x O 4 decreases slightly, but the cyclic performance is improved obviously resulting from the improvement of structure stability. In addition, low-temperature tempering is beneficial to the increase of discharge special capacity of LiCo x Mn 2− x O 4 . Comprehensively special capacity and cycling performance, at the current density of 0.1 mA/cm 2 and cutoff voltage of 3.5–4.4 V, LiCo 0.1 Mn 1.9 O 4 powder possesses the initial and stable discharge capacity of 123 and 113 mAh/g after 20 cycles, respectively.