Formation Mechanism of Al2O3-YAG Amorphous Ceramic Coating Deposited via Atmospheric Plasma Spraying

This study mainly investigated the formation mechanism of Al2O3-YAG(Al5Y3O12) amorphous coating prepared by atmospheric plasma spraying. Nano and micro-sized powders with low eutectic point ratio were selected as raw materials for comparison. XRD, SEM and EBSD were used to analyze the phase composition, morphologies, phase distribution and structure of the coating. The crystal structures of the possible existed phases were studied to analyze the crystallization chemistry of powder droplets. It is concluded that the composition ratio of powders and particle size should be also considered as the key factors for the preparation of amorphous coatings besides the high enthalpy and ultra-fast cooling rate of thermal spray technology. The as-sprayable powder chose multiple components with low eutectic point ratio distributed uniformly at nano-scale or sub-micro scale, and can reacted to form the new phase crystal with high coordination numbers of cations.

Investigation of Mechanical Properties of Twin Wire Arc Repair of Cast Iron Components

Twin wire arc is a commonly used thermal spray technology for application of steel coatings to cast iron components. Hardness and adhesion strength are critical properties of such coatings, and significant research is available reporting these properties. However, residual stresses and the anisotropic structure of the coatings leads to significantly different behavior in bending applications than in the purely tensile loading of the standard adhesion test. In addition, microstructural features that are controlled by certain process parameters during deposition of the coating can have a significant effect on these properties. This work seeks to relate the hardness and pull-off adhesion strength to the coating microstructure, and to assess the related bending strength and failure mode. Comparisons between bend tests and pull-off adhesion tests show significant differences to consider when evaluating twin wire arc coatings.

Special Issue: Advances in Thermal Spray Technology

Coatings deposited utilizing different thermal spray variants have been widely used for diverse industrial applications [...]

The Study on Optimum Spray Parameters and Characterization of Flame Sprayed PVC Coating

Thermoplastic polyvinyl chloride (PVC) is one of the most widely used polymers in the world. Due to its versatile nature, PVC is used extensively across a broad range of industrial, technical and everyday applications including widespread use in building, transport, packaging, electrical/electronic and healthcare applications. In this study, thermal spray technology was used to apply PVC powder on metal substrate. It was revealed that the spray parameters such as working distance, preheat and flame temperature played the important role on the properties of PVC coating.