Bin Hai

Bio: Bin Hai is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Surface roughness & Surface modification. The author has an hindex of 1, co-authored 1 publications receiving 94 citations.

Surface modification of epoxy using an atmospheric pressure dielectric barrier discharge to accelerate surface charge dissipation

Abstract: In this paper, an atmospheric-pressure dielectric barrier discharge is used to modify the surface of the epoxy material and enhance the dissipation of surface charge to reduce the accumulation of surface charge. In the experiments, atmospheric-pressure air dielectric barrier discharge is driven by a microsecond pulse generator. Surface properties of epoxy before and after the plasma treatment are characterized by water contact angle, surface potential, and surface/volume conductivity measurements. Atomic force microscope and X-ray photoelectron spectroscopy are used to investigate the changes of the morphology and the chemical composition of the epoxy surface. Experimental results indicate that the surface of epoxy is etched by the plasma and the increase of the surface roughness enhances the surface insulation ability. The O radicals in plasma and the carbonyl groups formed on the surface make the surface charge trap shallower, change the epoxy surface composition then increase the surface conductivity and accelerate surface charge dissipation. When the epoxy is treated for an appropriate time, the epoxy surface insulation performance will be enhanced obviously and the surface charge dissipation will be accelerated.

A self-assembled, nacre-mimetic, nano-laminar structure as a superior charge dissipation coating on insulators for HVDC gas-insulated systems.

Abstract: Nacre is well-known for its unique properties due to its “bricks-and-mortar” structure. We employed this biological paradigm to fabricate nano-laminar coatings with controlled arrangement of montmorillonite (MMT) nanoclay sheets and polyvinyl alcohol (PVA) polymer binders by a self-assembly process. The abundant inorganic/organic interfaces were demonstrated to play critical roles in enhancing charge dissipation laterally on the insulator surface, so that the surface charge accumulation is suppressed under dc stress. Moreover, the stacking barriers help to protect insulator surfaces from hot electron bombardment, inhibiting further electron avalanche. In this manner, the flashover strength of the insulator is improved by 18%. This strategy is practical and scalable, allowing for industrial applications.

Improvement of surface flashover in vacuum

Abstract: Surface flashover of insulation systems is a basic issue in the field of high voltage and electrical insulation. To improve the surface flashover performance is of great significance for the development of advanced power transmission equipment and insulation materials. This study reviews the research progress of surface flashover in vacuum regarding to effective methods to improve the surface flashover performance in vacuum, including insulation system optimisation and material modification. The former one is beneficial to reduce the electric field distortion, and the later one is able to adjust the surface trap parameters of the material through physical and chemical methods. In addition, the ‘U-shaped’ curve is proposed to reveal the relationship between surface flashover voltage and surface trap level, discovering the synthetic effects of surface traps on surface flashover. It is expected that the ‘U-shaped’ curve will become a guidance to improve surface flashover performance through adjusting trap parameters. Moreover, several suggestions are made to build unified surface flashover model which is suitable to the range from high vacuum to high pressure.

Atmospheric pressure plasmas and direct fluorination treatment of Al2O3-filled epoxy resin: A comparison of surface charge dissipation

Abstract: In this paper, three methods, including dielectric barrier discharge (DBD) etching and deposition, and direct fluorination, were used for the surface modification of Al2O3-filled epoxy resin (Al2O3-ER) insulators to improve surface charge dissipation properties. The surface charge dissipation properties of the Al2O3-ER samples after these three treatments were compared. Firstly, the experimental results showed that DBD deposition reduced the most accumulated surface charges among the three treatments. The surface charge decay rates after DBD deposition and direct fluorination exceeded 98%. Then, the surface morphology, chemical components, and electrical parameters before and after the treatments were analyzed. Among the above three treatments, the surface roughness of the DBD deposited sample was the smallest, which facilitated the reduction of surface charge accumulation. The increase of the surface conductivity of the DBD deposited sample accelerated surface charge dissipation. Furthermore, the ageing effects of these three treatments were investigated. After five days of storage, it showed no significant difference between the dissipation properties of the DBD etched and the untreated samples due to the reorientation of polar groups towards the interface. However, there was only subtle changes in the surface charge decay rates of those DBD deposited and fluorinated samples, indicating that no obvious ageing effects were observed after DBD deposition and direct fluorination. The introduction of SiOx and C-Fn functional groups improved the anti-ageing properties of the DBD deposited and fluorinated samples, respectively. These comparative results can stimulate the development of eco-friendly plasma deposition techniques for the surface modification of Al2O3-ER insulators.