Effect of Arc-anode Attachment on Thermal Plasma Jet
An interaction of plasma flow with an arc-anode attachment in a dc arc plasma torch was investigated. Statistical processing of the photographic images of plasma jet was used for analysis of an effect of the anode attachment on structure and stability of plasma flow. Deflection, flattening and flutter of the plasma jet was found to be caused by disturbing effect of the arc-anode attachment.
Properties of Hybrid Water/Gas DC Arc Plasma Torch
A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow was investigated. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet parameters within a wide range from high-enthalpy low-density plasmas typical for liquid stabilized torches to lower enthalpy higher density plasmas generated in gas stabilized torches. The torch was operated at an arc power from 22 to 130 kW with an exit centerline plasma velocity from 2 to 6.5 km/s and a plasma temperature from 14 000 K to 22 000 K. Moreover, gas flow in the cathode part protects a cathode tip and thus a consumable carbon cathode used in water torches could be replaced by a fixed tungsten cathode. The characteristics of the electric arc with combined gas/water stabilization were measured and the effect of gas properties and flow rate on plasma properties and gas-dynamic flow characteristics of the plasma jet were studied for argon, and mixtures of argon with hydrogen and nitrogen
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.