Determination of Optimal Pulse Current for ArcWelding
The manual and semi-automatic welding by pulse current (pulsing arc) is considered in the article. The advantages of welding by the pulsing arc are found out in comparison with welding by a constant arc. Using energetic calculation taking into account thermal balance at the electrode stub, optimal parameters of modulated current, such as frequency and duration of electrical pulses were established for different welding methods and regimes. By that stabilized heat, which needed for making melting drops, lower the level of metal splash and improve formation of the weld. Bibl. 12 (in English; summaries in English, Russian and Lithuanian).
Determination of pulse current optimal parameters for manual arc welding
Manual welding by pulsing arc (pulse current) is researched in the article. The advantages of welding by pulse current are found out in comparison with the welding by direct current. While using energy calculation and taking into account thermal balance at the electrode stub, optimal parameters of the modulated current, such as frequency and duration of electrical pulses were established for different welding regimes. This stabilizes heat, which is necessary for making melting drops, by lowering the level of metal splash and improves of the weld formation.
Characterization of ceramic composite membrane filters for hot gas cleaning
Abstract Novel composite ceramic membrane filters suitable for hot gas cleaning operations have been prepared from fly ash and titania particles on stainless steel woven mesh substrates. Both membranes had a structure like a solid packed bed with a thickness of less than 100 μm. In the domain of laminar flow, significant differences in the pressure drop between experimental results and those predicted from the Kozeny-Carman relationship were found, particularly for flow through the titania membrane. Membrane filters with extremely small pores such as the titania membrane are greatly affected by slip up to 80% in permeability at elevated temperatures. Efficiencies of filtration of typical coal fired power station exhaust fly ashes were found to be greater than 909% for both titania and ash membranes, whilst there was greater variation in the pressure drops in the ash membrane than in the titania at typical gas flows.