Influence of alloy components on arc erosion morphology of Ag/MeO electrical contact materials

Arc erosion morphologies of Ag/MeO（10） electrical contact materials after 50000 operations under direct current of 19 V and 20 A and resistive load conditions were investigated using scanning electron microscope（SEM） and a 3D optical profiler（3DOP）. The results indicated that 3DOP could supply clearer and more detailed arc erosion morphology information. Arc erosion resistance of Ag/SnO_2（10） electrical contact material was the best and that of Ag/CuO（10） was the worst. Arc erosion morphology of Ag/MeO（10） electrical contact materials mainly included three different types. Arc erosion morphologies of Ag/ZnO（10） and Ag/SnO_2（10） electrical contact materials were mainly liquid splash and evaporation, and those of Ag/CuO（10） and Ag/CdO（10） were mainly material transfer from anode to cathode. Arc erosion morphology of Ag/SnO_2（6）In_2O_3（4） electrical contact materials included both liquid splash, evaporation and material transfer. In addition, the formation process and mechanism on arc erosion morphology of Ag/MeO（10） electrical contact materials were discussed.

Grain refinement of 5A06 aluminum alloy welds caused by tungsten inert gas welding arc characteristics under Ar-He alternating gas supply conditions:a coupled method of water-cooled copper plate test/numerical simulation

The welding arc,as a carrier for the conversion of electrical energy to thermal energy,has a direct impact on the quality of welding by its properties and states.In the tungsten inert gas(TIG)welding process under the condition of Ar-He alternating gas supply,the arc is alternately converted between Ar arc and He arc with an alternating gas supply cycle,which has obvious arc change characteristics.The FLUENT software was used to numerically simulate the characteristics of the TIG arc under the condition of alternating gas supply,and the arc temperature field,arc pressure,electric potential and current density distribution under the condition of alternating gas supply were obtained.Combined with the real-time data of arc pressure measured by the water-cooled copper plate with holes,it is proved that the TIG arc has obvious dynamic characteristics under the condition of Ar-He alternating gas supply.This unique dynamic TIG arc acts on the 5A06 aluminum alloy weld,causing the molten pool to stir,resulting in uniform microstructure and grain refinement at the weld,and thereby improving the mechanical properties of the welded joint.

Synthesis of TiO_2 visible light catalysts with controllable crystalline phase and morphology from Ti-bearing electric arc furnace molten slag

TiO_2 visible light catalysts with different crystalline phases and morphologies were synthesized from titanium-bearing electric arc furnace molten slag（Ti-bearing EAF slag）by using a simple acidolysis process.The effects of the p H of the HCl solution,liquid to solid ratio（RL/S,HCl solution to the residue ratio,m L/g） and acidolysis time on the micro-morphology and crystalline phase of as-prepared TiO_2 photocatalysts were systematically investigated.The results indicated that with decreasing p H in the HCl solution and increasing RL/S,the crystalline phase and micro-morphology of the obtained TiO_2 nanostructures tended to transform from anatase type TiO_2 with spherical nanoparticle structures to rutile type TiO_2 with needle-like nanorod structures.The acidolysis time had little influence on the crystalline phase but great impact on the size of the obtained TiO_2.The growth mechanism of TiO_2 from Ti-bearing EAF slag during the acidolysis process was also discussed.In addition,the influence of RL/Son the photocatalytic properties of the synthesized nanostructured TiO_2 was studied.The results showed that the photodegradation efficiency for Rhodamine B solution could reach 91.00% in 120 min when the RL/Swas controlled at 50：1.