Surface treatment of titanium dioxide nanopowder using rotary electrode dielectric barrier discharge reactor

Titanium dioxide(Ti O_(2))nanopowder(P-25;Degussa AG)was treated using dielectric barrier discharge(DBD)in a rotary electrode DBD(RE-DBD)reactor.Its electrical and optical characteristics were investigated during RE-DBD generation.The treated TiO_(2)nanopowder properties and structures were analyzed using x-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR).After RE-DBD treatment,XRD measurements indicated that the anatase peak theta positions shifted from 25.3°to 25.1°,which can be attributed to the substitution of new functional groups in the TiO_(2)lattice.The FTIR results show that hydroxyl groups(OH)at 3400 cm-1 increased considerably.The mechanism used to modify the TiO_(2)nanopowder surface by air DBD treatment was confirmed from optical emission spectrum measurements.Reactive species,such as OH radical,ozone and atomic oxygen can play key roles in hydroxyl formation on the TiO_(2)nanopowder surface.

Electrochemical cutting of mortise-tenon joint structure by rotary tube electrode with helically distributed jet-flow holes

In aero-engines,mortise-tenon joint structures are often used to connect the blades to the turbine disk.The disadvantages associated with conventional manufacturing techniques mean that a low-cost,high-efficiency,and high-quality nickel-based mortise–tenon joint structure is an urgent requirement in the field of aviation engineering.Electrochemical cutting is a potential machining method for manufacturing these parts,as there is no tool degradation in the cutting process and high-quality surfaces can be obtained.To realize the electrochemical cutting of a mortise-tenon joint structure,a method using a tube electrode with helically distributed jet-flow holes on the side-wall is proposed.During feeding,the tube electrode rotates along its central axis.Flow field simulations show that the rotational speed of the tube electrode determines the direct spraying time of the high-speed electrolyte ejected from the jet-flow holes to the machining area,while the electrolyte pressure determines the flow rate of the electrolyte and the velocity of the electrolyte ejected from the jet-flow holes.The machining results using the proposed method are verified experimentally,and the machining parameters are optimized.Finally,mortise and tenon samples are successfully machined using 20 mm thick Inconel 718 alloy with a feeding rate of 5μm/s.