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In order to improve the performance of screw rotors, a novel screw rotor with variable cross-section profiles, in which the screw pitch and cross-section profile varying with the helical angle, is proposed for twin-screw vacuum pumps in this paper. The screw pitch of the proposed screw rotor decreases, on the contrary, its screw width increases continuously from the suction side to the discharge side...
In view of the problems that the existing rotor profiles of claw vacuum pumps contain non-smooth connection points, a novel smooth rotor profile was proposed in this paper. The proposed profile, which can achieve correct meshing, is composed of 6 circular arcs and 3 equidistant curves of epicycloid, and its design procedures as well as equations were given. The effects of geometric parameters on the...
Wurtzite Cu2ZnSnS4 (CZTS) nanoparticles with bandgaps of about 1.53 eV were synthesized by a simple solvothermal method with ethanediamine (En) as the reaction solvent. The effect of the annealing conditions on the structural stability and photoelectrical properties of wurtzite structured CZTS nanoparticles was detailedly studied. Raman spectra and X-ray photoelectron spectroscopy studies indicated...
Electron beam welding (EBW) is manufacturing parts with heavy thickness, but the evaluation of the properties is incomplete. We employed oscillation EBW to weld Ti6.5Al2Zr1Mo1V alloy with 60 mm thickness, and observed weld microstructures, and studied the properties of high cycle fatigue. Compared with base metal at constant peak stress, fatigue strength of the joints was equivalent to that of base...
Claw rotor profiles play an important role on performances of claw vacuum pumps. In this paper, an analytical model of claw rotor profiles, including profile equations, design methods, geometric theories and profile meshing relationships is established; and a working process model with the particular gas mixing process for claw vacuum pumps is also built in order to reveal characteristics of the mixing...
Claw rotor profiles greatly influence the performances and applications of claw vacuum pumps. This paper proposes a novel circular arc claw rotor profile, in which circular arcs are employed instead of cusps; and obtains the changing rules of claw rotor profiles varied with the value of circular arc radius. Numerical simulation of gas flow in the working process of claw vacuum pumps is carried out,...
Er 3+ -doped TiO 2 thin films were prepared by RF magnetron sputtering. The effects of Er 3+ concentration and annealing conditions upon up-conversion fluorescence were studied. The result shows that 490 nm green emission and 670 nm red emission can be obtained from Er 3+ -doped TiO 2 thin films excited by 980 nm lasers. TiO 2 thin films with 1.0 mol%...
Diffusion bonding of TiAl intermetallic to Ti 3 AlC 2 ceramic was carried out using Zr and Ni foils as interlayer. The interfacial microstructure and joining properties were characterized by electronic microscopy investigation and shear strength test, respectively. The microstructure observations revealed that the general interfacial microstructure of the joint bonded at 850 °C was...
Diamond-like carbon (DLC) films were deposited on the inner surface of 304-type stainless steel tube with an inner diameter of 10mm by DC glow discharge plasma. The influence of the deposition time, pressure and the ratios of CH 4 in CH 4 /Ar gas mixture on the DLC film deposition were investigated. The images of Scanning Electron Microscopy (SEM) show that the DLC films are featureless...
The intercorrelation of aluminate properties, such as structure, component and metal Os film coating with electron emission capability and longevity of Ba dispenser cathodes, has been investigated. It is shown that reactants react completely and the percentage of tribarium aluminates is larger in the normal environment, and that at 1723K the pulse of cathode impregnated in the above aluminates is...
ZnO/MgO multilayer thin films were fabricated on Si (111) substrates by pulsed laser deposition (PLD) at 600°C for 30min. The oxygen pressure and laser repetition were kept at 20Pa and 5Hz, respectively. The PL measurements suggest that the UV peaks have a blue excursion of 4nm from 379 to 375nm, compared with ZnO films. The XRD analysis indicates that the position of ZnO (002) peaks from ZnO/MgO...
Carbon molecular sieve (CMS) membranes for separating gases were deposited on porous Al 2 O 3 disks using CH 3 COCH 3 +CH 4 , by a remote inductively coupled-plasma (ICP) chemical vapor deposition (CVD). The new method for preparing membranes with a high H 2 /N 2 selectivity without any reduction of the permeance was introduced by combining the...
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