Graded doped structure fabricated by vacuum spray method to improve the luminance of polymer light-emitting diodes

An increase in luminance of a polymer light-emitting diode(PLED) was obtained by fabricating a graded doping structure using a vacuum spray method. The small electron transport molecule, Tris(8-hydroxyquinolinato) aluminum(III)(Alq3), was graded dispersed along the film in the direction of growth in the hole transport polymer poly(3-hexylthiophene-2,5-diyl)(P3HT, regiorandom) layer of the PLED, despite being dissolved in the same organic solvent as the polymer. The PLED reported here, which is composed of a graded structure, emitted brighter light than PLEDs composed of pure polymer or of a blend of active layers prepared by spin coating and/or vacuum spray methods.

PLASMA SPRAYED Ti AND HA COATINGS: A COMPARATIVE STUDY BETWEEN APS AND VPS

Titanium (Ti) and hydroxyapatite (HA) coatings have been prepared via air (APS) and vacuum plasma spraying (VPS), and then their composition, structure, bonding strength and bioactivity were examined. The results obtained reveal that in APS process many of Ti were oxidized, but in VPS the oxidization was avoided. VPS T i coating possesses better bonding condition than APS Ti coating. As for HA coat ing, higher crystallinity has been obtained while the coating was deposited by V PS as compared with APS. The simulated body fluid (SBF) tests show that both of APS and VPS HA coatings possess good bioactivity. As compared with APS, VPS is r ecommended as a better method to deposit Ti and HA coatings that can be applied as hard tissue replacement implants.

Thermal Performance Study of VPS-W Coatings on CuCrZr Under High Heat Flux

Three tungsten coatings with a thickness of 250 μm, 600μm and 220 μm, respectively, were deposited on a CuCrZr substrate by the vacuum plasma spraying technology. In order to study the thermal performance of the coatings, heat load limit, thermal fatigue lifetime and thermal response tests were performed by means of the electron beam irradiation with a heat flux from 0 MW/m^2 to 10 MW/m^2. Experimental results indicated that tungsten coatings on CuCrZr with a titanium or tungsten/copper interlayer could expel heat flux timely and had good thermal fatigue properties, titanium was a promising compliant layer which provided a reliable way to join tungsten onto the CuCrZr heat sink, even suffering from a heat flux of 10 MW/m^2 or withstanding 54 cycles of fatigue tests under 5 MW/m^2. However, the better quality of tungsten coating itself was necessary because its surface temperature was higher than that of the sample with a tungsten/copper interlayer.

Influence of laser re-melting and vacuum heat treatment on plasma-sprayed FeCoCrNiAl alloy coatings

FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to study the influence of different treatments on the structure and properties of the coatings.The phase constitution,microstructure and microhardness of the coatings after treatments were investigated using X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.Results showed that the as-sprayed coatings consisted of pure metal and Fe-Cr.The AlNi;phase was obtained after the vacuum heat treatment process.A body-centered cubic structure with less AlNi;could be found in the coating after the laser re-melting process.The average hardness values of the as-sprayed coating and the coatings with two different temperature vacuum heat treatments and with laser re-melting were 177,227,266 and 682 HV,respectively.This suggests that the vacuum heat treatment promoted the alloying process of the coatings,and contributed to the enhancement of the coating wear resistance.The laser re-melted coating showed the best wear resistance.