Applied Mechanics and Materials Vol. 778

Abstract: The OLEDs were fabricated with the structure of ITO/m-MTDATA(20nm)/NPB(10nm)/ DPVBi:BCzVBi(15 nm,x%)/TPBi(10 nm)/Alq3(20nm)/Cs₂CO₃：Ag₂O(2nm,20%)/ Al (100 nm) by using the method of fluorescent dyes dopant. The effect of different DPVBi:BCzVBi doping concentration(x=5,8, 10 and 15) on the properties of blue light device was studied．Results show that when the mass fraction of fluorescent dye BCzVBi was 10%, performances of the device were the best. This device had a maximum current efficiency of 4.19 cd /A and maximum luminance of 14757 cd /m² at 17 V.When the driving voltage changed from 8 to 17 V, the efficiency of the devices had been rising. There are not the phenomenon of efficient roll-off.

Abstract: The first-principles method based on density function theory (DFT) is carried out to assess the effect of reactive elements (Hf and Y) on the interfacial adhesion. Our calculations predict that RE prefers to segregate on Al₂O₃(0001)/Fe (110) interface region, meanwhile the segregation of S to the interface is suppressed, which may be beneficial to improve the interface adhesion of the Al₂O₃(0001)/ Fe (110) interface. The strong p-d covalent coupling formed between O and Fe atoms across Al₂O₃(0001)/Fe (110) interfaces. Hf and Y form stronger chemical bonds with O atoms across Al₂O₃(0001)/Fe (110) interface than Fe. The formation of strong covalent RE-O bonds across the interface attributes to the increase of the interface adhesion. The population analysis can quantify the covalent bond strengths. The bond population values of Hf-O, Y-O bonds are larger than that of Fe-O bond, which hints at the mechanism by which RE strengthen the Al₂O₃(0001)/Fe (110) interface, and as a result, the oxidation resistance of FeCrAl alloys are improved.

Abstract: The cube texture evolution during annealing of the heavy cold-rolled Cu-45at.%Ni alloy tapes were investigated by XRD and electron back scattering diffraction techniques. The results indicated that the fraction of Copper-type rolling texture was slightly strengthened during recovery, and then strongly reduced during recrystallization. The cube texture was formed by consuming the rolling texture components during recrystallization process, and the S, Copper and Brass orientations were consumed together via cube grain growth. A strong cube-textured Cu-45at.%Ni alloy substrate with the cube texture fraction of 98.6 % (< 10°) was obtained after annealing at 1000 oC for 1 h.

Abstract: Ag/AgCl electrodes as an important sensor are used in modern clinical detection and biomedical measurement, which have been widely applied in electrocardiograph (ECG), electroencephalogram (EEG), electromyography (EMG), electricity impedance technology (EIT) and so on. In this study, the electrode pairs were gel-to-gel connected. After a stimulating current, the alternating current (AC) or the direct current (DC), was injected through the electrode pair, the electrical potential was recorded, then impedance data of Ag/AgCl electrode was obtained. The results showed that the AC impedance of electrode increased, and then gradually decreased with the increase of current size. It was found that the DC impedance data of Ag/AgCl electrode was changed greatly after the electrode pair was injected into the alternating current. With the long time continuous measurement, the AC impedance of electrode pair gradually increased within the 12 hours. However, the significant fluctuations of AC impedance were observed after 12 hours. Comparing with the AC impedance, the DC impedance of electrode pair exhibited a great increase with the increase of measurement time.

Abstract: Aiming at the aluminum profile extrusion process of a large caliber aluminum tube with porthole die, this paper established the simulation models by using finite element method and finite volume method, respectively. The extrusion process was simulated by using the above two models. The advantages and disadvantages and the applicability of the two simulation methods in simulating large aluminum profile extrusion processes were compared. It is concluded that finite volume method is more suitable than finite element method for simulating aluminum profile extrusion processes with a severe deformation. In addition, the distributions of stress and strain and the material flow patterns in the large caliber aluminum tube extrusion process with porthole die were given in detail. The results can provide useful theoretical guidelines for the process and die design as well as process parameter optimal selection for large aluminum profile extrusion processes with porthole die.

Abstract: Poly (L-lactide) was grafted onto chitosan by ring-opening copolymerization under microwave irradiation in the presence of tin octoate (Sn (Oct)₂) as catalyst. The chemical structure and physical properties of the copolymers with different feeding ratios were discussed by FTIR, DTG and X-RD, taking pure chitosan as reference. The results showed that the application of microwave irradiation in the reaction could achieve the copolymer with high grafting percentage in a short time and low temperature. The thermal stability and crystallinity were decreased with the feeding ratio increasing, attributing to the increasing of grafting percentage.

Abstract: The aluminized coating on AISI H13 steel was prepared via hot-dipped aluminizing and subsequent high-temperature diffusion. Isothermal oxidation tests of the aluminized and untreated H13 steel were performed. The results showed that the aluminized coating consisting of FeAl and Fe₃Al was achieved with Kikendall porosity and carbide particles agglomeration. Compared to the untreated steel, the aluminized steel presented an excellent oxidation resistance and its weight gain slightly increased at 650 and 850°C. At 850°C, the untreated H13 steel had a worse oxidation resistance and the weight gain increased linearly with the increase of oxidation time. Al₂O₃ was preferentially formed on unspoiled surface and provided a barrier to obstruct the oxygen into the coating, while Fe₂O₃ formed around cracks had no protection.

Abstract: In this paper, an in-depth research adopted a creep model has been conducted to focus on the stress during the process of glass tempering based on the finite element software ANSYS.During this research an simplified model of glass tempering has been established, and as a result the expected stress value of surface and mid-plane was achieved.The results show that using the creep model can also achieve the same simulation effect of glass tempering.

Abstract: An oxidation coating on Ti-6Al-4V alloy was prepared by thermal oxidation and subsequent vacuum diffusion. The wear performance of the coating at elevated temperature was evaluated on a pin-on-disc high temperature wear tester under 50-300 N at 400°C. The results showed that the hardened coating with a thickness of 250 μm was produced on Ti-6Al-4V alloy. It was found that the elevated-temperature wear resistance of the coating was remarkably improved, compared with uncoated Ti-6Al-4V alloy. The oxidation coating on Ti-6Al-4V alloy presented extremely low wear losses. The excellent wear resistance of the coating could be attributed to high hardness of coating and its strong bond with substrate. Delamination wear was predominant wear mechanism during dry sliding at 400 °C.

Abstract: This study prepared a Graphene/TiO₂(G/TiO₂) thin films by using a sol–gel method The structure and morphology of the materials were characterized using X-ray diffraction (XRD), atomic force microscope (AFM) and thermo gravimetric- differential scanning calorimeter techniques (TG/DTG).AFM images showed that the G/TiO₂ film is typically amorphous hot-treated at 300°C. When the temperature was increased to 500 °C, G/TiO₂ thin films are all crystalline. The XRD results showed that G/TiO₂ thin films contained crystalline phase of anatase after calcining at 500°C. TG/DTG measurement showed that the change of the crystal phase did not occur in gel until to 500°C.