Advanced Materials Research Vols. 295-297

Abstract: First stretch bending process of aluminium extrusions given by Norwegian scholars is simulated by using revised model proposed in the paper. That maximum die force calculated is closer to experiment than Norwegian scholars’ one demonstrates that the revised model is rather accurate in forming simulation and lays the foundation for later springback simulation. Then springback is simulated by using dynamic explicit and static implicit FE codes, respectively. The influences on cross-sectional distortion and springback of two codes are compared. It is shown that dynamic explicit FE code can predict cross-sectional distortion accurately and static implicit FE code overestimates it. Neither of two codes can predict springback accurately. Dynamic explicit FE code overestimates it and static implicit one FE code underestimates it.

Abstract: A superhydrophobic polypropylene surface was obtained by a facile method. The water contact angle and sliding angle of the superhydrophobic polypropylene surface were 157±1.8ºand 1.6º, respectively. When the superhydrophobic polypropylene surface was contaminated, 99 % contaminant particles were removed from the superhydrophobic polypropylene surface by artificial rain, showing excellent self-cleaning property.

Abstract: This paper analyses the basic physique and the modeling technique. With the understanding of the language characters of the shape element, the complicated space in the high-rise building model will be analyzed thoroughly in order to use them in design and practice.

Abstract: As the integrated circuits developing, the line-width and space between the metal interconnection are shrinking. This increases the RC time delay. To reduce the RC time delay, the low dielectric constant (low-k) material was introduced in the ICs. For process integration considerations, the impact of electronic characters was investigated. In this paper, both static test and CMP(chemical mechanical polishing) process conditions were executed on the low-k material black diamond (BD) with slurry,which was explored by Hebei University of Technology. The slurry was utilized to evaluate the effect on the dielectric properties of BD films. Electrical analyses have shown dielectric properties of BD films would not be degraded during these processes. The static test was dipping the low–k material (BD)in the slurry for 30s and 2minutes, and the results showed the capacitance changed from 3.01to3.40 when dipping in 30s ,and the value reached 3.71 when dipping 2minutes. The resistance changed from 2.9-2.95 to 3.27-3.33 in 30s,and reached 3.57-3.63 in 2 minutes. The result of CMP process showed that the capacitance of five dots , which were selected on the BD film, changed from 2.94-2.98to 2.99-3.05. The dielectric integrity of low k BD films after CMP process remained at an acceptable region to meet requires of multilevel interconnection.

Abstract: Thixoforming of steel is a potential forming technology, which can realize near-net-shape forming process with good quality in one forming step. In this paper, thixoforming process was used to replace the conventional hot forging process to form the auto claw-pole. The finite element code Forge2008Ó was used to simulate the auto claw-pole thixoforming process. The impact of three main process parameters such as initial billet temperature, punch speed and die temperature on the forming process were investigated. The reasonable process parameters for the auto claw-pole thixoforming were obtained: initial billet temperature 1430~1440°C, punch speed 100~200mm/s and die temperature 300~400°C.

Abstract: According to the analysis of friction distribution on radial direction in the precision forging spur gear, the reason that the tooth corner was difficult to fill is revealed. Changing the motion mode of the floating die will change the friction condition between billet and floating die, as well as the filling situation of tooth corner. Finally, the scheme was further validated by DEFORM-3D, and the results show that the validity of floating die to tooth corner filling.

Abstract: In order to reduce the spur gear precision forging load and prevent load to rise sharply in final forging, on the basis of analysis the distribution of contact pressure of cylinder upsetting, mandrel exchange technology is put forward. As a result, the material always has free space to flow. The tool-set and experiment scheme are designed, finally, the scheme is further validated by Deform-3D, and the results show that the validity of mandrel exchange technology to reduce the load in gears precision forging.

Abstract: The waxy wheat straw surface and high SiO₂ content of wheat straw agrifibres make wheat straw-based panel production much more difficult than traditional wood-based panel manufacture. Plasma surface modification is regarded as one of the cost effective surface treatment techniques for many materials including natural fibers. In this study, plasma technique was employed to treat the surface of wheat straw. After the plasma treatment, the surface properties were then evaluated by determining the contact angles of 3 liquids on the wheat straw surface and by analysis using Fourier Transform Infrared Spectroscopy (FTIR).The results showed that the contact angles of water, glycerol, and UF resin after the plasma treatment decreased by 44.1%, 18.6%, and 24.9%, respectively. In the meantime, –OH, and -C=O groups increased according to the FTIR analysis. The FTIR analysis also indicated a significant SiO₂ reduction in the plasma treated wheat straw. Obviously, the plasma treatment improved the wettability of wheat straw, increased the numbers of oxygen-containing functional groups, and also removed the weak interface of wheat straw remarkably. By means of the plasma treatment, the internal bond property between modified wheat straw fibers was expected to enhance, and thus some cheaper traditional adhesives such as urea formaldehyde (UF) and phenol formaldehyde (PF) can be used for the wheat straw-based panel production instead of using expensive Diphenylmethane Diisocyanate (MDI).

Abstract: Linear explosively formed penetrator (LEFP) is an optimal combination of linear cutting sword and conical shaped charge but is completely different with those two above. Initiating manner of LEFP is one of the most important factors that can affect its performance obviously. LEFP forming mechanisms of linear shaped charge initiated from the mid-point were studied with combined method of theoretical analysis, experiments and numerical simulation. Liner movement driven by the detonation wave action was analyzed as a three-dimensional issue and a synthetical model of liner movement was established. The model were verified by the penetrating experiments with the LEFP initiated from midpoint under stand-off which is 5 times distance of the LEFP caliber size. Formation processes of LEFP were described through numerical simulation and the simulation results were in concordance with those of experiments.

Abstract: This paper examines the microstructure and performance of bead-on-plate welds on 21CrMoV5.11 steel continuous casting roll (dimensions:φ150mm×300mm) by submerged-arc overlaying under three types of welding heat (high, medium and low) input. The result shows that the microstructure of first, second and third tiers of bead-on-plate weld is martensite and ferrite, the ferrite is distributed in worm, streak or flake forms, the first tier of weld metal has slightly more ferrite, the deposited metal has even distribution of hardness, the third tier of weld metal has high hardness, when the input of welding heat is high, the bead-on-plate weld has low hardness, the wearing resistance is poor and ferrite is mostly distributed in batten form.