Advanced Materials Research Vols. 591-593

Abstract: Single and multi pass AISI 304 stainless layers tightly combined with substrate was obtained by laser cladding on the surface of 45 steel using the way of presetting powder. Effect of different scanning velocities on cladding layers was analyzed and interpreted in this paper; influence of scanning velocities on dilution rate was also acquired, the dilution rate come up to a maximum value which is 11.1% when the scanning velocity reached 800 mm/min, what is more, immersion test shows that scanning velocity has little effect on the weightlessness rate. Besides, XRD patterns shows that the cladding layers composed of ferrite and austenite phases.

Abstract: This study provides a series of investigation on the morphological characteristics and related mechanisms of a porous metal-fiber sintered felt (PMFSF). Multi-tooth cutting and high-temperature solid-phase sintering are used to create the PMFSF. Based on both modeling and experimental methods, the results suggest that the produced fiber has rough surface and curled shape due to cutting deformation. The processing parameters and material mechanical property both have significant effects on formation of fiber morphology. Results also reveal that the fibers in a PMFSF is randomly distributed and connected with each other by forming sintering necks. Besides, the influences of sintering parameters are also analyzed in this work.

Abstract: Burnishing is an important mechanical surface enhancement technique which can smooth the component surface and improve the component’s fatigue, wear and anti-corrosion properties. Fretting tests lubricated with mineral oil were performed on a pure copper (PC) against a Si3N4 ball. The burnished surface exhibited a significantly improved fretting wear resistance and higher friction coefficient in comparison with the coarse-grained (CG) form. The wear volume of the burnished PC is quite lower than that of the CG PC. The friction coefficient of the CG PC increases with an increasing load, while the friction coefficient of burnished PC decreases with an increasing load up to 100N and then increases. The enhanced wear properties of the burnished surface are correlated with the compressive residual stress and work-hardening, which may partly result from grain refinement induced by burnishing.

Abstract: The electrospinning technique was used to produce poly (vinylidene fluoride) (PVDF) membrane. Thermal treatment was introduced to improve the mechanical property and dimensional stability. In this paper, the PVDF membranes before and after thermal treatment were characterized by Scanning electron microscope (SEM), differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD), tensile testing. The crystallinity, tensile property, as well as melting temperature changed with the treated temperature. The results hows that thermal treatment could notably increase the tensile property of electrospun PVDF membrane and 160°C is a proper temperature for thermal treating

Abstract: The most apparent advantages of thermoplastics are the recyclability and processibility. To obtain recyclable and injectable conductive polymer, this paper studied the filling of carbon nanotubes (CNT) in polystyrene(PS) and the aligning of CNT in PS under high frequency electric field and ultrasonic vibration using an experimental set up developed in our laboratory. Results of these studies would be very useful to the development of a new generation of micro fabrication method for producing integrated micro electronic products using micro injection molding that is the most cost effective way to produce micro products massively.

Abstract: Study on Stress-strain model of metallic materials with residual stress. First of all, Stress-strain model of metallic materials with residual stress was analyzed, then, derivation of a stress-strain model was done. Finally, according to the model of stress and strain analysis and derivation of results, taking diaphragm spring as an example, using methods of derivation of kinds of material obtained from this model portfolio, using finite element modeling tools, calculate the relationship between load and deformation. The test result indicated that, using the method of many kinds of material model combination can get the higher precision of calculation.

Abstract: The novel method of using continuous variations of the electrical contact resistance and the friction coefficient for monitoring the tribological properties and the wear mechanisms of titanium pairs in air had been applied successfully by the authors. Therefore, this study further investigated the tribological properties and the wear mechanisms of self-mated titanium in pure water. In order to investigate the chemical reactions of titanium sliding against under water lubrication, the continuous variations of electrical contact resistance and friction coefficient were measured. SEM was used to observe the microstructures and of material transfer. The variations of electrical contact resistance were shown to produce clear and strong signals, superior to monitoring continuous friction coefficient variations for the self-mated titanium in pure water. According to the variations of electrical contact resistance, TiO2 was inferred to form at the interfaces of self-mated titanium in pure water. All of the experimental results demonstrated that the water lubrication has great potential for the research.

Abstract: In order to achieve high removal rate and high-quality processing on SiC wafer, we carried out the CMP processing experiment with the new type CMP machine (Bell-jar) by using the slurry with the addition of strong oxidant (KMnO₄). It was found that the high speed CMP processing was achieved by controlling the concentration of KMnO₄ in the slurry, the pH of slurry and the processing atmosphere. By using the slurry with the addition of KMnO₄ of 0.1mol/L, the removal rate was the fastest up to 1019nm/h in the fixed pH of 6. By use of the slurry of pH 3, the removal rate of C-face of SiC wafer was 1695nm/h On the other hand, the fastest removal rate of Si-face of SiC wafer was only 51nm/h by using the slurry whose pH is 7. In the open air atmosphere, the removal rate was 915nm/h, which was higher than that at the higher and lower atmospheric pressure.

Abstract: In this paper, we demonstrate using laser induced forward transfer (LIFT) technology to deposit Ti/Ni alloy on a glass substrate with high precision. Here the photonic feature of laser energy is used to move the Ti/Ni particles forward and deposit them on the glass, while the wave feature of laser is used to turn part of the Ti/Ni particles into ions. The characteristics of deposited films and their relations with the processing conditions are studied. A new method of depositing materials using photons instead of electrons in electric field may bring about a series of new technologies on surface deposition, which can be used to produce shape memory alloys.

Abstract: Optical coherence tomography is a non-invasive cross-sectional imaging technology for inhomogeneous samples. Spectral-domain optical coherence tomography is introduced to measure film and Silicon dovetail groove in this paper. A novel method is used to deal with the interference spectrum to improve the quality of the two-dimensional cross-sectional image. The experimental result shows the microstructure of the two samples can be clearly seen as expected. From the visualized two-dimensional cross-sectional imaging, the film thickness and the dimension of the Silicon dovetail groove are obtained with this technique. It is experimentally demonstrated that this system is useful for imaging the microstructure of the internal and surface of film and semiconductor. It can be further developed for other material detection in industrial fields.