Advanced Materials Research Vols. 239-242

Abstract: For its two unique properties of superelasticity and shape memory, nitinol is widely used in medical applications. Traditionally, most nitinol stents are normally heat set at 485°C, which induces the formation of the Ni-rich second phases such as Ti2Ni3 and Ti3Ni4, increases the austenite finish temperature and reduces material strength and fatigue performance. The addition of 600°C heat setting was applied to the nitinol stents after 485°C heat setting process and its effect on the mechanical, dimensional and functional properties of the nitinol stents were investigated. The experimental results showed that the nitinol stent tubes with the addition of 600°C heat setting process had higher elastic modulus, ultimate tensile strength, elongation percentage, inner dimension and outer dimension than those of the nitinol stents with 485°C heat setting process. Moreover, after the addition of 600°C expansion step, the nitinol stents almost had the same average deployment force and deployment accuracy as those of the nitinol stents with 485°C heat setting process and higher average inner dimension (ID) and outer dimension than that of those without the 600°C expansion step. Either treated with the addition of 600°C heat setting process or only 485°C heat setting process, the average austenite finish temperature (A_f ) of the nitinol stents was both lower than the body temperature and the average A_f of the fomer was 8°C lower than that of the latter.

Abstract: The simulated water was treated using the clay and the organoclay. Then, HPAM removal efficiency was compared with the produced water. The results show that both the clay and the organoclay could be used to remove HPAM. However, pH value had different effects on the simulated water and the produced water, maybe due to residue oil droplets and other impurities. The micro structures were observed with particle imager and scanning electron microscopy (SEM).

Abstract: This paper presents a novel method based on mixed integer linear programming (MILP) that addresses the optimization of water network in batch chemical processes with single contaminant to minimize wastewater discharge. In this method, a batch cycle is divided into several time intervals and a unit would be divided into several sub-units, if necessary. It ensures that each unit/sub-unit operates in only one time interval. Each unit/sub-unit is attached with a buffer tank to relax the time constraint. The sequence of units is pre-determined in ascending order of their outlet concentration, so that units and their buffer tanks only provide water to afterward units. A superstructure of units, buffer tanks, and water-using connections is developed. The corresponding mathematical model is a MILP problem that guarantees the global optimum and obtains a solution quickly. Heuristic rules are used to analyze and omit the redundant buffer tanks. The proposed method is applied to a case study in this paper. The results show that the method is effective.

Abstract: Antibacterial properties of compound coatings by Micro-arc oxidation and electroless silver plating were reached. Effects of main salt, reducing agent, complexing agent and solution pH on plating rate and solution stability were discussed. The surface morphology and antibacterial properties of compound coatings were analyzed. Bonding strength between compound coatings was tested by tensile peeling method. The results show that compound coatings have good antibacterial effects, the average bonding strength of compound coatings is higher than 22.6 MPa, and compound coatings are firmly bonded.

Abstract: In this paper, numerical simulation of square cup deep-drawing process under the different constraint degrees condition was investigated by means of advanced analysis software Dynaform5.5. The influence of different constraint degrees on the forming quality were analyzed by taking the inflow volume while parts forming 120mm as standard. The results showed that the effect of the uneven flow and deformation of metal have become bigger and bigger with the increase of constraint degrees. The rounded area at the bottom of square cup is no longer the most easy broke location, and the thickness of long side reduce little and uniform than other place.

Abstract: In this paper, Electro-Spark Deposition (ESD) technology was used to enhance the cavitation erosion resistance of the stainless steel. The microstructure and composition of the deposition layers were studied by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive Spectrometry (EDS) on cavitation erosion resistance was investigated. The microhardness was measured too. The cavitation erosion resistance was measured in ultrasonic equipment. The preliminary study confirmed that the cavitation erosion resistance of the deposition layer was enhanced compared to the untreated substrate. Now, vane wheel made of cast-iron, stainless steel and oil bump damaged by cavitation erosion have been repaired by ESD. And the properties of the repaired vane wheels were the same as the new ones.

Abstract: The formulation design and fundamental experiments of O/W type emulsions as lubricant and coolant in the hot rolling process of magnesium alloy were conducted in this work. The main components of emulsion were determined by the comparision of some candidates of base oil, polar oil additive and emulsifier in microstructure and properties, respectively. It is found that the conservation stability of emulsions is mainly dominated by the emulsifier concentration and type. The results showed that the suitable stability and microstructure was obtained by using compound emulsifier of nonionic and anionic surfactants. The feasible contents of both emulsifier and polar agents are about 10 percent, respectively.

Abstract: Magnesium alloys are used widely because of its good performance. However, its practical application is restricted by low corrosion resistance. In this study, the effects of corrosion time and NaCl concentration on the corrosion behavior of AZ61 magnesium alloy were investigated from the corrosion morphology and the corrosion rate. These results have displayed that the corrosion rate of AZ61 magnesium alloy decreases with the increasing etching time. Meanwhile, the corrosion rate of AZ61 magnesium alloy increases with the increasing sodium chloride concentration. This is mainly because that the Cl- ion in the solution destroys the protective film on the surface of magnesium alloy and the high Cl- ion concentration accelerates the corrosion rate.

Abstract: Smooth thin films of three metal(II) complexes were prepared by spin-coating process from 2,2,3,3- tetrafluoro-1-propanol solution and characterized atomic force microscopy (AFM). In order to examine their possible use as blu-ray recording media, the spin-coated films of the metal(II) complexes on K9 glass substrate with a silver reflective layer were evaluated by static optical recording testing system with a 406.7 nm laser. The morphologies of the thin films are smooth and have a root mean square surface roughness (RMS) of 0.34-0.41 nm with in 5 μ × 5 μ area. The results of the static optical recording test demonstrate that high reflectivity contrast (> 54 %) can be obtained at an optimum laser writing power and pulse width with high-to-low polarity, and the recording marks are durable even after 15000 times readout. In addition, the recording marks on the cobalt (II) complex thin film are very clear and circular, and their size can reach 200 nm or less.

Abstract: The change of thermal properties of Al-17 wt.% Si alloys in different heating-cooling cycles was studied by differential scanning calorimetry (DSC). The influence of heating-cooling cycles on the latent heat of melting was discussed in the view of microstructure of Al-Si alloy. The results showed the latent heat of as-cast Al–13 wt%Si alloy is 548.6 J/g, which Al-Si alloy possesses good thermal energy storage property. The onset of melting point of Al-Si alloy increases indistinctively and is about 577 °C. When the heating-cooling cycle was 1200 times, the latent heat increased to 526.0 J/g. With heating-cooling times increase, the grain size and shape of the primary Si decrease. The shape of eutectic Si is changed into stripe