Advanced Materials Research Vols. 79-82

Abstract: The medical stent is using widely for a surgical operation, because it can reduce the pain of cardiac. When it was developed initially, medical stent was made of stainless steel, however, the TiNi alloy is widely using presently instead of stainless steel. Because, TiNi alloy has not only super elasticity and Smart Material Effect (SME) but also excellent organism compatibility. For these reason, the TiNi alloy is currently highlighted for medical stent material better than other materials. Nevertheless, this TiNi alloy is not suitable to traditional machining process. When the traditional machining process is conducted to the TiNi alloy, it cannot be discharged the machining heat and inner stress. Also, traditional machining process makes a lot of microscopic burrs on the TiNi alloy surface. This microscopic burrs and the rough surface makes injury on vascular, so, it should be necessary non-traditional machining process without defect of traditional machining. In this paper, microscopic burrs on TiNi alloy for medical stent are removed, and surface roughness of the medical stent is evaluated by Electrochemical Polishing (EP) which is one of the non-traditional machining.

Abstract: The deformation processed Cu-based in-situ composite was a kind of structural function materials with high physical and mechanical performance and used widely in large scale integrated circuit. Especially, the sheet material of Cu-Fe in-situ composites was interested to researchers because the Fe was cheaper and the use of sheets was more widely in electron industry. In this study, the sheets of Cu-10Fe-1Ag in-situ composite were achieved by cold rolling which the thickness was from 6mm to 2.56mm, 1.28mm, 0.64mm and 0.32mm. Corresponding, the rolling ratio was 4.9, 5.3, 5.9 and 6.6. The maximum strength was 722Mpa at the rolling ratio 4.9. The conductivity was measured also with maximum 59.5% IACS. The experimental results show that the tensile strength and electrical resistance increase with the increasing of rolling strain. Although the conductivity of Cu-Fe in-situ composites was not very high, the matching of strength and conductivity was favorable. It is feasible that the high performance Cu-based in-situ composite can be obtained by cold rolling with merits of materials cheaper, melting simple and usage wide

Abstract: On the basis of the theory of electromagnetic wave propagation in monolayer construct of left-handed material(LHM) and right-handed material (RHM), a calculation method based on recurrence is proposed, this method can be used in the computation and forecasting of the absorbing efficiency of multi-layer materials .Then, the results are consistent with another derived from traditional transmission-line method. But compare to the later, the new calculation method is simpler and more direct. Furthermore, using in Structure consisting of LHM and RHM is also referred. At last, we use this model analyzes the effect by the LHM’s electromagnetic parameter to absorption, from that, we obtain some useful conclusions. Our research results indicate that when LHM is combined with conventional RHM to form a LHM-RHM double-layer structure absorber, the reflection loss will be increased and the absorbing band will be widened. This indicates that the LHM is hopeful to be one of the wave-absorber composite materials, which has better absorbing effect.

Abstract: The effect of rolling technology on the microstructure, electrochemical property and anti-corrosion property of Al-Mg-Sn-Bi-Ga-In alloy anode in alkaline solution (80°C, Na2SnO3 + 5mol/L NaOH) has been analyzed according to the chronopotentiometry (E-T curves), hydrogen collection tests and modern microstructure analysis. The results show that when controlling the pass deformation at 40%, with the increase of rolling temperature, both electrochemical activity and anti-corrosion property of Al anode increase first and then decrease. When the rolling temperature is 420°C, the aluminum alloy anode has the most negative electrode potential of about -1.521V (vs.Hg/HgO) and the lowest hydrogen evolution rate of 0.1716mL/ (min•cm2). The optimum comprehensive performance of Al alloy anode has been obtained.

Abstract: A preliminary study of active friction control method based on electrorheological (ER) effect is experimentally investigated. The friction coefficient can be changed from 0.07 to 0.9 continuously with the applied voltage in the range of 0 to 2000 V. Results show that by using proper ER fluids and structure design, active friction control based on ER effect has good potential in real industrial applications.

Abstract: dvanced mineral admixtures can lead to economical high performance concrete with enhanced durability and reduced cement content. When super fine steel slag powder is mixed into concrete as active admixture, resistance to abrasion and resistance to chloride penetration are improved as well as workability and mechanical properties of the concrete. Resistance to abrasion of steel slag concrete is measured and resistance to chloride penetration is also determined by the method of NEL and ASTM C1202 in this paper. Result shows that compound mineral admixtures as partial replacement for Portland cement in mortar enhance abrasion resistance. Mixing mineral admixture is an effective means for controlling the chloride permeability. Concrete specimens prepared with compound mineral admixture with steel slag powder and blast furnace slag powder has very low permeability.

Abstract: Concrete properties can be greatly improved with the advanced mineral admixtures such as steel slag powder. Used in combination with Super-plasticizer admixture, steel slag powder can lead to economical high performance concrete with enhanced durability and reduced cement content. The effectiveness of steel slag powder on suppressing Alkali Aggregate Reaction is analyzed. The effectiveness of steel slag powder on suppressing AAR expansion was assessed using the method of ASTM C441 and accelerated test method. Results show that mineral admixtures with steel slag powder as partial replacement for Portland cement in concrete is an effective means for controlling expansion due to AAR. At most a 50% decrease in expansion rate of mortar bars can be found.

Abstract: The affecting laws of boron and silicon on structure and properties of Fe-based superalloy were studied by analyses of scanning electron microscope (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Proper content of boron could not only purify the matrix and restrain the polymerizing and growing of carbides effectively, but also promote the forming of secondary precipitate of borides, which dispersed in form of micro particles to strengthen grain boundaries and enhance the heat strength for Fe-based superalloy. Boron was an adverse element to high temperature oxidation resistance. Silicon could toughen the matrix by solid solution strengthening. Overfed silicon in alloys caused great dropping of strength and toughness. The component of SiO2 endowed the oxide scale with flat and compact structure, fine and even grains, and few exfoliating. The optimum contents of boron and silicon in Fe-based superalloy are 0.02wt.% and 1.5wt.% respectively by comprehensive consideration of high temperature mechanical properties and oxidation resistance.

Abstract: Magnetic Shape Memory Alloys (MSMA) are attractive active materials because they have large strain (about 10%) as the classical shape memory alloys (SMA), but can provide a 100 times shorter time response, so, MSAM will be the ideal material of structural engineering vibration control. The main disadvantages of MSMA based actuators are the brittleness of the single-crystal material, the difficulty to apply the strong magnetic field required to obtain sufficient strain and the nonlinear behaviors. In this paper a novel MSMA based actuator changing the disadvantage of the hysteretic behaviors into an advantage. This device includes two pieces of MSMA material act in an opposite way. The hysteretic behavior of the material permits to keep a stable position when no current is applied. The use of current pulses permits also a reduction of the coil heating (Joule effect losses) and a reduction of the magnetic circuit size. The performances and characteristics of MSMA are between these of classical SMA and these of piezo-electric materials. A thermo-magneto-mechanical model of the actuator is currently in development in order to design an efficient control law well adapted to the specific MSMA properties.

Abstract: The relationship between the viscosity of Al84Mg10Ce6 alloy melt and liquid structure was studied by viscosity measurements, X-ray diffraction and DSC analysis in this paper. In addition, the glass forming ability of alloy ties produced by melt spinning was analyzed. Based on the above results, the relationship between alloy melts and its glass forming ability(GFA)was studied. The addition of element Ce leads to the abnormal change of Al84Mg10Ce6 melt’ s structure and enhances its GFA, furthermore, it results in completely amorphous ties with melt spinning at 850°C.Therefore, there is certain relationship between the Al-Mg based alloys melt and its GFA.