Advanced Materials Research Vols. 79-82

Abstract: A superhydrophobic film with an anti-corrosive propertyhas been fabricated on the anodized aluminium foil by myristic acid (CH3(CH2)12COOH, mya) chemically adsorbed. The surface structure and composition were then characterized by means of scanning electron microscopy (SEM) The static contact angle (CA) for seawater is measured to be larger than 150°. The fluoroscope and scanning electron microscopy (SEM) show the samples with the superhydrophobic film which is immersed into nature seawater for 24h significantly decrease adhesion of microorganisms. The appearance of the microorganisms is characterized by transmission electron microscopy (TEM). The study suggests the superhydrophobic film dose not only decrease the corrosion currents densities (icorr), but also microbially influencing corrosion acceleration inhibition (MICI) due to preventing colonization of microorganisms. A hypothesis is indicated that aluminums whit the superhydrophobic film could be used as a kind of excellent marine materials.

Abstract: In this work, an experiment was performed to demonstrate the possibility of the metallurgical bonding in plasma-sprayed cast iron coatings at high substrate temperature. A quantitative analysis of splat cooling and rapid solidification of cast iron splat is then presented. The effect of the substrate temperature on the development of melt undercooling within the splat is investigated in detail. The results indicated that the initial substrate temperature has a profound effect on the development of melt undercooling in a splat, the splat bottom melt temperature, and the substrate surface temperature. A high initial temperature of the substrate restrains the cooling of the splat and leads to a high melt temperature that may promote the grain growth directly on cast iron substrate surface to form the metallurgical bonding.

Abstract: Flexible fabric keyboard is a field of smart textile. It can overcome traditional horniness keyboard can’t be foldable and washing. Because conventional keyboard’s switch is matrix circuit, two conductive layers are not touchable due to action of a middle insulating layer in relaxing. When the key is pressed, two conductive layers contact and form electric current. In this laboratory study there are two kinds of methods adopted, for example, Three-layer Fabric Weaved Separately (TFWS) and Three-layer Fabric Shaped Once(TFSO). They were significantly different in weaving methods, fabric structure and weaving efficiency. Three species were designed for every method. Although Connection Ratio (CR) of 6×6 and 8×8 in TFWS was 100%, TFWS took many repeating and complex processes. Much time and labor were seriously spent so that weaving efficiency was consumedly reduced. However, if making use of Three-layer Fabric Shaped Once(TFSO) which adopted three dimensional weaving method, only one procedure was required for fabric keyboard matrix circuit. The three dimensional weaving fabric consisted of support part and orifice part. When pressed in the key position, the top and down layer of the orifice part can contact with each other. Then the circuit can connect. When the applied force was released, the top and down layer can return to primary position due to the action of the support part. TFSO didn’t require many repetitive and complex courses. Therefore the weaving efficiency can be greatly increased. To be more importantly, CR of 16 wefts in TFSO was comparatively not bad among in three species of TFSO. When considering all six species for two methods together, 16 wefts in TFSO appears to provide the most suitable fabric for flexible fabric keyboard matrix circuit as a result of shaping once, high weaving efficiency and 100% CR. These findings may assist in recommendations regarding the further development of flexible fabric keyboard.

Abstract: The notched tensile tests of Ti-6Al-6V-2Sn laser welds with distinct post-weld heat treatments (PWHTs) were carried out at 150, 300, and 450oC and the results were also compared with the mill-annealed base metal (BM). The BM specimen had the highest notched tensile strength (NTS) among the specimens being tested at room temperature but became the lowest at 450oC. At/above 150oC, all welds showed a decrease in NTS with increasing temperature. The cracks tended to grow along the α / β interface in the BM specimen. The formation of premature fine pores at the grain boundary in the weld with PWHT at 704oC accounted for the intergranular dimple fracture of the specimen. The fracture appearance of the as-welded (AW) and the 482oC-aged (W-482) welds comprised of mainly transgranular dimple and increased the extent of grain boundary shear at elevated temperature.

Abstract: Based on earlier theoretical works on RC beams ,the mechanical properties of steel reinforced concrete beams strengthened with FRP(fiber reinforce polymer) are further investigated theoretically including theirs failure mechanism and loadability. According to the design method of reinforced concrete beam strengthened with FRP, steel reinforced concrete beam strengthened with FRP mainly can have three kinds of destruction patterns: the first case is the tensile steel yield, the tensile shaped steel yield, the FRP are put off, the compressive zone’s concrete has not crushed; the second case is the tensile steel yield, the tensile shaped steel yield, the FRP are put off; the compressive zone’s concrete has crushed; the last case is the tensile steel yield, the tensile shaped steel yield, the FRP are not put off, the compressive zone’s concrete has crushed. The second case is discussed in this paper.Based on the different position of middle axle and steel, steel concrete beams strengthened with FRP include: middle axle through the steel web, and not through the steel and just in steel compression flange . Aim at these three kind of situations, the stress are analysed. According to the stress patterns of steel reinforced concrete beams strengthened with FRP and different position between neutral axis and steel, the discriminant formula of the boundary destroys and the formula of cross-section flexural capacity calculation are put forward by using limit equilibrium theory.The formula is expressed clearly, simple and easy to use.The depth of compressive region is given in view of different failure types.

Abstract: Outburst and random are typical characters of concrete when under external load. Traditional mechanics methods are difficult to be applied in. Depend on nonlinear science to set up the nonlinear dynamical equation that is fit for its characteristics. The subsystem dynamical equation of concrete is set up based on discontinuous medium mechanical model, and find that the concrete dynamical equation under external load is a Duffin equation. Then analyze and discuss the effect of external load on concrete by math analysis soft of maple. Results show that the concrete material take on complicated response to external load change.

Abstract: The reflective cracking in asphalt surface is a technical problem that exists in the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure, how to control its emergence and development is still a major problem for road engineering. At present, researches on the anti-cracking performance for Open-graded Large Stone asphalt Mix (OLSM) in China almost remain in the test road observations, very few study the mechanism of its anti-cracking from the mechanical point. Aiming at this problem, a method of using OLSM as the cracking relief layer is proposed, large mineral aggregate, low asphalt content and a great deal of void in OLSM can dissipate or absorb stress and strain around the crack. The 3-D finite element method is used to analyze the crack-alleviating layer of ordinary asphalt concrete and OLSM, and the large-scale commercial finite element software of ABAQUS is used to do numerical simulation analysis for the lean concrete base asphalt pavement structure with OLSM, the analysis result indicates that temperature-load coupling stress of OLSM are less than that of ordinary asphalt concrete. Depending on the test road on an expressway, research on the anti-crack mechanism of OLSM has been conducted. The investigation of the test road and the result of the theoretical calculation indicate that OLSM can prevent lean concrete base asphalt pavement from the reflective cracking effectively, OLSM has good anti-cracking performance, it is an effective material to alleviate the reflective cracking. As the crack-alleviating layer, OLSM can significantly enhance the anti-cracking ability of the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure.

Abstract: Physical models of cathodic protection (CP) for copper protected by 35# steel and for 35# steel protected by aluminum sacrificial anode respectively in seawater were built in this study. Weak form of Laplace equation was deduced to make finite element method (FEM) numerical calculation conveniently. Then, potential distribution of each physical model was computed by FEM following with measured experiments for validation. Typical FEM simulated data along X-axis and Y-axis of physical models agree well with measured experimental data. For 35# steel protected by aluminum sacrificial anode models, normal cathodic protection, over-protected (OP) and under-protected (UP) models were built, respectively. The results demonstrated that it should be feasible of CP for copper by 35# steel and for 35# steel by aluminum sacrificial anode respectively, and FEM could afford well forecast for CP design in engineering.

Abstract: In this work, the effects of creep behaviors for constituent materials in thermal barrier coatings (TBCs) on the morphology change occurring near the surface groove are investigated upon twenty-four purely thermal cycles using the finite element method. The formation of thermally grown oxide (TGO) in lateral and thickness directions at high temperature are simulated by means of material property change based on in-house measured material properties such as yield strength and TGO final thickness. The result shows that under the purely thermal cycles the creep in constituent materials significantly enhances the morphology change near the grooves. It is also found that creep in only substrate predominates at high temperature while creep only in TGO plays a less important role in the morphology change due to its relatively slower creep behavior compared to Fecralloy substrate.

Abstract: In this study, the residual stress in copper base brazed stainless steel plate-fin structure was investigated through thermo-mechanical coupled finite element analysis (FEA) models. The results show that the maximum residual tensile stress occurs in the brazed joint next to the plate side. In addition, the dependence of residual stress distribution on filler thickness was also analyzed. The detailed stress distribution would provide some constructive instructions in the practical brazing procedure.