Advanced Materials Research Vols. 622-623

Abstract: Graphene is a form of carbon just one atom thick, it has an array of physical properties that promise to revolutionize electronics and other technical fields. Since the first reports of its discovery in 2004, work on graphene has largely stressed understanding the fundamentals of the two-dimensional material over pursuing applications for it. Graphene may become a key enabling material, paving the way for a new generation of high-speed nanoscale electronics with consequences and breakthroughs similar to that of silicon’s in the last few decades. In this paper we present the evolution of this fascinating material, beginning with early observations and moving into the practical applications.

Abstract: Nano-biohybrid, based on biodegradable polyester, poly (3-hydroxybutyrate) (PHB), and a commercial organo modified montmorillonite (MMT), were prepared by solvent casting technique. Morphology and non-isothermal degradation of PHB and PHB/MMT hybrids were characterized by POM and TG-DTG technique. In the composite materials, an increase MMT loading in the PHB decreased the onset temperature (Tonset) of thermal degradation, while it achieved higher values upon increasing the heating rate. Kissinger plots deduced a trend of the degradation activation energy, Ed, which was related to the agglomeration of MMT. The thermal degradation rate constant, k, was related to the MMT loading in PHB. X-ray diffraction analysis confirmed the expansion of MMT silicate layers.

Abstract: Polycaprolactone (PCL) fiber bundles were successfully prepared by self-bundling electrospinning technique from two different concentrations (i.e. 12% and 15% w/v) of PCL solution. Self-bundling of electrospun fibers was induced by used of a grounded needle tip at the beginning of electrospinning process. Electrical conductivity of PCL solutions were increased and average fiber diameter were decreased by addition and increasing amount of pyridinium formate (PF) at concentration of 3, 4, and 5% w/v into either 12% or 15% w/v PCL solutions. The average diameter of electrospun fibers and bundles were in range of 2.1-3.3 m and 100-120 m, respectively.

Abstract: In this paper, a new kind of superabsorbent polymer (SAP) is designed and prepared. Using sodium persulfate as initiator and N,N’-methylene bisacrylamide as Crosslinker, monomer of acrylic acid can be grafted into the skeleton of natural mineral kaolin with the method of microwave irradiation. The performance of water adsorption for SAP is tested in saturated Ca(OH)2 solution. Also, the internal curing effect of SAP to hydration procedure of cement paste is studied. The result shows that the compressive properties and flexural strength of cement paste specimens in early stage have significant improvement in contrast to those without superabsorbent polymer or excessive or a small amount of superabsorbent polymer, when superabsorbent polymer is accounted for 0.3% to 0.5% of the total cement.

Abstract: Study microcosmic structure feature of ceramics water-mouth new materials using electron micro analysis, analyze its effect to mechanical properties, prove big or small crystal grains are the main factor affecting materials, the existing of structure defect can improve fracture toughness of materials. In the latest years, in order to solve Al₂O₃ forming a tumor, we develop Z_rO₂-C_aO-Al₂O₃ ceramics water mouth new materials whose main composition is Z_rO₂.[1] The thermal conductivity of this material is low, heating stability is good, chemical properties are stable and it don’t soak with most melting metal, so it obtain good effect in practical application. Reducing Al₂O₃ phenomenon of forming a tumor happening, which can extend the water mouth using time limit. But this materials’ sintering temperature is high, bending strength and fracture toughness are not good. Immersion water mouth made by the materials will easily occur disruption phenomenon after using a period of time. In order to solve this problem, this essay study microstructure feature of the materials using electron micro analysis, provide scientific basis for improving materials’ quality.

Abstract: Lead-free (Ba1-xCax)(Ti0.96Zr0.02Sn0.02)O3 (BCTZS) (x=0, 0.01, 0.02, 0.03) ceramics were prepared using conventional solid-state reaction technique. The effects of Ca content on the microstructure and electrical properties of the BCTZS ceramics were investigated. High piezoelctric coefficient was obtained for the sample at x=0.02.

Abstract: In this paper, a standard CFD code, COMSOL is used to describe the 3-dimensional modeling of friction stir welding using threaded tool and based on fully sticking friction. A standard threaded tool profile is used for the full flow analysis including heat generation and heat flow. Temperature distribution is analyzed for full sticking and sliding condition. The effect of different operating parameters on the temperature distribution was performed.The importance of cell Peclet number is also investigated in the temperature distribution on advancing and retreading side. The results are in reasonable agreement with the predictions.

Abstract: Through Transmission Laser Welding (TTLW) of plastic material is an emerging area of research and welding of plastic. For better process control, extensive research work is necessary to explore various aspects of this relatively newer joining process for plastics. This will lead to more effect utilization of the process yielding better weld quality. This paper reports transmission laser welding on acrylic plastic materials by using a diode laser system. Analysis of variance (ANOVA) has been used to study the significance of the parameters on the performance of the welded joint. The results obtained from the pull test of the welded plastic plates have been used to with an objective to optimize the parameter settings used in the TTLW process by using Taguchi method.

Abstract: In this research work, an attempt has been made to study the weldability of AISI 304L using filler materials ENiCu-7 and ENiCrMo-3 by Gas Tungsten Arc Welding (GTAW) process. Investigations are carried out on the metallurgical and mechanical properties of AISI 304L weldments. Further, cyclic hot corrosion studies are performed on the various zones of the weldment in air oxidation for 50 cycles at 600 ^°C. Thermogravimetric data is collected at the end of every cycle and the weldments are characterized using XRD analysis.

Abstract: This research work aims at investigating the performance of the gas tungsten arc welded dissimilar AISI 304 and AISI 310S when subjected to cyclic hot corrosion in air oxidation and in the molten salt environment of K₂SO₄ + 60% NaCl environment at 600°C. The weldments are characterized for its mechanical and metallurgical properties. Tensile strength of the weldment is found to be 529 Mpa. Further the hot corrosion studies are performed on the various zones of the weldment and the corrosion products are characterized by the combined techniques of optical microscopy, XRD and SEM/EDAX analysis.