Advanced Materials Research Vols. 875-877

Abstract: A novel anti-caking material (E-Oil) was prepared from waste animal/plant oil and triethanolamine by catalytic synthesis in this study. The E-Oil was analyzed by FTIR and the anti-caking effect of anti-caking materials was described by caking ratio. The FTIR results showed that the reaction product of Waste Animal/Plant Oil and Hydramine was surfactant with anti-caking effect. The anti-caking test results indicated that E-Oil made the caking ratio of compound fertilizer decrease from 39.75% to 16.33%. Taking the cost into consideration, the optimal fraction of E Oil was 5‰ and the caking ratio could reach 16.33%, which could approximately meet the application requirements.

Abstract: This study focused on the development of antibacterial cotton fabric using natural bioactive agent as the extracts from mango (Mangifera indica L) seed. The cotton fabrics have been treated with the extracts from mango seed. Moreover, the tamarind gum from Tamarind indica seed was used as an alternative natural mordant and compared with general chemical mordants (alum and ferrous sulfate) in order to search for eco-friendly process. Treated fabrics were tested for antimicrobial activities against Gram-positive cocci and Gram-negative rods. We have found that in terms of antibacterial activity, the treated fabrics combined with natural mordant were more effective against both tested bacteria. From the results, the tamarind gum could provide the synergic antibacterial activity when applied with the extracts from mango seed and obviously used as substitutes for toxic textile chemicals.

Abstract: According to the characteristic of polyhydroxy alcohol fracturing fluid system, the regeneration of the system was investigated for the first time. A stable organic boron crosslinking poly (vinyl alcohol) regenerable polyhydroxy alcohol fracturing fluid system was prepared, and the rheological property of the polyhydroxy alcohol fracturing fluid system with different regenerable times was also researched. The effect of regenerable times on the rheological property of the system was studied. The results indicated that the aims of gel breaking and regeneration can be achieved by regulating its pH value and controlling its crosslinking degree. With the increment of the regenerable time, both the temperature resistance and shearing resistance performances were decreased, and the viscoelasticity of the gel was also reduced.

Abstract: Hydrogel dressings for biomedical application were obtained by γ-irradiation of poly-N-vinipirrolidon (PVP), agar-agar, polyethylene glycol and silver nitrate solution. Influence of irradiation doses (range from 25 kGy to 75 kGy), silver nitrate concentration and PVP concentration in initial monomer mixture on properties of obtained material were investigated. Presence and distribution of silver nanoparticles in obtained bandages is confirmed by optical microscopy and atomic force spectroscopy. Antimicrobial activity study in vitro showed antimicrobial activity, flexibility, high sorption capacity to water and biological fluids.

Abstract: This paper presents an experiment conducted in Explosia, a.s., Pardubice. A bimetal prepared of AZ 31 Mg alloy - CrNi austenitic steel was tested in various conditions, and consequently its quality was assessed. Focus was particularly on the impact of atmosphere and vacuum on the interface character of the metals (bimetals) prepared by explosion. Parallel placement of the materials being welded was used for welding in both vacuum and air atmosphere. Welding sets were designed and manufactured. The welding parameters and conditions were set up utilising the available computational means, and then verified by simulation in ANSYS engineering-scientific program. Used was Semtex S 35, a loose explosive, as well as Startline 12, an initiation explosive. Bimetal was fabricated in the air atmosphere at the detonation speed 2613 m.s^-1 and in vacuum at the detonation speed 2597 m.s^-1. Quality of bimetals was assessed by optical microscopy, measuring deformations by a 3D scanner, measuring microhardness and also by EDX microanalysis.

Abstract: The work deals with welding of aluminium alloy typeAlMg4,5Mn and magnesium alloy type AZ 31 in solid state by FSW (Friction Stir Welding) process. Experiments were performed in cooperation with VÚZ PI SR (Welding Research Institute Industrial Institute of Slovak Republic) Bratislava, which has available a new installed equipment type FSW LM 060 manufactured in China. Welding parameters and conditions were proposed and approved. Quality of fabricated joints was assessed by optical microscopy, micro hardness measurement and radiographic test - RT. It was supposed that optimisation of welding parameters would allow to fabricate the joints of acceptable quality that might compete to technologies of fusion welding, including welding with concentrated power sources.

Abstract: Gallium trichloride (GaCl₃) and azidotrimethylsilane (CH₃)₃SiN₃ were employed as alternatives gallium and nitrogen precursors respectively in the growth of GaN nanowires via a metal-organic chemical vapor deposition (MOCVD) system. Au pre-deposition on Si (100) substrate was using as catalysis seed to grown of GaN nanowires. X-Ray, FE-SEM and AFM analyses reveal that nanowires grown at temperature 1050 C present morphology characteristic to model VLS. Scanning electron microscopy reveal a surface morphology made up of wurzite that suggests that wires growth involve a melting process. A nucleation and growth mechanism, involving the congruent melting clusters of precursor molecules on the hot substrate surface, is therefore invoked to explain these observations. We attributed the improved growth behavior to the nearer-to-equilibrium growth and may be close to local thermodynamic equilibrium.

Abstract: Several concrete additives have been innovated for improving concrete quality. In this research work the treated kaolin by heat has been used as concrete additive. Kaolin was subjected to the heat for 1 hour in different degree of temperatures. The crystal structure of Kaolin thermally is modified under heat and microstructure of the hydrated samples has been investigated using FESEM. The main objective is to introduce a cost effective concrete additive. The result is indicated that when kaolin subjected to 800 oC and used in 6% quantity as an additive in concrete mixed design, the concrete compressive strength of 14 days is 40% higher than concrete compressive strength of 28 days which is not used any additive. And if 12% additive is used the concrete compressive strength increased in same level on 7 days. This concrete additive reduces construction cost and time.

Abstract: A novel method to prepare the copper bonding on alumina substrate was presented. The cuprous Cu₂O on the surface of Cu foil was prepared by covering cupric oxide (CuO) powder on Cu foil and treating at 600°C in N₂ atmosphere. Then eutectic process was executed at 1075°C in N₂ atmosphere to bond the Cu and alumina substrate. The cuprous grew on copper foil and bonding between Cu foil-alumina substrate were identified by XRD spectrum and SEM micrographs.

Abstract: The contribution deals with resistance spot welding of low carbon steel to austenitic CrNi stainless steel. The thickness of welded dissimilar steels was 2 mm. DeltaSpot welding gun with process tape was utilized for welding of the above-mentioned combination of steels. Resistance spot welds were produced under different welding currents. The welding currents used were 7 kA, 7.5 kA and 8 kA, respectively. Optical microscopy, microhardness measurement across the weld joint and EDX analysis across the weld joint interface were used to evaluate the quality of resistance spot welds of dissimilar steels.