Reactive synthesis of Ti-Al intermetallics during microwave heating in an E-field maximum

The time-resolved X-ray diffraction synchrotron radiation technique was used in combination with E-field microwave heating to study in situ the kinetics of intermetallic phase formation in the Ti-Al system. The reaction of Ti with Al is triggered by the melting and spreading of Al onto the surface of Ti particles. The tetragonal TiAl 3 phase is the primary reaction product, formed by instantaneous nucleation at the interface between the unreacted Ti cores and the Al melt. The growth of TiAl 3 layers is diffusion-controlled. These preliminary results demonstrate that microwave heating can be used to rapidly synthesise intermetallic phases from high-purity elemental powders. © 2010 Elsevier B.V. All rights reserved.This work has been supported by the Swiss National Science Foundation (Grant 20PA21E-129193).Vaucher, S.; Stir, M.; Ishizaki, K.; Catalá Civera, JM.; Nicula, R. (2011). Reactive synthesis of Ti-Al intermetallics during microwave heating in an E-field maximum. Thermochimica Acta. 522(1):151-154. doi:10.1016/j.tca.2010.11.026S151154522

Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti–Ag–O films. The Ti–Ag–O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen on unheated glass substrate held on floating potentialUfl. It was found that addition of ~2 at.% of Ag into TiO2film has no negative influence on UV-induced hydrophilicity of TiO2film. Thick (~1,500 nm) TiO2/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (~1,500 nm) TiO2/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (~700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO2/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency ofEscherichia coliATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO2with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to killE. colieven under visible light due to direct toxicity of Ag

Effect of welding parameters on mechanical and microstructural properties of AL 2024 joints produced by friction stir welding

Results of Friction Stir Welding (FSW) of aluminium 2024 are presented in this paper. Investigations were conducted on the welding machine, built on the base of the conventional, vertical milling machine. The quality assessment of joints was done on the grounds of the visual inspection, tensile and fatigue tests, the analysis of the welds structure and hardness. Heat treatment was not done after the welding process. The goal of the research was to know the relationship between welding parameters and mechanical and microstructural properties of 2024joints. Results indicate that weldability of aluminium alloys of Al 2024 4 mm in thickness with FSW method is good. Properties ofjoints with the FSW method on the milling machine eąuipped with LOWSTIR device fulfil requirements of this kind of joints. The structure is correct and the tensile properties are higher than properties of arc welded joints. With wide range of welding parameters the high quality of joint is possible. Joints welded with the different tools and in different conditions had characteristic shape of nugget, heat affected zone and thermo-mechanically affected zone. The kind of tool is not affected on properties of FSW joint at the same parameters. The proper quality at four different kind of tool is possible to achieve. Fatigue properties of the FSW joints made in correct way are very high, higher than properties of arc welded joints. Hardness profile of welds had characteristic run, typical for joints welded with the FSW method. The LOWSTIR device is not getting worse the quality of FSW joints

Spark plasma sintering synthesis of porous nanocrystalline titanium alloys for biomedical applications

The reason for the extended use of titanium and its alloys as implant biomaterials stems from their lower elastic modulus, their superior biocompatibility and improved corrosion resistance compared to the more conventional stainless steel and cobalt-based alloys [Niinomi, M., Hattori, T., Niwa, S., 2004. Material characteristics and biocompatibility of low rigidity titanium alloys for biomedical applications. In: Jaszemski, M.J., Trantolo, D.J., Lewandrowski, K.U., Hasirci, V., Altobelli, D.E., Wise, D.L. (Eds.), Biomaterials in Orthopedics. Marcel Dekker Inc., New York, pp. 41-62]. Nanostructured titanium-based biomaterials with tailored porosity are important for cell-adhesion, viability, differentiation and growth. Newer technologies like foaming or low-density core processing were recently used for the surface modification of titanium alloy implant bodies to stimulate bone in-growth and improve osseointegration and cell-adhesion, which in turn play a key role in the acceptance of the implants. We here report preliminary results concerning the synthesis of mesoporous titanium alloy bodies by spark plasma sintering. Nanocrystalline cp Ti, Ti-6Al-4V, Ti-Al-V-Cr and Ti-Mn-V-Cr-Al alloy powders were prepared by high-energy wet-milling and sintered to either full-density (cp Ti, Ti-Al-V) or uniform porous (Ti-Al-V-Cr, Ti-Mn-V-Cr-Al) bulk specimens by field-assisted spark plasma sintering (FAST/SPS). Cellular interactions with the porous titanium alloy surfaces were tested with osteoblast-like human MG-63 cells. Cell morphology was investigated by scanning electron microscopy (SEM). The SEM analysis results were correlated with the alloy chemistry and the topographic features of the surface, namely porosity and roughness

"CATEAP: The Virtual Academic Writing Class"

This paper describes CATEAP software, which has been developed, and continues to be developed by Jon Mills at the University of Luton. CATEAP provides all the materials for the writing component of the Academic English and Study Skills module for first year undergraduate students whose first language is not English. CATEAP aims to explain and provide practice in a number of language functions that are employed in academic discourse and provides approximately 40 hours of writing activities. CATEAP is for classroom use with a teacher present and lock-step is necessary at various points during each lesson. Each lesson incorporates a variety of tasks and task types including pages of exposition, drills, short essay writing, peer critiquing and use of a concordancer. Peer critiquing of essays takes place over the intra-net with the students adopting pseudonyms. Students report that they like the anonymity that this virtual classroom provides. The role of the teacher is concerned with managing the virtual classroom, allowing students to sometimes work at their own pace and at other times focussing the entire class in lock-step