Corrosion Protection Properties of Various Ligand Modified Organic Inorganic Hybrid Coating on AA 2024-T3

The inclusion of zirconium precursors to prepare organosilane solgel coatings improves the corrosion protection performance of the coatings on aluminium and steel. The inherent differences in the hydrolysis rates of the silane and zirconium precursors, various ligands were used to control the hydrolysis by decreasing the number of reactive alkoxide group. Hybrid sols were synthesised using 3-(trimethoxysilyl) propylmethacrylate (MAPTMS) and zirconium n-propoxide chelated with organic ligands including different organic acids, acetyl acetone and 2 2’ bipyridyl. The effects of zirconia inclusion on the properties of the coatings were compared on the aerospace alloy AA 2024-T3. Electrochemical analysis and salt spray exposure characterized the corrosion protective properties. The results indicate that acid chelated systems possess better corrosion protection when compared to the other ligands, due to smaller zirconium nanoparticles being formed. In particular superior performance was displayed by the coatings involving 3,4 diaminobenzoic acid (DABA) due to inherent anticorrosive properties

Synthesis of High-Temperature Stable Anatase TiO2 Photocatalyst

In the absence of a dopant or precursor odification, anatase to rutile transformation in synthetic TiO2 sually ccurs at a temperature of 600 700 °C. Conventionally, metal oxide dopants (e.g., Al2O3 nd SiO2 are used o tune the anatase to rutile transformation. A simple methodology is reported here to extend the anatase utile transformation by employing various concentrations of urea. XRD and Raman spectroscopy were used uring thermal treatment. A significantly higher anatase phase (97%) as been obtained at 800 C with use of a 1:1 Ti(OPr)4 urea composition and 11% anatase composition is etained even after calcining the powder at 900 . On comparison a sample that has been prepared without rea showed that rutile phases started to form at a temperature as low as 600C. The effect of smaller mounts of urea such as 1:0.25 and 1:0.5 Ti(OPr) urea has also been studied and compared. The investigation oncluded that the stoichiometric modification by urea 1:1 Ti(OPr) urea composition is most effective in extending the anatase to rutile phase transformation by 200°C compared to the unmodified sample. In addition, ET analysis carried out on samples calcined at 500°C showed that the addition of urea up to 1:1 Ti(OPr4:urea increased the total pore volume (from 0.108 to 0.224 cm3/g) and average pore diameter (11 to 30 nm)compared to the standard sample. Samples prepared with 1:1 Ti(OPr)4:urea composition calcined at 900 °C how significantly higher photocatalytic activity compared to the standard sample prepared under similarconditions. Kinetic analysis shows a marked increase in the photocatalytic degradation of rhodamine 6G on oing from the standard sample (0.27 min, decoloration in 120 min) to the urea-modified sample (0.73min-1, decoloration in 50 min)

Nitrogen and Copper doped solar light active TiO2 photocatalyst for water decontamination

A novel class of photocatalytic coating capable of degrading bacterial and chemical contaminants in the presence of visible sunlight wavelengths was produced by depositing a stable photocatalytic TiO2 film on the internal lumen of glass bottles via a sol gel method. This coating was prepared in either undoped form or doped with nitrogen and/or copper to produce visible light-active TiO2 films which were annealed at 600 °C and were characterized by Raman, UV-Vis, and X-ray photoelectron spectroscopy. The presence of doped and undoped TiO2 films was found to accelerate the degradation of methylene blue in the presence of natural sunlight, while copper-doped TiO2 films were found to accelerate bacterial inactivation (of E. coli and E. faecalis) in the presence of natural sunlight

Measuring category intuitiveness in unconstrained categorization tasks

What makes a category seem natural or intuitive? In this paper, an unsupervised categorization task was employed to examine observer agreement concerning the categorization of nine different stimulus sets. The stimulus sets were designed to capture different intuitions about classification structure. The main empirical index of category intuitiveness was the frequency of the preferred classification, for different stimulus sets. With 169 participants, and a within participants design, with some stimulus sets the most frequent classification was produced over 50 times and with others not more than two or three times. The main empirical finding was that cluster tightness was more important in determining category intuitiveness, than cluster separation. The results were considered in relation to the following models of unsupervised categorization: DIVA, the rational model, the simplicity model, SUSTAIN, an Unsupervised version of the Generalized Context Model (UGCM), and a simple geometric model based on similarity. DIVA, the geometric approach, SUSTAIN, and the UGCM provided good, though not perfect, fits. Overall, the present work highlights several theoretical and practical issues regarding unsupervised categorization and reveals weaknesses in some of the corresponding formal models