Nano-indentation investigations of the mechanical properties of thin tio2, wo3 and their composites layers, deposited by spray pyrolysis

The aim of the present work is to determine the indentation hardness (HIT) and indentation modulus (EIT) of pure TiO2 and WO3 thin films, as well as thin films composed of different TiO2 and WO3 proportions and deposited by spray pyrolysis on a stainless-steel (OC 404) substrate. Since the HIT and EIT of the films are properties expected to depend on the phase-chemical composition, morphology, structure and their changes when increasing the WO3 content in the TiO2-WO3 composite film, the correlation between the mechanical and structural properties is also addressed. The obtained results show that HIT and EIT strongly depend on the concentration of the co-deposited WO3. The determined values of HIT and EIT noticeably decrease (in comparison with HIT and EIT of the pure (100 %) TiO2 layer) when very low concentrations of WO3 (up to 2.5 % of W) are co-deposited. At higher concentrations of the co-deposited WO3 (more than 2.5 % of W), the HIT and EIT values increase almost linearly with an increase of the WO3 in the precursor. The observed non-proportional behavior of HIT and EIT is associated with specific changes of the structure and a development of defects in the deposited TiO2-WO3 composite phase, as well as with the increase in the amount of the formed separate WO3 phase (with increasing of WO3 (H2W3O12) in the working solution) surrounded by solitary TiO2 particles

Improving the Corrosion Resistance of Anodized Al 1050 Alloy by Sealing in Cerium-Containing and Mixed Sodium Phosphate Mono Basic and Calcium Nitrate Solutions

This investigation presents results on the improvement of the corrosion-protective effect of consecutive sealing treatments of anodized Al 1050 (AlAnod). The treatments were performed in cerium-containing and mixed NaH2PO4 + Ca(NO3)2 solutions. The changes of the surface morphology, structure and chemical composition, chemical state of the elements, and basic corrosion parameters of the studied systems were investigated by SEM, EDXS, XRD, XPS, and a complex of electrochemical techniques (PDP, EOCP vs. timeplot, chronoamperometric transients, Rp and CR at EOCP, etc.). The results obtained show that the basic components of the obtained sealing conversion layers (before and after exposure to model Cl−-containing corrosion media) are characterized by Ca10(PO4)6(OH)2, AlO(OH), CePO4, and CeAlO3 (after the corrosion tests, they are converted to insoluble Me-PO3 and Me-P4O10). We conclude that the observed decrease in the corrosion rate of Al and the corresponding increase in the polarization resistance are accomplished by the two-step sealing treatment, which fills up the AlAnod pores with insoluble deposits

Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications

Single thin coating of matt nickel (Nimat), a mirror bright copper (Cubright), a mirror bright nickel (Nibright) and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings

Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications

Single thin coating of matt nickel (Nimat), a mirror bright copper (Cubright), a mirror bright nickel (Nibright) and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings

STUDY OF THE CHEMICAL FORMATION OF CERIUM OXIDE CONVERSION LAYERS ON ALUMINIUM AD-3

The effect of the concentration of cerium ions as а component of electrolytes, designed for conversion treatment, has been studied in view of the morphology and structure of the conversion films, formed on Al. The studies have been carried out in a complex electrolyte containing cerium and copper ions at temperature 25 °С and duration of the treatment 60 and 120 min. It has been found out that the presence of copper ions in the electrolyte leads to the formation of more compact and richer in cerium conversion films. The electrochemical characteristics (corrosion current, corrosion potential) of the formed films have been investigated applying potentiodynamic polarization method in 0.1 M NaCl solutions. The composition of the electrolytes has been optimized with respect to the concentrations of cerium and copper ions, aiming at obtaining conversion films having improved protection ability. Thereupon the influence of the microgalvanic couples copper/aluminium has been established

Curcumin - Prevention and Therapy of Inflammatory Diseases

Introduction: Curcumin is an active polyphenol derived from the spice turmeric, popular in Asian cuisine. Generally believed to be beneficial for human health, it has been an object of scientific studies for the last half century. It has been tested on animals many times, and it has proved to be safe and non-toxic for humans. Analyzing extensive studies, we found out that curcumin has chemopreventive and anti-inflammatory properties. In the near future, this may turn it into a  valuable tool in relieving and completely curing cancer, type 2 diabetes and obesity.Materials and Methods: We based our survey on a meta-analysis of 4 researches published in PubMed and the website of the American Diabetes Association.Results: Extensive clinical researches found that curcumin induces apoptosis in cancer and pre-cancer cells. The turmeric derivative affects cell-signaling pathways of cancer cells and inhibits their cell cycle. Curcumin reduces chronic inflammation by directly interacting with white adipose tissue and suppresses the activation of tumor necrosis factor-α, interleukin-6 and monocyte chemoattractant protein-1 by immune cells. In 2012, a diabetes research was conducted on a group of 240 patients classified as pre-diabetic. Subjects were randomly chosen to receive either curcumin or placebo capsules. To assess the progression of T2DM (type 2 diabetes mellitus), parameters such as insulin-resistance and changes in β-cells were monitored. After 9 months, 16.4% of the subjects in the placebo group developed T2DM. None of the patients in the curcumin-treated group developed diabetes and they showed an overall better function of the pancreatic β cells.Conclusions: Based on the data acquired through the research, we found an opportunity to introduce curcumin into clinics for treatment, prevention and therapy of inflammatory diseases such as T2DM and obesity related diseases. As of recently curcumin has been used in aiding chemo- and radiotherapy in battling cancer

Nanoindentation investigation of mechanical properties of ZrO2, ZrO2-Y2O3, Al2O3 and TiO2 thin films deposited on stainless steel OC 4O4 substrate by spray pyrolysis

Thin ZrO2, ZrO2-Y2O3, Al2O3 and TiO2 films were deposited by spray pyrolysis method on stainless steel DC 404 substrate with thickness 50 mu m. The thicknesses of obtained films varied from 0.50 to 0.64 mu m. The surface morphology and structure of the films were characterized by scanning electron microscopy in secondary electron imaging mode. The X-ray diffraction measurements for determination of the lattice parameters, the average crystallite size and the sample strain were performed. Mechanical properties of investigated films and substrate were investigated by nanoindentation experiments, using Nano Indenter G200 (Agilent Technologies). As a result of nanoindentation experiments, load-displacement curves were obtained and two mechanical characteristics of the substrate and investigated films - indentation hardness (H-IT) and indentation modulus (E-IT) - were calculated using Oliver & Pharr approximation method. Dependence of indentation modulus and indentation hardness on depth of indentation was investigated as well. 2013 Elsevier B.V. All rights reserved