جستجوی مقالات مرتبط با کلیدواژه "cr2o3" در نشریات گروه "مواد و متالورژی"

In this research Cr2O3-SiO2 and Cr2O3-TiO2 green pigments have been fabricated using a mixture of Cr2O3-SiO2 and Cr2O3-TiO2 powder by ceramic method. The samples have been homogenized using planetary mill in a solvent with a ratio of 1:4 for 5 h and then printed on the ceramic using screen printing method and heated in the industrial condition. The crystal structure of samples, the shape and the size of the particles and their optical properties have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis spectroscopy and CIE L*a*b* colorimetric methods. The XRD results show two-phase structure has been created in both samples. The average of crystallite size for Cr2O3-SiO2 and Cr2O3-TiO2 were measured 40 and 34 nanometers, respectively. The SEM images show that the average size of Cr2O3-SiO2 and Cr2O3-TiO2 are 290 and 143 nanometers, respectively. The physical properties of printed ceramic were investigated by SEM and colorimetric methods. The average particle size for printed samples, Cr2O3-SiO2 and Cr2O3-TiO2, on the ceramic were measured 131 and 106 nm respectively.

Alumina-mullite-zirconia composites were prepared by the reaction sintering method between alumina and zircon powders and the effect of two additives (chromium oxide and manganese oxide)were investigated on their properties. 2 and 4 wt% of each oxide were added to the raw material composition and after pressing, the samples were sintered at 1630°C. The results showed that chromium oxide decreased the density, strength, and hardness of the samples, while manganese oxide increased the density, strength, and hardness. The microstructure of the composite made with Chromium oxide was also uniform and homogeneous and the grain size was relatively smaller; whereas, unlike the improved mechanical properties with manganese oxide, this additive resulted in the growth of grains. The boundary phase which was formed between the grains in the samples containing manganese oxide was also investigated. The effect of chromium oxide and manganese oxide on the composition of the final phases (formation of mullite and zirconia) was different.

In the present work, Cr2O3 (C) and Cr2O3-YSZ (CZ) coating were produced using ball milling of the starting powders, mixing the milled powder, and subsequently atmospheric plasma spraying of the agglomerated powders on 304L steel substrate. The corrosion behavior of the coatings with and without sealing was evaluated by electrochemical potentiodynamic polarization and electrochemical impedance spectroscopy as well as immersion tests in a 3.5% NaCl solution. The results of microscopic image analysis showed that addition of YSZ to C coating caused an increase in coating porosity from 8.7% to 10.2% and a decrease in splats degree of flattening. Data obtained from electrochemical tests indicated the better corrosion resistance for individual Cr2O3 coating that was related to its denser microstructure. Sealing treatment by limiting electrolyte access to the substrate surface considerably increased the corrosion resistance (ohm.cm2) of the C and CZ coatings from 191 and 379 to 23189 and 77916, respectively.