Boron carbide is one of the hardest materials. The combustion method was used to synthesize B4C-TiB2 nanocomposite powder in a B2O3-Mg-TiO2-C system. An experimental study of the formation of B4C–TiB2 nanoparticles was conducted in the thermal explosion mode. A mixture of B2O3:TiO2:Mg:C at a molecular ratio of 3:1:12:1 was chosen to obtain the B4C–TiB2. This powder mixture was milled for different times. The combustion reaction of powders milled for up to 12 h was done in an inert atmosphere at 900°C. The synthesized powders were characterized by X-Ray diffraction, Scanning and Transmission Electeron Microscopies (SEM and TEM). It was demonstrated that mechanical activation is a useful method for obtaining B4C and TiB2 powders simultaneously; without milling, the B4C composition did not form. B4C formed after 3 h of milling of the reactants. Crystallite size of products obtained from reactant powders milled for 6 and 12 hour was less than 100 nanometer. تفاصيل المقالة

The 70SiO2-15TiO2-15ZrO2 membrane was prepared by a sol-gel procedure. The corrosion behavior of microporous toplayers along with the membrane characterization in terms of pore size, surface area, pore volume and weight loss is described. The final ceramic membrane with a thickness of 400 nm and uniform surface was obtained. This membrane confirmed the fine microporous characteristic with mean pore size < 2 nm. After corrosion test, the corroded membrane revealed a surface with non-uniform coverage of the toplayer. The heated ceramic membrane after and before corrosion test was amorphous. Dissolution of ions was increased in acidic and basic solutions. The weight less of samples increased when pH increased at RT. Porosity of samples increased after the corrosion test. The pore size of membrane increased as compared to the pore size of the original membrane after corrosion conditions. Surface area of the membrane increased in basic solution whereas decreased in acidic solution. تفاصيل المقالة