Application of methyl methacrylate for pressing and machining of alumina green ceramics

The addition of methyl methacrylate (MMA) in the amount of 2 mas% in the alumina mixture improved the pressing of alumina and achieved excellent quality of machining of green compacts. The compressibility test determined the optimal pressing pressure of alumina with MMA of 60 MPa. The value of green densities was analyzed depending on applied pressure up to 150 MPa. The exceptionally smooth and shiny surface of green compact indicates good pressing of alumina with MMA. After pressing, the samples were thermally treated at 115 o C to activate the side groups of MMA polymer chains at a temperature slightly higher than the glass transition temperature (103 o C) of PMMA. This way was to improve the strength of the green compact. Compacts prepared with MMA had higher values of green density and lower values of sintered density, total and open porosity than compacts without MMA. After sintering at 1620 o C, the relative linear shrinkage was about 15% for the entire range of applied pressing pressures. The machining of the green compact enables the precise production of complicated forms of technical ceramics for the needs of many areas of the economy.X Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 26-27, 2022; Belgrad

Macroporous monoliths based оn natural mineral sources, clay аnd diatomite

Macroporous silica ceramic was obtained using clay and diatomite. Boric acid as a low-cost additive in the amount of 1 wt% was used. These porous materials were obtained at low forming pressure (40-80 MPa) and lower sintering temperature (850-1300 ºC) for 4h in air. The influence of boric acid, forming pressure, and sintering temperature on the microstructure, porosity parameters, and mechanical properties of obtained porous monoliths were investigated. As-received and the modified samples were characterized by X-ray diffraction, FTIR, SEM, and mercury porosimetry measurements. As for modified clay and diatomite, they were pressed at 60 MPa and then sintered at 1150 ºC, obtaining porosities of about 10 % and 60 %, respectively. Both of the analyzed samples had the pore diameter in the range of macroporous materials. The pore diameters of clay samples are ranging from 0.1-10 μm, whereas the pore diameter of diatomite samples was slightly lower with values ranging from 0.05-5 μm. Modified diatomite samples have a lower Young modulus in comparison to modified clay samples

Preparation and characterization of clay and diatomaceous earth based porous ceramics with boric acid as additive

Poste

The effect of acrylate on the properties and machinability of alumina ceramics

Effect of methyl methacrylate (MMA) as a binder and heating treatment were investigated to improve green alumina compacts machinability. Properties of green compacts and their corresponding sintered samples prepared with and without MMA were compared. Investigation of green and sintered properties was performed on samples compacted at applied pressures up to 150 MPa. After pressing, samples with MMA were thermally treated at 115oC. The intention was to enhance the polymerization of MMA at a temperature a little higher than the glass transition temperature (Tg = 103oC) of poly (methyl methacrylate). Green compacts with MMA had higher green density values than those without MMA. Sintered samples with MMA had lower values of sintered density and higher values of total porosity; after sintering, relative linear shrinkage was around 15 % for the whole range of applied pressures. The possibility of easily machining the green compacts with MMA produces great possibilities for application in many field

Iron (III) Oxide Fabrication From Natural Clay With Reference to Phase Transformation gamma- - GT alpha- Fe2O3

Amorphous iron (III) oxide was obtained from clay, using ammonium hydroxide as a precipitating agent. Influence of freeze drying under vacuum, as a drying method, on particle size, chemical composition, and crystallinity of obtained iron (III) oxide powder was investigated. After freeze drying, precipitate was annealed in air at 500 C-o and 900 oC. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis were used to characterize obtained iron (III) oxide powder. All of three powders obtained by freeze drying and annealing, have low crystallinity and particles with irregular layered shape. Narrow particle size distribution was given by an average diameter value of around 50 mu m for all observed powders. Iron-bearing materials like a-Fe2O3 and gamma-Fe2O3 are obtained. Differential thermal analysis curve of obtained samples showed endothermic reaction at 620 oC which could be ascribed to phase transition from cubic form gamma- - GT alpha- Fe2O3. Thermal transformations of iron (III) oxide, obtained from clay as a natural source, is suitable to explore in the framework of materials chemistry, and opens the possibility to synthesize materials based on Fe2O3 with specific magnetic behavior

Application of FeAl-LDH@SiO2 for Phosphate Removal from Water

In present study FEAL-LDH@SIO2 were Used for removing phosphate from aqueous solutions. FeAl-LDH with molar ratio Fe/Al = 3/1 was synthesized by co- precipitation from aqueous solutions in the present of SIO2 PARTICLES. Silica obtained from rice husks were used as a substrate for the deposition of LDH particles. The prepared material was characterized by scanning electron microscope (FE-SEM), X-ray diffraction (XRD), N2 adsorption/desorption isotherms (BET method) and Fourier transform infrared spectroscopy (FTIR). XRD analysis showed that Fe-Al had formed LDH structure. SEM analysis revealed deposition of LDH particles on SIO2 SUBSTRATE. The adsorption characteristics for phosphate uptake of the obtained material were performed. Adsorption experiments were carried out as a function of LDHs dosage with three different mass ratios of LDH/silica = 1/1, 2/1, and 3/1 and different phosphate concentration AT INITIAL PH 4. Phosphate concentrations were determined using spectrophotometer. The results showed that the maximum sorption capacities of phosphates calculated based on Langmuir equation was 52.68 mg g-1.The book of abstract available at: [http://conf.univerzitetpim.com/wp-content/uploads/2022/06/Book-of-Abstracts_2022-1.pdf