Conventional Ball-milling Method Research Articles

Enhanced photocatalytic performance of gadolinium-doped lithium manganese oxide (Li4Mn5O12) by conventional ball milling method

Abstract Current research aims to improve the characteristics of lithium manganese oxide (LiMn2O4), a highly prospective for waste water treatment applications, by incorporating gadolinium (Gd-0.25 %) into the manganese position. This integration, achieved via conventional ball milling, aims to improve the structural, morphological, and electrical characteristics of Li4Mn5O12. A range of analytical methods, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and impedance testing, were utilized to evaluate the influence of Gd-0.25 % on Li4Mn5O12. The results indicate that the inclusion of Gd at the manganese sites enhances the thermal conductivity of Li4Mn5O12 (Li4Mn4.75Gd0.25O12), leading to improved conductivity compared to undoped Li4Mn5O12. Additionally, the enhanced material exhibits promising potential as an efficient photocatalyst, demonstrated by its degradation of methylene blue (MB) dye.

Fabrication of Al2O3/AlN composite ceramics with enhanced performance via a heterogeneous precipitation coating process

To improve the thermal and mechanical properties of Al2O3/AlN composite ceramics, a novel heterogeneous precipitation coating (HPC) approach was introduced into the fabrication of Al2O3/AlN ceramics. For this approach, Al2O3 and AlN powders were coated with a layer of amorphous Y2O3, with the coated Al2O3 and AlN powders found to favor the formation of an interconnected YAG second phase along the grain boundaries. The interconnected YAG phase was designed to act as a diffusion barrier layer to minimize the detrimental interdiffusion between Al2O3 and AlN particles. Compared with samples prepared by a conventional ball-milling method, the HPC Al2O3/AlN composites exhibited less AlON formation, a higher relative density, a smaller grain size and a more homogeneous microstructure. The thermal conductivity, bending strength, fracture toughness and Weibull modulus of the HPC Al2O3/AlN composite ceramics were found to reach 34.21 ± 0.34 W m−1 K−1, 475.61 ± 21.56 MPa, 5.53 ± 0.29 MPa m1/2 and 25.61, respectively, which are much higher than those for the Al2O3 and Al2O3/AlN samples prepared by the conventional ball-milling method. These results suggest that HPC is a more effective technique for preparing Al2O3/AlN composites with enhanced thermal and mechanical properties, and is probably applicable to other composite material systems as well.

Low-temperature sintering and microwave dielectric properties of Li2Mg3ZrO6 ceramics derived from high-energy ball milling

The effects of synthesis temperature, milling time and dwell time on phase formation and phase constitutes of Li2CO3–MgO–ZrO2 mixtures were investigated by high-energy ball milling (HEBM). The Li2Mg3ZrO6 (LMZ) nanopowders were obtained from the mixtures by HEBM 20 h and calcined at 900 °C for 2 h, 300 °C lower than that required by a conventional ball milling method. The sintering characteristics, microstructures and microwave dielectric properties of Li2Mg3ZrO6 ceramics doped with x wt% LiF (0 ≤ x ≤ 8) were investigated. Addition of 6 wt% LiF reduced the sintering temperature of Li2Mg3ZrO6 ceramics to 850 °C, with the fantastic microwave dielectric properties: er = 12.94, Q f = 131,420 GHz, τf = − 35.84 ppm/°C. The good effect of LiF on sintering process is due to substitution of F− for O2− and liquid-sintered process.

Low-firing Li4Mg3Ti2O9–CaTiO3 composite ceramics with temperature stable microwave dielectric properties

The nanopowders of Li4Mg3Ti2O9 (LMT, 37 nm) and CaTiO3 (CT, 110 nm) compounds were synthesized through a sol–gel method and calcined at 600 °C, about 450 °C lower than that required by conventional ball-milling method. The (1 − x)LMT-xCT (0.05 ≤ x ≤ 0.2) composite ceramics doped with 4 wt% LiF were prepared for low-temperature co-fired ceramics (LTCC). A near-zero τf value was obtained by adjusting composition x of CT. 4 wt% LiF-doped 0.85LMT-0.15CT ceramics sintered at 850 °C possess optimum microwave dielectric properties: er = 19.5, Q × f = 25,790 GHz, τf = − 5.8 ppm/°C. Such sample was compatible with Ag electrodes, which indicates the ceramic is a promising material for LTCC application.

Improved sintering ability of SiC ceramics from SiC@Al2O3 core-shell nanoparticles prepared by a slow precipitation method

SiC@Al2O3 composite nanoparticles with core-shell structure were prepared by a slow precipitation method, aimed at improving the sintering ability of SiC. SiC nanoparticles with average particle size of 100 nm were prepared by a fluidized bed-chemical vapor deposition (FB-CVD) method. The Al(OH)3 coating was formed by slow precipitation of aluminum nitrate in urea solution. The coating layer was then transformed to Al2O3 after further heat treatment. By controlling the rate of urea hydrolysis and the aluminum nitrate concentration in the solution, the thickness of the coating layer could be adjusted. The results of X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Energy Dispersive Spectrometer (EDS) indicated that Al2O3 was uniformly coated on the surface of SiC particles and the two phases were closely contacted. The improved sintering ability of SiC@Al2O3 composite nanoparticles were validated, and better mechanical properties were obtained compared with the sintering results using the conventional ball milling method.

Nanopowders preparation and dielectric properties of low-fired Li3Mg2NbO6 ceramics

The pure phase of Li3Mg2NbO6 powders was fabricated with an average grain size of 222 nm at 800 °C derived from high energy ball-milling method. By using the nanopowders as a precursor, well-densified Li3Mg2NbO6 ceramics were obtained with a relative density of 95.9% at 950 °C, which is 300 °C lower than that required by the conventional ball-milling method. Low-fired Li3Mg2NbO6 ceramics exhibited good microwave dielectric properties of er = 18.0, Q × f = 51,870 GHz, τf = − 23.01 ppm/°C, which suggests the developed materials are suitable for low-temperature co-fired ceramic applications.

Fabrication of translucent alumina ceramics from pre-sintered bodies infiltrated with sintering additive precursor solutions

Translucent alumina ceramics were fabricated by infiltrating aqueous solutions containing sintering dopant ions (Mg2+/Y3+/La3+) into pre-sintered alumina compacts and sintering in H2 atmosphere. The improved microstructural homogeneity, finer grain size and enhanced transmission properties of infiltration processed samples over those processed by conventional ball-milling method were corroborated by experimental results. Triple doping via infiltration appears to be significantly beneficial for achieving enhanced transmission (36.3% at wavelength 800 nm for sample thickness of 0.75 mm). This study indicates that infiltration technique can be used to fabricate translucent alumina ceramics with improved performance.

Effect of Alcohol Solvent on Mixing of Fine Ceramic Powders and Some Properties of Ceramic-Based Composites.

Effect of alcohol solvent in mixing process on the microstructure and sintering behavior of ceramic-based composites was investigated in detail. The mixture of fine ceramic powders was prepared through the conventional ball-milling method with various alcohol media. The particle distributions of fine ceramic powders were strongly dependent on the kind of alcohol employed during ball-milling. Ceramic-based composites were fabricated by hot-pressing the mixture of fine ceramic powders. Their microstructures and some mechanical properties of the ceramic-based composites were evaluated. It was found that the viscosity of alcohol, surface tension and contact angle greatly affect the sinterability and some of the mechanical properties of ceramic-based composites.

Mössbauer study of mechanically alloyed powders

Using the57Fe Mossbauer spectroscopy, the microscopic behavior of Fe powders has been investigated during and after the mechanical alloying (MA) process for Al−Fe and Ag−Fe systems. A repeated rolling method as well as a conventional ball-milling method are employed in order to understand the microscopic process of the kneading of Al and Fe powders during their MA and the resultant powders show quite similar Mossbauer spectra suggesting that the kneading by an impact between colliding balls is the same process as that of the thickness reduction by cold rolling. Mossbauer spectra show clearly the occurrence of the mutual atomic dispersion for the thermodynamically immiscible Ag−Fe system.

Mössbauer study on mixing and kneading of metallic powders

Utilizing57Fe and119Sn Mossbauer spectroscopy, the microscopic behavior of metallic powders has been investigated during and after the mechanical alloying (MA) process. A conventional ball-milling method is employed and the following combinations of metallic powders have been studied for their MA; Al−Fe, Fe−Sn and Ag−Fe. Mossbauer spectra show the occurrence of mutual atomic dispersion during the MA process even for the Ag−Fe system which is known as mutually immissible even in the liquid state. Formation of an amorphous phase in the Al−Fe system has been detected.