Effect of mechanical activation on mullite formation in an alumina-silica ceramics system at lower temperature

2016 ◽  
Vol 13 (4) ◽  
pp. 288-293 ◽  
Author(s):  
David O. Obada ◽  
David Dodoo-Arhin ◽  
Muhammad Dauda ◽  
Fatai O. Anafi ◽  
Abdulkarim S. Ahmed ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Milling Time ◽  
Batch Composition ◽  
Mullite Formation ◽  
X Ray Diffraction ◽  
Content Type ◽  
Mullite Phase ◽  
Lower Temperature ◽  
Precursor Powders ◽  
Structural Disordering

Purpose This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders. Design/methodology/approach A batch composition of kaolin, alumina and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM). Findings It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short milling times only helped in mixing of the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration. Originality/value It is noted that, a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded for the production of mullite from the specific stoichiometric batch formed.

A New Technology of Producing Fe-TiC Powder by Mechanical Activation-Reductive Diffusion

2011 ◽  
Vol 199-200 ◽  
pp. 1813-1818
Author(s):  
Wei Li ◽  
Kang Sun
Keyword(s):  
Mechanical Activation ◽  
Ball Milling ◽  
Milling Time ◽  
New Technology ◽  
Time Intervals ◽  
Mixed Powder ◽  
Cost Efficient ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Ball Milling Time

A lower-temperature and cost-efficient way is developed to produce Fe-TiC powders. Fe-TiC is produced by means of mechanical activation -reductive diffusion with ilmenite and graphite. The feasibility of this method and the kinetics of the carbothermic reduction are studied with both natural ilmenite and synthetic ilmenite, respectively. The result approved that Fe-TiC powder could be produced by this new technique; moreover, the particles were prominently diminished in size and activated after ball milling. No obvious reactions were detected when ball milling time was less than 8h by EPMA and XRD; however, the mixed powder of Fe and TiC was obtained after annealing for different time intervals. The kinetic study showed that the apparent activation energy of the reductive reaction decreased gradually with milling time due to mechanical activation, but this effect weakened after ball milling for 6h. As ascertained experimentally, the optimum ball milling time was between 4h and 6h.

scholarly journals Sol-Gel Synthesis of Mullite Starting from Different Inorganic Precursors

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Lucia Téllez Jurado ◽  
Rosa María Arévalo Hernández ◽  
Enrique Rocha-Rangel
Keyword(s):  
Sol Gel ◽  
Experimental Methodology ◽  
Isothermal Treatment ◽  
Mullite Formation ◽  
Lower Temperature ◽  
Precursor Powders ◽  
Sol Gel Synthesis ◽  
Inorganic Precursors ◽  
Mullite Ceramics

Using silicotetraetilortosilicate (TEOS) mixed with aluminum tri-sec-butoxide (TSBAI) or aluminum cloaures mullite ceramics were created by the sol-gel method. The quantities used of each substance were those that led to obtain stoichiometric mullite (3Al2O3·2SiO2). The experimental methodology used for obtaining mullite consisted in: sol-gel synthesis of precursor materials, isothermal treatment of those materials, and characterization of resulting materials. In order to determine the advance of reactions during mullite formation, isothermal treatments between 300°C and 1600°C were performed, keeping the samples at each temperature during 4 h. From XRD results, it may be said that precursor powders originally amorphous start to crystallize in Al2O3 and SiO2 at 1200°C, and the mullite formation starts at 1200°C, with being completed at 1600°C. The use of TSBAI favors the formation of mullite crystals at lower temperature. From SEM observations a microstructure that presents primary mullite with randomly oriented grains of secondary mullite with acicular shapes and sizes that range between 1.25 and 1.50 μm long may be determined.

Synthesis, Characterization and Properties of Forsterite Refractory Produced from Thai Talc and Magnesite

2018 ◽  
Vol 940 ◽  
pp. 46-50
Author(s):  
Surapattanapong Kullatham ◽  
Sakdiphon Thiansem
Keyword(s):  
Physical Properties ◽  
Mechanical Activation ◽  
Ball Mill ◽  
Milling Time ◽  
Raw Materials ◽  
True Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrf Scanning ◽  
Subsequent Calcination

This paper reports the synthesis, characterizations, microstructure and properties of forsterite powder produced in Thailand from talc and magnesite as raw materials by using mechanical activation with subsequent calcination. The synthesis forsterite powder were mixed by using talc and magnesite at 1:5 mole ratio. The maximum milling time was 24 h in a planetary zirconia ball mill. Afterward, the mixtures were calcined in an electric furnace for 1 h at 900, 1000, 1100, 1200 and 1300°C respectively. The synthesized powder was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and physical properties. Results of the physical properties of synthesized forsterite showed an increased in density as the calcining temperature increased. In contrast, porosity was decreased with an increase of the calcining temperature. Therefore, forsterite that was calcined at 1300°C provided the best results which were 2.96 g/cm3 of true density and 15.41% of true porosity. Results of XRD of synthesized powder indicated that the forsterite crystallization was constant for which sharpen appeared after 5 h of mechanical activation. Fraction of forsterite was appeared after being calcined at 1000°C for 1 h with an increasing of calcination temperature, the fraction of forsterite phase increased. Based on the mentioned characteristics, the forsterite produced from Thai talc and magnesite exhibited properties of an insulator and can potentially be used as refractory devices.

Tetragonal to orthorhombic transformation during mullite formation

1991 ◽  
Vol 6 (4) ◽  
pp. 819-824 ◽  
Author(s):  
Dong X. Li ◽  
William J. Thomson
Keyword(s):  
Solid Solution ◽  
Single Phase ◽  
Sol Gel ◽  
The Other ◽  
Processing Conditions ◽  
Mullite Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mullite Phase ◽  
Increasing Temperature

The mullite formation process in both single phase and diphasic sol-gel precursors to mullite was studied using dynamic x-ray diffraction (DXRD). A metastable, tetragonal-like mullite phase was observed in all the single gels at temperatures from 980 °C to 1200 °C, but not in any of the other precursors. The tetragonal to orthorhombic mullite transformation was very slow as the lattice parameters, a and b, split and moved gradually away from each other as a result of a gradual decrease of alumina content in the mullite solid solution with increasing temperature from 1100 °C to 1200 °C. The formation of tetragonal mullite coincides with that of the Al–Si spinel. The occurrence of tetragonal mullite or the spinel (or both) is determined mainly by the processing conditions of the sol-gel precursors.

Development of assembly techniques for connection of AlGaN/GaN/Si chips to DBC substrate

Circuit World ◽  
2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ryszard Kisiel ◽  
Marek Guziewicz ◽  
Andrzej Taube ◽  
Maciej Kaminski ◽  
Mariusz Sochacki
Keyword(s):  
Surface Condition ◽  
Diffraction Method ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
X Ray Diffraction ◽  
Content Type ◽  
Lower Temperature ◽  
Gan On Si ◽  
Solid Liquid ◽  
Metal Layers

Purpose This paper aims to investigate the sintering and solid liquid interdiffusion bonding (SLID) techniques to attach AlGaN/GaN-on-Si chips to direct bond copper (DBC) substrate. The influence of metal layers deposited on the backside of AlGaN/GaN-on-Si dies on the assembly process is also investigated. Design/methodology/approach The authors assumed the value of the shear strength to be a basic parameter for evaluation of mechanical properties. Additionally, the surface condition after shearing was assessed by SEM photographs and the shear surface was studied by X-ray diffraction method. The SLID requires Sn-plated DBC substrate and can be carried out at temperature slightly higher than 250°C and pressure reduced to 4 MPa, while the sintering requires process temperature of 350°C and the pressure at least 7.5 MPa. Findings Ag-, Au-backside covered high electron mobility transistor (HEMT) chips can be assembled on Sn-plated DBC substrates by SLID technology. In case of sintering technology, Cu- or Ag-backside covered HEMT chips can be assembled on Ag- or Ni/Au-plated DBC substrates. The SLID process can be realized at lower temperature and decreased pressure than sintering process. Research limitations/implications For SLID technology, the adhesion between Cu-backside covered HEMT die and DBC with Sn layer loses its operational properties after short-term ageing in air at temperature of 300°C. Originality/value In the SLID process, Sn-Cu and Sn-Ag intermetallic compounds and alloys are responsible for creation of the joint between Sn-plated DBC and micropowder Ag layer, while the sintered joint between the chip and Ag-based micropowder is formed in diffusion process.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

scholarly journals An accelerated and effective synthesis of zinc borate from zinc sulfate using sonochemistry

2020 ◽  
Vol 43 (1) ◽  
pp. 7-14
Author(s):  
Ali Can Ersan ◽  
Azmi Seyhun Kipcak ◽  
Meral Yildirim Ozen ◽  
Nurcan Tugrul
Keyword(s):  
Inorganic Compounds ◽  
Zinc Borate ◽  
High Yield ◽  
X Ray Diffraction ◽  
Ultrasonic Probe ◽  
Minimum Particle Size ◽  
Effective Synthesis ◽  
Ft Ir ◽  
Lower Temperature ◽  
Borate Compound

AbstractRecently, sonochemistry has been used for the synthesis of inorganic compounds, such as zinc borates. In this study using zinc sulphate heptahydrate (ZnSO4·7H2O) and boric acid (H3BO3) as starting materials, a zinc borate compound in the form of Zn3B6O12·3.5H2O was synthesized using an ultrasonic probe. Product’s characterization was carried out with using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Zinc borate compound’s chemical bond structure was observed with Raman and FTIR. From the XRD results it was seen that Zn3B6O12·3.5H2O can be quickly synthesized upon heating at 80°C and 85°C (55 min) or 90°C (45 min) in very high yield (>90%). The minimum particle size obtained was ~143 μm from the SEM results. Zinc borate compound was synthesized at a lower temperature in less time than other synthesized zinc metal compound in literature.

scholarly journals X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

scholarly journals Transport and Dielectric Properties of Mechanosynthesized La2/3Cu3Ti4O12 Ceramics

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 313
Author(s):  
Mohamad M. Ahmad ◽  
Hicham Mahfoz Kotb ◽  
Celin Joseph ◽  
Shalendra Kumar ◽  
Adil Alshoaibi
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Boundary Conductivity ◽  
X Ray ◽  
Giant Dielectric ◽  
Mechanochemical Milling ◽  
Giant Dielectric Constant ◽  
Lower Temperature

La2/3Cu3Ti4O12 (LCTO) powder has been synthesized by the mechanochemical milling technique. The pelletized powder was conventionally sintered for 10 h at a temperature range of 975–1025 °C, which is a lower temperature process compared to the standard solid-state reaction. X-ray diffraction analysis revealed a cubic phase for the current LCTO ceramics. The grain size of the sintered ceramics was found to increase from 1.5 ± 0.5 to 2.3 ± 0.5 μm with an increase in sintering temperature from 975 to 1025 °C. The impedance results show that the grain conductivity is more than three orders of magnitude larger than the grain boundary conductivity for LCTO ceramics. All the samples showed a giant dielectric constant (1.7 × 103–3.4 × 103) and dielectric loss (0.09–0.17) at 300 K and 10 kHz. The giant dielectric constant of the current samples was attributed to the effect of internal barrier layer capacitances due to their electrically inhomogeneous structure.

Development of Biodegradable Mg-Ti Alloy Synthesized Using Mechanical Alloying

2016 ◽  
Vol 1133 ◽  
pp. 75-79 ◽  
Author(s):  
Emee Marina Salleh ◽  
Sivakumar Ramakrishnan ◽  
Zuhailawati Hussain
Keyword(s):  
Mechanical Alloying ◽  
Milling Time ◽  
Milled Powder ◽  
Milling Process ◽  
Planetary Mill ◽  
Ti Alloy ◽  
X Ray Diffraction ◽  
Argon Flow ◽  
Diffraction Patterns ◽  
Ti Powder

The aim of this work was to study the effect of milling time on binary magnesium-titanium (Mg-Ti) alloy synthesized by mechanical alloying. A powder mixture of Mg and Ti with the composition of Mg-15wt%Ti was milled in a planetary mill under argon atmosphere using a stainless steel container and balls. Milling process was carried out at 400 rpm for various milling time of 2, 5, 10, 15 and 30 hours. 3% n-heptane solution was added prior to milling process to avoid excessive cold welding of the powder. Then, as-milled powder was compacted under 400 MPa and sintered in a tube furnace at 500 °C in argon flow. The refinement analysis of the x-ray diffraction patterns shows the presence of Mg-Ti solid solution when Mg-Ti powder was mechanically milled for 15 hours and further. Enhancements of Mg-Ti phase formation with a reduction in Mg crystallite size were observed with the increase in milling time. A prolonged milling time has increased the density and hardness of the sintered Mg-Ti alloy.

Sign in / Sign up

Export Citation Format

Share Document