Preparation of TiC/Ti3SiC2 Composite by Sintering Mechanical Alloyed Ti–Si–C Powder Mixtures

2020 ◽  
Vol 20 (7) ◽  
pp. 4580-4586
Author(s):  
Manuel Fellipe R. Pais Alves ◽  
Claudinei dos Santos ◽  
Bruno Xavier de Freitas ◽  
Alfeu Saraiva Ramos ◽  
Erika Coaglia Trindade Ramos ◽  
...  
Keyword(s):  
Particle Size ◽  
Mechanical Alloying ◽  
Crystallite Size ◽  
Average Particle Size ◽  
Lattice Parameter ◽  
Unit Cell ◽  
High Fracture Toughness ◽  
Cubic Phase ◽  
Average Particle ◽  
Crystalline Phases

The present work aims to evaluate the crystalline phases and microstructure of a TiC–Ti3SiC2 ceramic composite, obtained by mechanical alloying of Ti, C and Si powders and subsequent sintering. A mechanical alloying technique in a planetary ball mill for 1, 10, 50, 100 and 200 h using Ti, Si and C powders with molar ratios of 3:1:2 as feedstock in argon (Ar) gas was employed to prepare nano-sized Ti–Si–C powders. TiC crystallite size and lattice strain were evaluated by X-ray diffraction analysis (XRD) and the morphological characteristics and particle size distribution were examined using scanning electron microscope (SEM). After milling, a reduction of the average particle size and crystallinity is observed. Furthermore, after 10 h of milling time, TiC starts to crystallize. The powder mixture obtained after 200 h of milling was compacted and sintered at 1200 °C under controlled atmosphere, for 15 min, 2 h or 4 h with a heating rate of 5 °C/min. Almost full densification of samples sintered for 2 h and 4 h has been achieved, with relative densities close to 98.8±0.2% and TiC and Ti3SiC2 as crystalline phases with an average crystallite size of TiC near 0.7 μm. Rietveld refinement indicates that the majority TiC-cubic phase (>85 vol%) presents a unit cell volume of 8.03 nm3 after sintering at 1200 °C. Despite the maintenance of the volume of the hexagonal unit cell of Ti3SiC2, (15.05 nm3), the increase of the isothermal sintering time resulted in an increase of the lattice parameter “a”, from 0.315 nm to 0.320 nm, and a reduction of the lattice parameter “c” from 1.750 nm to 1.705 nm. The control of the changes in the residual stresses within the TiC matrix and the Ti3SiC2 precipitates, which is associated with the deformation in the lattice parameters, must be controlled to achieve high fracture toughness in the composite.

Microstructural and Magnetic Properties of Nanostructured Fe65Co35 Powders Prepared by Mechanical Alloying

2013 ◽  
Vol 829 ◽  
pp. 778-783 ◽  
Author(s):  
Mohsen Razi ◽  
Ali Ghasemi ◽  
Gholam Hossein Borhani
Keyword(s):  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Cooling System ◽  
Average Particle Size ◽  
Weight Ratio ◽  
Lattice Parameter ◽  
Milling Process ◽  
Protective Atmosphere ◽  
Average Particle

Nanostructured Fe65Co35 alloy powders were fabricated by mechanical alloying in an attritor mill with different milling times. The milling process carried out in speed of 350 rpm, with 20:1 ball to powder weight ratio and under argon protective atmosphere. A continuous cooling system applied to avoid increasing temperature during the milling. The effect of milling time on structural and magnetic properties investigated by X-ray diffraction, scanning electron microscopy and vibration sample magnetometer. According to the obtained results, nanostructured Fe65Co35 solid solution powders resulted with an average particle size of 400 nm and crystallite size of 6.8 nm by milling for 20 hours. With increasing the milling time, the lattice parameter decreased and the lattice strain increased for Fe65Co35 powders. The maximum saturation magnetization with 1311 emu/cc value and the minimum coercivity with 22 Oe value occurs after milling for 15 hours.

Analysis of the Promoter-Catalyst interaction between Mn and Rh by Transmission Electron Microscopy

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
B. Graham ◽  
R.F. Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Average Particle Size ◽  
Lattice Parameter ◽  
Average Particle ◽  
Fischer Tropsch ◽  
Transmission Electron ◽  
Three Samples ◽  
Promoter Interaction

In the hope of optimizing the Fischer-Tropsch mechanism to produce cleaner ethanol, the catalyst- promoter interaction between rhodium and manganese was examined by transmission electron microscopy. Three samples were analyzed on a carbon nanotube (CNT) substrate with 3 wt% rhodium (3%Rh/CNT), 1% manganese with 3 wt% rhodium (1%Mn/3% Rh/CNT), and 2% manganese with 3 wt% rhodium (2% Mn/3% Rh/CNT). The average particle size were found to be (1.9 ± 0.6) nm, (2.1 ± 0.5) nm, and (3.2 ± 0.6) nm, respectively. An increase in particle size indicates that the rhodium and manganese are interacting. The lattice parameter for rhodium were also determined to be (4.1 ± 0.1) Å, (4.2 ± 0.1) Å, and (3.8 ± 0.1) Å, respectively. The decrease in lattice parameter in the 2%Mn/3%Rh/CNT sample was most likely due to a change in the crystal structure of the rhodium particles as a result of the interaction between the manganese and rhodium.

Nanocrystalline BaTiO3 from freeze-dried nitrate solutions

1996 ◽  
Vol 11 (5) ◽  
pp. 1199-1209 ◽  
Author(s):  
J. M. McHale ◽  
P. C. McIntyre ◽  
K. E. Sickafus ◽  
N. V. Coppa
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
High Surface ◽  
Nitrate Solution ◽  
Average Particle Size ◽  
Volume Ratio ◽  
Product Formation ◽  
Cubic Phase ◽  
Average Particle ◽  
Freeze Dried

An aqueous, all nitrate, solution-based preparation of BaTiO3 is reported here. Rapid freezing of a barium and titanyl nitrate solution, followed by low temperature sublimitation of the solvent, yielded a freeze-dried nitrate precursor which was thermally processed to produce BaTiO3. XRD revealed that 10 min at temperatures ≧600 °C resulted in the formation of phase pure nanocrystalline BaTiO3. TEM revealed that the material was uniform and nanocrystalline (10–15 nm). The high surface to volume ratio inherent in these small particles stabilized the cubic phase of BaTiO3 at room temperature. It was also found that the average particle size of the BaTiO3 produced was highly dependent upon calcination temperature and only slightly dependent upon annealing time. This result suggests a means of selection of particle size of the product through judicious choice of calcination temperature. The experimental details of the freeze-dried precursor preparation, thermal processing of the precursor, product formation, and product morphology are discussed.

Synthesis of Mesoporous Silica Nanocomposites for Preparation of Gold Nanoparticles

2014 ◽  
Vol 925 ◽  
pp. 233-237 ◽  
Author(s):  
Mohamad Azani Jalani ◽  
Leny Yuliati ◽  
Salasiah Endud ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Mesoporous Silica ◽  
Sol Gel ◽  
Average Particle Size ◽  
Silica Film ◽  
Cubic Phase ◽  
Average Particle ◽  
Interpore Distance ◽  
Sol Gel Synthesis

Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d111 at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.

Hydrogen and its effect on the grinding of Ti-Ni powder

2021 ◽  
Vol 23 (3) ◽  
pp. 100-111
Author(s):  
Ekaterina Abdulmenova ◽  
◽  
Sergey Kulkov ◽  
Keyword(s):  
Particle Size ◽  
Dislocation Density ◽  
High Intensity ◽  
Ball Mill ◽  
Mechanical Treatment ◽  
Average Particle Size ◽  
Lattice Parameter ◽  
Planetary Ball Mill ◽  
Average Particle ◽  
X Ray

Introduction. Industrial nickel-titanium alloy PN55T45 closed to the equiatomic composition is widely used for the manufacture of products by powder metallurgy. To achieve high physical and mechanical properties of the material obtained by this method, it is necessary to use fine powders, which can be obtained by implementing high-intensity grinding in a planetary ball mill. However, during such treatment, contamination, powder oxidation and particle aggregation, etc. are possible. To solve this problem, preliminary hydrogenation is proposed for subsequent grinding in a planetary ball mill. The aim of the work is to study the effect of hydrogen on the grinding of titanium nickelide powder. Materials and methods. The morphology and average particle size of the powders were studied by scanning electron microscopy. The structure and phase composition of the powders were investigated by the methods of X-ray structural and X-ray phase analysis. The data of X-ray structural analysis were used to estimate the dislocation density. Results and discussions. It is shown that the use of pre-hydrogenation for 180 minutes before machining allows reducing the average particle size by about a half. After mechanical treatment of the powder, the parameters of the crystal lattices of the TiNi (austenite), Ti2Ni and Ni3Ti phases do not change within the error range. After mechanical treatment of the powder with preliminary hydrogenation, the crystal lattice parameter of only the Ti2Ni phase changes significantly, in particular, at 180 minutes of hydrogenation, the lattice parameter increases to 1.1457 ± 5×10-4 nm, which corresponds to the stoichiometry of the Ti2NiH0.5 hydride with a lattice parameter of 1.1500 nm. The highest dislocation density estimated by X-ray diffraction analysis is contained in the Ti2Ni (511) phase than in the TiNi (austenite) (110) and Ni3Ti (202) phases. Thus, preliminary hydrogenation can be an effective method of powder grinding due to the formation of brittle hydride and suppression of the aggregation of fine particles during high-intensity mechanical treatment.

Effect of Fuel to Oxidizer Ratio on the Structure, Micro Structure and EPR of Combustion Synthesized NiO Nanoparticles

2008 ◽  
Vol 8 (8) ◽  
pp. 4247-4253 ◽  
Author(s):  
K. Venkateswara Rao ◽  
C. S. Sunandana
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Nio Nanoparticles ◽  
Micro Structure ◽  
Visible Absorption ◽  
Surface Areas ◽  
Substitutional Solute

In this work we describe the synthesis, micro structure (XRD, SEM) and EPR of NiO nanoparticles synthesized by urea-based combustion method using Ni nitrate as the source of Ni. We used fuel-to-oxidizer ratio (Ψ) as a control parameter to investigate how lattice parameter, particle size and EPR susceptibility vary with Ψ = 0.25 to 2. Earlier we have studied NiO as a substitutional solute in MgO. The average particle size of NiO was estimated from the full width half maximum (gaussian and lorentzian fits) of the X-ray diffraction peaks of powders using Sherrer's formula and Williamson-Hall plot. The particle size varies from 7 nm to 38 nm as Ψ is varied systematically. The surface areas were measured using BET method. FT-IR confirms the Ni-O crystalline bond formation. We also calculated porosity and strain in the NiO nanoparticles with varying Ψ. EPR spectra have yielded the susceptibility of the NiO nanoparticles. Band gap of NiO was determined by UV-visible absorption edge.

scholarly journals Structural and optical studies of TiO2:Ag2O nanocomposite by sol-gel method

2020 ◽  
Vol 38 (2) ◽  
pp. 263-270
Author(s):  
Vaibhav Koutu ◽  
Rajesh Dhakar ◽  
Pragya Ojha ◽  
Lokesh Shastri ◽  
M.M. Malik
Keyword(s):  
Particle Size ◽  
Crystallite Size ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Crystallite Size ◽  
Wide Band ◽  
Spectroscopic Studies ◽  
Memory Storage ◽  
Average Particle ◽  
Vis Spectroscopy

AbstractAs TiO2 is suitable for electronic and electrical applications, in the present work the authors have successfully modified TiO2 by adding silver (Ag) to form titanium oxide-silver oxide (TiO2:Ag2O) nanocomposite samples by using sol-gel technique. Characterizations of these composites have been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and UV-Vis spectroscopy. XRD study revealed that the crystal structure of the samples consisted of tetragonal and cubic phases. This study further showed an increment in the average crystallite size from 8 nm to 38 nm with an increase in Ag concentration. The increase in crystallite size has been confirmed additionally by SEM and AFM. The increment in the average particle size of the samples may be attributed to an increase in silver molarity in the TiO2 matrix. Significant red shift in the absorption edge has been observed, causing reduction in the energy bandgap of the composites from 3.89 eV to 3.46 eV with an increase in particle size which is evident from UV-Vis spectroscopic studies. This wide-band gap properties of the TiO2:Ag2O nanocomposite make it suitable for memory-storage devices and dielectric applications.

Magnetic and Thermal Studies of Iron-Based Amorphous Alloys Produced by a Combination of Melt-Spinning and Ball Milling

2021 ◽  
Vol 1163 ◽  
pp. 99-105
Author(s):  
Zahra Allafe Razzaghi ◽  
Abbas Kianvash ◽  
Abolfazl Tutunchi
Keyword(s):  
Particle Size ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Melt Spinning ◽  
Thermal Studies ◽  
Average Particle Size ◽  
Ferromagnetic Behavior ◽  
Average Particle ◽  
Mechanically Alloyed ◽  
Melt Spun

In this study, we demonstrate the synthesis of an Fe78Si9B10P3 amorphous alloy by three pathways: mechanical alloying, melt-spinning and a combination of melt-spinning and ball milling. Microstructure, thermal stability and soft magnetic properties of the melt-spun and mechanically alloyed powders are comparatively studied. Ball milling of previously melt-spun samples led to an amorphous powder with an average particle size of ~2.4 μm after 20 hrs of milling. Mechanical alloying of elemental Fe-Si-B-P powders in a planetary ball mill for up to 100 hrs led only to a partial amorphisation of powder with a median particle size of ~1.3 μm. Differential thermal analysis of the amorphous ribbon revealed that the amorphous phase was stable up to ~520 °C, at which the crystallization process occurred. The melt spun ribbons exhibited excellent soft ferromagnetic behavior, including high saturation magnetization (Ms) of ~171 emu/g and a low coercivity (Hc) of ~2.8 Oe. In the 20 hrs milled ribbons, due to a probable partial anisotropy which induced by ball milling stress, the Ms value decreased slightly to ~161 emu/g but the Hc increased to ~38 Oe. The mechanically alloyed samples present a relatively lower Ms of ~154 emu/g and higher Hc of ~43 Oe. It is to be noted that the milling of ribbons is usually inevitable due to their technological restrictions in use.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

2020 ◽  
Vol 27 (22) ◽  
pp. 3623-3656 ◽  
Author(s):  
Bruno Fonseca-Santos ◽  
Patrícia Bento Silva ◽  
Roberta Balansin Rigon ◽  
Mariana Rillo Sato ◽  
Marlus Chorilli
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Drug Release ◽  
Drug Loading ◽  
Average Particle Size ◽  
Delivery Systems ◽  
Average Particle ◽  
Minor Importance ◽  
Routes Of Administration ◽  
Non Invasive

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

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