Mechano-Chemical Synthesis of TiB2-Al2O3 Nano-Composite by Reaction between TiO2, B2O3 and Al

2012 ◽  
Vol 488-489 ◽  
pp. 955-959 ◽  
Author(s):  
Amin Rabiezadeh ◽  
Abolghasem Ataie ◽  
Ali Mohammad Hadian
Keyword(s):  
Chemical Synthesis ◽  
Powder Mixture ◽  
Composite Structure ◽  
Ultrafine Particles ◽  
Milled Powder ◽  
Nano Composite ◽  
Particle Characteristics ◽  
Sem Micrograph ◽  
The Mean ◽  
Nano Size

In this research a composite structure containing of a TiB2 matrix with dispersed Al2O3 particles was obtained via mechanical alloying of Al, TiO2 and B2O3 powder mixture. The mixture was milled for different lengths of time. Phase evolutions of the milled powder mixture were investigated. Powder particle characteristics were evaluated by XRD, SEM and TEM techniques. The XRD results reveal that the reaction begins during first 10 h milling by formation of TiB2 and Al2O3¬ phases and further milling causes partial amorphization of powder mixture. SEM micrograph of the sample milled for 30 h exhibited ultrafine particles of Al2O3-TiB2, but TEM images show that particles consist of some grains in the range of nano-size. The mean crystallite size of final product is about 25 nm.

Preparing of CaCO3 Nano-Particles by Mechano-Chemical Method

2012 ◽  
Vol 445 ◽  
pp. 833-838
Author(s):  
J. Sargheini ◽  
Abolghasem Ataie ◽  
S.M. Salili ◽  
M. Johari ◽  
M. Hadad
Keyword(s):  
Ball Mill ◽  
Milled Powder ◽  
Nano Particles ◽  
Particle Sizes ◽  
Chemical Route ◽  
Particle Characteristics ◽  
Peak Broadening ◽  
Milled Sample ◽  
Milling Duration ◽  
The Mean

This research was aimed to synthesize calcium carbonate nanoparticles from CaCl2, NaCl and Na2CO3 precursors by mechano-chemical route without any subsequent heat treatment of the as-milled powder. Effects of intensive milling duration and amount of NaCl as a diluting agent on the powder particle characteristics have been investigated. XRD results showed that CaCO3 nanoparticles were obtained after 30 minutes of continuous milling in the planetary ball mill regardless of the amount of NaCl. Further milling up to 10 hour resulted in peak broadening indicating the crystallite refinement. For the 10-hour milled sample in the presence of 3.5 mole% NaCl, the mean crystallite and particle sizes were 12 and 56 nm, respectively. Those values decreased slightly when the amount of NaCl increased from 3.5 to 10.3 mole%.

scholarly journals The Effect of Route Choice in Children’s Exposure to Ultrafine Particles Whilst Walking to School

2021 ◽  
Vol 18 (15) ◽  
pp. 7808
Author(s):  
Mehrdad Rafiepourgatabi ◽  
Alistair Woodward ◽  
Jennifer A. Salmond ◽  
Kim Natasha Dirks
Keyword(s):  
Ultrafine Particles ◽  
Route Choice ◽  
The Other ◽  
Close Proximity ◽  
Public Health Officials ◽  
Risk Of Exposure ◽  
The Mean ◽  
Walking To School ◽  
Elevated Exposure ◽  
Children’S Exposure

Children walking to school are at a high risk of exposure to air pollution compared with other modes because of the time they spend in close proximity to traffic during their commute. The aim of this study is to investigate the effect of a walker’s route choice on their exposure to ultrafine particles (UFP) on the walk to school. During morning commutes over a period of three weeks, exposure to UFP was measured along three routes: two routes were alongside both sides of a busy arterial road with significantly higher levels of traffic on one side compared to the other, and the third route passed through quiet streets (the background route). The results indicate that the mean exposure for the pedestrian walking along the background route was half the exposure experienced on the other two routes. Walkers on the trafficked side were exposed to elevated concentrations (>100,000 pt/cc) 2.5 times longer than the low-trafficked side. However, the duration of the elevated exposure for the background route was close to zero. Public health officials and urban planners may use the results of this study to promote healthier walking routes to schools, especially those planned as part of organized commutes.

Phase Studies in WC-Stainless Steel AISI 347 Hardmetal System with Graphite Addition

2014 ◽  
Vol 1024 ◽  
pp. 239-242
Author(s):  
Zuhailawati Hussain ◽  
Emee Marina Salleh ◽  
Tran Bao Trung ◽  
Zainal Arifin Ahmad
Keyword(s):  
Stainless Steel ◽  
Powder Mixture ◽  
Milled Powder ◽  
Graphite Powder ◽  
Planetary Mill ◽  
Argon Atmosphere ◽  
Maximum Hardness ◽  
Steel Container ◽  
Steel Aisi ◽  
Stainless Steel Aisi

In this study, WC-stainless steel AISI 347 hardmetal system was produced to replace WC-Co hardmetal which uses the expensive, toxic and depleted resource Co. WC, stainless steel AISI 347 and graphite powder mixture were milled in a planetary mill under argon atmosphere using a stainless steel container and balls. Carbon was added in amounts ranging from 0 wt% until 4 wt% into the composition to avoid unwanted η (Fe3W3C) phase. As-milled powder was compacted at 300 MPa and sintered in a tube furnace at 1350°C. ɳ phase was detected in compositions with 0 and 1 wt% C addition. For 2 wt% C addition, no η (Fe3W3C) phase formation was identified. However, the η phase was detected for compositions containing 3 and 4 wt% C. Maximum hardness was achieved due to the absence of η phase.

Purification of Attrition Milled Nano-size Boron Carbide Powder

2012 ◽  
Vol 05 ◽  
pp. 94-101 ◽  
Author(s):  
A. Sokhansanj ◽  
A.M. Hadian
Keyword(s):  
Chemical Analysis ◽  
Boron Carbide ◽  
Sintering Temperature ◽  
Milled Powder ◽  
Carbide Powder ◽  
Sintering Behavior ◽  
Sintered Ceramic ◽  
Weight Percentage ◽  
Wide Range ◽  
Nano Size

Boron carbide is one of the advanced ceramic materials which is used in a wide range of applications. However, this material needs a high sintering temperature (~2200°C). Using nano-size powders for producing ceramic parts results in lowering sintering temperature and also enhances toughness and hardness of the material. One of the methods for producing ceramic nano powders is attrition milling. However, as the milling balls and wall are made of steel, some impurities specially iron will be introduced to the powder during milling. Chemical analysis of the milled powder shows that more than 33wt% of the powder consists of iron. These uncontrolled impurities affect the mechanical and physical properties of sintered ceramic parts that are made of such a powder. Therefore, these impurities must be removed from the powder. Hydro metallurgical beneficiation technique with two different solvents has been used for purification of the powder. The result of chemical analysis after purification showed that the weight percentage of iron in powder dropped to 9% and 0.8% (depending on the solvents). Moreover, the sintering behavior of hot-pressed boron carbide powder with different percentages of iron as sintering aid has been studied. The results showed excellent densification and hardness of the sintered parts.

ROLE OF PROCESS CONTROL AGENTS ON MILLING BEHAVIOR OF Al AND TiO2 POWDER MIXTURE TO SYNTHESIZE TiAl/Al2O3 NANO COMPOSITE

2012 ◽  
Vol 05 ◽  
pp. 638-645 ◽  
Author(s):  
S. ALAMOLHODA ◽  
S. HESHMATI-MANESH ◽  
A. ATAIE ◽  
A. BADIEI
Keyword(s):  
Process Control ◽  
Tio2 Powder ◽  
Nano Composite ◽  
Powder Mixtures ◽  
Gaussian Method ◽  
Opposite Behavior ◽  
Crystallite Sizes ◽  
The Mean ◽  
Milled Powders

In this study effect of adding various process control agents (PCAs) to powder mixtures of Al and TiO 2 which are mechanically activated so as to form TiAl - Al 2 O 3 nano-composite have been investigated. Phase constitutions and morphology of the milled powders were evaluated by XRD and SEM techniques, respectively. The mean crystallite sizes of the milled powders were calculated by Cauchy-Gaussian method. Thermal behavior of the milled powders was also studied by DTA to investigate formation of the final phases. The results showed that the mean crystallite size of the milled powders in the presence of PCAs was smaller than that of the sample milled without PCA addition. DTA traces showed that addition of PCAs retards the reduction of TiO 2 by Al . In samples milled in presence of PCA, the reductive reaction generally took place after melting of Al particles whereas the sample milled without PCA addition showed an opposite behavior. Also, in comparison with the sample milled with no PCA addition, in other samples the reductive reaction took place at relatively lower temperatures.

Why Are Relationships Between Lagrangian and Eulerian Scales Necessary for Gas-Particle Flow Modeling?

2003 ◽  
Author(s):  
Daniel Huilier
Keyword(s):  
Control Volume ◽  
Fluid Velocity ◽  
Measurement Techniques ◽  
Flow Modeling ◽  
Flow Properties ◽  
Markov Chain Models ◽  
Particle Characteristics ◽  
Particle Flows ◽  
Lagrangian Modeling ◽  
The Mean

Simulation of Gas-Particle flows can be fulfilled by Lagrangian modeling of the dispersed phase. Each type of Lagrangian method, Monte-Carlo/Eddy Interaction or Markov Chain models, needs the knowledge of Lagrangian scales associated with the turbulent flow under consideration and the type of particle dispersing in the gas carrier flow. Unfortunately, Lagrangian quantities (as well the interesting moving Eulerian time scale, that given by a sensor which would move with the mean fluid velocity) are still difficult to be obtained directly by most experimental measurement techniques (except by very recent techniques such as PIV.PTV.), contrary to Eulerian scales scales, such as those classically obtained from a fixed hot-wire or LDA control volume. It is therefore of great importance to have available accurate relationships between Eulerian and Lagrangian scales, based on fluid flow properties as well as particle characteristics.

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