Effect of Powder Characteristics on the Densification of Sintered Alumina

2011 ◽  
Vol 324 ◽  
pp. 65-68
Author(s):  
Ziyad S. A. Al Sarraj ◽  
S.S. Noor
Keyword(s):  
Particle Size ◽  
Processing Parameters ◽  
Average Particle ◽  
Particle Sizes ◽  
Scanning Electron Micrographs ◽  
Soaking Time ◽  
Density Measurements ◽  
Powder Characteristics ◽  
Effect Of Particle Size ◽  
The Difference

Abstract. The effect of particle size distribution, soaking time and sintering temperatures on the densification behaviors of α-Al2O3 was investigated. Two different average particle sizes of 36 and 45µ were examined as a variable to analyze the difference in density, radial and axial shrinkage, densification, and microstructure developments. Conventional powder technology route was used to prepare disc-shaped green pellets sintered at 1200-1600°C for different periods. Density measurements for both green and sintered compacts allow for the refinement of processing parameters to obtain dense sintered bodies. Compacts with particle size of 36 µm were noticed to attain higher relative densities as compared with those of 45µm. Densification parameter (∆P) calculations clearly reveals the presence of definite temperatures and times in which limited densification retardation occurred, which permits the suggesting of suitable sintering schemes for this material. Scanning electron micrographs analysis revealed a pore structure assist the observed behaviours for the different schemes.

scholarly journals Kinetics and Photodegradation Study of Aqueous Methyltert-Butyl Ether Using Zinc Oxide: The Effect of Particle Size

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Zaki S. Seddigi ◽  
Saleh A. Ahmed ◽  
Shahid P. Ansari ◽  
Ekram Danish ◽  
Abdullah Abu Alkibash ◽  
...  
Keyword(s):  
Particle Size ◽  
Zinc Oxide ◽  
Order Reaction ◽  
Average Particle ◽  
Particle Sizes ◽  
Mercury Lamp ◽  
Butyl Ether ◽  
First Order ◽  
Effect Of Particle Size ◽  
Kinetics Of

Zinc oxide of different average particle sizes 25 nm, 59 nm, and 421 nm as applied in the photodegradation of MTBE. This study was carried out in a batch photoreactor having a high pressure mercury lamp. Zinc oxide of particle size of 421 nm was found to be the most effective in degrading MTBE in an aqueous solution. On using this type of ZnO in a solution of 100 ppm MTBE, the concentration of MTBE has decreased to 5.1 ppm after a period of five hours. The kinetics of the photocatalytic degradation of MTBE was found to be a first order reaction.

Effect of Particle Size on the Oil Yield and Catechin Compound Using Accelerated Solvent Extraction

2013 ◽  
Vol 60 (1) ◽  
Author(s):  
Mohd Azizi Che Yunus ◽  
Manzurudin Hasan ◽  
Norasikin Othman ◽  
Siti Hamidah Mohd-Setapar ◽  
Liza Md.-Salleh ◽  
...  
Keyword(s):  
Particle Size ◽  
Solvent Extraction ◽  
Accelerated Solvent Extraction ◽  
Extraction Time ◽  
Oil Yield ◽  
Particle Sizes ◽  
Experimental Range ◽  
Areca Catechu ◽  
Effect Of Particle Size ◽  
Extraction Cycle

Kajian ini bertujuan untuk mengkaji kesan saiz zarah ke atas pengekstrakan sebatian catechin daripada biji Areca catechu L. dengan menggunakan Pengekstrakan Pelarut Terpecut (PPT). Saiz zarah biji Areca catechu dipelbagaikan dari 75 μm sehingga 500 μm. Pengekstrakan telah dijalankan padaparameter tetap iaitu suhu (140oC), tekanan (1500 psi), masa (10 minit), isipadu semburan (60%) dan satu kitaran pengekstrakan, masing-masing. Hasil minyak peratusan yang lebih tinggi adalah 300 mg minyak / gram sampel (30.00% pati minyak) ditemui pada 125 μm. Walaubagaimanapun, kandungan catechin dalam pati minyak hanya 0.0375 mg catechin / gram sampel. Saiz zarah yang terbaik dalam julat uji kaji ini telah dikenal pasti pada 500 μm yang memberikan kandungan catechin yang tinggi iaitu 0.0515 mg catechin / gram sampel dari 247.5 mg minyak / gram sampel (24.75% pati minyak). Kata kunci: Saiz zarah; catechin; LC-MS-TOF; pengekstrakan pelarut terpecut The purpose of this work is to investigate the effects of particle size on the extraction of catechincompound from Areca catechu L. seeds by using Accelerated Solvent Extraction (ASE). The particle sizes of Areca catechu L. seeds are varied from 75 µm until 500 µm. The extraction is conducted at fixed parameters which are temperature (140oC), pressure (1500 psi), extraction time (10 minutes), flush volume (60%) and the static cycle is done for 1 extraction cycle respectively. Higher percentage oil yield of 300mg oil/gram of sample (30.00% oil yield) is found at 125 µm. However, the amount of catechin in oil yields is only 0.0375 mg of catechin/gram of sample. The best of particle size within the experimental range has been identified at 500 µm which gives a high content of catechin with 0.0515 mg Catechin/gram of sample from 247.5 mg oil/gram of sample (24.75% oil yield). Keywords: Particle size; catechin; LC-MS-TOF; accelerated solvent extraction

The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 1: The predictive nature of packing models on coating properties

TAPPI Journal ◽  
2020 ◽  
Vol 19 (11) ◽  
pp. 585-593
Author(s):  
ETHAN GLOR ◽  
BRIAN EINSLA ◽  
JOHN ROPER ◽  
JIAN YANG ◽  
VALERIY GINZBURG
Keyword(s):  
Particle Size ◽  
Hollow Sphere ◽  
Particle Packing ◽  
Particle Sizes ◽  
Coating Properties ◽  
Ideal System ◽  
Thermal Paper ◽  
Effect Of Particle Size ◽  
Low Levels ◽  
Better Than

Hollow sphere pigments (HSPs) are widely used at low levels in coated paper to increase coating bulk and to provide gloss to the final sheet. However, HSPs also provide an ideal system through which one can examine the effect of pigment size and particle packing within a coating due to their unimodal and tunable particle sizes. The work presented in Part 1 and Part 2 of this study will discuss the use of blends of traditional inorganic pigments and HSPs in coating formulations across a variety of applications for improved coating strength. Part 1 of this study focuses on the theory of bimodal spherical packing and demonstrates the predictive nature of packing models on the properties of coating systems containing HSPs of two different sizes. This study also examines conditions where the model fails by examining the effect of particle size on coating strength in sytems like thermal paper basecoats where the non-HSP component has a broad particle size distribution, and how these surprising trends can be used to generate better-than-expected thermal printing performance in systems with low HSP/clay ratios. Part 2 of this study focuses on the incorporation of HSPs of different particle sizes into paperboard formulations to affect coating strength and opacity.

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

Producing Steam by Spraying Water on a Heated Bed of Steel Spheres

2021 ◽  
pp. 1-42
Author(s):  
D. Jordan Bouchard ◽  
HengSheng Yang ◽  
Sanjeev Chandra
Keyword(s):  
Particle Size ◽  
Thermal Mass ◽  
Steam Generation ◽  
Bed Porosity ◽  
The Media ◽  
Effect Of Particle Size ◽  
The Difference ◽  
Rate Of Evaporation ◽  
A Minor ◽  
Counter Current

Abstract Steam generators used in industrial baking ovens operate by pouring or spraying water on a preheated thermal mass. This paper presents a methodology to quantify the amount of steam generated from a thermal mass along with experiments to determine the effect of particle size and porosity on steam generation. Three sizes of steel spheres, 0.6 mm, 8 mm, and 16 mm in diameter, were used to construct porous media beds that were preheated in an oven after which water was sprayed onto them from a full-cone nozzle for a fixed duration. The weight of the heated bed and the impinging water were recorded during spraying. The difference in weight change when spraying on heated and unheated beds gave the rate of evaporation. Thermocouples were used to record the internal temperature of the bed. Steam generation rate increased with particle size while bed porosity had only a minor influence. The counter-current flow of steam within the media bed disrupts the downward flow of water enough to leave pockets of hot material, reducing steam production. To maximize steam generation the media size, material, and spray time should be matched to ensure the surfaces of particles remain above the boiling point of water during spraying.

scholarly journals Synthesis and Optical Performances of a Waterborne Polyurethane-Based Polymeric Dye

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xianhai Hu ◽  
Xingyuan Zhang ◽  
Jin Liu
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Waterborne Polyurethane ◽  
Average Particle ◽  
Particle Sizes ◽  
Hypsochromic Shift ◽  
Absorption Bands ◽  
Polymeric Dye ◽  
Emulsion Particle ◽  
Increasing Temperature

A waterborne polyurethane-based polymeric dye (WPU-CFBB) was synthesized by anchoring 1, 4-bis(methylamino)anthraquinone (CFBB) to waterborne polyurethane chains. The number molecular weight, glass transition temperature, and average emulsion particle size for the polymeric dye were determined, respectively. This polymeric dye exhibited intriguing optical behaviors. The polymeric dye engendered two new absorption bands centered at about 520 nm and 760 nm if compared with CFBB in UV-vis spectra. The 760 nm peak showed hypsochromic shift with the decrease of average particle sizes. The polymeric dye dramatically demonstrated both hypsochromic and bathochromic effects with increasing temperature. The fluorescence intensity of the polymeric dye was much higher than that of CFBB. It was found that the fluorescence intensities would be enhanced from 20°C to 40°C and then decline from 40°C to 90°C. The fluorescence of the polymeric dye emulsion was very stable and was not sensitive to quenchers.

scholarly journals MINERAL ABUNDANCE AND PARTICLE SIZE DISTRIBUTION DERIVED FROM IN-SITU SPECTRA MEASUREMENTS OF YUTU ROVER OF CHANG’E-3

2017 ◽  
Vol XLII-3/W1 ◽  
pp. 85-89
Author(s):  
H. Lin ◽  
X. Zhang ◽  
Y. Yang ◽  
X. Wu ◽  
D. Guo
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Landing Site ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Particle Sizes ◽  
The Mean ◽  
The Difference ◽  
Yutu Rover

From geologic perspective, understanding the types, abundance, and size distributions of minerals allows us to address what geologic processes have been active on the lunar and planetary surface. The imaging spectrometer which was carried by the Yutu Rover of Chinese Chang’E-3 mission collected the reflectance at four different sites at the height of ~ 1 m, providing a new insight to understand the lunar surface. The mineral composition and Particle Size Distribution (PSD) of these four sites were derived in this study using a Radiative Transfer Model (RTM) and Sparse Unmixing (SU) algorithm. The endmembers used were clinopyroxene, orthopyroxene, olivine, plagioclase and agglutinate collected from the lunar sample spectral dataset in RELAB. The results show that the agglutinate, clinopyroxene and olivine are the dominant minerals around the landing site. In location Node E, the abundance of agglutinate can reach up to 70 %, and the abundances of clinopyroxene and olivine are around 10 %. The mean particle sizes and the deviations of these endmembers were retrieved. PSDs of all these endmembers are close to normal distribution, and differences exist in the mean particle sizes, indicating the difference of space weathering rate of these endmembers.

Influence of Powder Particle Size of Slurries on Mechanical Properties of Porous Hydroxyapatite Ceramics

2005 ◽  
Vol 284-286 ◽  
pp. 365-368 ◽  
Author(s):  
Yin Zhang ◽  
Yoshiyuki Yokogawa ◽  
Tetsuya Kameyama
Keyword(s):  
Particle Size ◽  
Flexural Strength ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Particle Sizes ◽  
Wet Milling ◽  
Median Particle Size ◽  
Powder Characteristics ◽  
Median Particle

The effect of different particle sizes on the flexural strength and microstructure of three different types of hydroxyapatite (HAp) powders was studied. The powder characteristics of laboratory synthesized HAp powder (Lab1 and Lab2) were obtained through a wet milling method, and the median particle size and the specific surface area of powders are different with the dryness period. The median particle sizes of Lab1 and Lab2 are 0.34 µm and 0.74 µm, and the specific surface areas of Lab1 and Lab2 are 38.01 m2/g and 19.77 m2/g. The commercial HAp had median particle size of 1.13 µm and specific surface area of 11.62m2/g. The different powder characteristics affected the slip characteristics, and the flexural strength and microstructure of the sintered porous HAp bodies are also different. The optimum value for the minimum viscosity in these present HAp slip with respect to its solid loading and the optimum amount of the deflocculant were investigated. The flexural strengths of the porous HAp ceramics prepared by heating at 1200°C for 3 hrs in air were 17.59 MPa for Lab1 with a porosity of 60.48％, 10.51 MPa for Lab2 with a porosity of 57.75％, and 3.92 MPa for commercial HAp with a porosity of 79.37％.

Effects of Dissolving Agents on Particle Size Reduction of Titanium Dioxide Synthesized by Solution Combustion Technique

2016 ◽  
Vol 690 ◽  
pp. 236-239
Author(s):  
Oratai Jongprateep ◽  
Rachata Puranasamriddhi
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Average Particle Size ◽  
Average Particle ◽  
Particle Sizes ◽  
Solution Combustion ◽  
Initial Reagent ◽  
Combustion Technique

High photocatalytic activity of nanoparticulate titanium dioxide has attracted worldwide attention. Synthesis techniques of the nanoparticles, however, often require high energy supply or costly initial reagents. Solution combustion technique is an energy-effective technique capable of synthesizing nanosized titanium powders. This research aimed at utilizing a less expensive initial reagent in synthesis of nanoparticulate titanium dioxide by the solution combustion technique. The research also examined effects of dissolving agents on chemical composition and particle sizes of the synthesized powders. A low-cost initial reagent, titanium dioxide with average particle size of 154 nanometers, was dissolved in sulfuric acid or dispersed in nitric acid prior to the combustion. Experimental results revealed that the pure anatase phase titanium dioxide was successfully obtained in powders prepared from both sulfuric acid and nitric acid. The average particle size of the powder prepared from sulfuric acid was 77 nanometers, while that of the powder prepared from nitric acid was 117 nanometers. The difference in particle sizes was attributed to solubility of the initial reagent in the acid. Complete solution of initial reagent in sulfuric acid was the main factor attributed to finer particle size.

scholarly journals Effect of Particle Size on the HDS Activity of Molybdenum Sulfide

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Carola Contreras ◽  
Fernanda Isquierdo ◽  
Pedro Pereira-Almao ◽  
Carlos E. Scott
Keyword(s):  
Particle Size ◽  
Heavy Oil ◽  
Molybdenum Sulfide ◽  
Vacuum Gas Oil ◽  
Particle Sizes ◽  
Heavy Oils ◽  
Gas Oil ◽  
Oil Reserves ◽  
Effect Of Particle Size

More than half of the total world oil reserves are heavy oil, extra heavy oil, and bitumen; however their catalytic conversion to more valuable products is challenging. The use of submicronic particles or nanoparticles of catalysts suspended in the feedstock may be a viable alternative to the conversion of heavy oils at refinery level or downhole (in situ upgrading). In the present work, molybdenum sulfide (MoS2) particles with varying diameters (10000–10 nm) were prepared using polyvinylpyrrolidone as capping agent. The prepared particles were characterized by DLS, TEM, XRD, and XPS and tested in the hydrodesulfurization (HDS) of a vacuum gas oil (VGO). A correlation between particle size and activity is presented. It was found that particles with diameters around 13 nm show double the HDS activity compared with the material with micrometric particle sizes (diameter ≈ 10,000 nm).

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