Effect of Hydrolysis on High-Purity TiO2 Size for PTC Thermistor

2012 ◽  
Vol 528 ◽  
pp. 160-163
Author(s):  
Zhi Qiang Luo ◽  
Jian Qiao Du
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Heating Rate ◽  
Aging Time ◽  
High Purity ◽  
Volume Ratio ◽  
Solution Concentration ◽  
Thermal Hydrolysis ◽  
Optimum Volume

The effect of self-generated seeded thermal hydrolysis factors, such as TiOSO4 solution concentration, grey aging time, volume ratio of TiOSO4 to pre-adding water, and heating rate on high-purity TiO2 size for PTC thermistor were studied. The samples were characterized by particle size distribution, and SEM. The results show that with increase of TiOSO4 solution concentration, the high-purity TiO2 size decrease gradually, but with increase of grey aging time and volume ratio of TiOSO4 to pre-adding water respectively, the high-purity TiO2 size also increase. The suitable TiOSO4 concentration is 160g/l, grey aging time is 15min, the optimum volume ratio of TiOSO4 to pre-adding water is 4.0:1 and heating rate should be 1.5°C/min.

Effects of Hydrolysis Parameters on TiO2 White Pigment from Low Concentration Industrial TiOSO4 Solution via Sulfate Process

2012 ◽  
Vol 602-604 ◽  
pp. 1243-1249 ◽  
Author(s):  
Cong Xue Tian
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Aging Time ◽  
Volume Ratio ◽  
Narrow Particle Size Distribution ◽  
Water Volume ◽  
White Pigment ◽  
Anatase Titania ◽  
Sulfate Process

Short sulfate process was developed to produce TiO2 white by using unconcentrated industrial TiOSO4 solution as raw material. Herein, anatase titania white pigment was prepared by self-generated seeded thermal hydrolysis route. The effects of hydrolysis parameters (such as pre-adding water volume ratio, F value and aging time) on the structure and pigment properties of the as-prepared samples were investigated. The samples were characterized by XRD, particle size distribution, SEM and pigment properties test. These factors influenced the number and quality of the hydrolysis nuclei, hydrolysis velocity, crystal growth rate and the particles aggregation, eventually determined its structure and pigment properties. The optimized pre-adding water volume ratio was of 0.18:1, the F value was of 1.95 and the aging time after turning-grey-color point was of 20~30 min, and the prepared TiO2 was with anatase phase, narrow particle size distribution and excellent pigment properties.

Concentration of TiOSO4 on Rutile White via Short Sulfate Process

2014 ◽  
Vol 968 ◽  
pp. 40-43 ◽  
Author(s):  
Cong Xue Tian
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Raw Material ◽  
Thermal Hydrolysis ◽  
High Quality ◽  
White Pigment ◽  
Hydrolysis Process ◽  
Sulfate Process ◽  
Favorable Structure

Short sulfate process was developed to produce rutile TiO2 white pigment by using low concentration industrial TiOSO4 solution as raw material via self-generated seeded thermal hydrolysis route. The concentration of TiOSO4 solution had significantly influenced the structure and pigment properties of rutile TiO2 white pigment. The samples were characterized by XRD, particle size distribution and pigment properties test. Appropriate concentration of TiOSO4 was beneficial to promoting hydrolysis process in a proper way and obtaining favorable structure and high quality white pigment. The optimized concentration of TiOSO4 solution was of 191.20 g/L.

Investigations on Degradable and Figuline Calcium Alkaline Phosphate Cements with Multimodal Particle Size Distribution

2011 ◽  
Vol 493-494 ◽  
pp. 355-360
Author(s):  
F. Dombrowski ◽  
R. Hoffmann ◽  
Ute Ploska ◽  
Heidi Marx ◽  
Georg Berger
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Setting Time ◽  
Volume Ratio ◽  
Particle Sizes ◽  
Powder Mixtures ◽  
Setting Reaction ◽  
Tap Density

The paper presented here deals with rheological and hardening properties during the setting reaction, and density and compressive strength after the final setting of a figuline composite consisting of Ca2KNa(PO4)2and 2wt% medium gel strength gelatin. Compared to the composite with monomodal particle size distribution (d50=7.18µm; span=3.9) and its properties during and after setting reaction, the goal of this work is to increase the resulting product compressive strength by mixing different particle sizes in order to obtain bi- and trimodal distributions. For the bimodal powder mixtures the ratio in diameter (dcourse/dsmall) was chosen with 7/1 and volume ratio dcourse/dsmallwas 70/30%. For the trimodal powder mixtures the ratio in diameter (dcourse/dmedium/dsmall) was chosen with 70/7/1 and volume ratio dcourse/dmedium/dsmallwas set to 44/28/28%.After establishing an adequate crushing and sieving process the tap density and powder density of each fraction was determined. Subsequently, the different particle sizes were mixed and the densities and the Hausner ratio were determined again. The mixtures show an increase in both densities especially the tap density increased significantly. Rheological investigations show that the graphs of storage and loss moduli of the multimodal powder mixtures respectively are similar. The characteristic setting times show a slight decrease compared with the monomodal composite but not significantly different data. When comparing the resulting compressive strength of cylindrical samples, which were stored direct after reaching the initial setting time under physiological conditions, the studies illustrated in all cases for the multimodal mixtures a significant increase in compressive strength and a higher density.

Influence Factors on the Size of Spherical Silver Powder Used for Solar Cell Top Electrode Paste

2013 ◽  
Vol 743-744 ◽  
pp. 903-909
Author(s):  
Si Zhang ◽  
Yue Lin Zhu ◽  
Jia Song
Keyword(s):  
Particle Size ◽  
Ascorbic Acid ◽  
Particle Size Distribution ◽  
Acid Solution ◽  
Size Distribution ◽  
Silver Powder ◽  
Influence Factors ◽  
Solution Concentration ◽  
Face Centered Cubic ◽  
Ascorbic Acid Solution

The ultra-fine silver powders were prepared by chemical reduction using nitric acid silver (AgNO3) as raw material, ascorbic acid (C6H8O6) as deoxidizer and adding polyvinylpyrrolidone (PVP) as dispersing agent. The influence factors, such as AgNO3solution concentration, ascorbic acid solution concentration, PVP dosage and reaction conditions such as temperature, PH etc. were studied. The morphology and particle size distribution were observed by Field Emission Scanning Electron Microscopy (FSEM) and laser particle analyzer. The composition was analyzed by Energy Dispersive Spectrometer (EDS).The crystal phase was tested by X-ray Diffraction (XRD). It indicates that the spherical ultra-fine silver powder is face-centered cubic structure, its diameter is about 1.0 μm with homogeneous particle size distribution and smooth surface. It was prepared under the conditions as following: dropwise added 60 g/L AgNO3solution into 40g/L ascorbic acid solution, with the presence of PVP, and pH=3,45,360rpm. It meets the requirements of paste for solar cells top electrode.

Study on Particle Size Distribution of Diesel Bus Fueled with Biodiesel under Real Operating Condition

2013 ◽  
Vol 316-317 ◽  
pp. 1178-1182 ◽  
Author(s):  
Di Ming Lou ◽  
Feng Chen ◽  
Yuan Hu Zhi ◽  
Pi Qiang Tan ◽  
Wei Hu
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Operating Time ◽  
Volume Ratio ◽  
Gradual Transition ◽  
Operating Condition ◽  
Acceleration And Deceleration ◽  
Particulate Number ◽  
Real Operating Condition

With the use of the Engine Exhaust Particle Sizer (EEPS) developed by TSI, particle size distribution characteristics of China-IV diesel bus fueled biodiesel are studied under real operating condition. Four mixtures of volume ratio between restaurant waste oil and China-IV diesel 5%, 10%, 20%, 50% respectively (marked separately by BD5, BD10, BD20, BD50), pure biodiesel (BD100) and pure diesel (BD0) were tested. The results indicated that the average velocity of diesel bus is 18km/h. Of the entire operating time, idle operating period accounts for 30%, low and medium velocity 58%, and acceleration and deceleration 89%. In different velocity ranges, the size distribution of particulate number emissions (PNSD) is bimodal; in different acceleration ranges, PNSD shows a gradual transition from bimodal shape to unimodal when bus operation switches from decelerating to accelerating status. Biodiesel blended with higher mixture ratios show significant reduction in PN emissions for accumulated modes, and particulate number emission peaks move towards smaller sizes; but little change was obtained in PN emissions for nuclei modes with its particulate size of peak sustains around 10nm.

Reactivity of Iron/Zirconia Powder in Fluidized Bed Thermochemical Hydrogen Production Reactors

2012 ◽  
Author(s):  
F. Al-Raqom ◽  
J. F. Klausner
Keyword(s):  
Particle Size ◽  
Hydrogen Production ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Iron Powder ◽  
Volume Ratio ◽  
Apparent Volume ◽  
Fluidized Bed Reactors ◽  
Zirconia Powder

A fluidized bed reactor has been developed which uses a two-step thermochemical water splitting process with a peak hydrogen production rate of 47 Ncm3/min.gFe at an oxidation temperature of 850°C. Of particular interest, is that a mixture of iron and zirconia powder is fluidized during the oxidation reaction using a steam mass flux of 0.58 g/min-cm2, and the zirconia powder serves to virtually eliminate iron powder sintering while maintaining a high reaction rate. The iron/zirconia powder is mixed with a ratio of 1:2 by apparent volume, equivalent mass ratio, and both iron and zirconia particles are sieved to sizes ranging from 125–355 μm. Fluidized bed reactors are advantageous because they have high reactivity, strong thermal and chemical transport, and tend to be compact. There has been significant interest in developing fluidized bed reactors for solar thermochemical reactors, but sintering of the reactive powder has inhibited their development. The current powder mixture and reactor configuration shows great potential for achieving high hydrogen production rates for operation at high temperature. The experimental investigations for utilizing zirconia as a sintering inhibitor was found to be dependent on the iron and zirconia particle size, particle size distribution and iron/zirconia apparent volume ratio. For example at 650 °C the oxidation of iron powder with a mean particle size of 100 μm and a wide particle size distribution (40–250 μm) mixed with 44 μm zirconia powder with an iron/zirconia apparent volume ratio of 1:1 results in 75–90 % sintering. In all cases when iron is mixed with zirconia, the hydrogen production rate is not affected when compared with the pure iron case. When iron powder is mixed with zirconia, both with a narrow particle size distribution (125–355 μm) the first oxidation step results in 3–7% sintering when the reactions are carried out at temperatures ranging between 840–895 °C. The hydrogen fractional yield is high (94–97%). For subsequent redox reactions, the sintering is totally eliminated at 867 and 895 °C although the hydrogen fractional yield decreases to 27 and 33%, respectively. This study demonstrates that mixing iron with zirconia in an equivalent mass ratio and similar particle size can eliminate sintering in a fluidized bed reactor at elevated temperatures up to 895°C.

Effects of Concentration of TiOSO4 and Fe/TiO2 Ratio on TiO2 Anatase White Pigment Production via Short Sulfate Process

2013 ◽  
Vol 634-638 ◽  
pp. 391-396 ◽  
Author(s):  
Cong Xue Tian ◽  
Shuang Hua Huang ◽  
Ying Yang
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Narrow Particle Size Distribution ◽  
Crystal Formation ◽  
Aggregation Process ◽  
Thermal Hydrolysis ◽  
White Pigment ◽  
Sulfate Process

Using unconcentrated TiOSO4 solution from sulfate process as titanium source, anatase TiO2 white pigment was prepared by self-generating seed thermal hydrolysis route via short sulfate process. The effects of concentration of TiOSO4 solution and Fe/TiO2 ratio on the structure and pigment properties of the TiO2 white pigments were investigated. The samples were characterized by XRD, particle size distribution and pigment properties test. The concentration of TiOSO4 solution and Fe/TiO2 ratio had great effects on the super-saturation of TiO2+, crystal formation, nucleation, crystallization and aggregation process, eventually determined the crystal structure, particle size distribution and its pigment properties. The optimized concentration of TiOSO4 solution was of 195 g/L, and the Fe/TiO2 ratio was at 0.30.The as-prepared anatase white pigment was appropriate particle size, narrow particle size distribution and good pigment properties.

Hydrolysis Time on Rutile TiO2 White Pigment via Short Sulfate Process

2014 ◽  
Vol 968 ◽  
pp. 36-39
Author(s):  
Cong Xue Tian
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Hydrolysis Rate ◽  
Narrow Particle Size Distribution ◽  
Thermal Hydrolysis ◽  
Structure And Properties ◽  
Hydrolysis Time ◽  
White Pigment ◽  
Sulfate Process

Rutile TiO2 white pigment was prepared by self-seeded thermal hydrolysis route via short sulfate process from low concentration TiOSO4 solution. Hydrolysis time had significantly influenced the structure and pigment properties of rutile TiO2. The samples were characterized by XRD, particle size distribution and pigment properties test. The hydrolysis time had great influences on the hydrolysis rate, particle size distribution, crystal growth and particle aggregation of TiO2, eventually determined the pigment structure and properties. The optimized hydrolysis time after second boiling point was of 2.5h. And the prepared rutile TiO2 white pigment was with narrow particle size distribution and nice pigment properties.

Reactivity of Iron/Zirconia Powder in Fluidized Bed Thermochemical Hydrogen Production Reactors

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
F. Al-Raqom ◽  
J. F. Klausner
Keyword(s):  
Particle Size ◽  
Hydrogen Production ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Iron Powder ◽  
Volume Ratio ◽  
Apparent Volume ◽  
Zirconia Powder ◽  
Equivalent Mass

A fluidized bed reactor has been developed which uses a two-step thermochemical water splitting process with a peak hydrogen production rate of 47 Ncm3/min.gFe at an oxidation temperature of 850 °C. Of particular interest, is that a mixture of iron and zirconia powder is fluidized during the oxidation reaction using a steam mass flux of 58 g/min-cm2. The zirconia powder serves to virtually eliminate iron powder sintering while maintaining a high reaction rate. The iron/zirconia powder is mixed in a ratio of 1:2 by apparent volume and has a mass ratio of 1:1. Both iron and zirconia particles are sieved to sizes ranging from 125 μm to 355 μm. The efficacy of zirconia as a sintering inhibitor was found to be dependent on the iron and zirconia mean particle size, particle size distribution and iron/zirconia apparent volume ratio. At 650 °C, the oxidation of iron powder with a mean particle size of 100 μm and a wide particle size distribution (40–250 μm) mixed with 44 μm zirconia powder with an iron/zirconia apparent volume ratio of 1:1 results in 75–90% sintering. In all cases, when iron is mixed with zirconia, the hydrogen production rate is not affected when compared with the pure iron case assuming an equivalent mass of iron is in the mixture. When iron powder is mixed with zirconia, both with a narrow particle size distribution (125–355 μm), the first oxidation step results in 3–7% sintering when the reactions are carried out at temperatures ranging between 840 and 895 °C. The hydrogen fractional yield is high (94–97%). For subsequent redox reactions, the macroscopic sintering is totally eliminated at 867 and 895 °C, although the hydrogen fractional yield decreases to 27 and 33%, respectively. It is demonstrated that mixing iron with zirconia in an equivalent mass ratio and similar particle size range can eliminate macroscopic sintering in a fluidized bed reactor at elevated temperatures up to 895 °C.

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