Preparation and Performance of Andalusite Bonded SiC Solar Heat-Absorbing Ceramics

2013 ◽  
Vol 320 ◽  
pp. 52-59
Author(s):  
Jian Feng Wu ◽  
Meng Liu ◽  
Xiao Hong Xu ◽  
Ya Xiang Zhang ◽  
Kun Li ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Bending Strength ◽  
Thermal Power ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Expansion Rate ◽  
Testing Technology ◽  
Firing Shrinkage ◽  
And Performance ◽  
Physical And Chemical

Using andalusite, SiC, Su Zhou Kaolin and Guang Xi quartz as materials, andalusite bonded SiC heat absorbing ceramic was prepared by pressureless firing in the ceramic preparation process. The influence of gradient SiC on microstructure and properties of the samples were studied. Using the testing technology of XRD, SEM, and etc., physical and chemical properties, phase composition and microstructure were tested and analysised.The results indicate that andalusite bonded SiC heat absorbing ceramic, which prepared to have a low firing shrinkage rate, high refractoriness and a good microstructure. The best firing temperature of the best formula C4 is 1460°C, firing expansion rate is 0.98%, bending strength is 32.52MPa,porosity is 30.74%, bulk density is 2.05g·cm-3, refractoriness is 1650°C,growth rate of oxidation weight is 2.769mg·cm-2and have no crack after 30 times thermal shock. The bending strength has increased 11.15% after thermal shock. XRD analysis indicated that the main phase compositions are α-SiC, mullite and cristobalite.SEM studies show that there are many connected pores in the samples, the diameters of the pores are 10~20μm. Andalusite bonded SiC heat absorbing ceramic have a low firing expansion rate, high bending strength and good microstructure, which is suit for tower type solar thermal power generation.

Preparation and Performance of β-Sialon/Si3N4 Composite Ceramics for Solar Heat Absorber

2014 ◽  
Vol 692 ◽  
pp. 234-239
Author(s):  
Jian Feng Wu ◽  
Ya Xiang Zhang ◽  
Xiao Hong Xu ◽  
De Zhi He ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Physical Properties ◽  
Bulk Density ◽  
Bending Strength ◽  
Thermal Power ◽  
Composite Ceramic ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Testing Technology ◽  
Fine Microstructure ◽  
And Performance

β-Sialon/Si3N4composite ceramic were prepared from starting materials of α-Si3N4, AlN and Al2O3by pressureless sintering. The physical properties, phase composition and microstructure were tested by modern testing technology. The effect of different additives such as Y2O3, La2O3and borax on the sintering temperature and physical properties was studied. The results show that D3 is the best formula, firing shrinkage rate of the sample is 14.14%, water absorption 3.16%, porosity 9.02%, bulk density 2.85g·cm-3and bending strength 193.87MPa after firing at 1580°C. XRD analysis indicates that the main phases of D3 are β-Sialon, β-Si3N4and corundum. SEM analysis shows that the microstructure of D3 sample is quite dense and the pores distribution is uniform, the diameter of the pore is about 1~5μm. β-Sialon/Si3N4composite ceramic has high bulk density, bending strength and fine microstructure, which is a new choice of the heat absorb material for solar thermal power generation system.

Application of a-SiO2 Rich Additives in Cement Paste

2015 ◽  
Vol 749 ◽  
pp. 362-367 ◽  
Author(s):  
Jaroslav Pokorný ◽  
Milena Pavlíková ◽  
Eva Navrátilová ◽  
Pavla Rovnaníková ◽  
Zbyšek Pavlík ◽  
...  
Keyword(s):  
Cement Paste ◽  
Bending Strength ◽  
Setting Time ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Fast Reaction ◽  
Cement Pastes ◽  
Matrix Density ◽  
Physical And Chemical ◽  
And Chemical Properties

The effect of a-SiO2 of various origin on the properties of cement paste with incorporated different silica containing materials is experimentally studied in the paper. For the applied a-SiO2 materials, basic physical and chemical properties are accessed, together with their chemical composition. Amount of amorphous phase of SiO2 in particular siliceous materials is determined using XRD analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated a-SiO2 containing materials, together with initial and final setting time of fresh mixtures. The obtained data give evidence on a high and fast reaction activity of tested siliceous materials which results in a significant improvement of porosity and mechanical strength of a-SiO2 modified cement pastes.

Nanocrystals: The Preparation, Precise Control and Application Toward the Pharmaceutics and Food Industry

2018 ◽  
Vol 24 (21) ◽  
pp. 2425-2431 ◽  
Author(s):  
Cao Wu ◽  
Zhou Chen ◽  
Ya Hu ◽  
Zhiyuan Rao ◽  
Wangping Wu ◽  
...  
Keyword(s):  
Food Industry ◽  
Chemical Properties ◽  
Preparation Methods ◽  
Precise Control ◽  
Significant Process ◽  
Technology Applications ◽  
And Performance ◽  
Physical And Chemical ◽  
Analytical Technology ◽  
And Chemical Properties

Crystallization is a significant process employed to produce a wide variety of materials in pharmaceutical and food area. The control of crystal dimension, crystallinity, and shape is very important because they will affect the subsequent filtration, drying and grinding performance as well as the physical and chemical properties of the material. This review summarizes the special features of crystallization technology and the preparation methods of nanocrystals, and discusses analytical technology which is used to control crystal quality and performance. The crystallization technology applications in pharmaceutics and foods are also outlined. These illustrated examples further help us to gain a better understanding of the crystallization technology for pharmaceutics and foods.

scholarly journals Testing Engine Oil Specifications and Properties and its Effects on the Engines Maintenance and Performance

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Chemical Properties ◽  
Mechanical Tests ◽  
Engine Oil ◽  
Strong Relation ◽  
Degree Of Stability ◽  
And Performance ◽  
The Cost ◽  
Motor Oils ◽  
Physical And Chemical ◽  
And Chemical Properties

This paper presents the results of practical mechanical tests of motor oils, their specifications and characteristics and the effect of their physical and chemical properties on the performance of the engine. The performance of the engine has a strong relation with the engine oil type and efficiency. The degree of stability of oils properties is very important because if oil or lubricants lose their properties, mechanical and chemical excessive corrosion of the motor metals may occur. Consequently, damage occurs to one or more parts of the engine, thereby the system is breaking down where the cost of downtime is too expensive. It has been found that a higher viscosity value is not the optimum as it increases temperature and energy consumption due to frictional losses. The values required for viscosity is the ideals that gives the stable results regardless temperature variations under any conditions of operation, at which the power losses are minimal and the fuel economy is optimal.

scholarly journals Reactivity of fly ashes milled in different milling devices

2019 ◽  
Vol 58 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Yong-Sik Chu ◽  
Batmunkh Davaabal ◽  
Dae-Sung Kim ◽  
Sung-Kwan Seo ◽  
Yoo Kim ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Surface Area ◽  
Thermal Power ◽  
Chemical Properties ◽  
Particle Size Reduction ◽  
Attrition Mill ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Physical And Chemical

Abstract The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

Effects of dimethyl carbonate fuel additive on diesel engine performances

2005 ◽  
Vol 219 (7) ◽  
pp. 897-903 ◽  
Author(s):  
G D Zhang ◽  
H Liu ◽  
X X Xia ◽  
W G Zhang ◽  
J H Fang
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Diesel Engines ◽  
Dimethyl Carbonate ◽  
Chemical Properties ◽  
Fuel Additive ◽  
High Oxygen Content ◽  
Combustion Duration ◽  
And Performance ◽  
Physical And Chemical

The physical and chemical properties of some oxygenated compounds are discussed, including dimethoxymethane (methylal, or DMM), dimethyl carbonate (DMC), and ethyl acetate. In particular, DMC may be a promising additive for diesel fuel owing to its high oxygen content, no carbon-carbon atomic bonds, suitable boiling point, and solubility in diesel fuel. The aim of this research was to study the combustion characteristics and performance of diesel engines operating on diesel fuel mixed with DMC. The experimental results have shown that particulate matter (PM) emissions can be reduced using the DMC oxygenated compound. The combustion analysis indicated that the ignition delay of the engine fuelled with DMC-diesel blended fuel is longer, but combustion duration is much shorter, and the thermal efficiency is increased compared with that of a base diesel engine. Further, if injection is also delayed, NOx emissions can be reduced while PM emissions are still reduced significantly. The experimental study found that diesel engines fuelled with DMC additive had improved combustion and emission performances.

scholarly journals Microwave solid fuel ignition

2021 ◽  
Vol 2094 (5) ◽  
pp. 052054
Author(s):  
R V Kondratev
Keyword(s):  
Electromagnetic Field ◽  
Solid Fuel ◽  
Thermal Power ◽  
Experimental Studies ◽  
Chemical Properties ◽  
Ignition Process ◽  
Boiler Plant ◽  
Microwave Exposure ◽  
Unburned Fuel ◽  
Physical And Chemical

Abstract The article continues the study of the effect of microwave exposure on solid fuel. On the basis of the experimental studies, the dependences of changes in the temperature and humidity fields of the fuel on the time of microwave exposure, to arson, have been established. The possibility of using the microwave electromagnetic field to automate the process of burning solid fuel in a boiler plant, afterburning unburned fuel residues is considered. The mechanism and basic conditions of these processes are presented. The influence of this technology on the intensification of the fuel ignition process, its homogenization, an increase in energy characteristics and a change in the elemental composition, an increase in the efficiency of a boiler plant, a decrease in chemical, mechanical underburning and harmful emissions of a boiler plant is considered. The main conditions of the applied technology are: placement of the microwave generator on the combustion device of the boiler unit, the size of the solid fuel samples or its contacting pieces should be less than the wavelength of the microwave electromagnetic field (12.4 cm), the moisture content - within the range from 10 to 95%. The intensification of the process of burning solid fuel also depends on the type of fuel, its physical and chemical properties (various types of coal, wood fuel, including wood waste, peat, and others). Modernization of boiler plants using this technology is possible by unifying projects that take into account the correspondence of microwave generators to the thermal power of boiler units.

Investigating the properties and performance of 3A molecular sieves as an adsorbent to prevent coke formation in olefin dehydration process

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zoya Moslempour ◽  
Sepehr Sadighi ◽  
Ali Dashti ◽  
Ali Ahmadpour
Keyword(s):  
Molecular Sieves ◽  
Molecular Sieve ◽  
Coke Formation ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Na Ions ◽  
Temperature Programmed ◽  
And Performance ◽  
Physical And Chemical

Abstract To study the affinity of 3A aluminosilicate adsorbents to prevent oligomerization of olefin molecules and forming green oil, physical and chemical properties of 3A molecular sieves are measured by using characterization techniques such as temperature-programmed desorption (TPD), nitrogen (N2) and water adsorptions, X-ray diffraction (XRD), X-ray fluorescence (XRF), crushing strength, and carbon dioxide (CO2) adsorption. Moreover, coke formation affinities of the understudy adsorbents are evaluated in a bench-scale system using 1-butene and 1,3-butadiene at temperatures of 220 and 260 °C, and outcomes are validated against the actual data gathered from an industrial scale olefin dehydration plant. Results confirm that the type of binder and the amount of ion exchange affect the performance of a 3A molecular sieve nominated for dehydrating olefinic streams. The binder with the least amount of acidity is preferred, and at least 35% of Na ions of the 4A zeolite should be exchanged with K ions to make it applicable for synthesizing an appropriate 3A molecular sieve. Furthermore, to control the oligomerization and inhibit green oil formation, the CO2 adsorption and acidity of Trisiv shape molecular sieves with the sizes of 1/4 inch should be less than 0.5 wt % and 1.7 mmol NH3/g, respectively. For extrudate shape with the sizes of 1/16 inch CO2 adsorption and acidity should be less than 0.2 wt % and 2.2 mmol NH3/g, respectively.

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