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.

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.

Porous AlN Ceramics Fabricated by Carbothermal Reduction

2014 ◽  
Vol 788 ◽  
pp. 627-631
Author(s):  
Yuan Lu ◽  
Jing Long Li ◽  
Jian Feng Yang ◽  
Peng Li
Keyword(s):  
Mechanical Properties ◽  
Carbothermal Reduction ◽  
Glass Phase ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
High Porosity ◽  
Sintering Additives ◽  
Fine Microstructure ◽  
Complete Formation

A new method for preparing porous AlN ceramics with high porosity had been developed by carbothermal reduction of die-pressed green bodies composed of alumina, carbon, sintering additives and AlN seeds. The influences of sintering additives and sintering temperature on the microstructure and mechanical properties of porous AlN ceramics were investigated. XRD analysis proved that complete formation of AlN phase except for minor of glass phase. SEM analysis showed that the resultant porous AlN ceramics occupied fine microstructure and a uniform pore structure. Porous AlN ceramics with a porosity of 41~66% and a strength of 2.7~ 51.8 MPa were obtained.

Effects of Sintering Additives on Properties of Porous Silicon Nitride Ceramics Fabricated by Carbothermal Reduction

2008 ◽  
Vol 368-372 ◽  
pp. 878-880 ◽  
Author(s):  
Yuan Lu ◽  
Jian Feng Yang ◽  
Shao Yun Shan ◽  
Ji Qiang Gao ◽  
Zhi Hao Jin
Keyword(s):  
Carbothermal Reduction ◽  
Sintered Sample ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Sintering Additives ◽  
Sintering Additive ◽  
Fine Microstructure ◽  
Porous Si3n4 ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between silicon dioxide and carbon. The influences of four types of sintering additives on the microstructure and mechanical properties of the porous Si3N4 ceramics were investigated. XRD analysis proved complete formation of a single-phase β-Si3N4. SEM analysis showed that the resultant porous Si3N4 ceramics occupied fine microstructure and a uniform pore structure. The sintered sample with Lu2O3 as sintering additive showed finer, a higher aspect ratio β-Si3N4 grains. The addition of Eu2O3 accelerated the densification of porous Si3N4 ceramics, decreased the porosity and increased the flexural strength.

The Effect of CaCO3 Addition on Physical Properties of ZnO-Based Crystal Glaze

2012 ◽  
Vol 620 ◽  
pp. 12-16 ◽  
Author(s):  
Abdul Rashid Jamaludin ◽  
Shah Rizal Kasim ◽  
Zainal Arifin Ahmad
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Scanning Electron Microscope ◽  
Physical Properties ◽  
Crystallization Temperature ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The effects of calcium carbonate (CaCO3) addition on the physical properties of ZnO-based crystal glaze batches were investigated. Samples were fired at different gloss firing temperatures ranging from 1180-1220°C with 3 hours soaking at 1060°C crystallization temperature. X-ray diffraction (XRD) analysis identifiedthe crystal phase occurred as willemite (Zn2SiO4) and the scanning electron microscope (SEM) analysis indicated that willemite crystals are in the acicular needle like shape that formed spherulite. The intensities of willemite peaks decreased with CaCO3 addition and completely vanished at 5.0 wt% CaCO3. Varied formation of spherulites developed of the surface of crystal glaze as the flows of the glaze stretched further as the amount of CaCO3 increased.

Fabrication of Porous Silicon Nitride with High Porosity

2007 ◽  
Vol 336-338 ◽  
pp. 1105-1108 ◽  
Author(s):  
Shao Yun Shan ◽  
Jian Feng Yang ◽  
Ji Qiang Gao ◽  
Wen Hui Zhang ◽  
Zhi Hao Jin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Xrd Analysis ◽  
Reduction Reaction ◽  
Sem Analysis ◽  
High Porosity ◽  
Sintering Additive ◽  
Fine Microstructure ◽  
Porous Si3n4 ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

In this study, porous Si3N4 ceramics were fabricated by carbothermal reduction reaction between silicon dioxide and carbon. The influences of different starting powders and sintering additives on microstructure and mechanical properties were investigated. XRD analysis demonstrated the formation of single-phase β-Si3N4 except for glass phase and minor of α-Si3N4 phase. SEM analysis showed that the resultant porous Si3N4 ceramics occupied fine microstructure and uniform pore structure. The samples with fine starting powder showed fine, high aspect ratio of β-Si3N4 grains and good mechanical properties. The addition of Al2O3 accelerated the densification of porous Si3N4 ceramics. With an increasing in the sintering additive content, the porosity decreased, the flexural strength increased.

Sintering Properties of Fused Silica/Nano-Zirconia Composite Ceramic

2013 ◽  
Vol 750-752 ◽  
pp. 81-84
Author(s):  
Yong Wu He ◽  
Jing Long Bu ◽  
Rui Sheng Wang ◽  
Dong Mei Zhao ◽  
Jun Xing Chen ◽  
...  
Keyword(s):  
Bulk Density ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Composite Ceramic ◽  
High Energy ◽  
Fused Silica ◽  
Raw Material ◽  
Composite Powders ◽  
Wet Chemical Synthesis ◽  
Sintering Properties

Zirconyl chloride was used as zirconium source and fused silica particles were used as main raw material. First of all, the composite powders were prepared by wet chemical synthesis using ammonia as the precipitator and polyethylene glycol as the dispersant. Then, fused silica nanozirconia composite ceramic containing nanometer particle zirconia with different contents (5%, 15%, 25% and 35%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The bulk density and bending strength were measured, microstructure was observed by SEM. The result indicated bulk density and bending strength of composite ceramic increase and microstructure becomes denser with content of zirconia increasing. Bulk density of composite ceramic increases and bending strength which reaches maximum at 1350°C firstly increases then decreases with the increase of sintering temperature. Both high sintering temperature and nanozirconia possessing high energy interface can improve the composite ceramic sintering.

scholarly journals Short-Term Impact of Drip Irrigation Frequency on Soil Hydro-Physical Properties of an Alfisol and Performance of Two Maize Varieties

2020 ◽  
Vol 8 (8) ◽  
pp. 1675-1685
Author(s):  
Gabriel Oladele Awe ◽  
Busola Margret Ayuba ◽  
Japheth Umam ◽  
Toyin Peter Abegunrin
Keyword(s):  
Physical Properties ◽  
Bulk Density ◽  
Irrigation Water ◽  
Drip Irrigation ◽  
Yield Components ◽  
Irrigation Frequency ◽  
Short Term ◽  
Maize Varieties ◽  
Maize Variety ◽  
And Performance

Irrigation scheduling is important for efficient use of applied water and for maximizing crop yields. Therefore, the aim of this study was to evaluate the short-term effect of drip irrigation frequency on soil hydro-physical properties of an Alfisol and performance of two maize varieties, at the Teaching and Research Farm, Faculty of Agricultural Sciences, Ekiti State University, Ado Ekiti, Southwest Nigeria. The experiment was laid out using a split-plot experiment in randomized complete block design (RCBD) and three replications. Irrigation frequency constituted the main plot namely: irrigation four times a week (I4), irrigation thrice a week (I3), and irrigation twice a week (I2) of re-filling soil to field capacity while the subplot was maize variety namely: V1: SAMMAZ-27 and V2: OBA-super-6. Plant growth parameters and soil physical properties of soil water content (SWC), bulk density (BD) and saturated hydraulic conductivity (Ksat) were monitored during the growing cycle. Water use efficiency (WUE) and yield components were determined at maturity. There were significant interactions between irrigation regime and maize variety on SWC and Ksat. The maximum bulk density (BDmax) and optimum soil water content SWCopt were 1.41 g/cm3 and 0.12 g/g, respectively. Plant height (PH) did not differ between the two maize varieties throughout the growth cycle. Drip irrigation frequency did not significantly affect plant height until growth stage V12 (12 fully opened leaves), with I4 irrigation treatment having the tallest plant. Both drip irrigation and maize variety had no significant influence on both LAI and CC, neither was there any significant interaction effect. Increasing irrigation water increased maize yield and yield components. The treatment combination of I4V1 had the highest performance indices in terms of yield components. WUE decreased with increasing frequency of irrigation water application while the WUE of SAMMAZ-27 > OBA-super-6. Therefore, irrigating four times a week and SAMAZ-27 maize variety could be a suitable irrigation-variety combination for providing sustainable irrigation agriculture for maize in this region.

Preparation and Mechanism of Cordierite by Using Calcined Bauxite as Raw Material at Relatively Low Temperature

2013 ◽  
Vol 785-786 ◽  
pp. 1066-1071
Author(s):  
Jian Feng Wu ◽  
Bin Zheng Fang ◽  
Xiao Hong Xu ◽  
Xin Bin Lao
Keyword(s):  
Low Temperature ◽  
Bulk Density ◽  
Bending Strength ◽  
Raw Materials ◽  
Xrd Analysis ◽  
Raw Material ◽  
Synthetic Process ◽  
Synthetic Temperature ◽  
Sintering Method

The cordierite was synthesized at relatively low temperature by pressureless sintering method, using calcined bauxite, talcum , quartz and feldspar as raw materials in this paper. The water absorption (Wa), porosity (Pa), bulk density (Db) and bending strength of samples have been tested, and the synthetic process and mechanism have been investigated by XRD, SEM, and so on. The results showed that the cordierite could be synthesized at 1280°C and the range of synthetic temperature is 1160~1300°C, when the sample was sintered at 1280°C for 2h, its bulk density and bending strength were 2.20g/cm3and 72.13MPa, respectively. XRD analysis showed that the main phase of sample was cordierite, the cordierite content was about 88wt%, and the minor phases were MgAl2O4spinel and corundum. SEM results showed that the samples were dense and the pore sizes were 5 μm~100μm, the grains were growth and development well, the grains size were 0.5μm~6μm. High reaction activity corundum and mullite were provided by calcined bauxite, then coupled with the role of feldspar, thus reduced the synthetic temperature of cordierite.

Porous Silicon Nitride Ceramics Prepared by Reduction – Nitridation of Diatomite

2009 ◽  
Vol 620-622 ◽  
pp. 753-756
Author(s):  
Yao Hui Xue ◽  
Yuan Lu ◽  
Bo Wang ◽  
Jian Feng Yang ◽  
Wei Zhong Lu ◽  
...  
Keyword(s):  
Carbothermal Reduction ◽  
Sedimentary Rock ◽  
Aquatic Plant ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Main Ingredient ◽  
Nitride Ceramics ◽  
Fine Microstructure ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between carbon black and diatomite. Diatomite is a siliceous, sedimentary rock consisting principally of the fossilized skeletal remains of diatom, a unicellular aquatic plant related to the algae. The main ingredient of diatomite is the amorphous active silicon dioxide. The influence of diatomite particle size on the microstructure of sintering bodies was analyzed. XRD analysis demonstrated the formation of Si3N4 except for minor of glass phase. SEM analysis showed that the resultant porous β-Si3N4 ceramics occupied fine microstructure and uniform pore structure.

Effect of Zeolite Synthesized from Rice Husk Silica Towards Mixed Matrix Polysulfone Ultrafiltration Membrane

2014 ◽  
Vol 70 (2) ◽  
Author(s):  
Nurafiqah Rosman ◽  
Zawati Harun ◽  
Muhammad Zaini Yunos ◽  
Sulaiman Hasan
Keyword(s):  
Rice Husk ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Zeolite A ◽  
X Ray ◽  
Membrane Morphology ◽  
Membrane Flux ◽  
Field Emission Microscopy ◽  
And Performance

In the present work, polysulfone (PSf) ultrafiltration membranes were prepared by solution casting via phase inversion process. The effects of synthesized rice husk (RH) zeolite on the properties and performance of the casted PSf membrane were observed and investigated. Characterization of synthesized RH zeolite and morphology of membrane were conducted by using X-ray diffractometer (XRD), field emission microscopy (FESEM) and scanning electron microscopy (SEM). XRD analysis shows a mixture of zeolite A, Y and P, while FESEM images showed agglomeration of cubic-shaped morphology of the synthesized RH zeolite. SEM analysis on membrane morphology indicates that the addition of synthesized RH zeolite obviously changed the microstructure of the membrane sub layer. At 2g RHY content, the membranes held the highest water permeability (315.29 Lm-2h-1) and continuously decreased with higher RHY content. The incorporation of the RHY particles beyond 2% causes declination to the membrane flux and increment to the humic acid rejection from 95.8 to 99.6%.

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