Effect of Sintering Temperatures on the Reaction-Bonded Si3N4/SiC Composite Ceramics

2011 ◽  
Vol 399-401 ◽  
pp. 331-335 ◽  
Author(s):  
Jun Li ◽  
Wen Jie Yuan ◽  
Shuo Wang ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Silicon Powder ◽  
Processing Parameters ◽  
Nitrogen Atmosphere ◽  
Particle Sizes ◽  
Composite Ceramics ◽  
Strength Tests ◽  
Different Temperatures ◽  
Microstructure And Mechanical Property

Effect of sintering temperatures on reaction-bonded Si3N4/SiC composite ceramics under pressureless was investigated. Si3N4/SiC composite ceramics were sintered at different temperatures from 1450 to 1700 °C under nitrogen atmosphere by using SiC with different particle sizes, Si and additives Y2O3 as raw materials. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive strength tests. The results demonstrated that when the particle gradation consists of silicon carbide of 74 μm (5 wt.%), 44 μm (10 wt.%) and 0.5 μm(35 wt.%) and silicon powder of 74 μm (42 wt.%), the more dense samples with the bulk density of 2.43 g/cm3 and the higher compressive strength of 324 MPa could be obtained at the sintering temperature of 1550 °C for 3h as the optimum processing parameters.

Effect of Different Sintering Additives on the Reaction-Bonded Si3N4/SiC Composite Ceramics

2013 ◽  
Vol 634-638 ◽  
pp. 2349-2353 ◽  
Author(s):  
Jun Li ◽  
Wen Jie Yuan ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Silicon Powder ◽  
Nitrogen Atmosphere ◽  
Strength Test ◽  
Particle Sizes ◽  
Composite Ceramics ◽  
Sintering Additives ◽  
Compressive Strength Test ◽  
Microstructure And Mechanical Property

Effect of different sintering additives on reaction-bonded Si3N4/SiC composite ceramics under pressureless was investigated. Si3N4/SiC composite ceramics were sintered at the temperature 1550 °C under nitrogen atmosphere with different sintering additives Y2O3, Y2O3:Al2O3=1:1, Y2O3:Mg2AlO4 :Mg3(Si4O10)(OH)2: SiO2=5:2:1:1, and ZrO2 by using SiC with different particle sizes, and Si as raw materials. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive strength test. The results demonstrated that when the particle gradation consisted of silicon carbide of 74 μm (5 wt.%), 44 μm (10 wt.%) and 0.5 μm(30 wt.%) and silicon powder of 74 μm (42 wt.%), the more dense samples with the bulk density of 2.43 g/cm3 and the higher compressive strength of 324 MPa could be obtained when Y2O3 was used as sintering additives.

Effect of Sintering Temperature and Particle Size on Porous SiC/Si3N4 Composite Ceramics

2011 ◽  
Vol 399-401 ◽  
pp. 449-452
Author(s):  
Shuo Wang ◽  
Jun Li ◽  
Wen Jie Yuan ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng
Keyword(s):  
Mechanical Property ◽  
Particle Size ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Different Temperatures ◽  
Porous Sic ◽  
Microstructure And Mechanical Property ◽  
Compressive Tests

Porous SiC/Si3N4 composite ceramic was prepared at different temperatures by pressureless using SiC and Si3N4 as raw materials. The effects of sintering temperature and different particle size of SiC on porosity SiC/Si3N4 composite ceramic were investigated. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive tests respectively. The results indicate that the increase of sintering temperature is in favor of the formation of β-Si3N4 crystal phase, the porosity and the compression strengthof porous SiC/Si3N4 composite ; The porosity of Si3N4/SiC block which contain particle graded higher than single particle size, but weaker compression strength.

scholarly journals Development, Performance, and Microscopic Analysis of New Anchorage Agent with Heat Resistance, High Strength, and Full Length

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaohu Liu ◽  
Zhishu Yao ◽  
Weipei Xue ◽  
Xiang Li
Keyword(s):  
Compressive Strength ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Raw Materials ◽  
Microscopic Analysis ◽  
High Strength ◽  
Full Length ◽  
Technical Problems ◽  
Silane Coupling ◽  
Different Temperatures

To solve the difficult problems of failure of pretensioned bolt supports under high ground pressure and temperature, a new kind of anchorage agent with excellent performance is developed. First, the selection and compounding of raw materials were conducted. The new anchorage agent was obtained by modifying the PET resin by mixing with a phenolic epoxy vinyl ester resin (FX-470 resin) and adding a KH-570 silane coupling agent. Then, the viscosity, thermal stability, compressive strength under different temperatures, and anchorage capacity of the new anchorage agent were tested. Moreover, the best proportion ratio of anchorage agent by mixing resin : coarse stone powder : fine stone powder : accelerator : curing agent : KH-570 = 100 : 275 : 275 : 1 : 32.5 : 1 is obtained. The test results showed that, with the addition of a KH-570 silane coupling agent, the viscosity decreased significantly, thereby solving the difficult technical problems of pretensioned bolt supports in full-length anchorage support. Compared with the conventional anchorage agent, the compressive strength of the new anchorage agent increased by 20.4, 82.5, 118.2, and 237.5% at 10, 50, 80, and 110°C, respectively, and the anchorage capacity increased by 4.7, 8.7, 40.2, and 62.9% at 30, 50, 80, and 110°C, respectively. Finally, the enhancement in compressive strength and heat-resistant mechanism are revealed through microanalysis.

Preparation of Fe Coating Al2O3 Nanometer Composite Powder and its Mechanical Properties after Hot Press Sintering

2010 ◽  
Vol 105-106 ◽  
pp. 16-19 ◽  
Author(s):  
Hong Xia Lu ◽  
Zhang Wei ◽  
Rui Zhang ◽  
Hong Liang Xu ◽  
Hai Long Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Raw Materials ◽  
Precipitation Method ◽  
Hot Press ◽  
Composite Ceramics ◽  
Composite Powders ◽  
Al2o3 Composite ◽  
Fe Content ◽  
Different Temperatures ◽  
Hot Press Sintering

Nano-Fe particles coating Al2O3 composite powders were prepared by heterogeneous precipitation method with nanometer -Al2O3 and Fe(NO3)3•9H2O as raw materials. The composite powders were analyzed by DSC-TG, XRD,SEM and Zeta potential. Results showed that Fe coating Al2O3 nanometer composite powders were obtained in the condition of being sintered at 500°C for 30min and reduced at 700°C for 1h in H2. The coating Fe nanometer particles are in the shape of sphericity with diameter about 30nm and the dispersion of the powders is uniform. Al2O3/Fe composite ceramics were obtained by hot-pressing (30MPa). The mechanical properties of the composite were investigated after hot press at different temperatures. With the increasing of Fe content in composite ceramics, the hardness of the composite is decreased. Fracture toughness of 10mol%Fe content is 5.62MPa after sintered at 1400°C, which is increasing 57% high than that of monolithic Al2O3 ceramics.

Influence of Z Value and Sintering Temperature on Properties of β-Sialon Bonded Corundum Composite

2011 ◽  
Vol 287-290 ◽  
pp. 183-187 ◽  
Author(s):  
Yu Xiang Guo ◽  
Dian Li Qu ◽  
Yan Fen Sun ◽  
Sheng Xin Zhang
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Fine Powder ◽  
Silicon Powder ◽  
Nitrogen Atmosphere ◽  
Comprehensive Properties ◽  
Oxidation Performance ◽  
Shock Resistance ◽  
Z Value

Using corundum particles and fine powder, α-Al2O3 powder, silicon powder, aluminum powder and some additives as raw materials, β-Sialon bonded corundum composite was synthesized in-situ at the nitrogen atmosphere. The influence of Z value in sialon phase and sintering temperature on physical properties, mechanical properties, thermal shock resistance and anti-oxidation performance of β-Sialon bonded corundum composite was investigated. The results indicate that the comprehensive properties of β-Sialon bonded corundum composite is excellent on condition that Z=2.75, sintering temperature is 1500°C at nitrogen atmosphere.

scholarly journals Thermal resistance of alkaline fused phosphate sludge-based geopolymer mortar

2019 ◽  
Author(s):  
Samira Moukannaa ◽  
Ali Nazari ◽  
Ali Bagheri ◽  
Mohamed Loutou ◽  
Rachid Hakkou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Thermal Behaviour ◽  
Elevated Temperatures ◽  
Mineralogical Composition ◽  
Optimum Conditions ◽  
Strength Tests ◽  
Before And After ◽  
Different Temperatures ◽  
Fused Phosphate

The present study investigates the thermal behaviour of phosphate sludge-based geopolymers. Phosphate sludge which is a by-product from phosphate beneficiation processes was activated using the alkaline fusion method to improve the geopolymer activity of this material. Then, the mechanical properties as well as the thermal behaviour of the resulted geopolymer mortar were studied. The effect of sodium hydroxide addition and fusion temperature on the mechanical properties and the thermal behaviour of the geopolymers were assessed using compressive strength tests before and after thermal shock cycles at different temperatures (350, 500, 650 °C). The mineralogical composition of the fused materials was investigated using XRD measurement and the microstructure of the geopolymer mortars was studied using FTIR. The obtained results showed that NaOH content as well as the temperature of fusion are essential parameters controlling the structure and the strength of the developed geopolymeric gel. Exposure to elevated temperatures up to 650 °C induces a decrease in compressive strength between 58 and 71%. However, a further increase in the temperature of exposure till 800 °C induces a development of compressive strength. Overall, geopolymers with good compressive strength up to 40 MPa could be synthesized in the optimum conditions of fusion: 10% of NaOH and 550 °C.

Preparation and Properties of MgO-MgAl2O4-FeAl2O4 Bricks in Cement Kiln

2011 ◽  
Vol 250-253 ◽  
pp. 554-560 ◽  
Author(s):  
Shu Long Ma ◽  
Yong Li ◽  
Jia Lin Sun ◽  
Yue Li ◽  
Wen Bin Xia
Keyword(s):  
Compressive Strength ◽  
Thermal Shock ◽  
Adhesion Strength ◽  
Thermal Shock Resistance ◽  
Raw Materials ◽  
Volume Density ◽  
Cement Kiln ◽  
Particle Sizes ◽  
Tunnel Furnace ◽  
Shock Resistance

Sintered magnesia with different particle sizes, fused MgAl2O4and FeAl2O4were used as the raw materials. FeAl2O4is added in MgO-MgAl2O4bricks at different ratios to gradually replace MgAl2O4. After the raw materials were molded and sintered at the tunnel furnace with the temperature 1 530°C for 10 hours, the MgO-MgAl2O4-FeAl2O4bricks could be made. After the analysis of the phase composition, microstructure and routine performance of the specimens, the influence by adding FeAl2O4to the samples on the properties such as thermal shock resistance, adhesion strength of kiln crust are discussed as the key point. The result shows that the addition of FeAl2O4has no evidently influence on the apparent porosity and volume density. The cold compressive strength of the samples reduces gradually with the addition of FeAl2O4, and it decreases obviously when the amount of FeAl2O4is more than 8%. When the addition of FeAl2O4is 5% FeAl2O4in the MgO-MgAl2O4-FeAl2O4bricks, MgAl2O4and FeAl2O4can combine each other’s advantages. The thermal shock resistance not only decreased obviously but the adhesion strength to kiln crust is increased.

Effect of Sintering Temperature on the Physical Properties and Microstructure of In Situ Nitrides Bonded MgAl2O4-C Refractories

2016 ◽  
Vol 697 ◽  
pp. 591-594
Author(s):  
Shao Hua Wang ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu ◽  
Wen Jie Yuan
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Bulk Density ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Silicon Powder ◽  
Flake Graphite ◽  
High Quality ◽  
Liquid Calcium

The in situ nitrides bonded MgAl2O4-C refractories were prepared by using high quality fused spinel (MgAl2O4≥ 97%), natural flake graphite (C ≥ 96%) and silicon powder (Si ≥ 98%) as raw materials and the liquid calcium lignosulfonate with a concentration of 1.25 g/ml was used as binder (4 wt%). The effect of sintering temperatures on physical properties and phase compositions were investigated. The results show that β-sialon and α-Si3N4were formed in the samples sintered at 1400°C, 1450°C and 1500°C, and AlON and AlN were formed in the samples sintered at 1550°C. The sample that sintered at 1450°C exhibits the best bulk density and apparent porosity of 2.84 g/cm3 and 14.73%, respectively, and the highest compressive strength

scholarly journals EFFECT OF SINTERING AND CORDIERITE ADDITIVES ON THE PHYSICAL AND MECHANICAL PROPERTIES OF MULLITE BASED CERAMICS PREPARED FROM IRAQI RAW MATERIALS

2020 ◽  
Vol 53 (2F) ◽  
pp. 49-64
Author(s):  
Mojahid Najim
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Raw Materials ◽  
Physical And Mechanical Properties ◽  
Apparent Porosity ◽  
Pressing Method ◽  
Soaking Time ◽  
Dry Pressing ◽  
Different Temperatures ◽  
The One

Mullite and cordierite are produced in the laboratory from Iraqi raw materials, have been crushed individually to obtain dense ceramic bodies to a particle size smaller than 45µ. Five mixtures of cordierite and mullite have been prepared in which cordierite has been added to mullite with the percentages of 30, 40, 50, 60, and 70 %. One hundred and twenty disk samples have been prepared using the semi-dry pressing method, with the pressure of 1000kg/cm2. The samples were dried and fired at different temperatures of 1300, 1350, 1400, and 1450 oC, with a soaking time of 2h. Physical evaluation tests (volume shrinkage, water absorption, apparent porosity, and bulk density) in addition to mechanical evaluation tests (compressive strength) have been performed. Samples fired at 1400 oC showed the best rates for the evaluation tests in general, in which the apparent porosity and water absorption for the samples were very low while the rates of density and compressive strength were high. The characteristics of samples fired at 1450 oC were overall poor while samples containing 60 and 70 % cordierite were melted. The best samples in this investigation were proven to be the ones containing 30% cordierite and 70% mullite while samples made out of 40% cordierite and 60% mullite show good mechanical and physical characteristics. The best ideal sample was the one fired at 1400 oC and contained 30% cordierite and 70% mullite.

Revisiting Glycerol Esterification with Acetic Acid over Amberlyst-35 via Statistically Designed Experiments: Overcoming Transport Limitations

2019 ◽  
Author(s):  
Víctor Gabriel Baldovino Medrano ◽  
Karen V. Caballero ◽  
Hernando Guerrero-Amaya
Keyword(s):  
Acetic Acid ◽  
Active Sites ◽  
Batch Reactor ◽  
Catalyst Particle ◽  
Experimental Designs ◽  
Particle Sizes ◽  
Turnover Rates ◽  
Designed Experiments ◽  
Different Temperatures ◽  
Glycerol Esterification

Turnover rates for glycerol esterification with acetic acid over Amberlyst-35 were measured under different temperatures, reactants and active sites concentrations, and catalyst particle sizes. Data were collected in a batch reactor. Experiments were done following a sequence of factorial experimental designs.

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