Study of Thermal Shock Resistance of Sagger Plate Used in Floppy Magnets Sintering

2007 ◽  
Vol 280-283 ◽  
pp. 1667-1670 ◽  
Author(s):  
Feng Cao ◽  
Xing Rong Wu ◽  
Rainer Telle
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Rapid Development ◽  
Particle Surface ◽  
Sem Analysis ◽  
Sintering Process ◽  
Kiln Furniture ◽  
Dense Structure ◽  
Zircon Powder ◽  
Shock Resistance

The rapid development of magnetic materials has witnessed a sustained consumption increase in corundum-mullite kiln furniture application, yet a comparatively short duration of them. In this view, the thermal shock resistance of sagger plate in floppy magnets sintering turns out a factor of critical importance. This paper makes a study concerning the influence of factors including the size of critical electro-melted mullite particles, the electro-melted corundum or mullite as medium particles and the addition of upon the thermal shock resistance. The result shows that, with critical particles of 2 mm, the sheet of about 10mm thickness is characterized by better performance in modulus of rapture and thermal shock resistance. The latter proves to be more outstanding in samples rather than mullite. When zircon powder is added in a two-hour sintering process at the temperature of 1550°C, a remarkable improvement is made by the sample in terms of its thermal shock resistance. SEM analysis shows the existence of micropores in the section of samples with corundum as medium particles, whereas the glasses phase in that of mullite sample, resulting in a dense structure. Finally, zircon powder added makes for the improvement of thermal shock resistance due to the formation of baddeleyite on the particle surface of the corundum.

Preparation and Performance of β-Sialon Bonded ZrO2 Composites

2011 ◽  
Vol 415-417 ◽  
pp. 138-141
Author(s):  
Rui Sheng Wang ◽  
Jun Hong Zhao ◽  
Ying Na Wei ◽  
Fu Hua Peng ◽  
Heng Yong Wei
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Carbon Addition ◽  
Shock Resistance ◽  
And Performance ◽  
Sialon Powder

β-Sialon bonded ZrO2 composites were prepared by reaction sintering process using β-Sialon and CaO stabilized ZrO2 powders as raw materials.The effect of β-Sialon powder additions on the properties of the composites was investigated. The results show that the samples with 10 wt% of β-Sialon addition had the lowest apparent porosity (29.80%) and the highest of flexural strength (68.70MPa). The thermal shock resistance in carbon addition of the composites could be improved by addtion of 5wt% β-Sialon. It may be relative with that the sample had the lowest thermal expansion coefficient in vacuum.

Improvement in the Thermal Shock Resistance of Zirconia Ceramic by the Addition of Aluminium Titanate

2011 ◽  
Vol 194-196 ◽  
pp. 1724-1727 ◽  
Author(s):  
Heng Yong Wei ◽  
Li Xue Yu ◽  
Zhi Fa Wang ◽  
Jing Long Bu ◽  
Shu Long Ma ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Bending Strength ◽  
Sem Analysis ◽  
Precipitation Method ◽  
Zirconia Ceramic ◽  
Aluminum Titanate ◽  
Sintering Properties ◽  
Shock Resistance ◽  
Co Precipitation

ZrO2-Al2TiO5 composite materials with high bending strength and good thermal shock resistance expansion were prepared using partially stabilized zirconia (Y-PSZ) powders coated with Al2TiO5 by co-precipitation method. The effects of Al2TiO5 content on the sintering properties, phase composition, microstructure and thermal shock resistance of the zirconia ceramic were investigated．The results show that the apparent porosity of the samples decreased and their bending strength increased with the content of aluminum titanate increasing from 0 to 8 wt%. The samples with 5 and 8 wt% aluminum titanate addtion have excellent thermal shock resistance. The results showed that the addtion of aluminum titanate could enhance the mechanical strength and improve the thermal shock resistance of zirconia ceramic. The XRD and SEM analysis results indicated that the propriety improvement is relative with the change of the microstructure and the increase of tetragonal ZrO2 phase in the composites.

Effect of Molar Ratio of Al2O3 to Fe2O3 on the Sintering and Thermal Shock Resistance of Al2O3-Fe2O3 Composite

2011 ◽  
Vol 194-196 ◽  
pp. 1745-1748
Author(s):  
Zhi Fa Wang ◽  
Jian Sheng Wang ◽  
Yue Jun Chen ◽  
Li Xue Yu ◽  
Jing Long Bu ◽  
...  
Keyword(s):  
Composite Materials ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Bending Strength ◽  
Raw Materials ◽  
Sem Analysis ◽  
Molar Ratio ◽  
Alumina Powder ◽  
Linear Change ◽  
Shock Resistance

The Al2O3-Fe2O3 composite was prepared at 1550°C for 3h with alumina powder and ferric oxide powder as raw materials and with magnesia powder as additive. The effect of molar ratio of Al2O3 to Fe2O3 on the sintering and thermal shock resistance of the composite materials was studied. The results showed that the apparent porosity and bulk density of the samples both decreased with the molar ratio of Al2O3 to Fe2O3 increase, as a result, the linear change ratio and bending strength both increased. When the molar ratio of Al2O3 to Fe2O3 equals to 3, the sample exhibits excellent thermal shock resistance. The XRD and SEM analysis results indicated that the mechanical and thermal proprieties are relative to the microstructure and crystal phases of the composite materials.

Investigation of Mechanical Property and Thermal Shock Behavior of Machinable B4C/BN Ceramics Composites

2008 ◽  
Vol 569 ◽  
pp. 53-56
Author(s):  
Tao Jiang ◽  
Hai Yun Jin ◽  
Zhi Hao Jin ◽  
Jian Feng Yang ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Property ◽  
Fracture Toughness ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Sintering Process ◽  
Shock Temperature ◽  
Shock Resistance ◽  
Thermal Shock Behavior ◽  
Hot Pressing Sintering ◽  
Better Than

The machinable B4C/BN ceramics composites were fabricated by hot-pressing sintering process at 1850oC for 1h under the pressure of 30MPa. The mechanical property, thermal shock behavior and machinability of the B4C/BN ceramics composites were investigated in this article. The experimental results showed that the fracture strength and fracture toughness of the B4C/BN nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The Vickers hardness of the B4C/BN nanocomposites and B4C/BN microcomposites decreased gradually with the increasing content of h-BN, while the machinability of the B4C/BN nanocomposites and B4C/BN microcomposites were significantly improved. The B4C/BN ceramics composites with the h-BN content more than 20wt% exhibited excellent machinability. The thermal shock resistances of the B4C/BN ceramics composites were better than that of the B4C monolith, and the thermal shock resistance of the B4C/BN nanocomposites was much better than that of the B4C/BN microcomposites. The thermal shock temperature difference (-Tc) of B4C monolith was about 300oC, while the -Tc of the B4C/BN microcomposites was about 500oC, the -Tc of the B4C/BN nanocomposites was about 600oC.

Analysis to Mullite Bonded Corundum Purging Plug

2013 ◽  
Vol 423-426 ◽  
pp. 49-52 ◽  
Author(s):  
Xue Hua Ren ◽  
Ping Zhao ◽  
Qi Hui Lai ◽  
Xuan Qin
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Material Selection ◽  
Fluorescence Analysis ◽  
Secondary Phase ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Structure Control ◽  
Main Chemical Composition ◽  
Shock Resistance

We chose a purging plug with good performance to analyze its insert plate. By X ray fluorescence analysis method, the main chemical composition is alumina and the small amount is silica. XRD analysis shows its phase compositions, main crystal phase is corundum, the secondary phase is mullite. SEM analysis is for the microstructure, grains are packed closely. They are sintered tabular corundums with smooth shape, which means there is liquid phase in sintering process to help mass transfer. As a conclusion, this product is designed from the point of material selection and structure control to improve its thermal shock resistance. Compacted microstructure combining with good thermal shock-resistance mineral phases improve the service life of purging plug.

Effect of Glass Phase on the Thermal Shock Resistance of ZrB2-SiC Ultra High Temperature Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1727-1729 ◽  
Author(s):  
Shi Zhen Zhu ◽  
Qiang Xu ◽  
Chao Feng ◽  
Jun Feng Zhao ◽  
Jian Ling Cao ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Shock ◽  
Residual Strength ◽  
Thermal Shock Resistance ◽  
Glassy Phase ◽  
Sem Analysis ◽  
Sic Ceramics ◽  
Plasma Sintering ◽  
Shock Resistance ◽  
Ultra High Temperature

Two kinds of ultra high temperature ceramics (UHTC), ZrB2-20Vol.%SiC and ZrB2-15Vol.% SiC-5Vol.% SiCn (nano-size) were prepared by spark plasma sintering (SPS). The residual strength was used to characterize thermal shock resistance of ZrB2-SiC ceramics by quenching tests in the water. The mechanism of thermal shock damage of the ceramics was examined by SEM analysis. The results showed that the formed glassy phase has significant effect on thermal shock resistance of ZrB2-SiC ceramics. When the thermal shock temperature rises, the residual strength of ZrB2-SiC ceramics after thermal shock will decrease gradually. The formed glassy phase when quenched from the temperature of 1400°C can repair or heal the cracks and induce the higher residual strength. However, when the temperature increases to 1600°C, the residual strength of ZrB2-SiC ceramics decreases significantly due to the volatilization of the glassy phase. The residual strength of ZrB2-15Vol.% SiC-5Vol.% SiCn ceramic is higher than that of ZrB2-20Vol.%SiC ceramic, because nano SiC is easy to be oxidized and to induce the formation of more glassy phases and to improve the thermal shock resistance of the sample.

scholarly journals Blīva augsttemperatūras mullīta-ZrO2 keramika

2018 ◽  
Vol 35 ◽  
pp. 112-133
Author(s):  
Gaida Sedmale ◽  
Uldis Sedmalis ◽  
Ingunda Šperberga ◽  
Māris Rundāns
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Sintering Process ◽  
Ceramic Samples ◽  
Shock Resistance ◽  
Composition Structure ◽  
Plasma Dispersion ◽  
Sintering Processes

Parādīta piedevu (mālu minerāla – illīta, Si3N4, SiAlON), kā arī izejas pulveru izstrādes veida ietekme uz mullīta-ZrO2 keramikas saķepināšanas procesu (pielietojot tradicionālo saķepināšanas procesu un plazmas izlādes saķepināšanas procesu jeb SPS), fāžu sastāvu, struktūru, mehāniskajām un keramiskajām īpašībām.Mālu piedeva sekmē pulvera  daļiņu  izmēru  samazināšanos,  veicina  keramikas paraugu sablīvēšanos tradicionālā saķepināšanas procesā, bet dod pretēju efektu, pielietojot SPS procesu. Silīcija  nitrīda un  SiAlON nanopulveru  piedevas ir efektīvas SPS procesā, sasniegta paraugu spiedes izturība ap 600 MPa Si3N4 piedevas gadījumā, termiskā trieciena izturību un elastības moduļa  vērtības 180 – 220 GPa, kuras termiskā trieciena 1000/20 °C rezultātā samazinās pieļaujamās robežās. Šīs vērtības ir par aptuveni 20–25 % zemākas, pielietojot SiAlON piedevu.Keramikas paraugu, kas saķepināti tradicionāli un pielietojot SPS procesu, mikrostruktūrā ir mullīta vai pseidomullīta kristāliski veidojumi ar ieslēgtiem ZrO2 graudiem, kas pārsvarā ir kubiskā modifikācijā. Galvenā atšķirība starp abos saķepināšanas procesos iegūtajiem paraugiem ir tā, ka tradicionāli saķepināto paraugu mikrostruktūrā ir novērojama ‘tukšumu’ veidošanās, kuri aizpildās ar mullīta kristāliem, it sevišķi palielinoties Si3N4 piedevai. Mikrostruktūra keramikas paraugiem, kas saķepināti ar SPS tehnoloģiju ir blīvāka – mullīta kristāli ir blīvi izvietojušies, un tiem nav mullītam raksturīgās prizmatiskās formas.Dense high-temperature mullite-ZrO2 ceramicsThe influence of some additives (clay mineral illite, Si3N4, SiAlON) and the processing of the initial powders on sintering of mullite-ZrO2 ceramics (using traditional or plasma dispersion sintering processes), composition, structure, mechanical and ceramic properties of phases is shown.The clay additive contributes to the reduction of the particle size of the powder, facilitates the densification of the ceramic samples in the traditional sintering process, but vice versa if SPS is used. Silicon nitride and SiAlON nanopowder additives are effective in the SPS process; samples reach a compressive strength of approximately 600 MPa in the case of Si3N4 additive; thermal shock resistance and elastic modulus are in the range of 180–220 GPa, which under a thermal shock of 1000/20 °C will reduce within the permissible limits. These values are about 20–25 % lower if SiAlON additive is used.The microstructure of the ceramic samples traditionally sintered or sintered using a SPS process is formed by crystalline mullite or pseudomulite crystals with enclosed ZrO2 grains that mostly are in the cubic modification. The main difference between the samples obtained in both sintering processes is that formation of voids filled with mullite crystals can be observed in the microstructure of traditionally sintered samples, especially if the amount of Si3N4 additive is increased. The microstructure of the ceramic samples sintered with SPS technology is denser – the mullite crystals are densely distributed and do not have the prismatic shape that is characteristic to mullite.

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