The Wear Mechanism Comparison between MgO-Based Chrome-Free Brick and MgO-Cr2O3 Brick in the Lower Part of RH Vacuum Degasser

2012 ◽  
Vol 476-478 ◽  
pp. 1991-1996
Author(s):  
Guo Xiang Yin ◽  
Yong Li ◽  
Jun Hong Chen ◽  
Xin Kui Gao
Keyword(s):  
Solid Solution ◽  
Thermal Shock ◽  
Wear Mechanism ◽  
Thermal Shock Resistance ◽  
Air Permeability ◽  
Modulus Of Rupture ◽  
Spalling Resistance ◽  
Grain Refining ◽  
Vacuum Degasser ◽  
Shock Resistance

The damage and improvement mechanism of rebonded MgO-Cr2O3 brick and MgO-ZrO2 brick used in the lower part of RH vacuum degasser were studied. The results show that the main damage of rebonded MgO-Cr2O3 brick is structure spalling because of the penetration of slag. MgO-ZrO2 brick has characteristics of high direct-bonding degree, small air permeability and making the viscosity of penetrated slag increased by means of ZrO2 absorbing CaO in slag to form CaZrO3 or ZrO2 solid solution, which make the degree of slag penetration decrease and improve the structure spalling resistance. MgO-ZrO2 brick has the defect of poor thermal shock resistance in use, the incorporation of MgO-rich spinel into MgO-ZrO2 brick significantly improved both thermal shock resistance and hot modulus of rupture because of the formation of eutectoid structure of grain-refining spinel and zirconia, which also improved structure spalling resistance because air permeability was decreased to 5% of MgO-ZrO2 brick

Utilization of Fly Ash in the Synthesis of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 321 ◽  
pp. 131-140
Author(s):  
Martin Nguyen ◽  
Radomír Sokolař
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Power Plants ◽  
Linear Thermal Expansion ◽  
Aluminium Oxide ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Shock Resistance

Forsterite refractory ceramics is utilized in the metallurgical and cement industries as a lining of metallurgical furnaces and rotary kilns for its high refractoriness up to 1850°C and refractoriness under load above 1600°C. Another significant property of forsterite is its coefficient of linear thermal expansion utilized in the electrotechnical industry for ceramic-metal joints. Addition of aluminium oxide into the raw material mixture results in creation of magnesium-alumina spinel (MgO·Al2O3) which improves sintering, thermal shock resistance and mechanical properties in comparison with pure forsterite ceramics. Inexpensive source of aluminium oxide is fly ash. Utilization of fly ash, secondary energetic product of coal-burning power plants, is important for the environment and sustainable development. This paper evaluated properties of fly ash-based forsterite-spinel ceramics in comparison with alumina-based forsterite-spinel ceramics. Forsterite-spinel ceramics was synthesized from olivine, calcined magnesite and fly ash/alumina powders. XRD analysis was used to determine mineralogical composition, thermal analyses were used to determine the behaviour during firing and scanning electron microscopy to determine the morphology of crystal phases. Refractoriness of pyrometric cones, refractoriness under load, thermal shock resistance, coefficient of linear thermal expansion, water absorption, porosity and modulus of rupture were also determined on fired test samples.

Thermal and Thermomechanical Properties of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 325 ◽  
pp. 174-180
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář
Keyword(s):  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Raw Materials ◽  
Thermal Analyses ◽  
Aluminium Oxide ◽  
Thermomechanical Properties ◽  
Modulus Of Rupture ◽  
Shock Resistance

This article examines the utilization of fly ash in comparison with alumina as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1500°C for 2 hours. Sintered samples were characterized by X-ray diffraction analysis and scanning electron microscopy. Samples were also subjected to determination of porosity, water absorption and bulk density. Thermal and thermomechanical properties were determined by thermal analyses, refractoriness, refractoriness under load, thermal shock resistance and thermal dilatometric analysis with determination of thermal expansion coefficient. Mixtures with 10 wt.% and 20 wt.% of fly ash had the most promising results compared to alumina mixtures. Thermal shock resistance and modulus of rupture were improving with increasing content of aluminium oxide in the mixture.

Effect of MgTi2O5 Addition on Thermal Shock Resistance of Al2TiO5

2007 ◽  
Vol 280-283 ◽  
pp. 1187-1190 ◽  
Author(s):  
Qiang Shen ◽  
Yong Hu ◽  
Chuan Bin Wang ◽  
Ming Zhong Li ◽  
Lian Meng Zhang
Keyword(s):  
Solid Solution ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Experimental Results ◽  
Aluminum Titanate ◽  
Shock Resistance

In the present paper, magnesium dititanate (MgTi2O5, M2T) was introduced into aluminum titanate (Al2TiO5, AT) to form AT-M2T solid solution so that the thermal shock resistance of Al2TiO5 could be kept still good while without any decomposition. The effect of MgTi2O5 addition on thermal shock resistance of Al2TiO5 was investigated. The experimental results showed that the thermal shock resistance of Al2TiO5 began to decrease when a little amount of MgTi2O5 was added and then rose with the continuous addition of MgTi2O5, even overrunning that of pure Al2TiO5 when 30mol% MgTi2O5 was contained. It was found that fine solid solution was formed between Al2TiO5 and MgTi2O5, which enhanced the thermal shock resistance of Al2TiO5.

Thermal Fatigue Behavior of Ladle Purging Plug

2010 ◽  
Vol 105-106 ◽  
pp. 158-161
Author(s):  
Hui Zhang ◽  
Yan Ruo Hong ◽  
Hong Xia Li ◽  
Yang Bin
Keyword(s):  
Thermal Shock ◽  
Thermal Fatigue ◽  
Thermal Shock Resistance ◽  
Fatigue Behavior ◽  
Modulus Of Rupture ◽  
Coarse Grained ◽  
Fine Grained ◽  
Shock Resistance ◽  
Thermal Fatigue Behavior ◽  
Fracture Damage

The thermal fatigue behavior of alumina-magnesia based and alumina-chromia based purging plug materials are comparatively studied. By comparing thermal shock parameters, the changes of elastic modulus and hot modulus of rupture after thermal shock cycles, we come to a conclusion that microcracks emerge in the alumina-magnesia based material, which hinder the crack growth during thermal shock cycles. The fine-grained and network structure of alumina-magnesia based material are also helpful to improve thermal shock resistance. However, cracks are difficult to form in the alumina-chromia based material but it tends to fracture damage quickly once the cracks nucleation due to coarse-grained structure of alumina-chromia based material.

Fabrication, Microstructure and Properties of Nitrides Bonded Alumina Castables by In Situ Nitridation Reaction

2011 ◽  
Vol 284-286 ◽  
pp. 69-72 ◽  
Author(s):  
Quan Li Jia ◽  
Fang Bao Ye ◽  
Yu Cui Zhang
Keyword(s):  
Phase Composition ◽  
Physical Properties ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Modulus Of Rupture ◽  
Hot Strength ◽  
Nitridation Reaction ◽  
Shock Resistance ◽  
Alumina Castables

Nitrides(Si3N4/Sialon) bonded alumina castables were fabricated by in situ nitridation reaction. Effects of the formation of nitrides on the physical properties, hot strength and thermal shock resistance were investigated. The results show that the phase composition of castables is alumina, a-Si3N4, b-Si3N4and Si2N2O after fired at 1400ºC and 1450ºC, and is alumina, b-Sialon and O’-Sialon after fired at 1500ºC. Hot modulus of rupture and thermal shock resistance of specimens are noticeably improved due to the formation of nitrides.

Preparation of Yttria with Elongated Grains and Micro-Pores

2011 ◽  
Vol 197-198 ◽  
pp. 425-428
Author(s):  
Wen Bin Dai ◽  
Xin Li Wang ◽  
Peng Zhao ◽  
Jing Kun Yu
Keyword(s):  
Solid Solution ◽  
Thermal Shock ◽  
Grain Growth ◽  
Thermal Shock Resistance ◽  
Soaking Time ◽  
Water Quench ◽  
Shock Resistance ◽  
Quench Test

The effect of 1mol% calcia additive on sintering of yttria was investigated, and a yttria with elongated grains and micro-pores was developed in present work. The results showed that in calcia added samples heated at 1600°C, calcia contained yttria solid solution grains were formed and distributed among pure yttria grains. With the prolonging soaking time, they were concentrated into rod- or plate-like elongated grains and some of them were embedded into pure coarse yttria grains. Furthermore, in calcia added samples, grain growth was much faster and lots of micro-pores were left in coarse pure yttria grains. Water quench test revealed that thermal shock resistance of calcia added sample was greatly improved by elongated grains and micro-pores.

scholarly journals Impact of Fly Ash as a Raw Material on the Properties of Refractory Forsterite–Spinel Ceramics

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 835
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář
Keyword(s):  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Power Plants ◽  
Raw Materials ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Shock Resistance ◽  
Refractory Ceramics ◽  
The Impact

This article examines the process for the synthesis of forsterite–spinel (2MgO·SiO2/MgO·Al2O3) refractory ceramics from fly ash and alumina as sources of aluminum oxide. Raw materials were milled, mixed in different ratios and sintered at 1500 °C for 2 h. Sintered samples were characterized by XRD, thermal analyses and SEM. Porosity, water absorption, bulk density, refractoriness, refractoriness under load and thermal shock resistance were also investigated. The impact of fly ash as a raw material was investigated in accordance with the resulting properties and microstructure of samples with fly ash and alumina as the raw materials. Due to the positive effect of flux oxides (iron oxides and alkalis) on sintering, the mullite contained in fly ash completely decomposed into silica and alumina, which, together with magnesium oxide, formed spinel. This led to improved microstructural and mechanical properties and thermal shock resistance. In particular, mixtures with 10 wt.% and 20 wt.% of fly ash had the most promising results compared to alumina mixtures. Both modulus of rupture and thermal shock resistance were improved, while the impact on refractory properties was minimal. The novelty of this research lies in the recycling of fly ash, a by-product from coal-burning power plants, into a raw material for the production of forsterite–spinel refractory ceramics.

scholarly journals Effect of MgO on the Properties of Alumina-Graphite Based Refractory Including 20 wt% Non-Stabilized ZrO2

2020 ◽  
Author(s):  
Maryam Abolfazli ◽  
Mohammad Hossein Paydar
Keyword(s):  
Corrosion Resistance ◽  
Bulk Density ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Chemical Properties ◽  
Cold Isostatic Pressing ◽  
Modulus Of Rupture ◽  
Coarse Grained ◽  
Linear Change ◽  
Shock Resistance

Abstract In this study the effect of magnesium oxide in the range of 0 to 10 wt. % on the mechanical properties, corrosion rate, preventing carbon bond oxidation and microstructure of alumina-graphite (coarse-grained) refractory bodies including 20 wt. % of non-stabilized zirconia is investigated. The refractories were fabricated by mixing raw materials, where phenolic resin in the form of liquid was used as binder, and then granulation, cold isostatic pressing and firing at 1400 °C for 8 hours in a reducing atmosphere. Mechanical, physical and chemical properties of the fabricated refractories were evaluated by determining cold compressive strength, modulus of rupture and thermal shock resistance, bulk density, molten shock resistance, permeant linear change, oxidation and corrosion resistance. The results showed that in the presence of MgO, the zirconia grain size increases and it results in a decrease in bulk density that leads in more slag penetration and decreasing corrosion resistance. It has also revealed that addition of MgO to the base refractory leads to decreasing in cold crushing strength, modulus of rupture, and thermal shock resistance. It has been also proved that it causes an expansion during sintering process and results in positive permeant linear change.

scholarly journals Comparing the influence of different kinds of zirconia on properties and microstructure of Al2O3 ceramics

2016 ◽  
Vol 23 (4) ◽  
pp. 407-412
Author(s):  
Wenfeng Li ◽  
Suping Li ◽  
Xiangchong Zhong
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Yttria Stabilized Zirconia ◽  
Modulus Of Rupture ◽  
Monoclinic Zirconia ◽  
Stabilized Zirconia ◽  
Microstructure Characteristics ◽  
Shock Resistance ◽  
Room Temperature Strength

AbstractThis paper compared the influence of fused zirconia-corundum (AZ40), monoclinic zirconia (m-ZrO2), and 3 mol% yttria-stabilized zirconia (3Y-ZrO2) on physical properties at room temperature, hot modulus of rupture, and thermal shock resistance of Al2O3 ceramics, and their relationships with microstructure changes were investigated. It was found that m-ZrO2 or 3Y-ZrO2 addition promoted the process of sintering densification and enhanced the room temperature strength and the hot modulus of rupture of Al2O3 ceramics, and the effect of the latter was more distinct, while those of the sample with AZ40 addition decreased. In addition, the three kinds of ZrO2 were beneficial to improving the thermal shock resistance of Al2O3 ceramics. All these changes had close relationships with the changes of corresponding microstructure characteristics (including distribution of particles, degree of contact between crystals, grain boundary solid solution, microcrack density) and phase composition.

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