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.

Investigation of Microstructure and Thermal Shock Resistance of the B4C/BN Composites Fabricated by Hot-Pressing Process

2012 ◽  
Vol 512-515 ◽  
pp. 748-752 ◽  
Author(s):  
Tao Jiang ◽  
Chen Chao Tian
Keyword(s):  
Mechanical Property ◽  
Thermal Shock ◽  
Hot Pressing ◽  
Thermal Shock Resistance ◽  
High Fracture ◽  
Pressing Process ◽  
Low Elastic Modulus ◽  
Shock Resistance ◽  
Quenching Method ◽  
Better Than

The B4C/BN composites were fabricated by hot-pressing process. The B4C/BN composites included the B4C/BN microcomposites and B4C/BN nanocomposites. The B4C/BN microcomposites were fabricated by hot-pressing process, and the B4C/BN nanocomposites were fabricated by chemical reaction and hot-pressing process. In this research, the phase composition, microstructure, mechanical property and thermal shock resistance of the B4C/BN microcomposites and B4C/BN nanocomposites were investigated. The B4C/BN microcomposites and the B4C/BN nanocomposites exhibited the homogenous and compact microstructure, and the h-BN particles were homogenously distributed in the B4C matrix. The mechanical property of the B4C/BN microcomposites and B4C/BN nanocomposites decreased gradually with the increase of h-BN content, but the B4C/BN nanocomposites exhibited the higher mechanical property than that of the B4C/BN microcomposites. The thermal shock resistances of the B4C monolith and the B4C/BN composites were measured by water-quenching method. The thermal shock resistances of the B4C/BN microcomposites and the B4C/BN nanocomposites were remarkably improved in comparison with the B4C monolith. The thermal shock resistance of the B4C/BN nanocomposites was much better than that of the B4C/BN microcomposites. The thermal shock temperature difference (ΔTc) of the B4C monolith was about 300oC, the ΔTc of the B4C/BN microcomposites was about 500oC and the ΔTc of the B4C/BN nanocomposites was about 600oC. The B4C/BN composites exhibited the high thermal shock resistance due to the high fracture strength and low elastic modulus. The microstructure showed that the weak interface of B4C/BN and cleavage behavior of laminate structured h-BN particles would remarkably improve the thermal shock resistance of the B4C/BN composites.

Preparation and Characterization of Zirconia-Yttria/Zirconia-Magnesia Composites

2006 ◽  
Vol 530-531 ◽  
pp. 389-394 ◽  
Author(s):  
E. Caproni ◽  
R. Muccillo
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Electrical Response ◽  
X Ray Diffraction ◽  
Oxygen Pump ◽  
Impedance Spectroscopy Technique ◽  
Shock Resistance ◽  
Materials Used ◽  
Thermal Shock Behavior ◽  
Better Than

ZrO2: 3mol% Y2O3 powders were mixed in different proportions to ZrO2: 8 mol% MgO, pressed and sintered at 1500°C for producing composites with oxygen ion conductivity better than that of ZrO2: 8 mol% MgO and thermal shock resistance better than that of ZrO2: 3 mol% Y2O3. The electrical conductivity was evaluated by the impedance spectroscopy technique at 600°C as a function of the partial pressure of oxygen using zirconia-based oxygen pump and sensor. The thermal shock resistance was studied by room temperature- 1550°C dilatometry on sintered pellets. Moreover the composites were studied by X-ray diffraction and scanning electron microscopy. All composites are partially stabilized in the monoclinic-tetragonal phase and the apparent density is higher than 90% of the theoretical density. The thermal shock behavior of the composites is similar to that of ZrO2:8 mol% MgO materials used in disposable high temperature oxygen sensors. The electrical response of the composites at high temperatures is better than the electrical response of ZrO2:8 mol% MgO.

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.

Thermal Shock Behavior and Bonding Strength of MoSi2-BaO-Al2O3-SiO2 Gradient Porous Coating with Polymethyl Methacrylate Addition for Porous Fibrous Insulations

2018 ◽  
Vol 281 ◽  
pp. 493-498
Author(s):  
Ya Yu Su ◽  
Xiao Lei Li ◽  
Hui Jie Tang ◽  
Zhi Hao Zhao ◽  
Jian He
Keyword(s):  
Porous Structure ◽  
Thermal Shock ◽  
Bonding Strength ◽  
Thermal Shock Resistance ◽  
Porous Coating ◽  
Bonding Layer ◽  
Interface Bonding ◽  
Shock Resistance ◽  
Thermal Shock Behavior ◽  
Interface Bonding Strength

In order to improve the thermal shock behavior of high temperature resistant coating on porous fibrous referactory insulations, the MoSi2-BaO-Al2O3-SiO2(MoSi2-BAS) gradient porous coatings were designed by preparing a dense surface layer and a porous bonding layer with the method of brushing and subsequent sintering at 1773 K. The porous bonding layer was obtained by adding polymethyl methacrylate (PMMA) as pore former. As the content of PMMA increases, the MoSi2-BAS coatings changed from a dense structure into a gradient porous structure. The interface bonding strength and thermal shock resistance of the MoSi2-BAS coatings were investigated. The result shows that the as-prepared coating with gradient porous structure exhibited excellent thermal shock resistance, which remained gradient structure without cracking after thermal cycling 100 times between 1773 K and room temperature. And the interface bonding strength of the gradient porous coating reached 1.5±0.08 Mpa, which was much better than that of the dense coating.

Properties of Ceramic Coatings on the Wall of Coke Oven

2011 ◽  
Vol 189-193 ◽  
pp. 1105-1108
Author(s):  
Shu Xian Liu ◽  
Li Li Shen ◽  
Qian Ping Wang
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
High Hardness ◽  
Coke Oven ◽  
Ceramic Coatings ◽  
Good Adhesion ◽  
Before And After ◽  
Shock Resistance ◽  
Uncoated Specimen ◽  
Better Than

Flame sprayed ceramic coatings on the wall of coke oven are characterized before and after melting. The attempt has been made to investigate thermal shock resistant, carbon deposit resistant, wear resistant of the coated and melted samples. The techniques used are SEM and XRD. The results show that: 1) Presence of quartz, corundum and mullite are identified in the surface of the coated specimen. Good adhesion between the coating and the substrate is caused by presence of quartz which is the same content as the substrate.2) The thermal shock resistance cycles of the coating samples are 15 ~ 30 times, but uncoated samples are only 1~2 times. The main reason is that he coating–substrate interface shows no gaps or cracks, and it has a characteristic feature of good adhesion between the coating and the substrate. 3) The wear resistance of the coated samples are better than that of the uncoated samples because glass-coating is more smooth than the uncoated specimen and the mullite and corundum in the coating have the high hardness value that makes the hardness of the coating increased.

Effect of AlF3 Content on Microstructure and Properties of Mullite/Al2O3 Composite Ceramics

2018 ◽  
Vol 922 ◽  
pp. 62-67
Author(s):  
Ke Zheng Sang ◽  
Fan Wang ◽  
De Jun Zeng ◽  
Hong Wei Li
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Diameter Ratio ◽  
Pressureless Sintering ◽  
Composite Ceramics ◽  
Microstructure And Properties ◽  
Shock Resistance ◽  
Mullite Whiskers

To reinforce the mullite/Al2O3 composite ceramics through formation of mullite whiskers, the composite ceramics were prepared by pressureless sintering using different AlF3 content. The microstructure, porosity, fracture toughness and thermal shock resistance of the composite ceramics were investigated. The results show that the addition of AlF3 can promote the mullite whisker formations, and the whiskers with the size of 3～10μm in diameter and a length-diameter ratio of 10～15 are obtained by sintering at 1600°C with the AlF3 content of 5wt%. Fracture toughness and thermal shock resistance of the composite ceramics are improved by the formation of mullite whisker. The fracture toughness of 4.79MPa•m1/2 can be obtained, and the 95.18% flexural strength remained after thermal shock.

Numerical Simulation of Temperature Field and Thermal Shock Resistance Property of Permeable Brick

2008 ◽  
Vol 368-372 ◽  
pp. 1152-1154
Author(s):  
Hua Zhi Gu ◽  
Hou Zhi Wang ◽  
Mei Jie Zhang ◽  
Ao Huang ◽  
Wen Jie Zhang
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Gas Flow ◽  
Raw Materials ◽  
Large Change ◽  
Water Cooling ◽  
Working Face ◽  
Shock Resistance ◽  
The One ◽  
Better Than

The temperature distribution of the permeable brick was modeled using CFX software. The influence of magnesia and corundum on thermal shock resistance of non-cement bonded alumina-based permeable brick was investigated. The results indicated that, in the gas blow process, the high temperature regions near the working face of the brick gradually expanded with the increase of the gas flow rate. Therefore the inner part of the brick had the complex and large change of thermal stress. Further experiments demonstrated that thermal shock resistance of alumina-magnesia based castable refractory was better than that of alumina-chrome based castable refractory. With the increase of magnesia amount, the alumina-magnesia based castable refractory had more cycles of heating and water-cooling. When different kinds of corundum were added in the raw materials, the sample with tabular corundum showed the best thermal shock resistance, the one with white fused corundum performed worse and the one with fused dense corundum performed worst.

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