Fracture Features of Mullite Ceramic Regenerative Material under Thermal Shock Condition

2014 ◽  
Vol 633 ◽  
pp. 427-430 ◽  
Author(s):  
Qing Hui Shang ◽  
Yan Xia Wang ◽  
Bin Jiang ◽  
Dong Huan Zhang ◽  
Tian Tian Sun
Keyword(s):  
Fracture Toughness ◽  
Thermal Shock ◽  
Bending Strength ◽  
Heat Storage ◽  
Shock Condition ◽  
Mullite Ceramic ◽  
Result Show ◽  
Fracture Damage ◽  
Damage Characteristic ◽  
Temperature Water

For study the damage characteristic of the mullite heat storage ceramic under thermal shock condition, mechanical properties of mullite have been investigated. Under the different cooling mediums (room temperature water, boiling water, air), single and five cycles thermal shock conditions, The article studied the variation of flexural strength and fracture toughness along with temperature. The result show that with the increase of heat transfer coefficient of cooling medium, the bending strength of ceramic decreased. In the 600°C,the ceramic have a maximum bending strength and a minimum fracture toughness. The fracture toughness of precrack specimen is lower than that of non-precrack specimen on the whole. Both Precrack ceramic and non-precrack ceramic have a maximum fracture toughness at 400°C. The study of this paper provides a theoretical basis for the better predicting fracture damage and service life of heat storage ceramic.

Fracture energy of mullite ceramic heat storage material under thermal shock conditions

2015 ◽  
Vol 19 (sup9) ◽  
pp. S9-318-S9-321
Author(s):  
Y. X. Wang ◽  
Q. H. Shang ◽  
Y. Q. Liu ◽  
D. H. Zhang
Keyword(s):  
Fracture Energy ◽  
Thermal Shock ◽  
Heat Storage ◽  
Storage Material ◽  
Mullite Ceramic ◽  
Heat Storage Material

Investigation of Thermal Shock Behaviors for Machinable SiC/h-BN Ceramic Composites

2007 ◽  
Vol 544-545 ◽  
pp. 391-394 ◽  
Author(s):  
Hai Yun Jin ◽  
Guan Jun Qiao ◽  
Ji Qiang Gao
Keyword(s):  
Fracture Toughness ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Bending Strength ◽  
Ceramic Composites ◽  
The Matrix ◽  
Shock Resistance

The SiC/h-BN ceramic composites with different h-BN size were fabricated by Plasma Active Sintering (PAS) method. For the SiC/ nano-sized h-BN ceramic composites, when the h-BN content was increased, because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the bending strength and fracture toughness of the composites decreased slowly, but the hardness decreased sharply, therefore the machinability and thermal shock resistance were improved noticeable.

Study of Fracture Behaviors of 20g Steel under Short Period High Temperature and Thermal Shock Condition

2011 ◽  
Vol 217-218 ◽  
pp. 84-87
Author(s):  
Nai Chao Chen ◽  
Ping He ◽  
Tian Yu Chen ◽  
Yu Jie Shen
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Thermal Shock ◽  
Bending Test ◽  
Opening Displacement ◽  
Shock Condition ◽  
Fracture Properties ◽  
Short Period ◽  
Fracture Behaviors ◽  
Lower Temperature

The fracture properties of 20g steel used as one of boiler materials, after undergoing the heat treatment of short period high temperature and thermal shock, are investigated by evaluating their fracture toughness using the crash opening displacement (COD) and three-point bending test experiment. Meanwhile, the orthogonal test consisting of five temperature stages and four different durations of thermal shock is used to explore the relationships between fracture toughness and temperature or duration. The experimental conclusions show that thermal shock plays a more significant role on affecting the fracture properties, compared with the factor of temperature. Reducing the duration, especially at the high temperature, is useful to inhibit the decrease of fracture toughness. The ranger analysis illustrates that the lower temperature does not have the beneficial effect on the fracture behaviors. Furthermore, the experimental results facilitate providing the valuable reference on the effective safely management of utilize boiler.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Determining the Thermal Shock Elastic Behavior of Mullite Ceramic Regenerator Material by Ultrasonic Testing

2014 ◽  
Vol 633 ◽  
pp. 472-475 ◽  
Author(s):  
Tian Tian Sun ◽  
Yan Xia Wang ◽  
Hai Yun ◽  
Dong Huan Zhang ◽  
Qing Hui Shang
Keyword(s):  
Thermal Shock ◽  
Longitudinal Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Temperature Difference ◽  
Shear Wave Velocity ◽  
Modulus Of Elasticity ◽  
Longitudinal Wave Velocity ◽  
Mullite Ceramic ◽  
Mullite Ceramics

Mullite material is a material commonly used in honeycomb regenerator, because in the process of using material under big temperature difference effect, so have a great demand for its thermal shock resistance. The used mullite ceramics were made by the direct solid phase sintering method, and the modulus of elasticity of the mullite ceramics measured by ultrasonic pulse-echo method in a thermal shock and thermal fatigue experiment, respectively. In the air-cooling condition, the study found the mullite ceramic without thermal shock that the longitudinal wave velocity and shear wave velocity respectively 3970(m/s) and 2492(m/s). After 45 times thermal shock of temperature difference of 800°C, longitudinal wave velocity and shear wave velocity decreased to 3910(m/s) and 2457(m/s), and the value of the modulus of elasticity changed 1020MPa. By observing the change of the elastic modulus value rule, can know the elastic deformation of thermal shock on the material performance of thermal shock damage. Moreover, the results can provide the data basis for the calculation of the residual strength and the numerical simulation of thermal stress.

Effects of TiN Content on Mechanical Properties and Microstructure of ATN Materials

2013 ◽  
Vol 589-590 ◽  
pp. 590-593 ◽  
Author(s):  
Min Wang ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Tin Content

In order to investigate the effects of TiN content on Al2O3/TiN ceramic material (ATN), the ATN ceramic materials were prepared of TiN content in 30%, 40%, 50%, 60% in the condition of hot press sintering. The sintering temperature is 1700°C, the sintering press is 32MPa, and the holding time are 5min, 10min, 15min. The effects of TiN content on mechanical properties and microstructure of ATN ceramic materials were investigated by analyzing the bending strength, hardness, fracture toughness. The results show that ATN50 has the best mechanical property, its bending strength is 659.41MPa, vickers hardness is 13.79GPa, fracture toughness is 7.06MPa·m1/2. It is indicated that the TiN content has important effect on microstructure and mechanical properties of ATN ceramic materials.

The Effects of Warm Pre-Stressing of a Pre-Cracked Pressurised Thermal Shock Disk Specimen Under a LUCF Loading Cycle

2011 ◽  
Author(s):  
H. Teng ◽  
D. W. Beardsmore ◽  
J. K. Sharples ◽  
P. J. Budden
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Thermal Shock ◽  
Local Stress ◽  
Superposition Method ◽  
Element Analysis ◽  
Loading Cycle ◽  
Finite Element Software ◽  
Disk Specimen ◽  
Apparent Fracture Toughness

A finite element analysis has been performed to investigate the effects of warm prestressing of a pre-cracked PTS-D (Pressurized Thermal Shock Disk) specimen, for comparison with the experimental work conducted by the Belgium SCK-CEN organisation under the European NESC VII project. The specimen was loaded to a maximum loading at −50 °C, unloaded at the same temperature, cooled down to −150 °C, and then re-loaded to fracture at −150 °C. This is a loading cycle known as a LUCF cycle. The temperature-dependant tensile stress-strain data was used in the model and the finite element software ABAQUS was used in the analysis. The finite element results were used to derive the apparent fracture toughness by three different methods: (1) Chell’s displacement superposition method; (2) the local stress matching method; and (3) Wallin’s empirical formula. The apparent fracture toughness values were derived at the deepest point of the semi-elliptical crack for a 5% un-prestressed fracture toughness of 43.96 MPam1/2 at −150 °C. The detailed results were presented in the paper.

Fabrication of Carbon Nanotube Reinforced Boron Carbide Composite by Hot-Pressing Following Extrusion Molding

2014 ◽  
Vol 616 ◽  
pp. 27-31 ◽  
Author(s):  
Tomohiro Kobayashi ◽  
Katsumi Yoshida ◽  
Toyohiko Yano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Boron Carbide ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Extrusion Direction ◽  
Sem Observation

The CNT/B4C composite with Al2O3 additive was fabricated by hot-pressing following extrusion molding of a CNT/B4C paste, and mechanical properties of the obtained composite were investigated. Many CNTs in the composite aligned along the extrusion direction from SEM observation. 3-points bending strength of the composite was slightly lower than that of the monolithic B4C. Elastic modulus and Vickers hardness of the composite drastically decreased with CNT addition. Fracture toughness of the composite was higher than that of the monolithic B4C.

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