Improvement on Thermal Shock Resistance of Ceramic Components by Using Self-Healing

2010 ◽  
Author(s):  
Wataru Nakao
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Thermal Shock ◽  
Stress Fracture ◽  
Thermal Shock Resistance ◽  
Self Healing ◽  
Quenching Rate ◽  
Ceramic Components ◽  
Shock Resistance ◽  
Quenching Method

Availability of self-healing on the thermal shock resistance of ceramic components was investigated. Using gas quenching method, the crack-healed alumina-18 vol% SiC composite, which has excellent self-healing ability, was applied to thermal shock of the arbitrary quenching rate. The procedure could give rise to the thermal stress fracture at high temperature. The critical quenching rate at thermal stress fracture of the healed specimen was found to be 6.47 K/s, corresponding to the thermal stress of 452.3 MPa. Alternatively, that of the cracked specimen was found to be 5.02 K/s, corresponding to the thermal stress of 350 MPa. From the obtained results, usage of self-healing was confirmed to improve extremely thermal shock resistance. The present result suggests that usage of self-healing gives a large advantage to design the high temperature ceramic components, because the mechanically reliable design and thermal shock resistance cannot coexist due to low thermal conductivity.

Fabrication, Microstructure, and Properties of Zirconium Diboride Matrix Ceramic

2013 ◽  
pp. 354-412 ◽  
Author(s):  
Zhi Wang ◽  
Zhanjun Wu
Keyword(s):  
Thermal Stress ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Zirconium Diboride ◽  
Isothermal Oxidation ◽  
Rate Of Change ◽  
Oxide Layers ◽  
Sic Ceramic ◽  
Shock Resistance ◽  
Quenching Method

The crystal structure, synthesis, and densification of zirconium diboride (ZrB2) are summarized in detail. In this chapter, ZrB2-ZrC-SiC ceramic was synthesized by reactive hot pressing a mixture of Zr, B4C, and Si powders. The thermal shock resistance of the ZrB2-SiC-ZrC ceramic was estimated by the water-quenching method and was significantly greater than that of a ZrB2-15vol.% SiC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at constant temperatures of 1000±15, 1200±15, and 1400±15 ºC for different amounts of time at each temperature. The mechanism of strength increase for the oxidized specimen indicated that the strength increased with the reaction rate, which was related to the rate of change in volume induced by reaction, initial crack geometry, elastic modulus, and surface free energy. The formation of oxide layers resulted in (I) repair of surface flaws, (II) increase in flexural strength, (III) appearance of a compressive stress zone beneath the surface oxide layers, (IV) decrease in thermal stress, and (V) consumption of thermal stress. These five aspects were favorable to the improvement of the thermal shock resistance of the ZrB2-SiC-ZrC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at 1600±15 ºC. In the different oxidation stages, quantitative models were proposed for predicting oxidation kinetics.

Scaling Behavior of Superheater Tube Alloys in ASME High Temperature Steam Research Tests at 1100–1500 F

1962 ◽  
Vol 84 (3) ◽  
pp. 223-257 ◽  
Author(s):  
F. Eberle ◽  
C. H. Anderson
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Scaling Behavior ◽  
Effect Of Temperature ◽  
Relative Resistance ◽  
Superheater Tube ◽  
Shock Resistance ◽  
High Temperature Steam

The scales formed on seven ferritic and ten austenitic types of commercial tubing presently in use and of potential future use for superheater service were examined after 6, 12, and 18 months’ exposure to air and to flowing steam of 2000 psi at temperatures of 1100, 1200, 1350, and 1500 F. The effect of temperature and time of exposure on the adherence, thermal-shock resistance, thickness, structure, and chemical composition of the scales was investigated and the relative resistance to scaling of the various alloys evaluated.

scholarly journals High Temperature Bending Strength and Thermal Shock Resistance of Carbon-Ceramics Composites

TANSO ◽  
1985 ◽  
Vol 1985 (120) ◽  
pp. 21-27 ◽  
Author(s):  
Kenji Miyazaki ◽  
Hisayoshi Yoshida ◽  
Kazuo Kobayashi
Keyword(s):  
High Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Bending Strength ◽  
Shock Resistance

EFFECTS OF THERMAL ENVIRONMENTS ON THE THERMAL SHOCK RESISTANCE OF ULTRA-HIGH TEMPERATURE CERAMICS

2008 ◽  
Vol 22 (14) ◽  
pp. 1375-1380 ◽  
Author(s):  
WEIGUO LI ◽  
DAINING FANG
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Thermal Environment ◽  
Transfer Condition ◽  
Ultra High Temperature Ceramics ◽  
Thermal Environments ◽  
Shock Resistance ◽  
Ultra High Temperature

In the present study, the temperature-dependent thermal shock resistance parameter of Ultra-High Temperature Ceramics (UHTCs) was measured based on the current evaluation theories of thermal shock resistance parameters, since the material parameters of UHTCs are very sensitive to the changes of temperature. The influence of some important thermal environment parameters on the thermal shock resistance and critical temperature difference of rupture of UHTCs were studied. By establishing the relation between the temperature and the thermal or mechanical properties of the UHTCs, we found that thermal shock behavior of UHTCs is strongly affected by the surface heat transfer coefficient, heat transfer condition and initial temperature of the thermal shock.

Fabrication of Self-Healing Ceramic Coating Against Oxidation for Carbon/Carbon Composite Using Polysilazane and Fillers

2009 ◽  
Vol 79-82 ◽  
pp. 775-778 ◽  
Author(s):  
Hong Li Liu ◽  
Chun Ying Tian
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Loss Rate ◽  
Ceramic Coating ◽  
Carbon Composite ◽  
Self Healing ◽  
Weight Loss Rate ◽  
Shock Resistance ◽  
Polymer Pyrolysis ◽  
Sealing Layer

The self-healing ceramic coating against oxidation for carbon/carbon composite was fabricated via preceramic polymer pyrolysis process using polysilazane as preceramic and MoSi2, B4C powders as fillers. By means of SEM and XRD, the phase compose and microstructure of coating were characterized, and preliminarily study on its anti-oxidation ability and thermal shock resistance were conducted. The results showed that, the coating is composed of the resisting oxidation layer and the sealing layer. The thickness of the coating is about 50μm, and the coating is uniform and densified. Good contact at the interfaces is visible on the SEM photograph. At 1300°C temperature, the thermal shock resistance test was conducted 50 times, the weight loss rate was 2.12%. In range of 1200°C~1500°C, the anti oxidation ability of the coating is good.

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