The intrinsic strength of triangular symmetrical composite eutectic

2015 ◽  
Vol 12 (6) ◽  
pp. 533-540
Author(s):  
Jinfeng Yu ◽  
Xiequan Liu ◽  
Xinhua Ni
Keyword(s):  
Covalent Bond ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Eutectic Composite ◽  
Micro Structure ◽  
Macroscopic Structure ◽  
Pile Up ◽  
Distribution Of Stress ◽  
Intrinsic Strength ◽  
Structure Properties

Composite ceramic has the excellent properties at normal and high temperatures, especially when the structure of the composite eutectic is triangular symmetrical. Obviously, mechanical behavior and fracture properties of composite ceramic closely relates to the micro-structure of symmetrical triangular eutectic. In order to reveal the mechanical properties of eutectic composite ceramic, it is necessary to determine the intrinsic strength of triangular composite eutectic. Since the fiber and matrix of triangular symmetrical composite eutectic sharing a same covalent bond, the theoretical cohesion strength of symmetrical triangular eutectic was obtained by the combination-separation displacement of intrinsic bond. Basing on micro-structure plastic deformation before fracture of composite eutectic matrix, the dislocation pile-up model of eutectic composite ceramics was established. And then intrinsic bond fracture shear stress of triangular symmetrical composite eutectic was given by using the theory of dislocation pile-up. According to the macroscopic structure properties of triangular symmetrical composite eutectic and the distribution of stress field of composite eutectic, intrinsic strength of eutectic was obtained. The results shows that intrinsic strength of triangular symmetrical composite eutectic possessed clear size-dependence and the stress decreases with the increases of the diameter of fiber inclusions.

Elastic Constants of Eutectic Composite Ceramic Containing Parallel Lamellar Inclusion

2012 ◽  
Vol 251 ◽  
pp. 285-288
Author(s):  
Yun Wei Fu ◽  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Hong Na Cao
Keyword(s):  
Elastic Constant ◽  
Effective Stress ◽  
Elastic Constants ◽  
Transverse Isotropy ◽  
Analytical Formula ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Eutectic Composite ◽  
Effective Elastic Constants ◽  
The Matrix

The eutectic composite ceramic is composed of parallel lamellar inclusions distributed in the matrix. First, the recessive expression for the effective stress and the flexibility increment tensor of eutectic composite ceramic are obtained according to the four-phase model. Second, the analytical formula which contains elastic constant is given by applying Taylor’s formula. The eutectic composite ceramic is transverse isotropy, so there are five elastic constants. Third, the effective elastic constants of composite ceramics are predicted.

The Mechanical-Stress-Field of Matrix in Eutectic Ceramic Composite

2011 ◽  
Vol 121-126 ◽  
pp. 3607-3611
Author(s):  
Zhao Gang Cheng ◽  
Xin Hua Ni ◽  
Xie Quan Liu
Keyword(s):  
Stress Field ◽  
Mechanical Stress ◽  
Ceramic Composite ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Eutectic Composite ◽  
Nano Fiber ◽  
The Matrix ◽  
Stress Boundary Condition ◽  
Stress Boundary

Based on the interaction between nano-fiber and eutectic interphase, forth-phase mode is used to get the mechanical stress field of matrix in eutectic composite ceramics. The effective flexibility increment tensor of eutectic ceramic composite is obtained by the volumetric average strain. The remote stress boundary condition of the eutectic composite ceramis is accounted for getting the mechanical stress field in matrix. The results show the mechanical stress field of the matrix is associated with the stiffness and the volume fractions of each component in eutectic composite ceramic , the shape of interphase and nano-fiber. The stresses in matrix will decrease due to the strong constraining effects of the eutectic interphase. The eutectic interphase make the eutectic composite ceramics strengthen.

Effective Elastic Constants of Fiber-Eutectics and Transformation Particles Composite Ceramic

2010 ◽  
Vol 177 ◽  
pp. 182-185 ◽  
Author(s):  
Bao Feng Li ◽  
Jian Zheng ◽  
Xin Hua Ni ◽  
Ying Chen Ma ◽  
Jing Zhang
Keyword(s):  
Elastic Modulus ◽  
Elastic Constant ◽  
Effective Stress ◽  
Elastic Constants ◽  
Transverse Isotropy ◽  
Analytical Formula ◽  
Composite Ceramic ◽  
Phase Model ◽  
Composite Ceramics ◽  
Effective Elastic Constants

The composite ceramics is composed of fiber-eutectics, transformation particles and matrix particles. First, the recessive expression between the effective stress in fiber-eutectic and the flexibility increment tensor is obtained according to the four-phase model. Second, the analytical formula which contains elastic constant of the fiber-eutectic is obtained applying Taylor’s formula. The eutectic is transverse isotropy, so there are five elastic constants. Third, the effective elastic constants of composite ceramics are predicted. The result shows that the elastic modulus of composite ceramic is reduced with the increase of fibers fraction and fibers diameter.

scholarly journals Dielectric and varistor properties of rare-earth-doped ZnO and CaCu3Ti4O12 composite ceramics

2013 ◽  
Vol 03 (01) ◽  
pp. 1350001 ◽  
Author(s):  
Huafei Lu ◽  
Yuanhua Lin ◽  
Jiancong Yuan ◽  
Cewen Nan ◽  
Kexin Chen
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Nonlinear Coefficient ◽  
Composite Ceramic ◽  
Dielectric Behavior ◽  
Composite Ceramics ◽  
High Dielectric Permittivity ◽  
Doped Zno ◽  
Co Precipitation ◽  
High Dielectric

To investigate the multi-functional ceramics with both high permittivity and large nonlinear coefficient, we have prepared rare-earth Tb -and- Co doped ZnO and TiO 2-rich CaCu3Ti4O12 (TCCTO) powders by chemical co-precipitation and sol–gel methods respectively, and then obtained the TCCTO/ ZnO composite ceramics, sintered at 1100°C for 3 h in air. Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu3Ti4O12 (CCTO). Our results revealed that the TCCTO/ ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors. The composite ceramic of TCCTO: ZnO = 0.3 exhibited a high dielectric constant of ~210(1 kHz) with a nonlinear coefficient of ~11. The dielectric behavior of TCCTO/ ZnO composite could be explained by the mixture rule. With the high dielectric permittivity and tunable varistor behaviors, the composite ceramics has a potential application for the higher voltage transportation devices.

Synthesis of Al2O3/AlB12/Al Composite Ceramic Powders by Pulsed Nd:YAG Laser Igniting Method and a Study of their Mechanical Properties

2010 ◽  
Vol 26-28 ◽  
pp. 919-924
Author(s):  
Kai Jin Huang
Keyword(s):  
Fracture Toughness ◽  
Reaction Mechanism ◽  
Nd:Yag Laser ◽  
Bending Strength ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Ceramic Powders ◽  
Pulsed Nd:Yag Laser ◽  
Al Composite ◽  
Pure Al2o3

Based on the combined toughening principle, pure Al2O3/AlB12/Al composite ceramic powders have been synthesized using pulsed Nd:YAG laser igniting method. This method starts from Al and B2O3 powder mixtures, after which Al2O3/AlB12/AlN composite ceramics were fabricated by hot-press sintering at 1600°C for 2h under the protection of a N2 atmosphere. XRD and SEM techniques were used to characterize the phases and morphologies of the powders and the ceramics. The bending strength and the fracture toughness of the ceramics were measured by the three-point bending method and the indentation fracture method, respectively. The results show that the pure Al2O3/AlB12/Al composite ceramic powders can be successfully synthesized by pulsed Nd:YAG laser igniting method because the adiabatic temperature of Al-B2O3 system is more than 1800K. Al2O3 and AlB12 phases were formed by the liquid-liquid reaction mechanism and the liquid-solid reaction mechanism, respectively. The bending strength and the fracture toughness of the Al2O3/AlB12/AlN composite ceramics were 525.86MPa and 5.68MPa.m1/2, respectively. These values are 50.25% and 42% greater than those of the pure Al2O3 ceramic (350MPa and 4MPa.m1/2) due to the reinforcing and toughening in-situ formation of small AlN particles.

Micro-Stress-Field of Lamellar Inclusion in Eutectic Composite Ceramic

2012 ◽  
Vol 204-208 ◽  
pp. 4433-4436 ◽  
Author(s):  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Jing Zhang ◽  
Xiang Feng Meng
Keyword(s):  
Stress Field ◽  
Composite Ceramic ◽  
Apparent Size ◽  
Phase Cell ◽  
Ceramic Analysis ◽  
Eutectic Composite ◽  
Three Phase ◽  
Stress Boundary Condition ◽  
Stress Boundary ◽  
Remote Stress

According to the interaction between lamellar inclusion and interphase, forth-phase model is suggested to determine the micro-stress-field distribution of three-phase cell in eutectic composite ceramic. On the basis of the volumetric average strain, the effective compliance tensor increment of eutectic composite ceramic is obtained. The remote stress boundary condition of the eutectic composite ceramic is accounted for getting the micro-stress-field of lamellar inclusion in eutectic composite ceramic. Analysis shows that the micro-stress-field of the lamellar inclusion in eutectic composite ceramic is associated with the stiffness and the volume fractions of each component in eutectic composite ceramic, the shape of interphase and lamellar inclusion. The-micro-stress field has apparent size effect: three direction stresses increase with the thickness of lamellar inclusion.

Effects of Polarization Treatment on Mechanical Properties of Al2O3/LiTaO3 Composite Ceramics

2007 ◽  
Vol 353-358 ◽  
pp. 1314-1317
Author(s):  
You Feng Zhang ◽  
Qing Chang Meng ◽  
De Chang Jia ◽  
Yu Zhou
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Domain Switching ◽  
Composite Ceramic ◽  
Polarization Direction ◽  
Composite Ceramics ◽  
Pressing Method ◽  
Width Direction ◽  
Different Temperatures ◽  
Polarization Temperature

The Al2O3/LiTaO3 (ALT) composite ceramics were fabricated by hot pressing method and polarization treated at different temperatures along height and width directions. Effects of polarization treatment on mechanical properties of the ALT composite ceramic were investigated. Flexural strength decreased with the increase of polarization temperature. Meanwhile, the flexural strength of samples polarized in height direction is higher than that polarized in width direction. The composite ceramic fractures intragranularly, and many rupture steps in polarization direction were observed on fractographs of the composite ceramics. Domain switching in LiTaO3 particles increased the resistance of crack propagation and improved the mechanical properties of the polarized ALT composite ceramics.

The Damage Finite Element Analysis of Eutectic Composite Ceramic Containing Lamellae

2011 ◽  
Vol 121-126 ◽  
pp. 473-477
Author(s):  
Shu Qin Zhang ◽  
Xin Hua Ni ◽  
Xie Quan Liu ◽  
Ying Chen Ma
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Field ◽  
Composite Ceramic ◽  
Element Model ◽  
Eutectic Composite ◽  
Element Analysis ◽  
Matrix Fracture ◽  
Damage Process ◽  
The Finite Element Model

According to microstructures in eutectic composite ceramic, the finite element model of composite with eutectic interphase is established. The mechanical stress field of eutectic composite ceramic containing lamellae is simulated. APDL programming in ANSYS is used to analyze the damage process of eutectic composite ceramic. Results show that the failure of eutectic composite ceramic is determined by the damage of matrix. As load is increasing, the damage will elongate along the interphase and extend to the internal of matrix. At last the damage arouses matrix fracture.

Effects of SiO2 and ZrO2 Additives on Microstructure and Properties of Al2O3 Ceramic

2013 ◽  
Vol 745-746 ◽  
pp. 523-527
Author(s):  
Yi Hua Li ◽  
De Chang Jia ◽  
Zhi Hua Yang ◽  
Yu Zhou
Keyword(s):  
High Hardness ◽  
Composite Ceramic ◽  
High Tech ◽  
Composite Ceramics ◽  
High Mechanical Strength ◽  
Mullite Phase ◽  
Good Corrosion Resistance ◽  
Alumina Composite ◽  
Resistance Performance ◽  
Silicon Sol

Alumina ceramic, with high mechanical strength, good electric insulation, high hardness and good corrosion resistance performance, has been widely used in machinery, electronic and electrical, chemical, medicine, construction and other high-tech areas. In this study, both silicon sol and zirconia particles are incorporated into the system and dense alumina composite ceramics were prepared by cold isostatic processing and pressureless sintering at 1550 . The influence of additives on phase composition, microstructure and mechanical properties were investigated. The XRD results show that mullite phase was generated in the composite ceramic. The composite ceramic has excellent comprehensive performance. For example, the sample with 3wt.% SiO2 and 5wt.% ZrO2 has density of 3.87g·cm-3, Vickers hardness of 17.6GPa, flexural strength of 369.0MPa, youngs modulus of 374.2GPa and fracture toughness of 3.57MPa·m1/2.

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