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Study on Creep Characteristics in the Ultrasonic Vibration Assisted of Nanocomposite Ceramics

Author: YaoJianGuo
Tutor: ZhaoBo
School: Henan Polytechnic University
Course: Mechanical Engineering
Keywords: Nanocomposite ceramics Creep Ultrasonic vibration Superplastic Mechanical Properties
CLC: TQ174.758
Type: Master's thesis
Year: 2011
Downloads: 23
Quote: 1
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Abstract


Ceramic materials have many superior performance, such as high hardness, high strength, high temperature resistance, corrosion resistance, ablation resistance, low thermal conductivity, so that it has a broad application in the field of aerospace, automotive, energy, electronics, chemical prospects. Special internal structure of the ceramic material due to their brittleness great, so that the internal defects sensitive, will quickly develop internal cracks once produced, so that the material rapidly fracture. Creep as a special ceramic mechanical properties, caused widespread concern in the ceramic industry colleagues, become a hot ceramic industry research, this article from the ultrasonic vibration and general conditions both cases the comparison test, draw ultrasonic vibration You can change the mechanical properties of ceramics, in particular, the mechanical properties of high temperature ceramic creep have a certain impact. Mainly from the following aspects: 1, nanocomposite ceramics in ultrasonic vibration conditions under tensile creep rupture simulation test methods, tests showed that the application of ultrasonic vibration (frequency f = 20khz), the test piece to be cyclic stress is reduced by about 25%, verify the nonlocal theory important conclusion: When the ultrasonic vibration acting on the material on the existence of wave scattering force attenuation phenomenon. 2, obtained ultrasonic vibration by ultrasonic vibration ZTA nano-composite ceramic materials cycle fatigue properties of the test, the influence of crack propagation mode. Ultrasonic vibration can be drawn from a scanning electron microscope observation of fracture morphology changed the microstructure and creep mechanical properties of ceramic materials, contrast creep fracture mechanism under ordinary conditions and ultrasonic vibration. Fracture behavior under ordinary conditions of grain boundary diffusion creep that Coble creep fracture behavior under ultrasonic vibration for the grain diffusion creep that Nabarro-Herring creep. Intergranular fracture on the fracture test fracture mode under ordinary conditions, the transgranular fracture fracture mode ultrasonic vibration conditions, applying ultrasonic vibration to delay the rupture life of the ceramic material. 3, the theoretical analysis of the developmental process of the nanocomposite ceramics material creep damage and creep slow crack growth mechanism through model analysis. The three-point bending of nano-ceramic high temperature creep tests of the impact of nano-ceramic creep factor related with the temperature, but also related to the microscopic structure of the material as well as the grain size. Experimental Comparison The creep characteristics of the ultrasonic vibration and the two modes of vibration under the same conditions, the results show that, within the same duration of action of the ultrasonic vibration under the initial stage of the creep rate is significantly higher than under ordinary conditions vermicular variable rate, stable phase changes slowly. Nonlocal theory concluded that a certain degree of long-range forces between the wavelength and internal particle ultrasonic vibration makes waves scattering occurs the nonlocal modulus decreases, reducing the stress concentration, making changes slowly.

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CLC: > Industrial Technology > Chemical Industry > Silicate > Ceramic Industry > Ceramics > Industrial ceramic > Special ceramics
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