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Method for prefabricating straight through crack and dedicated device therefor

A special device and crack technology, applied in the preparation of test samples, etc., can solve the problems of difficult control of crack length and shape, huge cost and time, etc., to achieve easy sample preparation, prevent instability and fracture, and simple experimental methods Effect

Inactive Publication Date: 2005-06-29
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method still has several fatal weaknesses, for example: the crack length and shape are difficult to control, and some failed and invalid samples need to be removed after the experiment
More importantly, for quasi-brittle ceramic materials and coarse-grained ceramics, this method cannot be used, because indentation micro-cracks cannot be initiated.
Another method is to use high-frequency fatigue to prefabricate cracks, but the cost and time are very huge, and it is also ineffective for some coarse-grained ceramics

Method used

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  • Method for prefabricating straight through crack and dedicated device therefor
  • Method for prefabricating straight through crack and dedicated device therefor
  • Method for prefabricating straight through crack and dedicated device therefor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1: Crack initiation of titanium silicon carbon / silicon carbide composite ceramic samples

[0030] Processing titanium silicon carbon / silicon carbide composite ceramics to 3×4mm 2 For a sample with a cross-section and a length of 36 mm, cut a triangular incision in the center with a diamond circular slicer after polishing, conduct crack initiation and monitoring on the sample according to the above-mentioned implementation method, and use a camera to photograph the crack propagation process. About half of the sample width stops loading, and finally a prefabricated crack with the same crack width as the natural crack is obtained. The crack growth process is shown in Fig. 5(a-e).

Embodiment 2

[0031] Embodiment 2: Crack initiation and fracture toughness test of titanium silicon carbon ceramic sample

[0032] Processing titanium silicon carbon ceramics to 4×8mm 2 and 3×4mm 2 For a sample with a cross-section and a length of 36 mm, after polishing, cut a triangular incision and a mountain-shaped incision in the center of the sample with a diamond circular slicer for different samples, and conduct crack initiation and monitoring on the sample according to the above-mentioned implementation method, and use The camera photographs the crack growth process, and the loading is stopped when the crack reaches about half the width of the sample, and finally a prefabricated crack with the same crack width as the natural crack is obtained. The crack growth process of the sample with a triangular incision is as follows: Figure 6 shown.

[0033] The cracking process of the sample with a mountain-shaped incision is invisible under the microscope, and can only be judged by the s...

Embodiment 3

[0034] Example 3: Crack initiation of zirconia ceramic samples

[0035] Machining zirconia ceramics to 3×4mm 2 For a sample with a cross-section and a length of 30mm, cut a triangular incision in the center with a diamond circular slicer after polishing, conduct crack initiation and monitoring on the sample according to the above-mentioned implementation method, and use a camera to photograph the crack growth process to obtain a crack width The prefabricated cracks are exactly the same as the natural cracks, but the cracks are difficult to distinguish and see after unloading, and the crack growth process is as follows: Figure 9 shown.

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Abstract

This invention discloses a pre-process straight crack of engineer ceramics material and rigid material and its special device. The method is to use the strain rule of the ceramics material crack expansion; first to cut a •¢ shape cut or triangle cut in the outer round shear machine in the specimen; to make the strain of the crack top end under control through one limit deflection degree and vertical constrains bending load. The device comprises rigid rack, clock gage, adjustable top pillar, and tight screw. The parallel beam forms rigid rack through vertical beam. There fixed with clamping beam specimen tight screw. The clock gage test part is connected with the adjustable top pillar on the back of the beam specimen.

Description

technical field [0001] The present invention relates to the crack prefabrication during the fracture resistance test of engineering ceramic materials and hard and brittle materials, specifically a method for prefabricating straight through cracks and a special device thereof, which can control the crack propagation and crack arrest of brittle and quasi-brittle materials simple yet effective technique. Background technique [0002] Due to excellent physical and chemical properties, such as high hardness, high modulus, high temperature resistance, corrosion resistance, etc., engineering ceramic materials have attracted great attention in the field of materials at home and abroad in recent decades, and have been widely used in electronics, chemical and national defense industries. has been widely applied. Ceramic fracture toughness K IC It is an important performance index reflecting the application ability of ceramic engineering. In most cases, the test of fracture toughnes...

Claims

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Application Information

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IPC IPC(8): G01N1/28
Inventor 包亦望周延春
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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