Detecting method for elastic modulus and strength of fragile coating layer

A technology of elastic modulus and test method, which is applied in the direction of strength characteristics, the use of stable tension/pressure to test the strength of materials, and measurement devices, which can solve the problems of insufficient evaluation technology of film mechanical properties, unstable data, and rare reports. And other issues

Inactive Publication Date: 2004-07-14
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the evaluation technology for the mechanical properties of the film developed simultaneously or in support is not perfect enough.
Most of the studies focus on evaluating the elastic modulus of the film layer by means of microindentation or ultrasound. The disadvantage of this method is that the operation is complicated, the equipment requirements are high, and the obtained data is unstable and often inconsistent with The actual situation is quite different
In addition, film strength is an important parameter to reflect the mechanical properties of materials, and people's demand for film strength evaluation is becoming more and more intense, but there are few reports on the method of measuring film strength.

Method used

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  • Detecting method for elastic modulus and strength of fragile coating layer
  • Detecting method for elastic modulus and strength of fragile coating layer
  • Detecting method for elastic modulus and strength of fragile coating layer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Such as Picture 1-1 , 1-2 , diagram 2-1 , Pic 4-1 , 5-1 As shown, taking the elastic modulus and strength of the four-sided silicon carbide coating formed on the surface of the graphite substrate by CVD as an example, the length of the beam sample is 40 mm, the width B of the beam sample before coating is 4 mm, and the thickness of the beam sample before coating is H is 3mm, the film thickness h is about 0.18mm, the span L is 30mm, and the elastic modulus of the graphite matrix is ​​about 10GPa. The displacement is tested with a precision dial gauge. The measured elastic modulus of the silicon carbide coating is about 324GPa, and the strength is 249MPa. The results are basically consistent with the data measured with the single material.

[0042] Test method for elastic modulus of brittle film layer:

[0043] By comparing the changes in the bending stiffness of the beam sample under bending load before and after coating, according to the deformation of the beam ...

Embodiment 2

[0060] The difference with embodiment 1 is: as Figure 2-2 , image 3 , 4-2 , 5-2, taking the elastic modulus and strength of the single-sided glass film layer of the aluminum beam sample as an example, the length of the beam sample is 45mm, the span is 40mm, and the width B of the beam sample before coating is 4mm , the thickness H of the coated front beam sample is 3 mm, the load increment is 4 kg, and the displacement is tested by a precision dial gauge. The elastic modulus of the boron glass film layer on the surface of the aluminum alloy is measured to be about 68GPa, and the strength is about 120MPa. The results are basically consistent with the data measured with single material.

[0061] The expression of the moment of inertia of the asymmetric beam specimen coated on the lower surface is:

[0062] I b = BH 3 12 + α...

Embodiment 3

[0069] The difference from Example 2 is that the elastic modulus of the hard plastic beam sample with the upper and lower aluminum thin layers is tested, and the moment of inertia expression of the beam sample with coating on both sides is:

[0070] I 2 = αBh 3 6 + αBh 2 ( h + H ) 2 + BH 3 12 ; - - ( 6 )

[0071] The expression (7) for the modulus ratio is derived from this:

[0072] α = E 2 E 1 = I 1 ...

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Abstract

The present invention discloses the measurement method of elastic modulus and strength of fragile coating. Based on the variation of beam sample before and after coating in bending deflection under bending load, the formula of f2.I=f1.I1 for the deformation of the sample before and after coating under the same load, equivalent cross theory of composite beam in material mechanics and three-point bending formula, the inertia moment of the coated beam sample, further the ratio between the coating elastic modulus and the substrate elastic modulus, the ratio between deflection values before and after coating and the elastic modulus of the coating are found out. Then, through determining the elastic modulus of the substrate and the coating and calculating the stress distribution along the thickness direction, the maximum surface stress corresponding to the coating cracking as the strength of the coating is found out. The present invention can evaluate the elastic modulus and breaking strength of fragile coating simultaneously.

Description

technical field [0001] The invention relates to a film mechanical performance evaluation technology, in particular to a method for testing the elastic modulus and strength of a brittle film layer. Background technique [0002] A brittle ceramic coating with high hardness, high strength, corrosion resistance, wear resistance and high temperature resistance is plated on metal or other solid materials by physical or chemical methods. For modern mechanical fields including aviation, aerospace, automobiles and various It is of great significance to improve the performance of high-temperature wear-resistant devices. Therefore, the research on this kind of surface treatment and coating has attracted more and more attention of scientists from various countries, and has developed rapidly. However, the evaluation technology for the mechanical properties of the film developed simultaneously or supporting it is not perfect enough. Most of the studies focus on evaluating the elastic mo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/00G01N3/08
Inventor 包亦望周延春
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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