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Prediction method for surface thin film residual stress

A technology of residual stress and prediction method, applied in the direction of measuring force, measuring device, instrument, etc., can solve the problems of poor repeatability, influence, limitation, etc.

Active Publication Date: 2012-04-25
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

When the X-ray method is used to measure the residual stress of the film, the matrix diffraction will have an influence due to the small thickness of the film, and there is often a strong texture inside the film, resulting in large errors in the measurement results; although the Raman spectroscopy method is nearly In recent years, the method has been developed relatively rapidly, but when it is used for the determination of the residual stress of the film, the repeatability is poor, and it is limited to the stress test of the local position; although the curvature method can characterize the residual stress inside the film more accurately and quickly, However, precise measurements of the curvature of the specimen before and after film deposition are required

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  • Prediction method for surface thin film residual stress
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  • Prediction method for surface thin film residual stress

Examples

Experimental program
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Effect test

Embodiment 1

[0109] The surface of the nickel-based 617 alloy with a thickness of 1 mm was polished with 200-grit sandpaper, and then the surface was cleaned with chemical ultrasonic waves, and then a YSZ film with a thickness of 3.1 μm was deposited by magnetron sputtering. Determination of residual stress value σ of thin film by curvature method r It is -149MPa, and the Young's modulus E of the film and the substrate is measured by the nano-indentation method f and E s 70GPa and 214GPa, respectively, the Poisson's ratio v of the film and the substrate f and v s were set to 0.23 and 0.288, respectively. The four-point bending experiment of the film was carried out under the in-situ observation environment of the scanning electron microscope, and the critical strain value ε of the crack initiation observed in the experiment was c About 0.28%. After generating multiple cracks inside the film, at different bending strain values ​​ε a Next, stop the load, record the number N of internal...

Embodiment 2

[0113] The surface of the nickel-based 617 alloy with a thickness of 1 mm was polished with 400-grit sandpaper, and then the surface was cleaned with chemical ultrasonic waves, and then a YSZ film with a thickness of 7.1 μm was deposited by magnetron sputtering. Determination of the residual stress value σ of the film by X-ray diffraction method r It is -129MPa, and the Young's modulus E of the film and the substrate is measured by the nano-indentation method f and E s 68GPa and 214GPa, respectively, the Poisson's ratio v of the film and the substrate f and v s were set to 0.23 and 0.288, respectively. The four-point bending experiment of the film was carried out under the in-situ observation environment of an optical microscope, and the critical strain value ε of the crack initiation observed in the experiment was c About 0.22%. At different bending strains, the load is stopped, and the number N of cracks inside the film in the observation interval is recorded in good ti...

Embodiment 3

[0117] The surface of the nickel-based 617 alloy with a thickness of 1 mm was polished with 220-grit sandpaper, and then the surface was cleaned with chemical ultrasonic waves, and then a YSZ film with a thickness of 9.0 μm was deposited by magnetron sputtering. Determination of residual stress value σ of thin film by curvature method r It is -73MPa, and the Young's modulus E of the film and the substrate is measured by the nano-indentation method f and E s 68GPa and 214GPa, respectively, the Poisson's ratio v of the film and the substrate f and v s were set to 0.23 and 0.288, respectively. The four-point bending experiment of the film was carried out under the in-situ observation environment of the scanning electron microscope, and the critical strain value ε of the crack initiation observed in the experiment was c About 0.13%. At different bending strains, the load is stopped, and the number N of cracks inside the film in the observation interval is recorded in good tim...

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Abstract

The invention discloses a prediction method for surface thin film residual stress. The method comprises the following steps of: A, obtaining a relation curve for variation of density of internal cracks of a thin film along with a bending strain value by using a four-point bending experiment; B, establishing a theoretical prediction model for the relation of the density of the internal cracks of the thin film and the bending strain value based on the stress transfer condition in a thin film structure under the action of four-point bending load; C, establishing a theoretical relation curve for the density of the internal cracks of the thin film and the bending strain value at different residual stress values according to the theoretical prediction model in the step B; and D, selecting the theoretical relation curve in the step C which has the most matching degree with the relation curve in the step A, wherein the residual stress value corresponding to the theoretical relation curve is the predicted surface thin film residual stress. The method provided by the invention is easy to operate, can also be used for accurately predicting the residual stress of the thin film without being limited to the thin film material, and particularly has obvious advantages in the case of small thin film thickness.

Description

technical field [0001] The invention relates to the field of performance characterization of surface modified films, in particular to a method for predicting residual stress of surface films. Background technique [0002] The surface film has been widely used to improve the hardness, wear resistance and corrosion resistance of the surface of the base material or to achieve other special functions. However, during the film deposition process, due to the mismatch of the physical parameters of the film and the substrate, there is a large residual stress in the film; produce a large stress concentration. Residual stress may seriously affect some main properties of the film, such as resistance to peeling and delamination, fatigue life and bonding strength. How to accurately predict the residual stress inside the film is of great significance to the material and structure design of the film structure, and has become the focus of general attention in recent years. [0003] The c...

Claims

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Application Information

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IPC IPC(8): G01L1/00
Inventor 张显程轩福贞王正东涂善东
Owner EAST CHINA UNIV OF SCI & TECH
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