WO2019004211A1

WO2019004211A1 - Mechanical-property testing method and measurement device

Info

Publication number: WO2019004211A1
Application number: PCT/JP2018/024193
Authority: WO
Inventors: 達也宮島
Original assignee: 国立研究開発法人産業技術総合研究所
Priority date: 2017-06-28
Filing date: 2018-06-26
Publication date: 2019-01-03
Also published as: JP7046383B2; JPWO2019004211A1

Abstract

Provided is a technology for evaluating, in the nano-domain, mechanical stimulus response properties when an indenter having a known shape and known mechanical properties and the surface of a test body of an unknown sample are brought into contact with each other. In a mechanical-property testing method according to the present invention, in a state where an indenter is pressed into contact with the surface of a test body of a measurement sample, a change in the shape of the face of the indenter on the reverse side of the test body side is measured to evaluate the mechanical properties of the measurement sample. Furthermore, a mechanical-property measurement device according to the present invention includes: an indenter that is pressed into a test body of a measurement sample; and a measurement means that measures a change in the shape of the face of the indenter on the reverse side of the test body side.

Description

Mechanical property test method and measuring device

The present invention relates to a mechanical property test method and a measuring apparatus, and more specifically to a test method and a measuring apparatus for evaluating the mechanical property of a test body by an indentation test.

The indentation test is a test technique for evaluating various mechanical properties such as hardness and elastic modulus of a material from the condition of a depression formed by pressing a jig called an indenter against the surface of a test body of various materials.

When the indenter is pressed against the surface of the test body, the elastic modulus can be evaluated from the deformation behavior within the range of the elastic deformation of the material to be tested. Furthermore, when the stress generated immediately below the indenter exceeds the elastic limit, plastic deformation is induced in the test body, and it is observed from the surface as an indentation after unloading. The hardness of the test body can be evaluated from the size of the indentation and the maximum load value. The elastic modulus and hardness are one of the indices of the mechanical stimulus response when the indenter and the surface of the test body are brought into contact with each other.

In general metals, the size of the indentation is the same at maximum load and after unloading, as plasticity governs the total deformation behavior. On the other hand, for materials such as elasto-plastics and visco-elastics where components other than plasticity can not be neglected in deformation behavior, the size of the indentation after unloading is greater than that at maximum load, since elastic recovery occurs during unloading. It is known to decrease.

Therefore, in order to analyze the mechanical properties of the unknown sample strictly, it is necessary to know what kind of depression the sample forms in the situation where the indenter and the surface of the test body are in contact, that is, It is necessary to measure the mechanical stimulus response characteristics in

In addition, it is known that the types of depressions produced when loaded with an indenter on a test body include "sinking type" and "swelling type" paying attention to the difference in the form of surface deformation seen in the peripheral part Not only the depth from the original surface but also the contact area needs to be measured in order to quantitatively express the depression formed by the load applied to the surface of the test body.

There is an instrumented nanoindentation test method that can measure the depth of a depression as a mechanical stimulus response in a state where a load is applied to the surface of a test body. In this test method, it is assumed that the depressions of all the samples are formed to be depressions having a completely elastic "submersible" contact depth. The current instrumented nanoindentation technology uses a general-purpose approximation method to estimate the contact area from the relationship between the press-in depth and the applied load, but it has the greatest weakness that it can not know the contact area of "climbing type" I have it. Since the instrumented nanoindentation method that measures the depth of the depression can not calculate the contact area of the “raised” type, there is a problem in analyzing the elasto-plastic body that exhibits surface deformation of the “raised” type. is there.

There is a microindentation test method which can optically measure the projected contact area of a depression as a mechanical stimulus response in a state where a load is loaded on the surface of a test body. This test method is a method of directly evaluating the dynamic stimulus response characteristics when the indenter and the surface of the test body are in contact. In the micro indentation test method, the projected contact area can be measured for both surface deformation modes regardless of whether the depression is a "sinking type" or a "swelling type" (for example, Patent Document 1, Patent Document 1) Document 2, Patent Document 3, Patent Document 4, Patent Document 5, Non-Patent Document 1, Non-Patent Document 2, Non-Patent Document 3, Non-Patent Document 4, Non-Patent Document 5, and Non-Patent Document 6).

Unexamined-Japanese-Patent No. 2005-195357 (patent 4317743) Utility model registration 3182252 gazette JP, 2015-175666, A Japanese Patent Application No. 2016-016555 [Patent Document 1] Japanese Patent Application Publication No. 201-146294

However, the resolution in the horizontal direction of an optical microscope of the type that uses a lens to observe the visible light at a spot on a spot has a diffraction limit due to the wave nature of the light, so the conventional microindentation test method In addition, it has been sometimes difficult to evaluate mechanical stimulus response characteristics in the nano area using the optical microscope, which is limited to the submicron area that is half or less the wavelength of visible light.

The present invention has been made in view of such circumstances of the prior art, and the mechanical stimulus response characteristic when an indenter having a known shape and mechanical characteristics is brought into contact with the surface of the test sample of the unknown sample is referred to as the sample. It is an object of the present invention to provide a technique for evaluating the state of deformation of an indenter reflecting the mechanical characteristics possessed by in the nano area without using an optical microscope of an image observation method for narrowing visible light with a lens.

In order to solve the above problems, according to the present invention, the following technical means and technical procedures are provided.

[1] Mechanical property test method for evaluating the mechanical property of a measurement sample by measuring the shape change of the surface opposite to the test body side of the indenter in a state where the indenter is pressed into contact with the surface of the test sample of the measurement sample .
[2] Using a microindentation tester having the indenter, the test body, and a scanning probe microscope provided with a surface observation probe,
Measuring the shape change of the surface of the indenter opposite to the side of the test body, with the tip of the indenter pressed into contact with the surface of the test body by the scanning probe microscope [1] Mechanical property test method.
[3] Using a mechanical characteristic measuring device having the above-mentioned micro indentation test machine, a measurement control device, and an information processing device,
By the measurement control device,
Measuring the positional relationship between the surface of the test body and the tip of the indenter;
Position control is performed so that pressing of the test body and the indenter has a predetermined press-fit depth,
Controlling the scanning probe microscope for observing the back surface of the indenter;
The information processing apparatus
Receiving surface information of the back surface of the surface observation probe from the micro-indentation tester, and analyzing it as surface deformation or surface displacement distribution;
Store the analyzed surface deformation amount or surface displacement distribution in the storage device,
It is characterized in that the mechanical characteristics of the test body of the unknown sample are evaluated from the result of the micro-indentation test by the micro-indentation tester using the indenter having the known mechanical characteristics stored in the storage device. 2] Mechanical property test method.

[4] With reference to the contact center point of the indenter with the surface of the test body, the displacement of a point dropped vertically from the contact center point with respect to the surface of the indenter opposite to the test body side The mechanical characteristic test method in any one of [1] to [3] which measures displacement distribution as a function.

[5] an indenter which is pressed into the test sample of the measurement sample,
And a measuring means for measuring the shape change of the surface opposite to the measuring sample side of the indenter.
[6] equipped with a micro indentation tester, this micro indentation tester is
The indenter;
Said test body,
A scanning probe microscope equipped with a surface observation probe that measures the change in shape of the surface of the indenter opposite to the side of the test body in a state where the tip of the indenter is pressed into contact with the surface of the test body Have
The mechanical characteristic measuring device according to [5], wherein the measuring means includes the scanning probe microscope.
[7] The microscope indentation test machine, a measurement control device, and an information processing device,
The measurement control device
A displacement measuring device for measuring the positional relationship between the surface of the test body and the tip of the indenter;
A precision positioning device that performs position control such that the contact between the test body and the indenter has a predetermined press-fit depth;
It has a surface analysis device for controlling the scanning probe microscope for observing the back surface of the indenter,
The information processing apparatus is
A surface analysis unit that receives surface information of the back surface of the surface observation probe from the micro-indentation tester and analyzes it as a three-dimensional surface deformation amount or surface displacement distribution;
A storage device for storing the surface deformation amount or surface displacement distribution analyzed by the surface analysis unit;
The mechanical characteristics of the test body of the unknown sample are evaluated from the result of the micro indentation test by the micro indentation test using the indenter having the known mechanical characteristics stored in the storage device. [6] mechanical characteristic measuring device.

[8] The mechanical property measuring device according to [6] or [7], having a vertical double structure in which the indenter and the probe of the surface observation probe are arranged in the vertical direction. [9] The surface observation probe is attached to the XYZ scanning mechanism of the scanning probe microscope by a cantilever method so as to be interlocked with the XYZ scanning mechanism, any one of [6] to [8] Mechanical characteristic measuring device.

[10] The scanning probe microscope is a variation or a point at which the indenter is vertically lowered from the contact center point with respect to the surface opposite to the test body side of the indenter with respect to the contact center point of the indenter with the sample surface. The mechanical characteristic measurement device according to any one of [6] to [9], which is configured to measure a displacement distribution as a function of a distance from a point.

According to the present invention, there is provided a technique for evaluating, in the nano area, mechanical stimulus response characteristics when an indenter having a known shape and mechanical characteristics is brought into contact with a test object surface of an unknown sample.

In the micro indentation tester according to one embodiment of the present invention, it is a diagram for explaining an example of the arrangement of the probe for measuring the displacement change of the back surface of the indenter in a situation where the indenter tip contacts the surface of the test body. It is a block diagram explaining an example of basic composition of an indentation system including an indentation tester concerning one embodiment of the present invention. It is a figure explaining an example of composition of an indentation tester concerning one embodiment of the present invention. In Example 1 using a spherical indenter, it is a figure explaining an example of a result of finite element analysis of the relation between the amount of indentation to the test body and the displacement change of the back surface of the spherical indenter. It is a figure explaining an example of a result of finite element analysis about Example 1 which used a spherical indenter about the effect which the elasticity modulus of a test body and the pushing amount to a test body exert on the displacement change of an indenter back surface. It is a figure explaining an example of a result of finite element analysis about a relation of a modulus change of a test object and a spherical indenter, and displacement change of an indenter back surface about Example 1 using a spherical indenter. In Example 1 using a spherical indenter, the elastic modulus ratio between the test body and the indenter is determined from the maximum value of the displacement change of the back surface of the spherical indenter measured in the amount of indentation to the predetermined test body. It is a figure explaining an example which analyzes the elastic modulus of an unknown sample from the product with the elastic modulus of an indenter which is. In Example 2 using a conical indenter, it is a figure explaining an example of a result of finite element analysis of the relation between the amount of indentation to the test body and the displacement change of the back of the indenter. In Example 2 using a conical indenter, it is a figure explaining an example of a result of finite element analysis of the relation of elastic modulus ratio of a test object and an indenter, and displacement change of an indenter back. In Example 2 using a conical indenter, it is a figure explaining an example of a result of finite element analysis of the effect of the elastic modulus of the test body and the pressing amount to the test body on the displacement change of the back surface of the indenter. For Example 2 using a conical indenter, the elastic modulus ratio between the test body and the indenter is determined from the maximum value of the change in displacement of the back surface of the spherical indenter measured for the amount of indentation to the predetermined test body. It is a figure explaining an example which analyzes the elastic modulus of an unknown sample from the product with the elastic modulus of an indenter which is. With respect to Example 3 using a spherical indenter, the spherical indenter was made of polyurethane, the test body was made of polyurethane and an aluminum alloy, and the relationship between the additional weight of the constant load loading system to the test body and the displacement change of the back surface of the spherical indenter was tested. It is a figure explaining the example of a result. In Example 3 using a spherical indenter, the spherical indenter is made of polyurethane, the test body is polyurethane and an aluminum alloy, and the back surface displacement distribution of the spherical indenter is normalized by the indentation amount of the spherical indenter determined by a predetermined load. It is a figure explaining the example of the result of experiment showing the relationship between the additional load of the constant load loading system to a test body, and the load load dependency of the depth (valley) of a valley. In Example 3 using a spherical indenter, the elastic modulus ratio between the test body and the indenter is determined from the amount of change in elevation of the indenter back surface displacement measured at a predetermined additional weight under a constant load load on the test body, and the value It is a figure explaining an example which analyzes the elastic modulus of an unknown sample from the product with the elastic modulus of an indenter known.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a view for explaining an indenter portion of a microscopic indentation tester according to an embodiment of the mechanical characteristic measurement device of the present invention. The indenter portion of the indentation test apparatus (micro indentation testing machine) according to the present embodiment is a measuring means for measuring the shape change of the surface of the indenter on the side opposite to the test body of the indenter for mechanical testing (hereinafter also referred to as indenter). The probe (a probe, hereinafter, also simply referred to as a probe or a surface observation probe) 20 is arranged vertically in a vertical double probe structure. Here, an indenter having a spherical tip as shown in FIG. 1A (hereinafter referred to as a spherical indenter) and an indenter having a conical tip as shown in FIG. 1B (hereinafter referred to as a conical indenter) are exemplified. There is.

In FIG. 1, two orthogonal coordinates are drawn reflecting this double structure, the coordinate system for the indenter is (Xi, Zi), and the origin ((Xi, Zi) = (0, 0) Is a position where the tip of the indenter 4 and the surface of the test body 5 are in contact with each other. In the test in which the tip of the indenter 4 is pressed into the surface of the test body 5, Zi takes a negative sign. The coordinate system for the surface observation probe is (Xm, Zm), and the origin ((Xm, Zm) = (0, 0)) is the position where the tip of the surface observation probe 20 contacts the back of the indenter 4 (Strictly, for example, when the measurement means is a scanning tunneling microscope, the tip of the probe and the surface of the indenter do not contact mechanically because there is a gap of the order of sub-nanometers in which a tunnel current flows). In the test in which the tip of the indenter 4 is pressed into the surface of the test body 5, Zm is a plus sign because the back surface of the indenter 4 bulges up.

In FIG. 1, as an example, a spherical indenter (A) having a shape in which a solid sphere of radius r is cut at height H, and a solid conical shape having a surface inclination angle of β and a height of H A conical indenter (B) is drawn.
The tip of the indenter is shaped to have one protrusion, and is, for example, a sphere, a triangular pyramid, a square pyramid, or a cone. The structure of the indenter 4 shown in FIG. 1 is solid, but may be a shell. However, the back side needs to be smooth.

The method for producing the indenter 4 can be selected from, for example, nanoimprint, electrolytic polishing, wet etching, dry etching, plasma etching, photolithography, micromachining, etc., and has a very small radius of curvature of the order of submicron to nanometer. Can be Furthermore, according to the micromachining technology, it is possible to simultaneously fabricate the probe 20 of the measuring means (for example, a scanning probe microscope) having a beam structure (cantilever) and the indenter 4 for contact.

The measuring means is a device used to observe the displacement of the back surface of the indenter 4, and the probe 20 is installed so as to be interlocked with the movement of the indenter 4, and the back surface of the indenter 4 can always be monitored. By this, the moment when the indenter 4 contacts the test body 5 can be regarded as the deformation of the back surface of the indenter 4. Furthermore, in the process of pushing the indenter 4 into the test body 5, the displacement of the indenter 4 in the Z-axis direction can be measured as a shape change. The measuring means may include, for example, a scanning probe microscope 6 described later, and further, the measurement control device 2 or its components (displacement measuring device 7, precision positioning device 8, surface analysis device 9, etc.), information processing It may include one or more selected from the device 3 or its components (surface analysis unit 13, storage device 16 and the like).

That is, according to the micro indentation test apparatus which is one embodiment of the mechanical characteristic measurement apparatus of the present invention, the tip of the indenter 4 is brought into contact with the surface of the test body 5 to a predetermined indentation depth, and the contact center point is used as a reference. A conventional optical microscope is measured by measuring the displacement distribution as a function of the displacement of a point dropped vertically from the contact center point with respect to the surface opposite to the test body side of the indenter 4 or the distance from that point. It is possible to evaluate the mechanical properties in the nano area, which was difficult by the method used. The displacement distribution can be selected from general-purpose scanning probe microscopes capable of measuring with sub-nanometer precision or less, and can be selected from, for example, a scanning tunneling microscope, an atomic force microscope, a scanning near-field optical microscope, etc. . The horizontal resolution of a common scanning probe microscope is less than nanometre, the vertical resolution is less than sub-nanometer, and observation in the nano area with high measurement accuracy which was impossible with an optical microscope is possible.

FIG. 2 is a block diagram for explaining an example of a basic configuration of an indentation system including a micro indentation test apparatus according to an embodiment of the present invention.

The indentation system shown in FIG. 2 comprises a microscopic indentation tester 1, a measurement control unit 2, and an information processing unit (electronic computer) 3.

The micro-indentation tester 1 includes an indenter 4, a test object 5, and a scanning probe microscope 6 (hereinafter also referred to as a probe microscope) for observing the back surface of the indenter 4 bringing its tip into contact with the surface of the test object 5. It consists of

The measurement control device 2 is a displacement measurement device 7 that measures the positional relationship between the surface of the test body 5 and the tip of the indenter 4, and the precision that position control is performed so that the contact between the test body 5 and the indenter 4 becomes a predetermined press fit depth. It comprises a positioning device 8 and a surface analysis device 9 for controlling a probe microscope 6 for observing the back surface of the indenter 4.

The information processing apparatus 3 is a computer (electronic computer), and has an input / output I / F (Interface) 10, a CPU (Central Processing Unit) 11, a condition setting unit 12, a surface analysis unit 13, a characteristic value calculation unit 14, a position control unit 15 and the storage unit 16. The respective elements of the information processing device 3 are connected by a bus (Bus).

The analysis program used by the surface analysis unit 13 of the information processing device 3 is stored in the storage device 16, and prompts the user to input through the input / output I / F 10 so as to set the contact displacement amount which is the test condition. , And is executed on a main storage device such as a computer memory. Similarly, the position control program used by the position control unit 15 of the information processing device 3 is stored in the storage device 16 and input to the user through the input / output I / F 10 so as to set the contact displacement amount which is a test condition. In addition, it is deployed on the main storage device such as a computer memory to perform execution.

The calculation program used in the characteristic value calculation unit 14 is stored in the storage unit 16, and through the condition setting unit 12, the input / output I / F 10 is set to set test conditions such as the type of the indenter 4 and its elastic modulus. The user is prompted to input through the above, and the test conditions are met from the value of the back deformation of the indenter 4 analyzed by the surface analysis unit 13 and the result of the finite element analysis performed in advance stored in the storage unit 16 Data is selected, expanded on a main storage device such as a computer memory, and executed.

FIG. 3 is an example of a basic configuration of a micro-indentation test apparatus according to an embodiment of the present invention provided with a scanning probe microscope that functions as an apparatus for measuring a change in back surface displacement of an indenter.

Next, a mechanism for precisely measuring the back surface displacement of the indenter under test by the micro indentation testing device will be described.

<Structure of micro indentation test device>
FIG. 3 is an example of a functional configuration of a micro indentation test apparatus according to an embodiment of the present invention. In the following, the configuration example of the indentation system shown in FIG. 2 will also be described with appropriate reference.

Here, as an example of the probe microscope 6, an “optical lever” atomic force microscope is depicted, but the present invention is not limited to this, and various modifications are possible.

The surface observation probe 20 is attached to the XYZ scanning mechanism 21 by a cantilever method, and scans the selected area at high speed to collect surface information. The surface information is position information of the back surface of the surface observation probe 20. The surface information is detected by the laser 22 and the split photodiode 23, and is transferred to the surface analysis unit 13 of the information processing device 3 through the current / voltage conversion circuit 24 and the feedback circuit 25. Further, the position information is analyzed as a three-dimensional surface displacement distribution by an analysis program. Then, the back surface deformation amount or displacement distribution that has been digitized is written to the storage device 16 of the information processing device 3.

The axis of the surface observation probe 20 of the probe microscope 6 (scanning probe microscope) controlled by the surface analysis device 9 is arranged to coincide with the axis connecting the indenter 4 and the contact portion of the test body 5. By so doing, it becomes possible to observe the behavior of the back surface of the indenter 4 being deformed by the probe microscope 6 when the indenter 4 is brought into contact with the test body 5.

That is, according to the micro-indentation test apparatus according to the present embodiment, the tip of the indenter 4 is brought into contact with the surface of the test body 5 to a predetermined indentation depth, and the contact center point is used as a reference and opposite to the test body side of the indenter 4 It is difficult in the method using the conventional optical microscope by measuring the displacement distribution as a function of the displacement of the point dropped vertically from the contact center point with respect to the plane of the surface or the distance from the point by the probe microscope 6 Mechanical properties in the nano range can be evaluated.

The surface position of the test body 5 can be made to approach the tip of the indenter 4 by moving the test body support 27 on which the test body 5 is mounted up and down by the coarse movement mechanism 26. Furthermore, the absolute value of the air gap which is the proximity amount can be measured using the displacement measurement device 7 installed in the coarse movement mechanism 26, transferred to the information processing device 3, and displayed. However, it is necessary to carry out a calibration in which the contact point where the indenter 4 is in contact with the test body 5 is set as the zero point of the air gap in advance. Although the method of detecting this contact can be selected from various methods, for example, an event in which the probe microscope 6 captures the displacement of the back surface of the indenter 4 can be used to detect a contact point (the details will be described in the embodiment). Described in section).

The tip of the indenter 4 is brought into contact with the surface of the test body 5 by finely moving the precision positioning device 8. The displacement measuring device 7 and the precision positioning device 8 precisely adjust the value to a predetermined numerical value set by the condition setting unit 12 of the information processing device 3. By this, the press-fit amount (push-in amount) of the indentation test is determined. In order to hold the press-fit amount constant, the position control unit 15 of the information processing device 3 makes the precision positioning device 8 to have a predetermined numerical value set by the condition setting unit 12 based on the measurement value of the displacement measuring device 7 It has a closed loop function to perform feedback control.

The larger the load value generated by the contact, that is, the larger the pressing amount to the surface of the test body 5, the larger the back surface deformation amount of the indenter 4. Therefore, in order to quantitatively measure the back surface deformation of the indenter 4 accurately, the amount of movement of the precision positioning device 8 is increased. At this time, as the scanning mechanism 21 of the probe microscope 6 moves in conjunction with the movement of pressing the indenter 4 into the surface of the test body 5, the displacement amount of the indenter 4 pushing into the surface of the test body 5 is cancelled. , Only deformation of the back of the indenter is measured. The surface observation probe 20 can always observe the back surface of the indenter 4 by the device arrangement in which the indenter 4 and the surface observation probe 20 are relatively at the same position.

Next, the present invention will be described in detail by way of examples.

With regard to the problem of the present invention, the finite element method was selected as the numerical analysis and the problem was analytically verified. Finite element analysis is selected here as a large-scale finite element analysis program (FrontISTR) as a solver that has already been validated for contact problems involving elasto-plastic deformation. The contact analysis was performed by combining nonlinear static analysis and step analysis.

Prior to calculation by the finite element method, model preparation and mesh formation were performed using general purpose computer application software (CAD) as preprocessing. The number of elements here is about 60,000 to about 100,000. Furthermore, as a post-process of finite element analysis, calculation results are illustrated using general purpose computer application software for visualization.
Example 1

Details of analysis contents using the micro indentation test apparatus having the spherical indenter shown in FIG. 1 (A) will be described.

The shape of the spherical surface of the spherical indenter is the surface of a solid sphere of diameter D and radius r. The height H of the spherical indenter is 1⁄4 of the diameter D (hereinafter also referred to as “1⁄4 D spherical indenter”). The Young's modulus Ei of the spherical indenter was fixed at 1000 MPa, and the Young's modulus Es of the test sample was changed to 250, 500, 750, 1000 and 1500 MPa. In addition, the Poisson's ratio of the spherical indenter to the test sample was 0.0.

In the analysis by the finite element method, the absolute value of the dimension has no meaning, but here, the diameter D is 10 microns, and the height H of the spherical indenter is 2.5 microns. In addition, the test body was a solid rectangular parallelepiped in which the vertical B and the horizontal W of the surface in contact with the indenter are square. Here, vertical B and horizontal W were 10 microns, and height h was 5 microns. Moreover, as a setting value of the pressing amount of the spherical indenter into the test body, it was changed to 50, 100, 200, 300, 400, 500 nm.

Fig. 4 shows the results of finite element analysis focusing on the displacement distribution on the back surface of the spherical indenter when increasing the amount of indentation to the test object under the condition that the Young's modulus has the same value of 1000 MPa for both the spherical indenter and the test object. FIG. 7 is a diagram showing the distance L from the contact center as the horizontal axis.

Since this test is a test in which the indenter tip is pressed into the surface of the test body, the distance between the indenter and the test body becomes narrow, and the Z-axis displacement amount that indicates the displacement of the back surface of the spherical indenter takes a negative sign. From this, when looking at the analysis results of the displacement distribution under each condition, a shift ΔZ from the set value occurs at the coordinates of the back surface of the analyzed indenter, that is, the back surface is raised by the shift ΔZ Further, it can be seen that the maximum value of the deviation ΔZ is the back surface (X = 0) of the back of the contact point. The figure on the right of FIG. 4 is normalized and displayed by the setting value of the amount of indentations to a test body from the result shown by the figure on the left.

The displacement of the back surface of the spherical indenter increases with the increase of the amount of indentation into the test body, and there is a 37.6 nm ridge on the back surface of the contact point for the indentation amount of 500 nm. The vertical resolution of a typical scanning probe microscope is sub-nanometers or less, so it can be seen that the displacement distribution can be measured with high accuracy.

FIG. 5 shows that the Young's modulus Es of the test body is variously changed (500, 750, 1000, 1500 MPa) under the condition that the Young's modulus Ei of the spherical indenter is fixed at 1000 MPa, and further, the indentation of the indenter tip to the surface of the test body In the example (50, 100, 200, 300, 400, 500 nm) where the amount was changed variously, it is the result of the finite element analysis paying attention to the displacement distribution of the back of the spherical indenter, and the distance L from the contact center It is the figure shown as a horizontal axis.

In FIG. 6, the Young's modulus Es of the test sample was variously changed under the condition that the Young's modulus Ei of the spherical indenter was fixed at 1000 MPa and the amount of indentation (-Z ₀ ) of the indenter tip to the surface of the test sample was 500 nm. Example (250, 500, 750, 1000, 1500MPa), that is, the elastic modulus ratio between the test body and the spherical indenter is variously changed from 0.25 to 1.5, and attention is paid to the displacement distribution of the back surface of the spherical indenter. It is the result of element analysis, and it is the figure which showed distance L from the contact center as a horizontal axis.

The figure on the right of FIG. 6 shows the results shown in the figure on the left, re-normalized by the set value of the press-fit amount to the test body. As the Young's modulus Es of the test body increases, the maximum displacement of the back surface of the spherical indenter increases. The bulge seen on the back of the spherical indenter was 46.7 nm when the Young's modulus of the test sample was high (Es = 1500 MPa). On the other hand, if the ridge seen at the back of the spherical indenter is the smallest (Es = 250 MPa), there is a ridge of 24.4 nm at the back of the contact point of the specimen, so displacement using a common scanning probe microscope It can be seen that the distribution can be measured with high accuracy.

FIG. 7 is a calibration curve for evaluating the Young's modulus of a test sample of an unknown sample from the results of a micro-indentation test using a spherical indenter having a known Young's modulus. As described above, the bumps seen on the back of the spherical indenter are uniformly determined by the amount of indentation into the test body and the Young's modulus ratio of the test body to the indenter. Therefore, as exemplified by the two arrows shown in FIG. 7, from the maximum value of the change in displacement of the back surface of the spherical indenter measured at the amount of indentation (-Z ₀ ) to the predetermined test object, the test object and the indenter The Young's modulus ratio Es / Ei of is calculated. Furthermore, the elastic modulus Es of the unknown sample can be evaluated by integrating the elastic modulus Ei of the indenter which is known with respect to the value.
Example 2

Details of analysis contents using the micro indentation test apparatus having a conical indenter shown in FIG. 1 (B) will be described.

The shape of the conical indenter is a solid cone with a surface inclination angle β of 19.7 degrees. This angle is a value determined from an equivalent cone having the same volume when the indenter pressing amount is the same as that of a general Berkovich type triangular pyramid indenter. From this surface inclination angle (β = 19.7) and the diameter of the circle on the back of the conical indenter (D = 10.0 microns), the height H of the back of the indenter was 1.79 microns. In this example, the Young's modulus Ei of the conical indenter was fixed at 1000 MPa, and the Young's modulus Es of the test sample was changed to 250, 500, 750, 1000, and 1500 MPa. Also, the Poisson's ratio of the conical indenter to the test sample was 0.0.

The test body was a solid rectangular parallelepiped in which the vertical B and the horizontal W of the surface in contact with the indenter were square. Here, vertical B and horizontal W were 10 microns, and height h was 5 microns. Moreover, as a setting value of the pressing amount to the test body of a spherical indenter, it was changed with 50, 100, 200, 300, 360, 450, 500 nm.

FIG. 8 shows the results of finite element analysis focusing on the displacement distribution on the back surface of the conical indenter when increasing the amount of indentation to the specimen under the condition that the Young's modulus has the same value of 1000 MPa for both the conical indenter and the specimen. FIG. 7 is a diagram showing the distance L from the contact center as the horizontal axis.

Since this test is a test in which the indenter tip is pressed into the surface of the test body, the distance between the indenter and the test body is narrowed, and the Z-axis displacement amount indicating the displacement of the back surface of the conical indenter has a minus sign. From this, when looking at the analysis results of the displacement distribution under each condition, a shift ΔZ from the set value occurs at the coordinates of the back surface of the analyzed indenter, that is, the shift ΔZ Further, it can be seen that the maximum value of the deviation ΔZ is the back surface (X = 0) of the back of the contact point. The figure on the right of FIG. 8 shows the results shown in the figure on the left normalized and re-displayed with the set value of the press-fit amount to the test body.

The displacement of the back of the conical indenter increases with the increase of the amount of indentation into the test body, and there is a 35.9 nm ridge on the back of the contact point for the indentation amount of 500 nm. The vertical resolution of a typical scanning probe microscope is sub-nanometers or less, so it can be seen that the displacement distribution can be measured with high accuracy.

FIG. 9 shows that the Young's modulus Es of the test body is variously changed (500, 750, 1000, 1500 MPa) under the condition that the Young's modulus Ei of the conical indenter is fixed at 1000 MPa, and further, the indentation of the indenter tip to the test body surface In the example (50, 100, 200, 300, 360, 450, 500 nm) where the amount was changed variously, it is the result of the finite element analysis paying attention to the displacement distribution on the back of the conical indenter, and the distance from the contact center It is the figure which showed L as a horizontal axis.

In FIG. 10, the Young's modulus Es of the test sample was variously changed under the condition that the Young's modulus Ei of the conical indenter was fixed at 1000 MPa and the amount of indentation (-Z ₀ ) of the indenter tip into the surface of the test sample was 500 nm. Example (250, 500, 750, 1000, 1500MPa), that is, changing the elastic modulus ratio of the test body to the conical indenter from 0.25 to 1.5 and focusing on the displacement distribution on the back of the conical indenter It is the result of element analysis, and it is the figure which showed distance L from the contact center as a horizontal axis.

The drawing on the right of FIG. 10 shows the results shown in the drawing on the left, renormalized by the set value of the press-fit amount to the test body and displayed again. As the Young's modulus Es of the test body increases, the maximum displacement of the back surface of the spherical indenter increases. The bulge seen on the back of the spherical indenter was 40.9 nm when the Young's modulus of the test sample was high (Es = 1500 MPa). On the other hand, if the ridge seen at the back of the spherical indenter is the smallest (Es = 250 MPa), there is a ridge of 13.7 nm at the back of the contact point of the specimen, so displacement using a common scanning probe microscope It can be seen that the distribution can be measured with high accuracy.

FIG. 11 is a calibration curve for evaluating the Young's modulus of a test sample of an unknown sample from the results of a microscopic indentation test using a conical indenter having a known Young's modulus. As described above, the bumps seen on the back of the conical indenter are uniformly determined by the amount of indentation into the test body and the Young's modulus ratio of the test body to the indenter. Therefore, as the two arrows illustrate that shown in the figure 11, from the maximum value of the pressing amount (-Z ₀₎ measured displacement change of the conical indenter back in to a given specimen, test specimen and the indenter The Young's modulus ratio Es / Ei of is calculated. Furthermore, the elastic modulus Es of the unknown sample can be evaluated by integrating the elastic modulus Ei of the indenter which is known with respect to the value.
Example 3

Details of the experiment contents using the micro indentation test apparatus having the spherical indenter shown in FIG. 1 (A) will be described.

In this embodiment, a laser beam is selected as the surface observation probe 20 shown in FIG. 1A, and a reflection type CCD laser displacement meter (manufactured by KEYENCE, LK-G35, laser wavelength: 650 nm) and an automatic drive mechanism (Sigma) A scanning probe microscope was constructed by using an optical scanner, SGSP20-85). The repetition accuracy of displacement measurement in the Z-axis direction is 10 nm.

The shape of the spherical surface of the spherical indenter is the surface of a solid sphere having a diameter D of 44 mm, and the height H of the spherical indenter is 16 mm. The material of the spherical indenter was polyurethane, and the Young's modulus Ei of the spherical indenter was fixed at 230 kPa. The material of the test body was polyurethane and an aluminum alloy, and two types of polyurethane different in Young's modulus Es from 100 and 510 kPa were selected. The Young's modulus Es of the aluminum alloy is 70 GPa.

The amount of pressing of the spherical indenter into the test body was a constant load control method by dead load. The weight of the spherical indenter itself is 13.44 gf (131.8 mN), and the weight of the weight added thereto (hereinafter also referred to as additional weight) is 0 gf (no additional weight, 0 mN), 5.28 gf (51.8 mN) Or it was set to 10.48 gf (102.8 mN). Accordingly, the total load applied to the surface of the test body is 13.44 gf (131.8 mN), 18.72 gf (183.6 mN), 23.92 gf (234.6 mN).
In addition, it is understood that the load force described in connection with the present embodiment is converted according to “1 kgf = 9.80665N”.

In FIG. 12, polyurethane (Young's modulus Es: 100 kPa) is selected as a representative of a low elastic body, and an aluminum alloy (Young's modulus Es: 70 GPa) is selected as a representative of a high elastic body. It is illustrated. In the experiment, when only the spherical indenter was placed on the test body (when no additional weight was loaded), the additional weight was loaded sequentially (5.28 gf, 10 in the figure), using the reference (hereinafter also referred to as “Reference”). The back surface displacement distribution of the spherical indenter was measured.

FIG. 13 is a back surface displacement distribution of a spherical indenter of two types of polyurethane having a Young's modulus Es of 100 or 510 kPa as a test body and an aluminum alloy having a Young's modulus Es of 70 GPa. In this figure, since the back surface displacement distribution of the spherical indenter is represented by the value (-Z / Z ₀ ) normalized by the indentation amount (-Z ₀ ) of the spherical indenter determined by the predetermined load, the back surface of the spherical indenter is The ridges of the are illustrated as valleys. It can be seen that as the load on the test body is increased, the valleys in each figure are deeper, ie the bumps become larger. In addition, it can be seen that the maximum value of the bulge is the back surface (X = 0) of the back of the contact point between the indenter and the test body. Furthermore, focusing on the load-load dependence of the ridge, that is, the relationship between the ridge change from the Reference (valley depth change) and the additional weight, the higher the Young's modulus of the test body, the more the ridge change ΔZ for the same additional weight It can be seen that 'x = 0 is large.

FIG. 14 is a diagram in which the ratio Es / Ei of the Young's modulus Ei of the spherical indenter to the Young's modulus Es of the test body is plotted on the abscissa, with the elevation change amount ΔZ'x = 0 in FIG. 13 taken on the ordinate. This figure is a calibration curve for evaluating the Young's modulus of the test sample of the unknown sample from the result of the micro indentation test using a spherical indenter having a known Young's modulus. As exemplified by the two arrows shown in FIG. 14, the Young's modulus ratio Es / Ei between the test body and the indenter from the amount of change in elevation of the indenter back surface displacement ΔZ'x = 0 measured with a predetermined additional weight. Is required. Furthermore, the elastic modulus Es of the unknown sample can be evaluated by integrating the elastic modulus Ei of the indenter which is known with respect to the value.

While the preferred embodiments of the present invention have been described in detail by way of example with reference to the accompanying drawings, the present invention is not limited to such specific embodiments, but rather is described in the claims. Within the scope of the gist of the present invention, various modifications and changes are possible.

1 Micro Indentation Tester 2 Measurement Control Device 3 Information Processing Device (Electronic Computer)
4 indenter 5 test body 6 probe microscope 7 displacement measuring device 8 precise positioning device 9 surface analysis device 10 input / output I / F
11 CPU
12 condition setting unit 13 surface analysis unit 14 characteristic value calculation unit 15 position control unit 16 storage device 20 surface observation probe 21 XYZ scanning mechanism 22 laser 23 split photodiode 24 current-voltage conversion circuit 25 feedback circuit 26 coarse movement mechanism 27 test body Holding stand

Claims

The mechanical property test method which evaluates the mechanical property of a measurement sample by measuring the shape change of the opposite side to the test body side of an indenter in the state where the indenter is pressed into contact with the surface of the test sample of the measurement sample.
Using a micro-indentation tester comprising the indenter, the test body, and a scanning probe microscope equipped with a surface observation probe,
The scanning probe microscope measures the shape change of the surface of the indenter opposite to the side of the test body while the tip of the indenter is pressed into contact with the surface of the test body and brought into contact with the tip of the indenter. Mechanical property test method described.
By using a mechanical characteristic measuring apparatus having the above-mentioned micro indentation test machine, a measurement control apparatus, and an information processing apparatus,
By the measurement control device,
Measuring the positional relationship between the surface of the test body and the tip of the indenter;
Position control is performed so that pressing of the test body and the indenter has a predetermined press-fit depth,
Controlling the scanning probe microscope for observing the back surface of the indenter;
The information processing apparatus
Receiving surface information of the back surface of the surface observation probe from the micro-indentation tester, and analyzing it as surface deformation or surface displacement distribution;
Store the analyzed surface deformation amount or surface displacement distribution in the storage device,
The mechanical properties of the test body of the unknown sample are evaluated from the results of the micro indentation test by the micro indentation test using the indenter having the known mechanical properties stored in the storage device. The mechanical property test method of claim 2.
Based on the contact center point of the indenter with the surface of the test body, the displacement of a point dropped vertically from the contact center point with respect to the surface of the indenter opposite to the test body side or the distance from that point is used as a function. The dynamic characteristic test method according to any one of claims 1 to 3, wherein the displacement distribution is measured.
An indenter that is pressed into the test sample of the measurement sample,
And a measuring means for measuring the shape change of the surface of the indenter opposite to the test body side.
The micro indentation tester is equipped with a micro indentation tester.
The indenter;
Said test body,
A scanning probe microscope equipped with a surface observation probe that measures the change in shape of the surface of the indenter opposite to the side of the test body in a state where the tip of the indenter is pressed into contact with the surface of the test body Have
The mechanical property measuring device according to claim 5, wherein the measuring means includes the scanning probe microscope.
The microscope indentation test apparatus, a measurement control apparatus, and an information processing apparatus
The measurement control device
A displacement measuring device for measuring the positional relationship between the surface of the test body and the tip of the indenter;
A precision positioning device that performs position control such that the contact between the test body and the indenter has a predetermined press-fit depth;
It has a surface analysis device for controlling the scanning probe microscope for observing the back surface of the indenter,
The information processing apparatus is
A surface analysis unit that receives surface information of the back surface of the surface observation probe from the micro-indentation tester and analyzes it as a three-dimensional surface deformation amount or surface displacement distribution;
A storage device for storing the surface deformation amount or surface displacement distribution analyzed by the surface analysis unit;
The mechanical characteristics of the test body of the unknown sample are evaluated from the results of the micro indentation test by the micro indentation test using the indenter having the known mechanical characteristics stored in the storage device. Mechanical property measuring device as described.
The mechanical characteristic measurement device according to claim 6 or 7, having a vertical double structure in which the indenter and the probe of the surface observation probe are arranged in the longitudinal direction.
The mechanics according to any one of claims 6 to 8, wherein the surface observation probe is attached to the XYZ scanning mechanism of the scanning probe microscope by a cantilever method so as to be interlocked with the XYZ scanning mechanism. Characteristic measurement device.
The scanning probe microscope is based on a contact center point of the indenter with the surface of the test body, and a variation or a point from a point dropped vertically from the contact center point with respect to a surface opposite to the test body side of the indenter. 10. A mechanical property measuring device according to any one of claims 6 to 9, configured to measure a displacement distribution as a function of distance.