JP7046383B2 - Mechanical property test method and measuring device - Google Patents

Description

The present invention relates to a mechanical property test method and a measuring device, and more specifically, to a test method and a measuring device for evaluating the mechanical property of a test piece 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 state of a dent formed by pressing a jig called an indenter against the surface of a test piece of various materials.

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

In general metals, the size of the indentation is the same at the time of maximum load and after unloading because plasticity controls the total deformation behavior. On the other hand, in materials such as elasto-plastic bodies and viscoelastic bodies, in which components other than plastic cannot be ignored in the deformation behavior, the size of the indentation after unloading is larger than that at the time of maximum load because the elasticity recovers during unloading. It is known to decrease.

Therefore, in order to strictly analyze the mechanical properties of an unknown sample, it is necessary to know what kind of depression the sample forms under the condition that the indenter and the surface of the specimen are in contact with each other, that is, in-situ. It is necessary to measure the mechanical stimulus response characteristics.

In addition, it is known that there are two types of dents that occur when a test piece is loaded with an indenter, "subduction type" and "swelling type", paying attention to the difference in the form of surface deformation seen in the peripheral part. Therefore, in order to quantitatively express the dent formed by applying a load to the surface of the test piece, it is necessary to measure not only the depth from the original surface but also the contact area.

There is an instrumented nanoindentation test method that can measure the depth of the depression as a mechanical stimulus response when a load is applied to the surface of the test piece. In this test method, it is assumed that the depressions of all the samples are formed with depressions having a "subduction type" contact depth of a fully elastic body. The current instrumentation nanoindentation technology uses a general-purpose approximation method that estimates the contact area from the relationship between the press-fitting depth and the load, but the biggest weakness is that it is not possible to know the "bulging type" contact area. I'm holding it. The instrumented nanoindentation method, which measures the depth of the depression, cannot calculate the contact area of the "bulging type", so there is a problem in analyzing the elasto-plastic body showing the surface deformation of the "bulging type". be.

There is a microindentation test method that can optically measure the projected contact area of a depression as a mechanical stimulus response when a load is applied to the surface of the test piece. This test method is a method for directly evaluating the mechanical stimulus response characteristics when the indenter is brought into contact with the surface of the test piece on the spot. The microindentation test method can measure the projected contact area for both surface deformation modes regardless of whether the depression is "submerged" or "raised" (for example, Patent Document 1, Patent). 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).

Japanese Unexamined Patent Publication No. 2005-195357 (Patent No. 4317743) Utility Model Registration No. 3182252 JP-A-2015-175666 Japanese Patent Application No. 2016-016555 Japanese Unexamined Patent Publication No. 2017-146294

T. Miyajima and M. Sakai, Optical indentation microscopy-a new family of instrumented indentation testing, Philosophical Magazine, Vol. 86, pp. 5729-5737 (2006) Norio Hagiri, Motoji Sakai, Tatsuya Miyajima "Development of Microscopic Indenter and Application to Indenter Mechanics", Materials, Vol. 56, No. 6, pp. 510-515 (2007) Mototsugu Sakai "Construction of Viscoelastic Indenter Mechanics and Rheology Measurement in the Micro Region", Journal of the Society of Rheology, Japan, Vol. 39, No. 1-2, pp. 7-15 (2011) N. Hakiri, A. Matsuda, and M. Sakai, Instrumented indentation microscope applied to the elastoplastic indentation contact mechanics of coating / substrate composites, Journal of Materials Research, Vol. 24, No. 6, pp. 1950-1959 (2009) Tadashi Mineda, Seiji Miura, Kazuhiko Oka, Tatsuya Miyajima, "Observation of Plastic Deformation Behavior of Mg-Y Single Crystal by In-situ Brinell Indentation", Journal of the Japan Institute of Metals, Vol. 81, No. 4, pp. 196-205 (2017) ) T. Mineta, S. Miura, K. Oka, and T. Miyajima, Plastic deformation behavior of Mg-Y alloy single crystals observed using in situ Brinell indentation, Materials Transactions, Vol. 59, No. 4, pp. 206-211 (2018) )

However, the horizontal resolution of an optical microscope in which visible light is focused on a spot using a lens and the image is observed has a diffraction limit due to the wave motion of light. In addition, it is limited to the submicron region, which is less than half the wavelength of visible light, and it may be difficult to evaluate the mechanical stimulus response characteristics in the nano region using the optical microscope.

The present invention has been made in view of the actual situation of such a 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 a test piece of an unknown sample is the sample. It is an object of the present invention to provide a technique for evaluating the deformation of an indenter reflecting the mechanical properties of the indenter in the nano region without using an image observation type optical microscope that focuses visible light with a lens.

In order to solve the above problems, the present invention provides the following technical means and methods.

[1] A mechanical property test method for evaluating the mechanical properties of a measurement sample by measuring the shape change of the surface of the indenter opposite to the test piece side in a state where the indenter is pushed into contact with the surface of the test piece of the measurement sample. ..
[2] Using a microindentation tester having the indenter, the test piece, and a scanning probe microscope provided with a surface observation probe,
With the scanning probe microscope, the shape change of the surface of the indenter opposite to the test piece side is measured in a state where the tip of the indenter is brought into contact with the surface of the test piece by pushing the indenter. [1] Mechanical property test method.
[3] Using the mechanical characteristic measuring device having the microindentation tester, the measurement control device, and the information processing device,
By the measurement control device
The positional relationship between the surface of the test piece and the tip of the indenter was measured.
The position is controlled so that the indentation between the test piece and the indenter has a predetermined press-fitting depth.
Control the scanning probe microscope to observe the back surface of the indenter,
With the information processing device
The surface information on the back surface of the surface observation probe is received from the microindentation tester and analyzed as the amount of surface deformation or the surface displacement distribution.
The analyzed surface deformation amount or surface displacement distribution is stored in the storage device, and
It is characterized in that the mechanical properties of a test piece of an unknown sample are evaluated from the results of a microindentation test by the microindentation tester using the indenter having known mechanical properties 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 piece, the displacement of the point perpendicularly lowered from the contact center point with respect to the surface of the indenter opposite to the test piece side or the distance from the point. The mechanical property test method according to any one of [1] to [3], which measures the displacement distribution as a function.

[5] An indenter to be pushed into the test piece of the measurement sample,
Measurement of indenter A mechanical property measuring device equipped with a measuring means for measuring a shape change of a surface opposite to the sample side.
[6] A micro-indentation tester is provided, and this micro-indentation tester is equipped with a micro-indentation tester.
With the indenter
With the test piece
A scanning probe microscope equipped with a surface observation probe that measures the shape change of the surface of the indenter opposite to the test piece side in a state where the tip of the indenter is brought into contact with the surface of the test piece by pushing the indenter. Have,
The measuring means is the mechanical property measuring apparatus according to [5], which includes the scanning probe microscope.
[7] The microindentation tester, the measurement control device, and the information processing device are provided.
The measurement control device is
A displacement measuring device that measures the positional relationship between the surface of the test piece and the tip of the indenter,
A precision positioning device that controls the position so that the contact between the test piece and the indenter has a predetermined press-fitting depth.
It has a surface analysis device that controls the scanning probe microscope for observing the back surface of the indenter.
The information processing device is
A surface analysis unit that receives surface information on the back surface of the surface observation probe from the microindentation tester and analyzes it as a three-dimensional surface deformation amount or surface displacement distribution.
It has a storage device that stores the surface deformation amount or surface displacement distribution analyzed by the surface analysis unit.
It is characterized in that the mechanical properties of a test piece of an unknown sample are evaluated from the results of a microindentation test by the microindentation tester using the indenter having known mechanical properties stored in the storage device. [6] Mechanical characteristic measuring device.

[8] The mechanical property measuring apparatus according to claim [6] or [7], which has a vertical double structure in which the indenter and the probe of the surface observation probe are vertically arranged. [9] Any one of [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. Mechanical characteristic measuring device.

[10] The scanning probe microscope is a variation of a point perpendicular to the contact center point of the indenter with respect to the surface opposite to the test piece side of the indenter, or a variation thereof, with reference to the contact center point of the indenter with the surface of the test piece. A mechanical property measuring device according to any one of [6] to [9], which is configured to measure a displacement distribution having a distance from a point as a function.

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

It is a figure explaining an example of the arrangement of the probe which measures the displacement change of the back surface of an indenter in the situation where the tip of an indenter is in contact with the surface of a test body in the microindentation tester which concerns on one Embodiment of this invention. It is a block diagram explaining an example of the basic structure of the indene system including the indene tester which concerns on one Embodiment of this invention. It is a figure explaining an example of the structure of the indene tester which concerns on one Embodiment of this invention. It is a figure explaining an example of the result of finite element analysis about the relationship between the amount of pushing into a test body and the displacement change of the back surface of a spherical indenter about Example 1 using a spherical indenter. It is a figure explaining an example of the result of the finite element analysis about the effect which the elastic modulus of a test piece and the amount of pushing into a test piece have on the displacement change of the back surface of an indenter about Example 1 using a spherical indenter. It is a figure explaining an example of the result of finite element analysis about the relationship between the elastic modulus ratio of a test piece and a spherical indenter, and the displacement change of the back surface of an indenter about Example 1 using a spherical indenter. For Example 1 using a spherical indenter, the elastic modulus ratio between the test piece and the indenter was obtained from the maximum value of the measured displacement change of the back surface of the spherical indenter in the amount of pushing into a predetermined test piece, and the value is known. 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. It is a figure explaining an example of the result of finite element analysis about the relationship between the amount of pushing into a test body and the displacement change of the back surface of an indenter about Example 2 using a conical indenter. It is a figure explaining an example of the result of finite element analysis about the relationship between the elastic modulus ratio of a test body and an indenter, and the displacement change of the back surface of an indenter about Example 2 using a conical indenter. It is a figure explaining an example of the result of the finite element analysis about the effect which the elastic modulus of a test piece and the amount of pushing into a test piece have on the displacement change of the back surface of an indenter about Example 2 using a conical indenter. For Example 2 using a conical indenter, the elastic modulus ratio between the test piece and the indenter was obtained from the maximum value of the measured displacement change of the back surface of the spherical indenter in the amount of pushing into a predetermined test piece, and the value is known. 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. In Example 3 using a spherical indenter, the spherical indenter was made of polyurethane, the test piece was made of polyurethane and an aluminum alloy, and the relationship between the additional weight of the constant load load method on the test piece and the displacement change of the back surface of the spherical indenter was tested. It is a figure explaining the example of the result. In Example 3 using a spherical indenter, the spherical indenter is made of polyurethane, the test piece is made of polyurethane and an aluminum alloy, and the back displacement distribution of the spherical indenter is standardized by the pushing amount of the spherical indenter determined by a predetermined load. It is a figure explaining the example of the result of the experiment, which shows the relationship between the additional weight of the constant load method to the test piece, and the load-load dependence of the valley depth (raising). For Example 3 using a spherical indenter, the elastic modulus ratio between the test piece and the indenter was obtained from the amount of change in the uplift of the indenter backside displacement measured with a predetermined additional weight under a constant load load on the test piece, and the value thereof. It is a figure explaining an example which analyzes the elastic modulus of an unknown sample from the product of the elastic modulus of a known indenter.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a diagram illustrating an indenter portion of a microindentation tester according to an embodiment of the mechanical property measuring device of the present invention. The indentation portion of the indentation test apparatus (microscopic indentation tester) according to the present embodiment is a measuring means for measuring the shape change of the indenter for mechanical test (hereinafter, also referred to as an indenter) 4 and the surface of the indenter opposite to the test piece side. The probe (probe, hereinafter simply referred to as a probe or a surface observation probe) 20 and the probe (probe) 20 are arranged in the vertical direction to form a vertical double probe structure. Here, FIG. 1A exemplifies an indenter having a spherical tip (hereinafter referred to as a spherical indenter), and FIG. 1B exemplifies an indenter having a conical tip (hereinafter referred to as a conical indenter). There is.

In FIG. 1, two Cartesian coordinates are drawn to reflect this dual structure, the coordinate system for the indenter is (Xi, Zi), and the origin ((Xi, Zi) = (0, 0)). ) Is the position where the tip of the indenter 4 and the surface of the test piece 5 come into contact with each other. In the test in which the tip of the indenter 4 is pushed into the surface of the test piece 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 at the position where the tip of the surface observation probe 20 and the back surface of the indenter 4 come into contact with each other. (Strictly speaking, for example, when the measuring means is a scanning tunneling microscope, there is a sub-nanometer-order gap in which the tunnel current flows between the probe tip and the surface of the indenter, and they are not in mechanical contact with each other). In the test in which the tip of the indenter 4 is pushed into the surface of the test body 5, the back surface of the indenter 4 rises so as to be raised, so that Zm is a positive sign.

In FIG. 1, as an example, a spherical indenter (A) having a shape obtained by cutting a solid sphere with radius r at a height H, and a solid conical shape with a surface inclination angle of β and a height of H. A conical indenter (B) is drawn.
The tip of the indenter has a shape with one protrusion, for example, a spherical surface, a triangular pyramid, a quadrangular pyramid, or a cone. The structure of the indenter 4 shown in FIG. 1 is solid, but it may be a shell. However, its back surface 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 minimum tip radius of curvature on the order of submicron to nanometer. Can be given. Further, according to the micromachining technique, it is possible to simultaneously create a probe 20 of a measuring means (for example, a scanning probe microscope) having a beam structure (cantilever) and an indenter 4 for contact.

The measuring means is a device used for observing 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 be constantly monitored. As a result, the moment when the indenter 4 comes into contact with the test piece 5 can be regarded as a deformation of the back surface of the indenter 4. Further, 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 includes a 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, etc.).

That is, according to the microscopic indentation test device which is an embodiment of the mechanical property measuring device of the present invention, the tip of the indenter 4 is brought into contact with the surface of the test piece 5 to a predetermined pushing depth, and the contact center point is used as a reference. A conventional optical microscope can be obtained by measuring the displacement of a point perpendicularly lowered from the contact center point with respect to the surface of the indenter 4 opposite to the test piece side or the displacement distribution using the distance from that point as a function. It is possible to evaluate the mechanical properties in the nano region, which was difficult with the method used. Various general-purpose scanning probe microscopes capable of measuring with an accuracy of sub-nanometer or less can be used, and the displacement distribution can be selected from, for example, a scanning tunneling microscope, an atomic force microscope, a scanning near-field optical microscope, and the like. .. The horizontal resolution of a general scanning probe microscope is nanometer or less, and the vertical resolution is sub-nanometer or less, enabling observation in the nano region with high measurement accuracy, which was not possible with an optical microscope.

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

The indentation system shown in FIG. 2 is composed of a microindentation tester 1, a measurement control device 2, and an information processing device (electronic computer) 3.

The microindentation tester 1 includes a scanning probe microscope 6 (hereinafter, also referred to as a probe microscope) for observing the indenter 4, the test piece 5, and the back surface of the indenter 4 whose tip is brought into contact with the surface of the test piece 5. Consists of.

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

The information processing device 3 is a computer (electronic computer), and is 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, and a position control unit. It is composed of 15 and a storage device 16. Each element of the information processing apparatus 3 is connected by a bus.

The analysis program used in 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 a test condition, and further. , Is deployed and executed on a main storage device such as computer memory. Similarly, the position control program used in the position control unit 15 of the information processing device 3 is stored in the storage device 16 and is input to the user through the input / output I / F 10 so as to set the contact displacement amount which is a test condition. Furthermore, it is expanded on the main storage device such as the memory of the computer and executed.

The calculation program used in the characteristic value calculation unit 14 is stored in the storage device 16, and the input / output I / F10 is set so as to set test conditions such as the type of the indenter 4 and its elastic coefficient through the condition setting unit 12. The test conditions are met from the value of the back surface 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 device 16. Data is selected and expanded on a main storage device such as computer memory for execution.

FIG. 3 is an example of a basic configuration of a microindentation test device according to an embodiment of the present invention, which includes a scanning probe microscope that functions as a device for measuring changes in the back displacement of an indenter.

Next, a mechanism for accurately measuring the backside displacement of the indenter during the test using the microindentation test device will be described.

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

Here, as an example of the probe microscope 6, an atomic force microscope of the "light lever" type is drawn, but the present invention is not limited to this, and various changes can be made.

The surface observation probe 20 is attached to the XYZ scanning mechanism 21 by a cantilever method, and scans within a selected range at high speed to collect surface information. The surface information is the position information on the back surface of the surface observation probe 20. The surface information is detected by the laser 22 and the divided photodiode 23, and is transferred to the surface analysis unit 13 of the information processing apparatus 3 via 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 the analysis program. Then, the digitized back deformation amount or displacement distribution is written in 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 apparatus 9 is arranged so as to coincide with the axis connecting the contact portion between the indenter 4 and the test piece 5. By doing so, it becomes possible to observe the behavior of the back surface of the indenter 4 being deformed when the indenter 4 is brought into contact with the test body 5 with the probe microscope 6.

That is, according to the microscopic indentation test apparatus according to the present embodiment, the tip of the indenter 4 is brought into contact with the surface of the test piece 5 to a predetermined pushing depth, and the contact center point is used as a reference, which is opposite to the test piece side of the indenter 4. By measuring the displacement of the point perpendicular to the surface of the contact with the probe microscope 6 or the displacement distribution using the distance from the point as a function, it was difficult to use the conventional optical microscope method. It is possible to evaluate the mechanical properties in the nano region.

The surface position of the test body 5 can be brought closer to the tip of the indenter 4 by moving the test body holding table 27 on which the test body 5 is placed up and down by the coarse movement mechanism 26. Further, the absolute value of the void, which is the proximity amount, can be measured by using the displacement measuring device 7 installed in the coarse motion mechanism 26, transferred to the information processing device 3, and displayed. However, it is necessary to perform calibration in advance so that the contact point where the indenter 4 comes into contact with the test piece 5 is the zero point of the void. The method for 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 for detecting the contact point (details are in Examples). Described in the section).

The tip of the indenter 4 is brought into contact with the surface of the test piece 5 by finely moving the precision positioning device 8. It is precisely adjusted by the displacement measuring device 7 and the precision positioning device 8 so as to have a predetermined value set by the condition setting unit 12 of the information processing device 3. As a result, the press-fitting amount (pushing amount) of the indentation test is determined. In order to keep the press-fitting amount constant, the position control unit 15 of the information processing device 3 has the precision positioning device 8 so as to have a predetermined value set by the condition setting unit 12 based on the measured value of the displacement measuring device 7. It has a closed loop function to apply feedback control.

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

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

Regarding the problem of the present invention, the finite element method was selected as the numerical analysis and the problem was verified analytically. For the finite element analysis, the large-scale finite element method analysis program (FrontISTR) was selected here as a solver that has already been confirmed to be effective for contact problems including elasto-plastic deformation. Contact analysis was performed by combining non-linear static analysis with step analysis.

Prior to the calculation by the finite element method, model creation and mesh creation 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-processing of finite element analysis, the calculation results were illustrated using general-purpose computer application software for visualization.
<Example 1>

The details of the analysis contents using the microindentation test apparatus having the spherical indentation shown in FIG. 1 (A) are described.

The spherical shape of the spherical indenter is the surface of a solid sphere with a diameter of D and a radius of r. The height H of the spherical indenter is 1/4 of the diameter D (hereinafter, also referred to as 1/4D 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 piece was changed to 250, 500, 750, 1000, 1500 MPa. The Poisson's ratio between the spherical indenter and the test piece was 0.0.

In the analysis by the finite element method, the absolute value of the dimension is meaningless, but here, the diameter D is 10 microns and the height H of the spherical indenter is 2.5 microns. The test piece was a solid rectangular parallelepiped with square vertical B and horizontal W on the surface in contact with the indenter. Here, the vertical B and the horizontal W are 10 microns, and the height h is 5 microns. Further, the set value of the press-fitting amount of the spherical indenter into the test piece 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 the amount of pushing into the test piece is increased under the condition that the Young's modulus is the same value of 1000 MPa for both the spherical indenter and the test piece. It is a figure showing the distance L from the contact center as the horizontal axis.

Since the test is to push the tip of the indenter into the surface of the test piece, the distance between the indenter and the test piece becomes narrow, and the Z-axis displacement amount, which indicates the displacement of the back surface of the spherical indenter, has a negative sign. From this, looking at the analysis results of the displacement distribution under each condition, the coordinates of the analyzed indenter back surface have a deviation ΔZ from the set value, that is, the deviation ΔZ causes the back surface to rise. Furthermore, it can be seen that the maximum value of the displacement ΔZ is the back surface (X = 0) directly behind the contact point. The figure on the right of FIG. 4 is a standardized display based on the set value of the press-fitting amount into the test piece from the result shown in the figure on the left.

The displacement of the back surface of the spherical indenter increases as the amount of pushing into the test piece increases, and there is a ridge of 37.6 nm on the back surface of the contact point with respect to the press-fitting amount of 500 nm. Since the vertical resolution of a general scanning probe microscope is sub-nanometer or less, it can be seen that the displacement distribution can be measured with high accuracy.

In FIG. 5, under the condition that the Young's modulus Ei of the spherical indenter is fixed at 1000 MPa, the Young's modulus Es of the test piece is variously changed (500, 750, 1000, 1500 MPa), and the tip of the indenter is press-fitted into the surface of the test piece. It is the result of finite element analysis focusing on the displacement distribution of the back surface of the spherical indenter in the example (50, 100, 200, 300, 400, 500 nm) in which the amount is variously changed, and the distance L from the contact center is calculated. It is a figure shown as a horizontal axis.

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

The figure on the right of FIG. 6 is a redisplay of the result shown in the figure on the left, standardized by the set value of the press-fitting amount to the test piece. As the Young's modulus Es of the specimen increases, the maximum displacement of the back surface of the spherical indenter increases. The ridge seen on the dorsal surface of the spherical indenter was 46.7 nm when the Young's modulus of the specimen was high (Es = 1500 MPa). On the other hand, if the ridge seen on the back of the spherical indenter is the smallest (Es = 250 MPa), there is a ridge of 24.4 nm on the back of the contact point of the specimen, so it is displaced using a general 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 piece of an unknown sample from the result of a microindentation test using a spherical indenter having a known Young's modulus. As mentioned above, the ridge seen on the back surface of the spherical indenter is uniformly determined by the amount of pushing into the test piece and the Young's modulus ratio between the test piece and the indenter. Therefore, as illustrated by the two arrows shown in FIG. 7, the test piece and the indenter are obtained from the maximum value of the displacement change of the back surface of the spherical indenter measured at the pushing amount (-Z ₀ ) into the predetermined test piece. Young's modulus ratio Es / Ei with. Further, the elastic modulus Es of the unknown sample can be evaluated by integrating the known elastic modulus Ei of the indenter with respect to the value.
<Example 2>

The details of the analysis contents using the microindentation test apparatus having the conical indenter shown in FIG. 1 (B) are described.

The shape of the cone indenter is a solid cone with a plane inclination angle β of 19.7 degrees. This angle is a value determined from an equivalent cone having the same volume when the indenter press-fit amount is the same as that of a general Berkovich-type triangular pyramid indenter. From this plane inclination angle (β = 19.7) and the diameter of the circle on the back surface of the conical indenter (D = 10.0 microns), the height H of the back surface 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 piece was changed to 250, 500, 750, 1000, 1500 MPa. The Poisson's ratio between the conical indenter and the test piece was 0.0.

The test piece was a solid rectangular parallelepiped with square vertical B and horizontal W on the surface in contact with the indenter. Here, the vertical B and the horizontal W are 10 microns, and the height h is 5 microns. Further, the set value of the press-fitting amount of the spherical indenter into the test piece was changed to 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 the amount of pushing into the test piece is increased under the condition that the Young's modulus is the same value of 1000 MPa for both the conical indenter and the test piece. It is a figure showing the distance L from the contact center as the horizontal axis.

Since the test is to push the tip of the indenter into the surface of the test piece, the distance between the indenter and the test piece becomes narrow, and the Z-axis displacement amount, which indicates the displacement of the back surface of the conical indenter, has a negative sign. From this, looking at the analysis results of the displacement distribution under each condition, the coordinates of the analyzed indenter back surface have a deviation ΔZ from the set value, that is, the deviation ΔZ has a raised back surface. Furthermore, it can be seen that the maximum value of the displacement ΔZ is the back surface (X = 0) directly behind the contact point. The figure on the right of FIG. 8 is a standardized and redisplayed with the set value of the press-fitting amount into the test piece from the result shown in the figure on the left.

The displacement of the back surface of the conical indenter increases as the amount of indentation into the test piece increases, and there is a ridge of 35.9 nm on the back surface of the contact point with respect to the press-fitting amount of 500 nm. Since the vertical resolution of a general scanning probe microscope is sub-nanometer or less, it can be seen that the displacement distribution can be measured with high accuracy.

In FIG. 9, under the condition that the Young's modulus Ei of the conical indenter is fixed at 1000 MPa, the Young's modulus Es of the test piece is variously changed (500, 750, 1000, 1500 MPa), and the tip of the indenter is press-fitted into the surface of the test piece. This is the result of finite element analysis focusing on the displacement distribution of the back surface of the conical indenter in the examples (50, 100, 200, 300, 360, 450, 500 nm) in which the amount was varied, and the distance from the contact center. It is the figure which showed L as the horizontal axis.

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

The figure on the right of FIG. 10 is a redisplay of the result shown in the figure on the left, standardized by the set value of the press-fitting amount into the test piece. As the Young's modulus Es of the specimen increases, the maximum displacement of the back surface of the spherical indenter increases. The ridge seen on the dorsal surface of the spherical indenter was 40.9 nm when the Young's modulus of the specimen was high (Es = 1500 MPa). On the other hand, if the ridge seen on the back of the spherical indenter is the smallest (Es = 250 MPa), there is a ridge of 13.7 nm on the back of the contact point of the specimen, so it is displaced using a general 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 piece of an unknown sample from the result of a microindentation test using a conical indenter having a known Young's modulus. As mentioned above, the ridge seen on the back of the conical indenter is uniformly determined by the amount of indentation into the test piece and the Young's modulus ratio between the test piece and the indenter. Therefore, as illustrated by the two arrows shown in FIG. 11, the test piece and the indenter are taken from the maximum value of the displacement change of the back surface of the conical indenter measured at the pushing amount (-Z ₀ ) into the predetermined test piece. Young's modulus ratio Es / Ei with. Further, the elastic modulus Es of the unknown sample can be evaluated by integrating the known elastic modulus Ei of the indenter with respect to the value.
<Example 3>

The details of the experiment contents using the microindentation test apparatus having the spherical indentation shown in FIG. 1 (A) are described.

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

The spherical shape of the spherical indenter is the surface of a solid sphere with 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 piece was polyurethane and an aluminum alloy, and two types of polyurethane having a Young's modulus Es of 100 and 510 kPa were selected. The Young's modulus Es of the aluminum alloy is 70 GPa.

The amount of the spherical indenter press-fitted into the test piece was a constant load control method based on dead weight. The weight of the spherical indenter itself is 13.44 gf (131.8 mN), and the weight of the weight added to it (hereinafter, also referred to as an additional weight) is 0 gf (no additional weight, 0 mN), 5.28 gf (51.8 mN). Alternatively, it was set to 10.48 gf (102.8 mN). Therefore, the total load applied to the surface of the test piece is 13.44 gf (131.8 mN), 18.72 gf (183.6 mN), and 23.92 gf (234.6 mN).
It is understood that the load force described for this 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, and they are overlapped for comparison. It is illustrated. In the experiment, the case where only the spherical indenter is mounted on the test piece (when no additional weight is mounted) is used as a reference (hereinafter, also referred to as Reference), and the additional weight is sequentially mounted (5.28 gf, 10 in the figure). The backside displacement distribution of the spherical indenter at .48 gf) was measured.

FIG. 13 shows the back displacement distribution of a spherical indenter of two types of polyurethane having a Young's modulus Es of 100 or 510 kPa and an aluminum alloy having a Young's modulus Es of 70 GPa as a test piece. In this figure, the backside displacement distribution of the spherical indenter is displayed as a value (-Z / Z ₀ ) normalized by the indentation amount (-Z ₀ ) of the spherical indenter determined by a predetermined load, so that the back surface of the spherical indenter is displayed. Uplift is illustrated as a valley. It can be seen that when the load applied to the test piece is increased, the valleys in each figure become deeper, that is, the ridges become larger. Further, it can be seen that the maximum value of the ridge is the back surface (X = 0) directly behind the contact point between the indenter and the test piece. Furthermore, focusing on the load-load dependence of the uplift, that is, the relationship between the uplift change (change in valley depth) from Reference and the additional weight, the higher the Young's modulus of the test piece, the greater the uplift change amount ΔZ with respect to the same additional weight. It turns out that'x = 0 is large.

FIG. 14 is a diagram in which the amount of change in uplift ΔZ'x = 0 in FIG. 13 is plotted on the vertical axis and the ratio Es / Ei of the Young's modulus Ei of the spherical indenter to the Young's modulus Es of the test piece is plotted on the horizontal axis. This figure is a calibration curve for evaluating the Young's modulus of a test piece of an unknown sample from the result of a microindentation test using a spherical indenter having a known Young's modulus. As illustrated by the two arrows shown in FIG. 14, the Young's modulus ratio Es / Ei between the test piece and the indenter from the uplift change amount ΔZ'x = 0 of the indenter backside displacement measured at a predetermined additional weight. Is required. Further, the elastic modulus Es of the unknown sample can be evaluated by integrating the known elastic modulus Ei of the indenter with respect to the value.

Hereinafter, preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings by way of exemplary embodiments, but the present invention is not limited to such specific embodiments and is described in the scope of claims. Various modifications and changes are possible within the scope of the gist of the present invention.

1 Microscopic indentation tester 2 Measurement control device 3 Information processing device (electronic computer)
4 Indenter 5 Specimen 6 Probe microscope 7 Displacement measuring device 8 Precision 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 Divided photodiode 24 Current / voltage conversion circuit 25 Feedback circuit 26 Roughing mechanism 27 Specimen Holding stand

Claims (10)

It includes a step of evaluating the mechanical properties of the measurement sample by measuring the shape change of the surface of the indenter opposite to the test piece side in a state where the indenter is pushed into contact with the surface of the test piece of the measurement sample.
A mechanical property test method characterized in that the tip of the indenter on the side in contact with the test piece has a shape having one protrusion. Using a microindentation tester comprising the indenter, the test piece, and a scanning probe microscope provided with a surface observation probe,
According to claim 1, the shape change of the surface of the indenter opposite to the test piece side is measured in a state where the tip of the indenter is brought into contact with the surface of the test piece by pushing the indenter with the scanning probe microscope. The described mechanical property test method. Using the mechanical characteristic measuring device having the microindentation tester, the measurement control device, and the information processing device,
By the measurement control device
The positional relationship between the surface of the test piece and the tip of the indenter was measured.
The position is controlled so that the indentation between the test piece and the indenter has a predetermined press-fitting depth.
Control the scanning probe microscope to observe the back surface of the indenter,
With the information processing device
The surface information on the back surface of the surface observation probe is received from the microindentation tester and analyzed as the amount of surface deformation or the surface displacement distribution.
The analyzed surface deformation amount or surface displacement distribution is stored in the storage device, and
A claim characterized in that the mechanical properties of a test piece of an unknown sample are evaluated from the results of a microindentation test by the microindentation tester using the indenter having known mechanical properties stored in the storage device. Item 2. The mechanical property test method according to Item 2. With reference to the contact center point of the indenter with the surface of the test piece, the displacement of the point perpendicularly lowered from the contact center point with respect to the surface of the indenter opposite to the test piece side or the distance from that point is used as a function. The mechanical property test method according to any one of claims 1 to 3, wherein the displacement distribution is measured. The indenter that is pushed into the test piece of the measurement sample and
It is equipped with a measuring means for measuring the shape change of the surface of the indenter opposite to the test piece side.
A mechanical property measuring device characterized in that the tip of the indenter on the side in contact with the test piece has a shape having one protrusion. Equipped with a micro-indentation tester, this micro-indentation tester is
With the indenter
With the test piece
A scanning probe microscope equipped with a surface observation probe that measures the shape change of the surface of the indenter opposite to the test piece side in a state where the tip of the indenter is brought into contact with the surface of the test piece by pushing the indenter. Have,
The mechanical property measuring apparatus according to claim 5, wherein the measuring means includes the scanning probe microscope. The microindentation tester, the measurement control device, and the information processing device are provided.
The measurement control device is
A displacement measuring device that measures the positional relationship between the surface of the test piece and the tip of the indenter,
A precision positioning device that controls the position so that the contact between the test piece and the indenter has a predetermined press-fitting depth.
It has a surface analysis device that controls the scanning probe microscope for observing the back surface of the indenter.
The information processing device is
A surface analysis unit that receives surface information on the back surface of the surface observation probe from the microindentation tester and analyzes it as a three-dimensional surface deformation amount or surface displacement distribution.
It has a storage device that stores the surface deformation amount or surface displacement distribution analyzed by the surface analysis unit.
The sixth aspect of the present invention is to evaluate the mechanical properties of a test piece of an unknown sample from the results of a microindentation test by the microindentation tester using the indenter having the known mechanical properties stored in the storage device. The described mechanical property measuring device. The mechanical property measuring apparatus according to claim 6 or 7, which has a vertical double structure in which the indenter and the probe of the surface observation probe are arranged in the vertical 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 measuring device. The scanning probe microscope uses the contact center point of the indenter with the surface of the test piece as a reference.
Claims 6 to 9 are configured to measure the displacement of a point perpendicularly lowered from the contact center point with respect to the surface of the indenter opposite to the test piece side or the displacement distribution using the distance from the point as a function. The mechanical property measuring device according to any one of the items.

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