CN112014237B - Device and method for preparing cement stone microscopic sample and testing bending tensile strength - Google Patents
Device and method for preparing cement stone microscopic sample and testing bending tensile strength Download PDFInfo
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- CN112014237B CN112014237B CN202010928290.1A CN202010928290A CN112014237B CN 112014237 B CN112014237 B CN 112014237B CN 202010928290 A CN202010928290 A CN 202010928290A CN 112014237 B CN112014237 B CN 112014237B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/20—Investigating strength properties of solid materials by application of mechanical stress by applying steady bending forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0023—Bending
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Abstract
The invention discloses a device and a method for preparing a cement stone microscopic sample and testing bending tensile strength, wherein the device comprises a workbench, wherein the workbench is fixedly provided with a support frame and a chute track; the supporting frame is fixedly provided with a grinding and cutting assembly for grinding and cutting a sample to form a sample, and the supporting frame is also fixedly provided with a testing assembly for testing the bending and pulling strength of the sample; the grinding and cutting assembly and the testing assembly are both located above the sliding groove rail, and an operating platform for fixing a sample or a specimen is arranged on the sliding groove rail and can move along the sliding groove rail.
Description
Technical Field
The invention belongs to the technical field of civil engineering, and particularly relates to a device and a method for preparing a cement stone microscopic sample and testing bending tensile strength.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Nowadays, concrete materials are widely applied to modern civil engineering construction such as buildings, ocean ports, road bridges, water conservancy and electric power and the like. In recent years, engineering construction is developed towards huge, large-span and special structures, and infrastructures are gradually expanded to complex and severe engineering environments, such as projects of sea-crossing bridges, submarine tunnels and the like, so that higher requirements on service performance of concrete are provided. However, during long-term use of concrete materials in complex environments, damage such as cracking and peeling inevitably occurs, which adversely affects the normal use performance and durability of the structure and may even jeopardize the safe operation of the structure. Therefore, the research on the damage mechanism of the concrete material is significant and necessary for guiding the toughening design of the concrete material, improving the performance of the concrete material and prolonging the service life of a concrete structure.
The tensile strength of the concrete is low, generally only 1/20-1/10 of compressive strength, but the tensile strength plays an important role in the crack resistance of the concrete. Therefore, in order to better explore the mechanical properties of concrete, in addition to the required compressive strength, the tensile strength is also an important parameter to be considered in the design. The service performance of concrete is mainly influenced by the mechanical property of the concrete, however, most of the research on the mechanical property of the concrete is integrated and macroscopic at present, for example, the standard sample size of the splitting tensile strength test of the concrete material is a cube with the side length of 150mm, which is specified in the concrete physical mechanical property test method standard (GB/T50081-2019), and the splitting tensile strength of the concrete material is directly measured. However, the mechanical properties of the concrete are affected by various factors on various scales (nm-m) because the concrete is a blended multiphase system, and if the mechanical properties of the concrete are directly analyzed macroscopically by neglecting the properties of microscopic phases, the property formation mechanism and the damage failure mechanism of the concrete cannot be deeply and accurately explored. Therefore, in addition to the analysis of macroscopic properties, the study of the mechanical behavior of concrete materials on a smaller scale should also be carried out.
With the development of microscopic testing technology of materials, in the mechanical property test of micro-nano-scale materials, a nanoindenter is gradually becoming a common tool for testing miniaturized test pieces as a high-precision instrument capable of recording small loads and small displacements. The micromechanics research is carried out by utilizing the nano indentation technology, and a foundation is provided for developing various miniaturized test researches, such as a bending test of a micro beam. However, from a multi-scale analysis method, the nano-indenter is still used for testing the micromechanical property of the set cement, for example, because a test piece for the nano-indenter is limited by the size (within 10 μm), the test result can only reflect the physical property of a certain hydration product in the set cement, and the mechanical property of the complex system of the set cement cannot be tested; in addition, the nanoindentor using the pointed indenter cannot be accurately centered on the top of the micro-nano-scale particles, and may generate a "slip needle" or a "deflection needle", which cannot ensure the accuracy of the experiment. And the local indentation deformation of the indentation apparatus, the deflection of the micro-cantilever beam along the width direction of the cross section and the deflection of the beam support can increase the effective deflection, and the accuracy of the evaluation result is reduced.
In view of the above, the inventors found that at the microscopic scale, an apparatus for preparing cement paste (i.e. set cement) and testing the mechanical properties thereof is lacking. Therefore, it is necessary to complete the flexural tensile strength test of the micro-cement stone with high precision and high quality, promote the research progress of various micro-performances and fracture mechanisms of the cement stone, fill up the blank of a nano-dielectric-macro multi-scale fracture simulation system, and further deeply analyze the strength formation mechanism and damage degradation behavior of the cement stone material.
Disclosure of Invention
Aiming at the defects in the prior art, the first purpose of the invention is to provide a device and a method for preparing a cement stone micro sample and testing the bending and pulling strength.
The second purpose of the invention is to provide a method for preparing a cement stone microcosmic sample and testing the bending tensile strength, the method has simple process, short time consumption and high precision, can effectively realize the preparation and the test of the micron-sized cement stone microcosmic sample, and better analyzes various mechanical properties and fracture mechanisms of the cement stone microcosmic sample; in a bending test, a miniaturized three-point bending test method is adopted, and the microscopic elasticity, plasticity and fracture mechanism of the material are deduced by using the microscopic deformation behavior of a test piece.
In order to achieve the purpose, the invention is realized by the following technical scheme:
in a first aspect, the embodiment of the invention provides a device for preparing a cement micro sample and testing bending tensile strength, which comprises a workbench, wherein the workbench is fixedly provided with a support frame and a chute track; the supporting frame is fixedly provided with a grinding and cutting assembly for grinding and cutting a sample to form a sample, and the supporting frame is also fixedly provided with a testing assembly for testing the bending and pulling strength of the sample; the grinding and cutting assembly and the testing assembly are both located above the sliding groove rail, and an operating platform for fixing a sample or a specimen is arranged on the sliding groove rail and can move along the sliding groove rail.
As a further technical scheme, the grinding and cutting assembly comprises a first horizontal rod, the first horizontal rod is connected with the grinding and cutting sheet through a connecting structure, the connecting structure comprises a first connecting block rotatably connected with the first horizontal rod, and the first connecting block can rotate in a vertical plane; the first connecting block is rotatably connected with the second connecting block, the second connecting block can rotate in the horizontal plane, and the second connecting block is fixedly connected with the grinding and cutting piece.
As a further technical scheme, a temperature sensor and a pressure sensor are arranged in the first horizontal rod; the outer ring of the grinding and cutting piece is made of polyurethane rubber material, and the surface of the inner ring of the grinding and cutting piece is provided with a diamond grinding piece.
As a further technical scheme, the testing assembly comprises a second horizontal rod, nano-indentation equipment is fixedly arranged at the bottom of the second horizontal rod, the nano-indentation equipment comprises a diamond wedge-shaped pressure head, and a loading module and an image module are arranged in the nano-indentation equipment; and a temperature sensor and a pressure sensor are arranged in the second horizontal rod.
As a further technical scheme, the operation platform comprises an upper layer of object carrying platform and a lower layer of object carrying platform, wherein the upper layer of object carrying platform is provided with a clamping groove, a vacuum sucking disc is arranged in the clamping groove, the bottom of the lower layer of object carrying platform is provided with a pulley, and the pulley is arranged on a sliding groove track in a matched mode.
As a further technical scheme, the chute track comprises a base, the base is provided with a slide rail, the slide rail is formed by arranging a plurality of X-direction tracks and Y-direction tracks in a staggered mode, and a track changer is arranged at the joint of the X-direction tracks and the Y-direction tracks.
As a further technical scheme, the support frame comprises two oppositely arranged upright posts, a first cross beam is fixedly arranged at the top ends of the two upright posts, a second cross beam is also arranged between the two upright posts, and a telescopic rod is arranged between the first cross beam and the second cross beam to push the second cross beam to move up and down; and the grinding and cutting assembly and the testing assembly are fixed on the second cross beam.
As a further technical scheme, a microscopic observation assembly is fixedly arranged on the lower portion of the upright column and used for collecting an image of a sample or a sample of the operating platform, the microscopic observation assembly is connected with a controller, the controller is connected with a display, the display is arranged on one side of the operating platform, and an operation assembly is further arranged on the side portion of the operating platform.
As a further technical scheme, a cooling liquid spray head is fixedly arranged on the second cross beam and is connected with a cooling liquid supply source; the second cross beam is also fixedly provided with a displacement sensor for monitoring the movement conditions of the grinding and cutting assembly and the testing assembly, and the displacement sensor is connected with the controller; the workbench and the chute rails are both provided with drain holes.
In a second aspect, an embodiment of the present invention further provides a testing method using the apparatus described above, including the following steps:
bonding a cement stone thin sheet sample to a glass slide, and fixing the glass slide to an operation table;
adjusting the position of the operating platform on the chute track to enable the operating platform to be positioned right below the grinding and cutting assembly;
adjusting the turning direction of the grinding and cutting assembly grinding and cutting piece, and enabling the grinding and cutting piece to sequentially perform right grinding, X-direction cutting and Y-direction cutting on the sample to obtain a plurality of cement bending and pulling test micro-beam samples;
taking down the micro-beam sample from the glass slide, placing the micro-beam sample on a micro-beam supporting device, and fixing the micro-beam supporting device on an operation table;
adjusting the position of the operating platform on the chute track to enable the operating platform to be positioned right below the testing assembly;
and applying a displacement load to the sample through a nano-indentation device of the testing assembly to damage the sample, and obtaining a process curve from loading to damage of the sample.
The beneficial effects of the above-mentioned embodiment of the present invention are as follows:
1) according to the device disclosed by the invention, the test component can be used for developing the mechanical behavior research of the set cement under a smaller scale on the basis of the analysis of the macroscopic mechanical property of the set cement, so that a multi-scale fracture analysis system of the concrete is constructed, and the cracking mechanism and the damage failure mechanism of the micro-cracks of the concrete are explored.
2) The grinding and cutting assembly of the device provided by the invention overcomes the defect that no device for specially manufacturing micron-sized cement stone samples exists in the field of civil engineering industry at present, not only can the manufacturing quantity of the cement stone samples be ensured, but also the high-precision and high-quality preparation of the cement stone samples can be realized, further, the mechanical property of the cement stone materials can be deeply analyzed, and the research progress of the fracture behavior of concrete and cement stones is promoted.
3) The device provided by the invention integrates preparation and testing, so that the test time can be saved, the working efficiency is improved, the prepared cement stone sample is not required to be stored and moved, the sample is prevented from being damaged possibly in the disturbance process, the molding quality of the test sample can be ensured, and the accuracy of the test result is further ensured.
4) The device can ensure the moving precision of the operating platform, improve the precision of grinding, cutting and testing the cement stone sample, ensure the accuracy of the obtained test data and greatly improve the test efficiency at the same time by arranging the chute track.
5) The preparation and test method of the invention reduces the difficulty of preparing the cement stone micro sample and testing the bending tensile strength, and provides a new idea for researching and analyzing the mechanical property of the cement stone micro sample.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic view of a manufacturing and testing apparatus according to the present invention;
FIG. 2 is a schematic view of the abrasive cutting assembly;
FIG. 3 is an enlarged view of the abrasive cut sheet;
FIG. 4 is a schematic view of a test assembly;
FIG. 5 is a schematic view of the supporting frame;
FIG. 6 is a schematic view of the operation and control assembly, the display and the workbench;
FIG. 7 is a schematic view of the console;
FIG. 8 is a schematic view of a chute track;
FIG. 9 is a schematic view of the abrasive cutting blade of the abrasive cutting assembly facing the test sample;
FIG. 10 is a schematic view of the abrasive cutting segment of the abrasive cutting assembly cutting perpendicular to the Y direction;
FIG. 11 is a schematic view of the abrasive cutting segment of the abrasive cutting assembly cutting perpendicular to the X direction;
FIG. 12 is a schematic view of a micro-beam support apparatus;
FIG. 13 is a schematic view of a typical load-displacement curve;
in the figure: the device comprises a grinding and cutting assembly 1, a testing assembly 2, a microscopic observation assembly 3, a control assembly 4, a support frame 5, an operating platform 6, a display 7, a chute track 8, a workbench 9, a drain hole 10, a stand column 11, a first beam 12, a telescopic rod 13, a cooling liquid spray head 14, a displacement sensor 15, a first horizontal rod 16, a grinding section 17, a connecting structure 18, a first connecting block 19, a second connecting block 20, an outer ring section 21, a diamond grinding disc 22, a second horizontal rod 23, a nano indentation device 24, a fixed block 25, a diamond wedge-shaped pressure head 26, a control button 27, a control rod 28, an upper stage 29, a clamping groove 30, a pulley 31, a base 32, a slide rail 33, a rail changer 34, a sample 35, a micro-beam supporting device 36, a second beam 37 and a lower stage 38.
The spacing or dimensions between each other are exaggerated to show the location of the various parts, and the illustration is for illustrative purposes only.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, unless the invention expressly state otherwise, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "up", "down", "left" and "right" in the present invention, if any, merely indicate correspondence with up, down, left and right directions of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, rather than indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
The terms "mounted", "connected", "fixed", and the like in the present invention should be understood broadly, and for example, the terms "mounted", "connected", "fixed", and the like may be fixedly connected, detachably connected, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.
As described in the background of the invention, the prior art has disadvantages, and in order to solve the above technical problems, the present invention provides a device and a method for preparing a micro sample of set cement and testing flexural tensile strength.
Example 1:
in a typical embodiment of the present invention, as shown in fig. 1, a device for preparing a cement micro sample and testing flexural tensile strength is provided, which comprises a worktable 9, wherein the worktable 9 is provided with a grinding and cutting component 1, a testing component 2, a microscopic observation component 3, a control component 4, a support frame 5, an operation platform 6, a display 7 and a chute track 8; the support frame 5 and the chute rail 8 are both fixed on the workbench, and the workbench and the chute rail are respectively provided with a drain hole 10 for discharging waste liquid.
As shown in fig. 5, the supporting frame 5 includes two upright posts 11, two cross beams and a telescopic rod 13, the two upright posts 11 are vertically arranged oppositely, and the bottom ends of the two upright posts 11 are fixed on the working table 9. A first beam 12 is fixedly arranged at the top ends of the two upright posts 11; two stand upper portions set up a second crossbeam 37, and the second crossbeam is located first crossbeam below, and two crossbeams are parallel and the certain distance setting of interval, and the second crossbeam that is located the lower part is sliding connection with the stand, sets up telescopic link 13 between two crossbeams, and the telescopic link can promote the second crossbeam that is located the lower part and reciprocate.
The lower parts of the two upright posts 11 are provided with microscopic observation components 3. The microscopic observation assembly comprises a microscope, a lens regulator and a graph acquisition system; the microscope is provided with a high-resolution color CCD and a pattern acquisition system matched with the high-resolution color CCD, the microscope is provided with a position feedback control device and is used for adjusting a lens, the microscope can observe and detect an operation table at 180 degrees, the lens of the microscope is a high-speed lens, the process of loading a sample to damage can be captured, and 50 images can be captured per second; and the optical image on the surface of the sample can be accessed in real time by pressing an observation key in the control assembly in combination with an image acquisition system, wherein the maximum magnification is more than or equal to 1000X on a screen by matching with an objective lens with the magnification of 40X. The microscopic observation assembly is connected with a controller, and the controller is connected with a display.
A cooling liquid spray head 14 is arranged on one side of the second cross beam positioned at the lower part, the cooling liquid spray head is connected with a cooling liquid supply source and is used for cooling the grinding section and the sample, the direction of the spray head can be adjusted and can move along with the grinding section, and the spraying direction does not need to be adjusted in the cutting process; and the other side of the second cross beam at the lower part is provided with a laser displacement sensor 15, the resolution ratio is less than or equal to 0.01 mu m and is used for monitoring the movement conditions of the grinding and cutting assembly and the testing assembly, the displacement sensor is connected with a controller, the controller is connected with a display, and displacement data are displayed on the display in real time.
As shown in fig. 1, the grinding and cutting assembly 1 is fixed on one side of the second beam of the support frame 5, and can be controlled by the telescopic rod to lift;
as shown in fig. 2, the grinding and cutting assembly is composed of a first horizontal rod 16 and a grinding and cutting piece 17, a digital temperature sensor and a piezoresistor type pressure sensor are arranged in the first horizontal rod 16, the first horizontal rod is connected with the grinding and cutting piece through a connecting structure 18, and the connecting structure can drive the grinding and cutting piece to adjust the direction of the grinding and cutting piece, so that the grinding and cutting piece is opposite to the sample, the grinding and cutting piece is perpendicular to the X direction, and the grinding and cutting piece is perpendicular to the Y direction.
The connecting structure 18 comprises a first connecting block 19 and a second connecting block 20, the first connecting block 19 is rotatably connected with the first horizontal rod 16, and the first connecting block can rotate in a vertical plane; the second connecting block 20 is rotatably connected with the first connecting block 19 and can rotate in the horizontal plane, and the second connecting block 20 is fixedly connected with the grinding and cutting plate 17. Thus, when the first connecting block rotates from a state of being parallel to the horizontal rod to a state of being perpendicular to the horizontal rod, the ground slice can be opposite to the sample, as shown in fig. 9; when the first connecting block is kept parallel to the horizontal rod and the second connecting block is parallel to the horizontal rod, the abrasive cutting piece cuts perpendicularly to the Y direction of the sample, as shown in FIG. 10; the ground blade cuts perpendicular to the X direction of the sample as shown in fig. 11 while the first connecting block is held parallel to the horizontal bar and the second connecting block is rotated to be perpendicular to the horizontal bar.
As shown in FIG. 3, the diameter of the grinding and cutting piece is 5-15cm, the outer ring cutting piece 21 is made of polyurethane rubber material, the thickness of the cutting piece is 260 μm, the diamond grinding piece 22 is arranged on the surface of the inner ring, the diameter is 1-3cm, the thickness is 35 μm, and the granularity is 30-125 μm.
The 90-degree turning of the grinding slice in two vertical directions is realized by being driven by a connecting structure, and the rotation of the connecting structure can be controlled by a transmission device.
As shown in fig. 1, the testing component 2 is fixed on one side of the second cross beam at the lower part of the supporting frame, and is controlled to lift by the telescopic rod;
as shown in fig. 4, the testing assembly 2 is composed of a second horizontal rod 23 and a nanoindentation device 24, a digital temperature sensor and a piezoresistance-type pressure sensor are arranged in the second horizontal rod, and the nanoindentation device 24 is fixed at the lower end of the second horizontal rod 23;
the nano indentation equipment comprises a fixed block 25, the fixed block 25 is fixed at the bottom of the second horizontal rod, a diamond wedge-shaped pressure head 26 is arranged at the bottom end of the fixed block, the radius of the tip end of the diamond wedge-shaped pressure head is 9.6 micrometers, the length of the diamond wedge-shaped pressure head is 700 micrometers, a loading module and an image module are both arranged in the nano indentation equipment 24, the loading module can be driven by electromagnetism, the loading force and the displacement can be continuously adjusted in a certain range, the maximum load is more than or equal to 500mN, the maximum indentation depth is more than 500 micrometers, the load resolution is less than or equal to 50nN, and the displacement resolution is less than 0.01 nm;
the image module can scan the sample section, adjust the scanning parameter and image post-processing in real time. The maximum scanning area is 500um multiplied by 500um, which can ensure the image definition and the scanning speed; the integral flatness can reach 0.1 percent per 100 um.
The control component 4 and the display 7 are disposed on one side of the working platform 9, as shown in fig. 6, the control component includes a control button 27 and a control lever 28, the control button can electrically control different components, the control lever can adjust positions X, Y of the operating platform 6 in two directions, the operating platform 6 can move by 100 μm when the control lever is pushed once, the size of the position movement can be observed in real time through the display, the movement accuracy is ensured, and the positioning accuracy is less than or equal to 1 μm.
As shown in fig. 1, the operation table 6 is disposed on the chute track and can move along the chute track in the X direction and the Y direction, as shown in fig. 7, the operation table includes an upper stage and a lower stage, the upper stage 29 is disposed above the lower stage 38, and the upper stage 29 is disposed with a 50mm × 50mm slot 30 for placing a carrier and fixing a sample; a vacuum chuck is arranged in the clamping groove 30 and used for adsorbing a carrier; the lower stage 38 is connected to four pulleys 31, the movement direction of which is controlled by a joystick.
As shown in fig. 1, the chute track is arranged on the table top of the workbench; as shown in fig. 8, the chute track comprises a base 32, a slide rail 33 and a rail changer 34, and is fixed on the workbench, the base is a wood board with the thickness of 5cm, the middle of the base is provided with a water drainage hole 10, and the base is arranged to be low in the middle and high at two sides, so that the waste liquid can be collected and discharged conveniently;
the slide rail 33 is arranged on the base 32, is a two-dimensional slide rail, and is formed by arranging a plurality of X-direction and Y-direction rails in a staggered manner, the operation table can move along the X direction when being positioned on the X-direction rails, and can move along the Y direction when being positioned on the Y-direction rails.
The sliding rail is made of PC engineering plastics, PC has good extensibility and dimensional stability, can resist high temperature of 125 ℃ and low temperature of-40 ℃, the sliding rail takes 100 mu m as a scale, the operating platform can move 100 mu m when the operating rod pushes once, the moving range in the X direction is more than or equal to 200mm, the moving range in the Y direction is more than or equal to 200mm, and the effective working area is more than or equal to 200mm multiplied by 200 mm; the end heads of the sliding rails are provided with supporting and blocking structures to prevent the operating platform from sliding out of the rails; the rail changer is arranged at the junction of the X direction and the Y direction of the sliding chute and used for adjusting the direction of the pulley, thereby changing the running track of the operating platform.
The display can switch display pictures at any time, and monitors and displays the running condition of each component in real time.
Example 2:
the embodiment provides a method for preparing a cement stone micro sample and testing the bending tensile strength, and the device for preparing the cement stone micro sample and testing the bending tensile strength in the embodiment 1 is adopted.
The specific process comprises the following steps:
(1) demoulding the cement stone sample after the curing period is finished, cutting the cement stone sample into a cement stone sheet sample with the thickness of 2mm by using a precision cutting machine, and preventing the hydration by adopting an isopropanol solvent; adhering a sample on a glass slide (with the size of 50mm multiplied by 5mm) by using ultraviolet hardening resin (UV glue), putting the slide into a clamping groove on an operation table, and pressing the slide to enable the slide to be firmly adsorbed on the operation table by a vacuum chuck;
(2) the position of the operating platform is adjusted through the operating lever of the workbench, so that the operating platform is positioned in the middle of the left half part of the sliding groove track (namely under the grinding and cutting assembly), and the operating platform is fixed by selecting an interlocking mode to ensure that the operating platform cannot move; opening the high-speed lens of the microscope, and adjusting the rotation direction of the lens to clearly display the position of the sample on a display of the workbench; checking the use state of each component of the workbench, and starting a test after confirming that the states are normal;
(3) turning on the first motor of the grinding and cutting assembly, adjusting the rotation direction of the grinding sheet to enable the grinding sheet surface to face the sample 35 (the position is schematically shown in figure 9), and turning off the first motor; opening a second motor of the grinding and cutting assembly to adjust the telescopic rod, so that the grinding and cutting assembly descends at a constant speed of 20mm/s until the grinding and cutting piece just contacts the surface of the sample;
the diameter of the grinding slice is 3cm, and the slice thickness is 260 mu m; grinding the plate to 35 μm in thickness and 50 μm in particle size;
controlling a cooling liquid spray head, adjusting the spray head to face to the surface of the sample, and opening a cooling liquid outlet;
(4) opening a third motor of the grinding and cutting assembly to drive the grinding and cutting piece to rotate, adjusting the telescopic rod when the rotation speed of the grinding and cutting piece is more than or equal to 3500r/min, reducing the height of the grinding and cutting assembly at a moving speed of less than 10 mu m/s, and avoiding the reduction of sample precision and the sample breakage caused by over-high speed until the sample is ground to the thickness of 500 mu m +/-5 mu m; in this embodiment, the height of the grinding and cutting assembly can be controlled by adopting a moving speed of 5 μm/s;
the whole operation process can ensure that the sample is not damaged due to the problems of overhigh temperature and the like by observing the surface pressure stress and the temperature value of the sample displayed by the display;
(5) after polishing, the height of the grinding and cutting assembly is increased at the speed of 20mm/s, the distance between the grinding and cutting piece and the surface of the sample is more than or equal to 75mm (80 mm can be selected), and the second motor and the third motor are switched off;
(6) turning on a first motor of the grinding and cutting assembly, adjusting the rotation direction of the grinding sheet to enable the grinding sheet surface to be perpendicular to the Y direction (the position is schematically shown in figure 10), and turning off the first motor; opening a second motor of the grinding and cutting assembly to adjust the telescopic rod, so that the height of the grinding and cutting assembly is reduced until the grinding slice just contacts the surface of the sample;
(7) reopening the third motor of the grinding and cutting assembly to drive the grinding and cutting piece to rotate, moving the grinding and cutting piece at a moving speed of less than 5 mu m/s when the rotating speed of the grinding and cutting piece is more than or equal to 3500r/min, and cutting the sample in the X direction to a cutting depth of 20 mu m into the glass slide;
moving the operating platform to the next cutting point on the sliding chute along the Y direction through the operating lever, ensuring that the linear distance between the two cutting points is 500 micrometers +/-5 micrometers, and repeating the operation until the cutting of the sample in the X direction is completed; the operation table can be fixed at the corresponding position of the chute track after each movement is finished;
(8) after the sample X is cut, the height of the grinding and cutting assembly is increased at the speed of 20mm/s, the distance between the grinding and cutting piece and the surface of the sample is enabled to be more than or equal to 75mm (80 mm can be selected), and a second motor and a third motor of the grinding and cutting assembly are turned off and are naturally cooled for a period of time;
(9) turning on a first motor of the grinding and cutting assembly, adjusting the rotation direction of the grinding sheet to enable the grinding sheet surface to be perpendicular to the X direction (the position is schematically shown in figure 11), and turning off the first motor; opening a second motor of the grinding and cutting assembly to adjust the telescopic rod, so that the height of the grinding and cutting assembly is reduced until the grinding slice just contacts the surface of the sample;
(10) reopening the third motor of the grinding and cutting assembly to drive the grinding and cutting piece to rotate, wherein the rotation speed of the grinding and cutting piece is more than or equal to 3500r/min so as to ensure the cutting precision and stability of the sample, moving the grinding and cutting piece at the moving speed of less than 5 mu m/s, and cutting the sample in the Y direction, wherein the cutting depth is 20 mu m of cutting into the glass slide;
moving the operating platform to the next cutting point on the sliding chute along the X direction by using an operating lever, ensuring that the linear distance between the two cutting points is more than or equal to 12mm plus the thickness of a cutting piece, repeating the operation until the cutting of the sample in the Y direction is completed, finally obtaining a plurality of cement stone bending and pulling test micro-beam samples with the cross section size of 500 micrometers multiplied by 12mm and the single-side error of +/-5 micrometers, moving the grinding and cutting assembly and the operating platform to the initial position after the completion, closing the second motor and the third motor of the grinding and cutting assembly, and closing the cooling mechanism;
(11) taking out the glass slide, taking out the micro-beam sample from the glass by using an acetone solvent, and placing the micro-beam sample on a micro-beam supporting device 36 (shown in a schematic diagram in fig. 12), wherein the surface of the micro-beam supporting device is provided with a plurality of accommodating grooves for accommodating the micro-beam sample; placing the micro-beam supporting device into a clamping groove on an objective table, and enabling the micro-beam supporting device to be firmly adsorbed on the objective table by a vacuum chuck;
(12) the operating platform is moved to the right middle of the right half chute track (namely right below the nano indentation equipment) along the X direction on the chute through the operating lever, and is fixed at a corresponding position;
(13) turning on a testing motor, adjusting a telescopic rod to enable the nanoindentation equipment to descend at the speed of 20mm/s until the tip of the diamond wedge-shaped pressure head just contacts the surface of the micro-beam sample, and adjusting the descending speed to be below 0.1 mu m/s until the micro-beam sample is damaged; capturing an image of the process from the loading to the damage of the micro-beam sample through a high-speed lens of the microscope, and observing a three-dimensional scanning image through a workbench display;
(14) repeating the steps (12) to (13) until the test work of a plurality of batches of the cement stone micro-beam samples is completed; turning off the test motor, taking out the micro-beam supporting device and the micro-beam sample, and cleaning and drying the workbench after controlling the operation platform to move to the initial position; and (5) disconnecting the power supply and arranging the workbench.
A typical load-displacement curve during the test is shown in figure 13. Flexural tensile strength f of cement micro-cube sampletAnd the modulus of elasticity E can be expressed as:
wherein L is the span length, d is the cross-sectional dimension of the square, S is the average slope of the curve within the range of 50% -80% of the maximum load, and FmaxIs the maximum loading force in the test.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A device for preparing a cement stone microscopic sample and testing bending tensile strength is characterized by comprising a workbench, wherein a support frame and a chute track are fixedly arranged on the workbench; the supporting frame is fixedly provided with a grinding and cutting assembly for grinding and cutting a sample to form a sample, and the supporting frame is also fixedly provided with a testing assembly for testing the bending and pulling strength of the sample;
the grinding and cutting assembly comprises a first horizontal rod, the first horizontal rod is connected with a grinding and cutting piece through a connecting structure, the outer ring of the grinding and cutting piece is made of polyurethane rubber materials, and a diamond grinding disc is arranged on the surface of the inner ring of the grinding and cutting piece; the grinding and cutting assembly and the testing assembly are both positioned above the chute track, and an operating platform for fixing a sample is arranged on the chute track and can move along the chute track;
the supporting frame comprises two upright columns which are oppositely arranged, a microscopic observation assembly is fixedly arranged at the lower parts of the upright columns, the microscopic observation assembly acquires images of samples or samples on an operating platform, the microscopic observation assembly is connected with a controller, the controller is connected with a display, the display is arranged on one side of the operating platform, and an operation assembly is further arranged on the side part of the operating platform;
the testing assembly comprises a second horizontal rod, nano-indentation equipment is fixedly arranged at the bottom of the second horizontal rod and comprises a diamond wedge-shaped pressure head, and a loading module and an image module are arranged in the nano-indentation equipment; and a temperature sensor and a pressure sensor are arranged in the second horizontal rod.
2. The apparatus for preparing a cement micro-specimen and testing flexural tensile strength of claim 1, wherein the connection structure comprises a first connection block rotatably connected to a first horizontal bar, the first connection block being rotatable in a vertical plane; the first connecting block is rotatably connected with the second connecting block, the second connecting block can rotate in the horizontal plane, and the second connecting block is fixedly connected with the grinding and cutting piece.
3. The apparatus for preparing a micro-scale sample of set cement and testing flexural tensile strength of claim 2, wherein the first horizontal rod is provided with a temperature sensor and a pressure sensor.
4. The apparatus according to claim 1, wherein the operation table comprises an upper stage and a lower stage, the upper stage is provided with a slot, a vacuum chuck is disposed in the slot, and a pulley is disposed at the bottom of the lower stage and is engaged with the chute.
5. The apparatus for preparing a cement micro-specimen and testing flexural tensile strength according to claim 1, wherein the chute track comprises a base, the base is provided with a slide rail, the slide rail is formed by a plurality of X-direction tracks and Y-direction tracks which are arranged in a staggered manner, and a rail changer is arranged at the joint of the X-direction tracks and the Y-direction tracks.
6. The apparatus for preparing a cement microscopic sample and testing flexural tensile strength according to claim 1, wherein the support frame comprises two opposite upright columns, a first beam is fixedly arranged at the top ends of the two upright columns, a second beam is arranged between the two upright columns, and a telescopic rod is arranged between the first beam and the second beam to push the second beam to move up and down; and the grinding and cutting assembly and the testing assembly are fixed on the second cross beam.
7. The apparatus for preparing a cement micro-sample and testing flexural tensile strength according to claim 6, wherein the second beam is fixedly provided with a cooling liquid nozzle, and the cooling liquid nozzle is connected with a cooling liquid supply source; the second cross beam is also fixedly provided with a laser displacement sensor to monitor the movement conditions of the grinding and cutting assembly and the test assembly, and the displacement sensor is connected with the controller; the workbench and the chute rails are both provided with drain holes.
8. The method for testing the device for preparing the cement micro-sample and testing the flexural tensile strength according to any one of claims 1 to 7, which is characterized by comprising the following steps of:
bonding a cement stone thin sheet sample to a glass slide, and fixing the glass slide to an operation table;
adjusting the position of the operating platform on the chute track to enable the operating platform to be positioned right below the grinding and cutting assembly;
adjusting the turning direction of the grinding and cutting assembly grinding and cutting piece, and enabling the grinding and cutting piece to sequentially perform right grinding, X-direction cutting and Y-direction cutting on the sample to obtain a plurality of cement bending and pulling test micro-beam samples;
taking down the micro-beam sample from the glass slide, placing the micro-beam sample on a micro-beam supporting device, and fixing the micro-beam supporting device on an operation table;
adjusting the position of the operating platform on the chute track to enable the operating platform to be positioned right below the testing assembly;
and applying a displacement load to the sample through a nano-indentation device of the testing assembly to damage the sample, and obtaining a process curve from loading to damage of the sample.
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| US6120352A (en) * | 1997-03-06 | 2000-09-19 | Keltech Engineering | Lapping apparatus and lapping method using abrasive sheets |
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| CN103940685A (en) * | 2014-04-25 | 2014-07-23 | 华侨大学 | Method for testing high-frequency fatigue characteristic of material under microscale |
| CN203875732U (en) * | 2014-06-19 | 2014-10-15 | 中国民航大学 | Flexible grinding and polishing mechanism |
| CN104359769A (en) * | 2014-11-11 | 2015-02-18 | 吉林大学 | In-situ test instrument for micromechanics performances of materials under three-point and four-point bending action |
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