Contact type accurate detection method for surface roughness of explosive crystal

Abstract

The invention provides a contact type accurate detection method for the surface roughness of an explosive crystal. The method comprises the following steps: step 1, determining the number of particles to be detected; 2, determining the to-be-measured area of a single explosive crystal; step 3, probe imaging; 4, calculating an average tilt vector; 5, calculating the roughness; and step 6, calculating a roughness average value. Probe imaging of nanoindentation is adopted as a detection means, and the number of particles to be detected and the sampling area of each crystal are respectively determined according to the total number of particles of the crystals and the total area of the crystals. And measuring the surface appearance of the sample to be measured, and calculating the roughness in the tilt vector direction through two-dimensional linear fitting. The method is low in environmental influence, high in explosive crystal safety in the testing process, and has the advantages of no damage, accurate result and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic material detection, relates to surface roughness detection, and specifically relates to a contact-type precise detection method for the surface roughness of explosive crystals. Background Art

[0002] Surface roughness is the most commonly used parameter to describe the microscopic morphology of an object's surface. It reflects the error in the microscopic geometric shape of the object's surface. In PBX explosives, surface roughness affects the wetting properties and microinterface effects between single-element explosive crystals and polymer materials. Too low roughness will reduce the process rheological properties. However, too high roughness will increase the probability of surface hot spots, thereby increasing the friction sensitivity of the sample, which is not conducive to the safety of energetic materials. Therefore, it is necessary to control the surface roughness of explosive crystals within a certain range. Therefore, it is of great significance to accurately obtain the surface roughness of explosive crystals.

[0003] At present, the main methods for measuring surface roughness include direct visual method, comparison method, stylus method and optical method.

[0004] The direct visual method is to observe the microscopic morphology of the surface with the naked eye or a magnifying glass to evaluate the surface roughness. Although this method is simple, it is greatly affected by subjective factors and therefore has low accuracy.

[0005] The comparison method is a relative measurement method that evaluates the surface roughness by comparing the surface to be measured with a standard sample of known surface roughness. This method depends on the accuracy of the standard sample and the operator's experience, so there is also a certain error.

[0006] The stylus method uses a stylus to slide on the surface and measures the tiny concave and convex displacement of the stylus on the surface to reflect the surface roughness. This method has high measurement accuracy and good stability. However, when the stylus slides on the surface, it will cause certain scratches on the surface, causing secondary damage to the sample.

[0007] The optical method uses optical principles to image the surface and evaluate the surface roughness by analyzing the imaging results. The optical method can be divided into interference method, laser method and confocal method. The optical method has fast measurement speed and is non-destructive, but the light source may cause the explosive crystal to burn and explode, and the measurement results are greatly affected by environmental conditions, such as temperature and humidity. Summary of the invention

[0008] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a contact-type accurate detection method for the surface roughness of explosive crystals, so as to solve the technical problem that the accuracy of the detection method in the prior art needs to be further improved.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0010] A contact-type precise detection method for the surface roughness of explosive crystals, the method comprising the following steps:

[0011] Step 1: Determine the number of particles to be measured:

[0012] Randomly select K from the total sample 1 / 3 particles as the number of particles to be tested, K 1 / 3 Take a positive integer, K is the total number of particles.

[0013] Step 2: Determine the area to be measured of a single explosive crystal:

[0014] For a single explosive crystal particle, the single measurement area of ​​the local region to be measured is set to 10 μm×10 μm, and N local regions to be measured are randomly selected as the area to be measured of the single explosive crystal.

[0015] Step 3: Probe imaging:

[0016] Nanoindentation probe imaging was performed using a nanoindenter to obtain the crystal surface morphology.

[0017] Step 4: Calculate the average tilt vector:

[0018] Perform two-dimensional plane linear fitting on the crystal surface morphology obtained from the same explosive crystal particle to obtain the plane unit normal vector Calculate the unit normal vector of the plane The mean vector of as the mean tilt vector.

[0019] Step 5: Calculate the roughness:

[0020] Calculate the crystal surface topography at any point (x i ,y i , z i ) to the plane L(ax+by+cz=0) i , get the average vertical distance h from all points to plane L 平均 .

[0021] The average tilt vector is the normal vector, and its distance from plane L is h 平均 The plane is used as the reference plane; the average value of the absolute value of the vertical distance from each point on the plane to the reference plane is calculated, that is, the arithmetic mean deviation of the profile R a , R a That is the roughness of the measured area; the same method is used to calculate the roughness R of N areas a . Calculate the roughness R of N regions a The average value is taken as the roughness of the single explosive crystal particle.

[0022] Step 6: Calculate the average roughness value:

[0023] According to step 2, step 3, step 4 and step 5, the roughness of all the explosive crystal particles to be tested is measured. Finally, the average roughness of all the explosive crystal particles to be tested is taken as the result.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] The present invention adopts probe imaging through nanoindentation as a detection means, and determines the number of particles to be tested and the sampling area of ​​each crystal by the total number of crystal particles and the total area of ​​the crystal. The surface morphology of the sample to be tested is measured, and the roughness is calculated in the direction of the inclined vector by two-dimensional linear fitting. The method is less affected by the environment, the test process is highly safe for explosive crystals, and has the advantages of being non-destructive and accurate in results.

[0026] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a crystal surface image of a single Octometalate sample used in the application example.

[0028] Figure 2 It is a two-dimensional plane linear fitting of the 10um×10um morphological data obtained in the application example. DETAILED DESCRIPTION

[0029] It should be noted that all raw materials and instruments in the present invention, unless otherwise specified, are all raw materials and instruments known in the prior art and can be obtained from commercial channels. All test methods in the present invention, unless otherwise specified, are conventional methods.

[0030] The present invention uses nanoindentation probe imaging as a detection method, and determines the number of particles to be tested and the sampling area of ​​each crystal by the total number of crystal particles and the total area of ​​the crystal. The surface morphology of the sample to be tested is measured, and the roughness is calculated in the direction of the tilt vector by two-dimensional linear fitting.

[0031] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0032] Example:

[0033] This embodiment provides a contact-type precise detection method for the surface roughness of explosive crystals, the method comprising the following steps:

[0034] Step 1: Determine the number of particles to be measured:

[0035] Randomly select K from the total sample 1 / 3 particles as the number of particles to be tested, K 1 / 3 Take a positive integer, K is the total number of particles.

[0036] Step 2: Determine the area to be measured of a single explosive crystal:

[0037] For a single explosive crystal particle, the single measurement area of ​​the local region to be measured is set to 10 μm×10 μm, and N local regions to be measured are randomly selected as the area to be measured of the single explosive crystal.

[0038] In step 2, the value of N is (S / 100) 1 / 3 , (S / 100) 1 / 3 Take a positive integer, S is the total crystal surface area of ​​a single explosive crystal particle, the unit is μm 2 .

[0039] Step 3: Probe imaging:

[0040] Nanoindentation probe imaging was performed using a nanoindenter to obtain the crystal surface morphology.

[0041] In step three, the conditions for nanoindentation probe imaging are as follows: a conical indenter with a semi-cone angle of 60° is selected, the contact force is set to 20 μN, and the scanning rate is 1 Hz.

[0042] Step 4: Calculate the average tilt vector:

[0043] Perform two-dimensional plane linear fitting on the crystal surface morphology obtained from the same explosive crystal particle to obtain the plane unit normal vector Calculate the unit normal vector of the plane The mean vector of as the mean tilt vector.

[0044] in:

[0045] n represents the nth detection area of ​​the same particle;

[0046] a represents the mean vector Coordinate values ​​of axes in three-dimensional space coordinate system;

[0047] b represents the mean vector The coordinate value of the Y axis in the three-dimensional space coordinate system;

[0048] c represents the mean vector The coordinate value of the Z axis in the three-dimensional space coordinate system.

[0049] Step 5: Calculate the roughness:

[0050] Calculate the crystal surface topography at any point (xi ,y i , z i ) to the plane L(ax+by+cz=0) i , get the average vertical distance h from all points to plane L 平均 .

[0051] The average tilt vector is the normal vector, and its distance from plane L is h 平均 The plane is used as the reference plane; the average value of the absolute value of the vertical distance from each point on the plane to the reference plane is calculated, that is, the arithmetic mean deviation of the profile R a , the calculation formula is:

[0052]

[0053] Where:

[0054] R a represents the arithmetic mean deviation of the contour;

[0055] S represents the reference plane;

[0056] x represents the variable of the X-axis of the three-dimensional space coordinate system;

[0057] y represents the variable of the Y axis of the three-dimensional space coordinate system;

[0058] z represents the variable of the Z axis of the three-dimensional space coordinate system;

[0059] h represents the vertical distance from each point on the plane to the reference surface;

[0060] R a This is the roughness of the measured area.

[0061] The same method is used to calculate the roughness R of N areas. a . Calculate the roughness R of N regions a The average value is taken as the roughness of the single explosive crystal particle.

[0062] Step 6: Calculate the average roughness value:

[0063] According to step 2, step 3, step 4 and step 5, the roughness of all the explosive crystal particles to be tested is measured. Finally, the average roughness of all the explosive crystal particles to be tested is taken as the result.

[0064] Application examples:

[0065] This application example provides a contact-type precise detection method for the surface roughness of explosive crystals based on the above-mentioned embodiment.

[0066] In this application example, the instrument and the sample are:

[0067] Nanoindenter (HiSilicon TI950).

[0068] 60° semi-conical cone indenter.

[0069] Octogen (Xi'an Institute of Modern Chemistry).

[0070] In this application example, the method includes the following steps:

[0071] Step 1: Determine the number of particles to be measured:

[0072] The total number of particles in the same batch of Octogen is 100. Since the cube root of 100 is approximately equal to 4.6, 5 explosive crystals are randomly selected and numbered 1, 2, 3, 4, and 5. They are fixed on a flat iron sheet with glue and placed in the nanoindenter.

[0073] Step 2: Determine the area to be measured of a single explosive crystal:

[0074] Use an optical microscope to photograph the crystal surface of Octogen numbered 1. Figure 1 As shown, the boundary is defined and the total area of ​​the crystal surface is calculated to be S = 296921.3 μm 2 . Based on N>(S / 100) 1 / 3 ≈14.4, and N is 15. Fifteen positions were randomly selected, and the surface morphology of the sample in an area of ​​10 μm × 10 μm was scanned.

[0075] Step 3: Probe imaging:

[0076] A conical indenter with a semi-cone angle of 60° was selected, the contact force was set to 20 μN, the scanning frequency was set to 1 Hz, and nanoindentation probe imaging was performed using a nanoindenter to obtain the crystal surface morphology.

[0077] Step 4: Calculate the average tilt vector:

[0078] The 15 local morphology images obtained were fitted with two-dimensional plane line shapes in Matlab, as shown in Figure 2 As shown, the analytical equations of these fitting surfaces are obtained, and then the unit normal vectors are calculated and listed in Table 1. The mean vector of these normal vectors is calculated This is referred to as the tilt vector.

[0079] Table 1 Fitting equations and unit normal vectors of each test area

[0080]

[0081]

[0082] Step 5: Calculate the roughness:

[0083] Calculate any point (x i ,y i ,z i ) to the vertical distance h from the plane L0.00392x+0.059076y-0.99791z=0 i , get the average vertical distance h from all points to plane L 平均 .by is the normal vector, and its distance from plane L is h 平均 The plane is used as the reference surface. The average arithmetic deviation value R of the topographic profile is calculated. a , that is, the average value of the absolute value of the vertical distance from each point on the contour to the midplane. The results are shown in Table 2.

[0084] Table 2 Rough calculation results of all tested areas of Octojin numbered 1

[0085]

[0086]

[0087] Step 6: Calculate the average roughness value:

[0088] The remaining four Octogen particles were measured in the same way, and the results are listed in Table 3. The average roughness of these five particles was calculated to be 25.45 nm, so the roughness of this batch of particles was 25.45 nm.

[0089] Table 3 Roughness measurement results of all particles

[0090] serial number Roughness / nm 1 22.38 2 26.74 3 19.56 4 30.12 5 28.45 result 25.45

Claims

1. A contact-type accurate detection method for the surface roughness of explosive crystals, characterized in that: The method comprises the following steps: Step 1: Determine the number of particles to be measured: Randomly select K from the total sample 1 / 3 particles as the number of particles to be tested, K 1 / 3 Take a positive integer, K is the total number of particles; Step 2: Determine the area to be measured of a single explosive crystal: For a single explosive crystal particle, the single measurement area of ​​the local test area is set to 10 μm × 10 μm, and N local test areas are randomly selected as the test area of ​​a single explosive crystal; Step 3: Probe imaging: Use a nanoindenter to perform nanoindentation probe imaging to obtain the crystal surface morphology; Step 4: Calculate the average tilt vector: Perform two-dimensional plane linear fitting on the crystal surface morphology obtained from the same explosive crystal particle to obtain the plane unit normal vector Calculate the unit normal vector of the plane The mean vector of as the mean tilt vector; in: n represents the nth detection area of ​​the same particle; a represents the mean vector Coordinate values ​​of axes in the three-dimensional space coordinate system; b represents the mean vector The coordinate value of the Y axis in the three-dimensional space coordinate system; c represents the mean vector The coordinate value of the Z axis in the three-dimensional space coordinate system; Step 5: Calculate the roughness: Calculate the crystal surface topography at any point (x i ,y i , z i ) to the plane L(ax+by+cz=0) i , get the average vertical distance h from all points to plane L 平均 ; The average tilt vector is the normal vector, and its distance from plane L is h 平均 The plane is used as the reference plane; the average value of the absolute value of the vertical distance from each point on the plane to the reference plane is calculated, that is, the arithmetic mean deviation of the profile R a , the calculation formula is: Where: R a represents the arithmetic mean deviation of the contour; S represents the reference plane; x represents the variable of the X-axis of the three-dimensional space coordinate system; y represents the variable of the Y axis of the three-dimensional space coordinate system; z represents the variable of the Z axis of the three-dimensional space coordinate system; h represents the vertical distance from each point on the plane to the reference surface; R a This is the roughness of the measured area. The same method is used to calculate the roughness R of N areas. a ; Calculate the roughness R of N regions a The average value of is taken as the roughness of the single explosive crystal particle; Step 6: Calculate the average roughness value: According to step 2, step 3, step 4 and step 5, the roughness of all the explosive crystal particles to be tested is measured; finally, the average value of the roughness of all the explosive crystal particles to be tested is taken as the result.

2. The contact-type accurate detection method for the surface roughness of explosive crystals according to claim 1, characterized in that: In step 2, the value of N is (S / 100) 1 / 3 , (S / 100) 1 / 3 Take a positive integer, S is the total crystal surface area of ​​a single explosive crystal particle, the unit is μm 2 .

3. The contact-type accurate detection method for the surface roughness of explosive crystals according to claim 1, characterized in that: In step three, the conditions for the nanoindentation probe imaging are: using a conical indenter with a semi-cone angle of 60°, setting the contact force to 20 μN, and the scanning rate to 1 Hz.

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