CVD-sic-oriented multi-abrasive scratching subsurface damage detection and evaluation method

Abstract

The application discloses a kind of multi-abrasive scribing subsurface damage detection evaluation methods for CVD-SiC, belong to hard and brittle material processing detection evaluation field.This method includes: preparation mirror level CVD-SiC material workpiece;Preparation fixed at least two diamond abrasive scribing tool;Workpiece is clamped in force measuring device, to set the linear scribing of cutting depth at least two scribe, set multiple groups of change abrasive distribution characteristic parameters Experiment;Collect scribing force and calculate average scribing force;Microscopic observation scribe morphology obtains scribe interference characteristics;Preparation detection section and polishing, identify subsurface crack and measure damage depth;With subsurface damage depth as main evaluation index, combine average scribing force and scribe interference characteristics, evaluate the influence of abrasive distribution characteristics on subsurface damage, determine interference intensity and subsurface damage degree.This method can reflect the subsurface damage state under the coupling scribing of multiple abrasives.

Description

Technical Field

[0001] This invention belongs to the field of hard and brittle material processing quality inspection and evaluation technology, specifically involving a method for detecting and evaluating subsurface damage from multi-abrasive scribing in CVD-SiC (chemical vapor deposition silicon carbide). It can be used for the detection and evaluation of subsurface damage after grinding of CVD-SiC materials, and provides a basis for the design of grinding wheel abrasive arrangement and the optimization of grinding process. Background Technology

[0002] CVD-SiC materials are silicon carbide ceramic materials prepared by chemical vapor deposition. Silicon carbide ceramics are typically prepared through four methods: chemical vapor deposition, hot pressing sintering, atmospheric pressure sintering, and reaction sintering. Among these, chemical vapor deposition of silicon carbide has a long production cycle and high production cost, and is mainly used to manufacture precision components with high surface quality requirements, such as mirror-grade silicon carbide optical mirrors. Silicon carbide ceramics possess excellent properties such as high hardness, high wear resistance, oxidation resistance, strong acid and alkali resistance, low coefficient of thermal expansion, and high thermal conductivity, and are widely used in aerospace, machinery, electronics, and chemical industries.

[0003] Silicon carbide ceramics are typical hard and brittle materials, exhibiting high hardness and low fracture toughness, making them difficult to machine with ordinary cutting tools. Diamond wheel grinding is typically employed. During grinding, the diamond abrasive grains on the wheel surface scribble at high speed across the workpiece surface, causing brittle fracture and material removal. This results in chipping, microcracks, and other damage on the workpiece surface and subsurface. Subsurface damage, hidden beneath the machined surface, can lead to sudden microcrack propagation during use, severely impacting the performance and lifespan of silicon carbide devices. Therefore, accurate detection and evaluation of subsurface damage after grinding are essential for ensuring the processing quality and lifespan of silicon carbide devices.

[0004] A single abrasive grain is the basic unit that makes up a grinding wheel and completes the removal of material from the workpiece. Single-grain marking, as a simplified mode of abrasive machining, is an important means of understanding complex grinding processes. However, the distribution of abrasive grains on the actual grinding wheel surface is complex and random, and the shape and position of abrasive grains in space are difficult to control quantitatively. During the grinding process, multiple abrasive grains jointly mark the workpiece, and coupling interference occurs between adjacent abrasive grains. Single-grain marking cannot reflect this multi-grain coupled marking behavior, and the detection and evaluation results based on single-grain marking cannot accurately reflect the subsurface damage state under real grinding conditions.

[0005] In the detection of subsurface damage, existing methods mainly include static indentation, cross-sectional polishing, and surface roughness-based prediction methods. Static indentation tests neglect the impact of abrasive grains on the workpiece and the interference between adjacent abrasive grains, and cannot fully explain the damage characteristics and removal mechanisms of silicon carbide during processing. Although cross-sectional polishing or interface bonding techniques can directly obtain subsurface crack morphology, current applications are mostly for ordinary grinding or single-grain scribing conditions, and are not combined with multi-grain coupled scribing processes. Among the surface roughness-based prediction methods, there are many uncertainties in the grinding process, and the measurement results of surface roughness are uncertain, resulting in large prediction errors. In addition, existing research lacks systematic detection and evaluation methods for how abrasive distribution characteristics such as radial spacing, height difference, and scribing sequence affect subsurface damage.

[0006] Therefore, existing technologies lack a detection and evaluation method that can reflect the coupled scribing conditions of multiple abrasive grains and systematically evaluate the impact of abrasive grain distribution characteristics on subsurface damage. Summary of the Invention

[0007] The technical problem to be solved by this invention is that existing methods for detecting and evaluating subsurface damage cannot reflect the true formation state of subsurface damage in CVD-SiC materials under the coupled scribing action of multiple abrasive grains on the grinding wheel surface. It is difficult to accurately detect and evaluate subsurface damage under multi-abrasive scribing conditions, and it is also difficult to systematically evaluate the influence of abrasive distribution characteristic parameters such as radial spacing, height difference, and scribing sequence on subsurface damage.

[0008] To address the aforementioned technical problems, this invention provides a method for detecting and evaluating subsurface damage caused by multi-abrasive scribing in CVD-SiC. This method first prepares a mirror-grade CVD-SiC material workpiece, then prepares a multi-abrasive scribing tool with at least two diamond abrasive grains fixed on the tool substrate; the workpiece is clamped on a force measuring device, and a fixed-depth linear scribing is performed on the workpiece surface to form at least two scratches, and multiple sets of experiments are set up, each set of experiments changing at least one abrasive grain distribution characteristic parameter; the scribing force signal of each set of experiments is collected by the force measuring device, and the signal of the stable scribing section is extracted to calculate the average normal scribing force and the average tangential scribing force; the surface of the scribed workpiece is observed under a microscope to obtain the scratch morphology and scratch interference characteristics; a test section is prepared and polished, and the test section is observed under a microscope to identify subsurface cracks and measure the subsurface damage depth; finally, the subsurface damage depth is used as the main evaluation index, combined with the average scribing force and scratch interference characteristics, to evaluate the influence of abrasive grain distribution characteristics on subsurface damage, and to determine the interference intensity of multi-abrasive scribing and its corresponding subsurface damage degree.

[0009] In one embodiment, the abrasive grain distribution characteristic parameters include at least one of the following: radial spacing between adjacent abrasive grains, height difference between adjacent abrasive grains, and marking sequence determined by the circumferential spacing between abrasive grains; each group of experiments changes one parameter while keeping other parameters constant, so as to facilitate the individual examination of the influence of each parameter.

[0010] In one embodiment, the radial spacing of multiple sets of experiments takes at least two values ​​from 20μm, 50μm, 80μm, 100μm and 150μm; the scribing sequence is divided into sequential scribing type and non-sequential scribing type. In the sequential scribing type, multiple abrasive grains enter the scribing area sequentially along the circumference. In the non-sequential scribing type, when at least one abrasive grain enters the scribing area, it is affected by the combined influence of the scratches already formed by the adjacent abrasive grains on both sides.

[0011] In one embodiment, the multi-abrasive scribing tool adopts a cylindrical tool base, the diamond abrasive grains are conical abrasive grains with a cone angle of 90° or 120°, a grain diameter of 160μm to 250μm, and a grain protrusion height of one-third of the grain diameter to ensure the rigidity of the abrasive grains and prevent the abrasive grains from falling off.

[0012] In one embodiment, the cutting depth is set to 20μm, 30μm or 40μm, and the scribing speed is 700mm / min; the force measuring device is a piezoelectric force measuring device, and the scribing force signal is amplified by a charge amplifier and then collected by a data acquisition device and transmitted to a computer.

[0013] In one embodiment, the detection section is prepared by a section polishing method or an interface bonding method, both of which can directly expose the subsurface crack morphology below the scratch; the identified subsurface cracks include at least one of the following: median cracks, transverse cracks, radial cracks, intragranular cracks, grain boundary cracks, and transgranular cracks, and the maximum depth of the subsurface crack from the processed surface is taken as the subsurface damage depth.

[0014] In one embodiment, when the radial spacing is greater than or equal to the critical spacing, a complete ridge is formed between adjacent scratches, and the adjacent scratches are determined to be independent of each other; when the radial spacing is less than the critical spacing, material fusion and breakage occur between adjacent scratches, and the adjacent scratches are determined to interfere, thereby determining the interference intensity and the corresponding subsurface damage degree.

[0015] In one implementation, based on the correspondence between the subsurface damage depth and abrasive particle distribution characteristic parameters and the set cutting depth in each group of experiments, a subsurface damage depth prediction model is established through multiple linear regression to predict the subsurface damage depth under other abrasive particle distribution characteristic parameters.

[0016] In one implementation, a multi-abrasive grain scribing finite element model is established based on the JH-2 constitutive model. The scribing force, stress distribution, scratch morphology, and subsurface damage distribution are obtained through simulation and compared with experimental test results for verification.

[0017] The present invention also provides a multi-abrasive scribing subsurface damage detection and evaluation system for CVD-SiC materials, including a machine tool, a multi-abrasive scribing tool, a workpiece fixture, a force measuring device, a signal acquisition and processing device, and a computer. The computer performs a comprehensive evaluation of the scribing force processing and interference intensity, as well as the degree of subsurface damage.

[0018] The beneficial effects of this application are as follows: First, multi-abrasive grain scribing can reproduce the real working condition of multiple abrasive grains coupled together on the surface of the grinding wheel, making up for the insufficiency of single abrasive grain scribing in reflecting the interference effect of abrasive grain coupling; Second, through multiple sets of experiments with controllable abrasive grain distribution characteristic parameters, the influence of radial spacing, height difference and scribing sequence on subsurface damage can be systematically evaluated, and the interference spacing with the strongest interference effect and the critical spacing between independent scratches can be determined, providing a basis for the design of grinding wheel abrasive grain arrangement and the optimization of grinding process parameters; Third, using subsurface damage depth as the main evaluation index and comprehensively considering the average scribing force and scratch interference characteristics, the evaluation is carried out from multiple dimensions such as damage results, mechanical response and morphological characteristics, resulting in a more comprehensive evaluation; Fourth, the cross-sectional polishing method and interface bonding method can directly obtain the morphology and propagation characteristics of subsurface cracks, and the detection principle is simple; Fifth, the combination of finite element simulation and experimental detection is conducive to improving the reliability of detection and evaluation results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the multi-abrasive scribing subsurface damage detection and evaluation system for CVD-SiC according to the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the multi-abrasive grain scribing tool of the present invention;

[0021] Figure 3 This is a flowchart of the multi-abrasive scribing subsurface damage detection and evaluation method for CVD-SiC according to the present invention;

[0022] Figure 4 This is a schematic diagram of the subsurface crack type of the present invention. Detailed Implementation

[0023] Example 1: Detection and Evaluation System.

[0024] like Figure 1As shown, the CVD-SiC material multi-abrasive scribing subsurface damage detection and evaluation system of this embodiment includes a machine tool, a multi-abrasive scribing tool 2, a CVD-SiC workpiece 3, a workpiece fixture 4, a force measuring device 5, a signal acquisition and processing device 7, and a computer 8. The multi-abrasive scribing tool 2 is clamped on the machine tool spindle 1; the force measuring device 5 is installed on the machine tool worktable 6, and the workpiece fixture 4 is fixed on the force measuring device 5, in which the CVD-SiC workpiece 3 is clamped; the force measuring device 5 is connected to the signal acquisition and processing device 7 via a cable, and the signal acquisition and processing device 7 is connected to the computer 8. During scribing, the multi-abrasive scribing tool 2, driven by the machine tool spindle 1, performs linear scribing of the CVD-SiC workpiece 3 at a set depth; the scribing force generated during the scribing process is detected by the force measuring device 5 and transmitted to the computer 8 for storage and analysis via the signal acquisition and processing device 7. The machine tool can be a vertical machining center, the force measuring device 5 can be a piezoelectric force gauge, and the signal acquisition and processing device 7 includes a charge amplifier and a data acquisition device.

[0025] Example 2: Multi-abrasive scribing tool and abrasive grain distribution characteristics.

[0026] like Figure 2 As shown, the multi-abrasive scribing tool 2 includes a tool base 9 and a first diamond abrasive grain 10 and a second diamond abrasive grain 11 fixed to the end of the tool base 9. The tool base 9 is a cylindrical base made of 45# steel, with a length of approximately 13mm, and the clamping part is cylindrical; the first diamond abrasive grain 10 and the second diamond abrasive grain 11 are conical diamond abrasive grains with a cone angle of 90° or 120° and a grain diameter of 160μm to 250μm, and are fixed to the tool base 9 by brazing; the abrasive grain protrusion height is set to one-third of the grain diameter. If the protrusion height is too large, the abrasive grain is prone to falling off during scribing. This setting can ensure the rigidity of the abrasive grain while preventing it from falling off.

[0027] The abrasive grain distribution characteristics of adjacent abrasive grains include radial spacing d, height difference Δh, and the marking sequence determined by the circumferential spacing. Radial spacing d is the lateral distance between the marking trajectories of adjacent abrasive grains, and height difference Δh is the difference in the exit height of adjacent abrasive grains. The marking sequence is divided into sequential marking and non-sequential marking. In sequential marking, multiple abrasive grains enter the marking area sequentially along the circumference. In non-sequential marking, the abrasive grain in the middle position is affected by the combined scratches already formed by the adjacent abrasive grains on both sides. The multi-abrasive grain marking tool of this embodiment can also be configured with a third diamond abrasive grain 24 to form a three-abrasive grain marking tool for studying more complex abrasive grain coupling marking behavior.

[0028] Example 3: Detection and evaluation method flow.

[0029] like Figure 3As shown, the CVD-SiC material multi-abrasive scribing subsurface damage detection and evaluation method of this embodiment includes workpiece preparation step 31, scribing tool preparation step 32, multi-abrasive scribing experiment step 33, scribing force acquisition step 34, surface morphology observation step 35, subsurface damage detection step 36, and comprehensive evaluation step 37; as optional steps, it also includes finite element simulation verification step 38 and subsurface damage prediction model establishment step 39.

[0030] In step 31 of the workpiece preparation process, the CVD-SiC material workpiece blank is cut into blocks, and the surface is polished on both sides to obtain a mirror-level surface quality, which facilitates subsequent microscopic observation of scratch morphology and detection of subsurface damage. As an example, the workpiece can be a block sample of 20mm×20mm×5mm, and the sample size can be adjusted according to the testing requirements.

[0031] In step 32 of the tool preparation process, at least two diamond abrasive grains are fixed at the end of the tool substrate 9, and the radial spacing, height difference and other abrasive grain distribution characteristic parameters of adjacent abrasive grains are set according to the experimental design.

[0032] In step 33 of the multi-abrasive scribing experiment, the workpiece is clamped in the workpiece fixture 4 and fixed on the force measuring device 5. The multi-abrasive scribing tool 2 performs linear scribing at a set depth on the workpiece surface, forming at least two scratches. Multiple sets of experiments are set up, and each set of experiments changes one abrasive distribution characteristic parameter while keeping other parameters constant, so as to examine the effect of this parameter on subsurface damage individually. In this embodiment, the depth of cut is set to 20μm, 30μm or 40μm, and the scribing speed is 700mm / min; the radial spacing takes multiple values ​​from 20μm, 50μm, 80μm, 100μm and 150μm; the height difference takes multiple values ​​from 0, 0.005mm, 0.01mm, 0.015mm and 0.02mm; the scribing sequence is divided into two groups: sequential scribing type and non-sequential scribing type.

[0033] In step 34 of the scratching force acquisition process, the scratching force signal is acquired by the force measuring device 5. In this embodiment, the force measuring device 5 is a piezoelectric force gauge. The scratching force signal is amplified by a charge amplifier and then acquired by a data acquisition device and transmitted to the computer 8. The computer 8 selects a stable scratching section from when the abrasive grains have completely entered the workpiece to when they are about to exit the workpiece, and calculates the average value of the normal scratching force and the tangential scratching force in this section to obtain the average normal scratching force and the average tangential scratching force. When multiple abrasive grains are used for scratching, the scratches formed by the independent action of a single abrasive grain are ordinary scratches, while the scratches affected by the interference of adjacent abrasive grains are interference scratches. The scratching forces of the two types of scratches are statistically analyzed separately to compare and analyze the influence of interference on the scratching force.

[0034] In step 35 of surface morphology observation, the surface of the etched workpiece is observed under a microscope, which can be done using a scanning electron microscope to obtain the scratch morphology and scratch interference characteristics. Scratch interference forms include scratch overlap, partial scratch overlap, and scratch separation: when the scratch spacing is small, the interference region 14 of the two scratches undergoes material fusion and breakage, resulting in scratch overlap; when the scratch spacing is moderate, the two scratches partially overlap, forming a ridge 15 between them; when the scratch spacing is sufficiently large, the two scratches separate from each other, and the separated scratches are respectively designated as the first scratch 12 and the second scratch 13. Scratch interference characteristics include the ridge 15 between adjacent scratches, the broken area at the scratch edge, and chipped edges.

[0035] In step 36 of the subsurface damage detection, the detection cross-section is prepared and polished, and then microscopically observed. The detection cross-section can be prepared using either a cross-section polishing method or an interface bonding method. The cross-section polishing method involves cutting the workpiece perpendicular to the scratch direction, pre-grinding the obtained detection cross-section 21 with diamond wet-grind sandpaper, then polishing it to a mirror finish, cleaning, and then microscopically observing the detection cross-section 21. The interface bonding method involves cutting the workpiece parallel to the scratch direction and polishing the cut surface. The two polished surfaces are placed opposite each other and bonded together with an adhesive layer 25 to form an adhesive sample. A scratch test is performed on the surface of the adhesive sample. After the test, the adhesive sample is disassembled, and the original polished surface is microscopically observed. Figure 4 As shown, the subsurface damage obtained by microscopic observation includes the plastic deformation zone 19, the median crack 16, the transverse crack 17, and the radial crack 18, which together constitute the subsurface damage region 23. For polycrystalline silicon carbide materials, intragranular cracks, grain boundary cracks, and transgranular cracks can also be observed. The maximum distance of each crack from the processed surface 22 is measured as the subsurface damage depth of this set of experiments.

[0036] In the comprehensive evaluation step 37, the subsurface damage depth measured in each group of experiments is used as the main evaluation index, combined with the average scratch force and scratch interference characteristics for comprehensive evaluation. Specifically, by comparing the subsurface damage depth of each group of experiments, the influence of abrasive distribution characteristic parameters on subsurface damage is obtained; by combining the changes in average scratch force and scratch interference characteristics, the interference spacing that makes the interference between adjacent scratches strongest and the critical spacing that makes adjacent scratches independent are determined; based on the correspondence between interference spacing, critical spacing and subsurface damage depth, the degree of subsurface damage under different abrasive distribution characteristics is evaluated. As an example, for dual abrasive scribing with an abrasive cone angle of 90°, the radial spacing with the strongest interference is around 50 μm; for dual abrasive scribing with an abrasive cone angle of 120°, the radial spacing with the strongest interference is around 100 μm; when the cutting depth is set to 20 μm, the critical spacing that makes adjacent scratches independent is around 0.1 mm; when the cutting depth is set to 30 μm, the critical spacing is around 0.08 mm. The above determination results of interference spacing and critical spacing can be used to guide the design of grinding wheel abrasive grain arrangement: in cases where it is necessary to control subsurface damage, the spacing between abrasive grains on the grinding wheel surface can be made greater than the critical spacing to reduce interference between scratches; in cases where it is necessary to improve material removal efficiency, the abrasive grain spacing corresponding to the strongest interference spacing can be used as a reference for abrasive grain arrangement.

[0037] Example 4: Finite element simulation verification.

[0038] This embodiment establishes a multi-abrasive grain scribing finite element model based on the JH-2 constitutive model to simulate and verify the multi-abrasive grain scribing process. Workpiece 3 is a CVD-SiC material workpiece, and a finite element model with dimensions of 1mm×0.5mm×0.2mm is established; the mesh adopts hexahedral elements, and the workpiece is cut into upper and lower layers. The upper layer mesh is more finely divided, and the lower layer mesh is more sparsely divided to reduce the amount of calculation and improve the calculation accuracy; the first diamond abrasive grain 10 and the second diamond abrasive grain 11 are modeled as conical abrasive grains with a height of 0.4mm, a grain diameter of 0.15mm, a apex cone angle of 90°, and a radial spacing of d, which move along the scribing direction under a set cutting depth; the simulation adopts a dynamic-explicit analysis step, and surface-to-surface contact and general contact are set between the abrasive grains and the workpiece. The friction coefficient of the contact surface is 0.3, and the diamond abrasive grains are defined as rigid bodies. The simulation outputs scratch force, stress distribution, scratch morphology, and subsurface damage distribution. The simulation results are compared with the experimental test results of Example 3 to verify the reliability of the test evaluation results. The simulation results can also be used to supplement combinations of abrasive particle distribution characteristic parameters that are difficult to cover experimentally, thus expanding the evaluation scope.

[0039] Example 5: Subsurface damage prediction model.

[0040] Following step 37 of the comprehensive evaluation, this embodiment establishes a subsurface damage depth prediction model based on the correspondence between the subsurface damage depth and abrasive particle distribution characteristic parameters and the set cutting depth in each experimental group. This model is then used to predict the subsurface damage depth under other abrasive particle distribution characteristic parameters, thereby obtaining subsurface damage prediction results over a large parameter range with fewer experiments. The prediction effect of this model under abrasive particle distribution characteristic parameters is within the design expectations and requires further experimental verification.

Claims

1. A method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC, characterized in that, Includes the following steps: Step 1: Prepare a CVD-SiC material workpiece, cut the workpiece into sections, and polish the surface to a mirror finish. Step 2: Prepare a multi-abrasive scribing tool, fixing at least two diamond abrasive grains on the tool substrate, ensuring adjacent grains have predetermined abrasive grain distribution characteristics. Step 3: Clamp and fix the workpiece on a force measuring device, allowing the multi-abrasive scribing tool to perform linear scribing at a predetermined depth on the workpiece surface, forming at least two scratches. Multiple sets of experiments are conducted, each changing at least one abrasive grain distribution characteristic parameter. Step 4: Collect the scribing force signal during each set of experiments using the force measuring device, extract the scribing force signal from the stable scribing section, and calculate the average scribing force. The scratching force, which includes the average normal scratching force and the average tangential scratching force; Step 5, perform microscopic observation on the surface of the workpiece after scratching to obtain the scratch morphology and scratch interference characteristics; Step 6, prepare a detection section for observing subsurface damage and polish the detection section, perform microscopic observation on the polished detection section to identify subsurface cracks and measure the subsurface damage depth; Step 7, use the subsurface damage depth measured in each group of experiments as the main evaluation index, combined with the average scratching force and the scratch interference characteristics, evaluate the influence of abrasive distribution characteristics on the subsurface damage of the CVD-SiC material, and determine the interference intensity of multi-abrasive scratching and its corresponding subsurface damage degree.

2. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 1, characterized in that, The abrasive grain distribution characteristic parameters include at least one of the following: radial spacing between adjacent abrasive grains, height difference between adjacent abrasive grains, and marking sequence determined by circumferential spacing between abrasive grains. In each group of experiments, one abrasive grain distribution characteristic parameter is changed while keeping other abrasive grain distribution characteristic parameters unchanged.

3. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 2, characterized in that, In the multiple sets of experiments, the radial spacing takes at least two values ​​from 20μm, 50μm, 80μm, 100μm and 150μm.

4. The method for detecting and evaluating subsurface damage caused by multi-grained scribing on CVD-SiC according to claim 2, characterized in that, The marking sequence includes sequential marking and non-sequential marking. In the sequential marking type, multiple abrasive grains enter the marking area sequentially along the circumference. In the non-sequential marking type, at least one abrasive grain is affected by the combined scratches already formed by the adjacent abrasive grains on both sides when it enters the marking area.

5. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 1, characterized in that, The tool base of the multi-abrasive scribing tool is a cylindrical base, the diamond abrasive is a conical diamond abrasive with a cone angle of 90° or 120°, a particle size of 160μm to 250μm, and the abrasive tip height is set to one-third of the particle size.

6. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 1, characterized in that, The set cutting depth is 20μm, 30μm or 40μm, and the scribing speed is 700mm / min.

7. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 1, characterized in that, In step six, the test cross section is prepared by either cross section polishing or interface bonding. The cross section polishing method involves cutting the workpiece along a direction perpendicular to the scratch, polishing the cut cross section, and then performing microscopic observation. The interface bonding method involves bonding the two polished surfaces of the workpiece together and then scratching them. After scratching, the bonded sample is separated, and the original polished surface is then observed under a microscope.

8. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 1, characterized in that, The subsurface cracks identified in step six include at least one of the following: median cracks, transverse cracks, radial cracks, intragranular cracks, grain boundary cracks, and transgranular cracks. The subsurface damage depth is the maximum depth of the subsurface crack from the machined surface of the workpiece.

9. The method for detecting and evaluating subsurface damage caused by multi-abrasive scribing on CVD-SiC according to claim 2, characterized in that, The scratch interference features described in step five include at least one of the following: ridges between adjacent scratches, broken areas at the edge of scratches, and chipped edges; when the radial spacing is greater than or equal to the critical spacing, a complete ridge is formed between adjacent scratches, and the adjacent scratches are determined to be independent of each other; when the radial spacing is less than the critical spacing, material fusion and breakage occur between adjacent scratches, and the adjacent scratches are determined to interfere with each other.

10. A method for detecting and evaluating subsurface damage caused by multi-grained scribing on CVD-SiC, characterized in that, include: The machine tool includes a spindle for mounting a multi-abrasive scribing tool, the multi-abrasive scribing tool having at least two diamond abrasive grains fixed on its base; a workpiece fixture for fixing a CVD-SiC material workpiece; a force measuring device mounted on the machine tool's worktable, the workpiece fixture fixed to the force measuring device; a signal acquisition and processing device connected to the force measuring device; and a computer connected to the signal acquisition and processing device, configured to: receive the scribing force signal output by the signal acquisition and processing device; extract the scribing force signal of a stable scribing section and calculate the average scribing force; receive the scratch morphology, scratch interference characteristics, subsurface crack identification results, and subsurface damage depth obtained from microscopic observation; and, using the subsurface damage depth as the primary evaluation index, combine the average scribing force and the scratch interference characteristics to output the evaluation results of the interference intensity of the multi-abrasive scribing and the corresponding subsurface damage degree.

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