Nanosecond laser precision machining method for low-index crystal face of monocrystal diamond

Abstract

The invention relates to a nanosecond laser precision machining method for a low-index crystal face of a single crystal diamond, and aims to solve the machining problems caused by high hardness, high chemical stability and low toughness of the single crystal diamond. According to the method, a nanosecond laser technology is adopted, microgroove machining is carried out on low-index crystal faces such as {100}, {110} and {111} of single crystal diamond, and high-precision material removal and surface appearance control are achieved by adjusting laser power and scanning speed. In the machining process, laser energy is accumulated, so that diamond lattices are subjected to graphitization transformation, a graphite layer is formed, gaseous carbon is generated through evaporation stripping, and finally, an amorphous carbon layer is formed near the groove through condensation. According to the method, the oxidation and graphitization effects in the diamond laser machining process are considered, and accurate control over the hierarchical structure of the side wall of the diamond microgroove is achieved by optimizing technological parameters. Compared with the prior art, the method has the advantages of high efficiency, high precision, low damage, wide application and simplicity and convenience in operation, can meet the processing requirements of complex structures and high precision requirements, and provides important support for application of the single crystal diamond in the fields of precision manufacturing, optical devices and the like.

Description

Technical Field

[0001] The invention relates to a diamond precision machining method, in particular to a nanosecond laser precision machining method for a low-index crystal surface of a single-crystal diamond. Background Art

[0002] Diamond is widely used in the industrial field due to its excellent physical and chemical properties, such as extremely high hardness, thermal conductivity and chemical stability, especially in applications that require wear resistance and high temperature environments. However, the processing of diamond has always been a technical challenge, and traditional mechanical processing methods are difficult to achieve high-precision and high-quality surface treatment. With the development of micro-nano manufacturing technology, laser processing has become an important means of diamond precision processing due to its advantages such as non-contact, high energy density and controllability.

[0003] In laser processing of diamond, the selection of crystal planes has a significant impact on the processing quality. Low-index crystal planes usually have better mechanical properties and chemical stability due to their higher atomic density and lower surface energy. Therefore, precision processing of low-index crystal planes of single-crystal diamond can significantly improve the application performance and life of diamond materials. However, traditional laser processing technology is difficult to meet the needs of precision processing when processing low-index crystal planes due to problems such as large heat-affected zone and low processing accuracy. Summary of the invention

[0004] The purpose of the present invention is to propose a nanosecond laser precision processing method for low-index crystal planes of single-crystal diamond, aiming to solve the deficiencies in the prior art. This method achieves efficient and high-precision processing of low-index crystal planes of single-crystal diamond by precisely controlling laser parameters such as pulse width, energy density and repetition frequency. This technology can not only reduce thermal effects, improve processing speed and surface quality, but also flexibly adjust processing parameters according to material properties and processing requirements to achieve customized precision processing. This innovative method is expected to promote the application and development of diamond materials in high-end manufacturing, aerospace, biomedicine and other fields.

[0005] The technical solution adopted by the present invention is a nanosecond laser precision processing method for a low-index crystal surface of a single-crystal diamond, which comprises the following steps:

[0006] Step 1: Diamond planarization treatment: each crystal surface of the single crystal diamond sample is subjected to mechanical polishing pretreatment, using a cast iron disc as a grinding disc, and the grinding disc speed is 4000rpm / min. After polishing, the surface roughness is reduced to 2-4nm;

[0007] Step 2: Arrange the surfaces to be processed of each crystal plane sample close to the bottom surface of the abrasive tool in sequence, and fix them with a mounting machine so that the {100}, {110}, and {111} crystal planes as the surfaces to be processed are in the same plane after sample preparation;

[0008] Step 3: After the sample preparation is completed, the diamond sample is fixed with a fixture, and the laser processing environment is adjusted to ensure the temperature and humidity conditions; the laser processing program is set to linear processing, and its laser processing parameters are set to process the three crystal planes to obtain diamond surface microgrooves;

[0009] Step 4: Take out the sample and store it to avoid contamination for subsequent material characterization.

[0010] Preferably, it is to select the {100}, {110} or {111} crystal plane of single crystal diamond as the processing plane, and use a nanosecond laser to perform microgroove processing on the crystal plane. As the laser power increases, the width and depth of the microgrooves on each crystal plane increase accordingly, and as the laser scanning rate increases, the width and depth of the microgrooves on each crystal plane decrease accordingly.

[0011] Furthermore, the laser power ranges from 100 to 10000 mW, and the scanning rate ranges from 10 to 1000 mm / s.

[0012] Furthermore, the laser processing equipment has a laser pulse width of 50ns-80ns, a frequency of 5-15kHz, a laser filling spacing of 4-8mm, and a defocus distance of -1.0-0.0mm.

[0013] Preferably, when the laser power is in the range of 2000-8000 mW, the width of the microgrooves on the {100} crystal plane of the single crystal diamond is in the range of 0.1-1 mm, and the depth is in the range of 0.05-0.5 mm.

[0014] Preferably, when the laser scanning rate is in the range of 50-500 mm / s, the width of the microgrooves on the {110} crystal plane of the single crystal diamond is in the range of 0.08-0.8 mm, and the depth is in the range of 0.04-0.4 mm.

[0015] Preferably, the hierarchical structure of the diamond microgroove sidewall includes a diamond original layer, an induced metamorphic layer sublayer, a graphite layer and an amorphous carbon layer. These hierarchical structures have a significant impact on the processing process and the performance of the final product. Diamond original layer: This is the outermost layer of the diamond surface before microgroove processing, and has typical physical and chemical properties of diamond, such as high hardness and chemical stability. Induced metamorphic layer sublayer: During laser processing, due to the high temperature of the laser, the material near the diamond surface may undergo a phase change to form an induced metamorphic layer. This layer may exhibit different physical properties from the original diamond layer, such as reduced hardness or changed chemical stability. Graphite layer: The accumulation of laser energy causes the diamond lattice to undergo a graphitization transformation to form a graphite layer. The formation of the graphite layer is a key step in the laser processing process because it involves phase change and removal of the material. Amorphous carbon layer: The graphite layer evaporates under the action of the laser, and the gaseous carbon produced condenses near the groove to form an amorphous carbon layer. This layer has a different structure and properties from diamond and graphite, which may affect the surface quality of the microgroove and subsequent processing or application.

[0016] Furthermore, the laser processing process also includes the removal of diamond, which is to remove the diamond material itself, that is, the carbon atomic structure of single crystal diamond, by vaporization, oxidation, stripping and fragmentation. Vaporization: The high temperature of the laser allows some carbon atoms on the surface of the diamond to obtain enough energy to directly transform from solid to gas. This process is called laser-induced vaporization or photolysis. Vaporization is one of the main ways to remove diamond materials. Oxidation: In the atmospheric environment, carbon atoms on the surface of diamond may react with oxygen to form oxides (such as carbon monoxide CO and carbon dioxide CO2), which are then released from the surface, resulting in the removal of material. Stripping: The thermal stress and thermal expansion generated during laser processing can lead to layered stripping of the surface or near-surface area of ​​the material. This stripping effect helps to remove the material, especially in the removal of the induced metamorphic layer sublayer. Fragmentation: In some cases, laser processing may cause thermal stress concentration in local areas, leading to the expansion of microscopic cracks in the material and ultimately causing the material to break. This fragmentation effect helps to further remove the diamond material.

[0017] Beneficial effects of the present invention:

[0018] (1) Improving processing efficiency: The nanosecond laser technology used in the present invention realizes the rapid processing of low-index crystal planes of single-crystal diamond by optimizing laser parameters, significantly improving production efficiency while maintaining processing quality.

[0019] (2) Optimizing processing quality: By precisely controlling the laser pulse, the present invention effectively reduces the thermal impact during the processing and avoids thermal damage to the material, thereby improving the surface quality of the processed diamond and ensuring the integrity and consistency of the material.

[0020] (3) Enhanced material properties: By precisely machining low-index crystal planes, the present invention can better demonstrate the excellent physical properties of diamond, such as hardness and thermal conductivity, thereby enhancing the performance of the material in various applications.

[0021] (4) Reducing production costs: The processing method of the present invention reduces the reliance on complex equipment, simplifies the processing flow, and reduces the consumption of materials and energy, thereby effectively reducing production costs.

[0022] (5) Improving material utilization: The present invention reduces material waste and improves material utilization through precise laser processing, which has important economic significance for expensive diamond materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The width of microgrooves on {100}, {110}, and {111} crystal planes processed with different laser powers.

[0024] Figure 2 The depth of microgrooves on {100}, {110}, and {111} crystal planes processed with different laser powers.

[0025] Figure 3 Material removal rates of {100}, {110}, and {111} planes under different laser powers. DETAILED DESCRIPTION

[0026] Example 1

[0027] High temperature and high pressure synthetic single crystal diamond is selected, and its particle size is about 4mm. The {100} crystal plane is selected as the processing surface. Before laser processing of single crystal diamond particles, its surface needs to be pre-treated to ensure the accuracy and precision of the processing effect. First, its surface will be polished, and then pickled with concentrated sulfuric acid to remove impurities and make the surface flat (Ra is about 3nm). This will facilitate subsequent observation and improve the accuracy and reliability of laser processing.

[0028] Before mounting, the sample needs to be flattened with a flattener to ensure its surface level. Then the single crystal diamond particles are mounted and fixed on the sample holder for subsequent laser processing experiments. The importance of this step lies in ensuring the stability and accuracy of the sample, thereby achieving high-quality laser processing results.

[0029] The sample was placed in a laser processing device and a 4W nanosecond laser was used to process the low-index crystal surface of single-crystal diamond. The laser pulse width was set to 50ns, the repetition frequency was 10kHz, and the energy density was 1J / cm 2During the processing, the laser beam moves at a speed of 10m / min and the processing depth is controlled within 0.05mm. Through this method, we have successfully achieved precision processing of the diamond surface with a material removal rate of 5.23×10 -7 g / pulse.

[0030] Example 2

[0031] High temperature and high pressure synthetic single crystal diamond is selected, and its particle size is about 4mm. The {110} crystal plane is selected as the processing surface. Before laser processing of single crystal diamond particles, its surface needs to be pre-treated to ensure the accuracy and precision of the processing effect. First, its surface will be polished, and then pickled with concentrated sulfuric acid to remove impurities and make the surface flat (Ra is about 3nm). This will facilitate subsequent observation and improve the accuracy and reliability of laser processing.

[0032] Before mounting, the sample needs to be flattened with a flattener to ensure its surface level. Then the single crystal diamond particles are mounted and fixed on the sample holder for subsequent laser processing experiments. The importance of this step lies in ensuring the stability and accuracy of the sample, thereby achieving high-quality laser processing results.

[0033] The sample was placed in a laser processing device and a 12W nanosecond laser was used to process the low-index crystal surface of single-crystal diamond. The laser pulse width was set to 50ns, the repetition frequency was 10kHz, and the energy density was 1J / cm 2 During the processing, the laser beam moves at a speed of 10m / min and the processing depth is controlled within 0.05mm. Through this method, we have successfully achieved precision processing of the diamond surface with a material removal rate of 44.85×10 -7 g / pulse.

Claims

1. A nanosecond laser precision processing method for low-index crystal planes of single-crystal diamond, characterized by: It includes the following steps: Step 1: Diamond planarization treatment: each crystal surface of the single crystal diamond sample is subjected to mechanical polishing pretreatment, using a cast iron disc as a grinding disc, and the grinding disc speed is 4000rpm / min. After polishing, the surface roughness is reduced to 2-4nm; Step 2: Arrange the surfaces to be processed of each crystal plane sample close to the bottom surface of the abrasive tool in sequence, and fix them with a mounting machine so that the {100}, {110}, and {111} crystal planes as the surfaces to be processed are in the same plane after sample preparation; Step 3: After the sample preparation is completed, the diamond sample is fixed with a fixture, and the laser processing environment is adjusted to ensure the temperature and humidity conditions; the laser processing program is set to linear processing, and its laser processing parameters are set to process the three crystal planes to obtain diamond surface microgrooves; Step 4: Take out the sample and store it to avoid contamination for subsequent material characterization.

2. The nanosecond laser precision machining method for a low-index crystal plane of a single-crystal diamond according to claim 1, characterized in that: It selects the {100}, {110} or {111} crystal plane of single crystal diamond as the processing plane, and uses a nanosecond laser to perform microgroove processing on the crystal plane. As the laser power increases, the width and depth of the microgroove on each crystal plane increase accordingly, and as the laser scanning rate increases, the width and depth of the microgroove on each crystal plane decreases accordingly.

3. The nanosecond laser precision machining method for a low-index crystal plane of a single-crystal diamond according to claim 1, characterized in that: The laser power ranges from 100-10000mW and the scanning rate ranges from 10-1000mm / s.

4. The nanosecond laser precision machining method for a low-index crystal plane of a single-crystal diamond according to claim 1, characterized in that: The laser processing equipment has a laser pulse width of 50ns-80ns, a frequency of 5-15kHz, a laser filling spacing of 4-8mm, and a defocus distance of -1.0-0.0mm.

5. The nanosecond laser precision machining method for low-index crystal planes of single-crystal diamond according to claim 1, characterized in that: When the laser power is in the range of 2000-8000 mw, the width range of the microgroove on the {100} crystal plane of single crystal diamond is 0.1-1 mm, and the depth range is 0.05-0.5 mm.

6. The nanosecond laser precision machining method for low-index crystal planes of single-crystal diamond according to claim 1, characterized in that: When the laser scanning rate is in the range of 50-500 mm / s, the width of the microgrooves on the {110} crystal plane of single crystal diamond is in the range of 0.08-0.8 mm, and the depth is in the range of 0.04-0.4 mm.

7. The nanosecond laser precision machining method for low-index crystal planes of single-crystal diamond according to claim 1, characterized in that: The laser processing process also includes the removal of diamond, which is the removal of the diamond material itself, that is, the carbon atomic structure of single crystal diamond, through vaporization, oxidation, peeling and crushing.

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