Simple preparation method of large-size high-quality self-supporting diamond thick film
By depositing carbon compounds and nanodiamond layers on the surface of molybdenum blocks in multiple layers, the problems of growth rate and quality instability of diamond films on large-sized molybdenum blocks in the prior art have been solved. The multilayer deposition technology has solved the problems of slow film growth rate and unstable quality in the prior art, and realized the preparation of high-quality diamond films with high efficiency and low cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN FAMOUS DIAMOND IND CO LTD
- Filing Date
- 2026-02-24
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies result in slow growth rates and unstable quality of diamond films on large-size molybdenum blocks, and traditional methods are costly, making it difficult to meet the demands of high-performance applications.
A multilayer deposition technique was employed to form a carbon compound layer and a nanodiamond layer on the surface of a molybdenum block using a CVD device. Combined with diamond micron powder treatment, growth conditions were optimized to improve the uniformity and adhesion of the film and reduce thermal stress cracking.
It has achieved high-quality, low-cost growth of large-size diamond films, improved production efficiency and film mechanical properties, broadened the application fields of high performance, has strong adaptability, and reduced preparation costs.
Smart Images
Figure CN121992367A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of diamond thin film preparation technology, specifically relating to a simple method for preparing large-size, high-quality, self-supporting diamond thick films. Background Technology
[0002] In the preparation of high-quality diamond films, large-size molybdenum blocks are a key factor as the substrate material, and their surface treatment and film growth techniques directly affect the uniformity, adhesion, and mechanical properties of the film. With the continuous expansion of diamond film applications, the requirements for film quality are becoming increasingly stringent. Therefore, how to achieve the growth of high-quality diamond films on large-size molybdenum blocks has become an important research direction in the field of diamond film preparation technology.
[0003] Currently, the main methods used to address the challenge of growing diamond films on large-sized molybdenum blocks include traditional chemical vapor deposition (CVD) and physical vapor deposition (PVD) methods. For example, while traditional CVD can grow diamond films on the surface of molybdenum blocks, this method often suffers from slow growth rates, unstable film quality, and high equipment costs. PVD, on the other hand, can increase the growth rate, but the adhesion and uniformity of the films are often inferior to those grown using CVD.
[0004] Although existing technologies have improved the growth quality of diamond films to some extent, some problems and shortcomings still exist. First, the traditional CVD method has a slow growth rate, resulting in low production efficiency, and the film quality is affected by various factors, making it difficult to achieve large-scale, high-quality diamond film production. Second, although the PVD method has a fast growth rate, the film adhesion and uniformity are poor, limiting its use in high-performance applications. In addition, existing technical solutions have certain limitations in practical applications and cannot meet the diamond film quality requirements under different production conditions.
[0005] Therefore, developing a novel method for growing high-quality diamond films on large-size molybdenum blocks is of significant practical importance and application value. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention first provides a simple method for preparing large-size, high-quality self-supporting diamond thick films, so as to prepare diamond films with good uniformity, no cracks, and good mechanical properties, and to achieve the growth of high-quality diamond films on large-size molybdenum blocks at a low cost.
[0007] To achieve the above-mentioned objectives, this invention proposes a simple method for preparing large-size, high-quality self-supporting diamond thick films, comprising the following steps:
[0008] 1) Surface pretreatment: Large molybdenum blocks are ground with diamond micro powder to remove surface impurities, and then the surface of the large molybdenum blocks is plasma treated with CVD equipment; 2) CVD growth: 21) Under the conditions of 850-950℃, 5-8slm hydrogen, 2-4slm argon, and 3.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use CVD equipment to form a 100-200nm thick carbon-molybdenum compound layer on the surface of a large molybdenum block; after shutting down, use diamond micron powder for surface treatment. 22) Under the conditions of 800-850℃, 5-8slm hydrogen, 2-4slm argon, and 3.5-5.5kpa pressure, a dense nanodiamond and amorphous carbon mixture layer with a thickness of 200-300nm is grown on the surface of the carbon molybdenum compound layer using a CVD device with 3-5vol% methane and 0.2-1vol% oxygen in the mixed gas. Then, the carbon flow rate is gradually reduced to 0, and the temperature is cooled to 300℃ at a rate of 4℃ / min before the machine is turned off. The surface is then treated with diamond micron powder to remove excess carbon impurities. 23) Under the conditions of 850-950℃, 5-8slm hydrogen, and 3.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use CVD equipment to form a 100-200nm thick nanocrystalline layer on the surface of the dense nanodiamond and amorphous carbon mixture layer. After turning off the equipment, use diamond micro powder for surface treatment. 24) Under the conditions of 800-850℃, 5-8slm hydrogen, and 4.0-5.5kpa pressure, turn on 3-5vol% methane and 0.2-1vol% oxygen in the mixed gas, and use CVD equipment to continue to grow a dense nanodiamond and amorphous carbon mixture layer with a thickness of 100-200nm on the surface of the nanocrystalline layer. Then gradually reduce the carbon flow rate to 0, and after shutting down, use diamond micro powder for surface treatment. 3) Repeat steps 23)-24) 2 to 5 times according to the required polycrystalline film thickness. Under the conditions of 850-950℃, 5-8slm hydrogen, and 4.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use a CVD device to grow a nanocrystalline layer with a thickness of 0.3-1mm on the surface of the dense nanodiamond and amorphous carbon mixture layer generated in step 24), thereby preparing a high-quality diamond film.
[0009] Preferably, the nominal maximum linear dimension of the large molybdenum block is 2 to 4 inches, and the height is 40 to 100 mm.
[0010] Preferably, in steps 1) and 2), the particle size of the diamond powder is 0.5-1 μm.
[0011] Preferably, in step 1), the plasma treatment is carried out at 850-900°C using oxygen (0.2-2 vol%), hydrogen (5-8 slm), and argon (2-4 slm) in the mixed gas.
[0012] Preferably, in step 1), the plasma treatment time is 5-10 hours.
[0013] The principle of this invention is to directly deposit a multilayer composite layer of carbon and nanodiamond on the surface of a molybdenum block using a chemical vapor deposition (CVD) device. This solves the problem of thermal stress cracking in the thin film caused by high temperature changes, thereby improving the uniformity and consistency of the product surface. This technical solution achieves the growth of high-quality diamond films on large-size molybdenum blocks at low cost through precise control of CVD growth conditions and multilayer deposition technology.
[0014] Compared with existing CVD and PVD methods, this approach has the following advantages: 1) By optimizing the process flow, the growth rate and quality stability of diamond films were improved, thereby increasing production efficiency; 2) The film has stable quality, no cracks, good mechanical properties, and good adhesion, uniformity and consistency, which broadens its application in high-performance applications. 3) The equipment cost is relatively low. By reusing the equipment and materials used in the preparation process and by optimizing the chemical vapor deposition conditions, diamond film preparation at a lower cost is achieved, which is easy to realize for large-scale production. 4) Parameters can be adjusted according to different production conditions to meet diverse diamond film quality requirements, thus enhancing the adaptability of the technology; 5) It achieves a high film integrity rate for self-supporting thick films, reduces thermal shock stress, and thus improves the integrity of the film.
[0015] In summary, the preparation method of this invention is simple and convenient, can be reused multiple times, reduces the cost of using the substrate in the later stages, and achieves high film integrity and low thermal shock stress in self-supporting thick films. This not only improves the quality of diamond films but also reduces the preparation cost, making the application of diamond films more economical and efficient, with broad market demand and good application prospects. Attached Figure Description
[0016] Figure 1 This is the Raman spectrum of the high-quality diamond film prepared in Example 1 of the present invention.
[0017] Figure 2 A photograph of the product prepared in Example 1 of this invention. Detailed Implementation
[0018] The embodiments of the present invention are described in detail below. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention.
[0019] Example 1 1) Surface pretreatment: A large molybdenum block measuring 3 inches in size and 60 mm in height was taken and ground with 0.8 μm diamond powder to remove surface impurities. After pretreatment, the surface of the large molybdenum block was subjected to plasma treatment at 870°C with 1 vol% oxygen, 6 slm hydrogen, and 3 slm argon for 8 hours using a CVD device.
[0020] 2) CVD Growth: A 150 nm thick molybdenum carbide compound layer was formed under conditions of 870 °C, 6 slm hydrogen and 3 slm argon, and a pressure of 4 kPa, with 2.5 vol% methane. After shutdown, the surface was treated with 70 nm microparticles, and then a 250 nm thick dense nanodiamond and amorphous carbon mixture was grown on the surface under conditions of 4% methane, 0.5% oxygen, 830 °C, 6 slm hydrogen and 3 slm argon, and a pressure of 4 kPa. The carbon flow rate was gradually reduced to 0, and the temperature was lowered to 300 °C at a rate of 4 °C / min before shutdown. The surface was then treated with 70 nm microparticles for 45 minutes to remove excess carbon impurities. Then, under conditions of 870℃, 6slm hydrogen, and 4kPa pressure, 2vol% methane was turned on, and a 150nm thick nanocrystalline layer was formed on the surface of the dense nanodiamond and amorphous carbon mixture layer using a CVD device. After shutting down, 70nm diamond micropowder was used for surface treatment. Next, under conditions of 800℃, 6slm hydrogen, and 4kPa pressure, 4vol% methane and 0.5vol% oxygen were turned on, and a 150nm thick dense nanodiamond and amorphous carbon mixture layer was grown on the surface of the nanocrystalline layer using a CVD device. Then, the carbon flow rate was gradually reduced to 0, and after shutting down, 70nm diamond micropowder was used for surface treatment. 3) Multilayer deposition: After repeating steps 23)-24) 3 times, under the conditions of 870℃, 6slm hydrogen, and 5kpa pressure, 2.5vol% methane is turned on, and a nanocrystalline layer with a thickness of 0.5mm is grown on the surface of the dense nanodiamond and amorphous carbon mixture layer generated in step 24) using a CVD device, thereby preparing a high-quality diamond film.
[0021] Figure 1 The image shows the Raman spectrum of the high-quality diamond film prepared in Example 1. Figure 2 A photograph of the product prepared in Example 1 of this invention.
[0022] Example 2 1) Surface pretreatment: A large molybdenum block measuring 4 inches in size and 80 mm in height was taken and ground with 0.6 μm diamond powder to remove surface impurities. After pretreatment, the surface of the large molybdenum block was subjected to plasma treatment for 6 hours at 890℃ using a CVD device with 0.5 vol% oxygen, 7 slm hydrogen, and 4 slm argon.
[0023] 2) CVD Growth: Under conditions of 890℃, 7 slm hydrogen and 4 slm argon, and a pressure of 4.5 kPa, 3 vol% methane was used to form a 180 nm thick carbon-molybdenum compound layer. After shutdown, surface treatment was performed using 90 nm microparticles. Then, a 280 nm thick dense nanodiamond and amorphous carbon mixture was grown on the surface under conditions of 3.5% methane, 0.8% oxygen, 820℃, 7 slm hydrogen and 4 slm argon, and a pressure of 4.5 kPa. The carbon flow rate was gradually reduced to 0, and the temperature was lowered to 300℃ at a rate of 4℃ / min before shutdown. The surface was then treated with 90 nm microparticles for 50 minutes to remove excess carbon impurities. Then, under conditions of 850℃, 7slm hydrogen, and 4.5kPa pressure, 2vol% methane was turned on, and a 180nm thick nanocrystalline layer was formed on the surface of the dense nanodiamond and amorphous carbon mixture layer using a CVD device. After shutting down, 90nm diamond micropowder was used for surface treatment. Next, under conditions of 850℃, 7slm hydrogen, and 4.5kPa pressure, 3vol% methane and 0.2vol% oxygen were turned on, and a 180nm thick dense nanodiamond and amorphous carbon mixture layer was grown on the surface of the nanocrystalline layer using a CVD device. Then, the carbon flow rate was gradually reduced to 0, and after shutting down, 90nm diamond micropowder was used for surface treatment. 3) Multilayer deposition: After repeating steps 23)-24) 4 times, under the conditions of 890℃, 7slm hydrogen, and 5.5kpa pressure, 2.8vol% methane is turned on, and a nanocrystalline layer with a thickness of 0.8mm is grown on the surface of the dense nanodiamond and amorphous carbon mixture layer generated in step 24) using a CVD device, thereby preparing a high-quality diamond film.
[0024] The above embodiments demonstrate that this technical solution can flexibly adjust CVD growth parameters and the number of multilayer depositions to achieve the growth of high-quality diamond films based on different large-size molybdenum blocks and film thickness requirements. Compared with traditional methods, this solution offers higher production efficiency and better film quality, and is expected to be widely used in the field of diamond film preparation.
Claims
1. A simple method for preparing large-size, high-quality self-supporting diamond thick films, characterized in that, Includes the following steps: 1) Surface pretreatment: Large molybdenum blocks are ground with diamond micro powder to remove surface impurities, and then the surface of the large molybdenum blocks is plasma treated with CVD equipment; 2) CVD growth: 21) Under the conditions of 850-950℃, 5-8slm hydrogen, 2-4slm argon, and 3.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use CVD equipment to form a 100-200nm thick carbon-molybdenum compound layer on the surface of a large molybdenum block; after shutting down, use diamond micron powder for surface treatment. 22) Under the conditions of 800-850℃, 5-8slm hydrogen, 2-4slm argon, and 3.5-5.5kpa pressure, a dense nanodiamond and amorphous carbon mixture layer with a thickness of 200-300nm is grown on the surface of the carbon molybdenum compound layer using a CVD device with 3-5vol% methane and 0.2-1vol% oxygen in the mixed gas. Then, the carbon flow rate is gradually reduced to 0, and the temperature is cooled to 300℃ at a rate of 4℃ / min before the machine is turned off. The surface is then treated with diamond micron powder to remove excess carbon impurities. 23) Under the conditions of 850-950℃, 5-8slm hydrogen, and 3.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use CVD equipment to form a 100-200nm thick nanocrystalline layer on the surface of the dense nanodiamond and amorphous carbon mixture layer. After turning off the equipment, use diamond micro powder for surface treatment. 24) Under the conditions of 800-850℃, 5-8slm hydrogen, and 4.0-5.5kpa pressure, turn on 3-5vol% methane and 0.2-1vol% oxygen in the mixed gas, and use CVD equipment to continue to grow a dense nanodiamond and amorphous carbon mixture layer with a thickness of 100-200nm on the surface of the nanocrystalline layer. Then gradually reduce the carbon flow rate to 0, and after shutting down, use diamond micro powder for surface treatment. 3) Repeat steps 23)-24) 2 to 5 times according to the required polycrystalline film thickness. Under the conditions of 850-950℃, 5-8slm hydrogen, and 4.5-5.5kpa pressure, turn on methane, which accounts for 2-3 vol% of the mixed gas, and use a CVD device to grow a nanocrystalline layer with a thickness of 0.3-1mm on the surface of the dense nanodiamond and amorphous carbon mixture layer generated in step 24), thereby preparing a high-quality diamond film.
2. The simple method for preparing large-size, high-quality self-supporting diamond thick films according to claim 1, characterized in that, The nominal maximum linear dimension of the large-size molybdenum block is 2 to 4 inches, and the height is 40 to 100 mm.
3. The simple method for preparing large-size, high-quality self-supporting diamond thick films according to claim 1, characterized in that, In steps 1) and 2), the particle size of the diamond powder is 0.5-1μm.
4. The simple method for preparing large-size, high-quality self-supporting diamond thick films according to claim 1, characterized in that, In step 1), the plasma treatment is carried out at 850-900°C using oxygen (0.2-2 vol%), hydrogen (5-8 slm), and argon (2-4 slm) in the mixed gas.
5. A simple method for preparing large-size, high-quality self-supporting diamond thick films according to claim 4, characterized in that, In step 1), the plasma treatment time is 5-10 hours.