High-temperature-resistant diamond-like carbon film and preparation method thereof

Abstract

The application discloses a high-temperature-resistant and heat-conducting diamond-like film and a preparation method thereof, and relates to the field of film coating technology. The high-temperature-resistant and heat-conducting diamond-like film is a same-element hetero-interface structure plated on the surface of a substrate; the sp 3 -C bond content in the diamond-like film continuously changes along the thickness direction of the diamond-like film; the average sp 3 -C bond content accounts for more than 40% of the total carbon-carbon bond content in the diamond-like film. The application improves the interface thermal resistance effect of the whole film, improves the high-temperature-resistant performance of the diamond-like film, guarantees the balanced state of the film-substrate bonding force, internal stress, heat conduction and surface lubricity of the film, makes the film have excellent comprehensive performance, and further improves the applicable environment of the diamond-like material.

Description

Technical Field

[0001] This application relates to the field of coating technology, and in particular to a high-temperature resistant, thermally conductive diamond-like thin film and its preparation method. Background Technology

[0002] Diamond-like carbon (DLC) is a superhard material composed of layered graphite phases. 2 -C bond and tetrahedral diamond phase sp 3 Amorphous carbon composed of -C bonds, according to the diamond phase sp 3 The proportion of -C bonds in the total carbon-carbon bonds can be classified as high sp. 3 High-hardness hydrogen-free diamond with high -C bond content, and high sp 3 Hydrogen-containing amorphous carbon with moderate hardness and less sp bond content. 3 Diamond-like carbon (DLC) is a type of graphite-like carbon with a relatively soft C-bond content. It can be fabricated into thin films to improve the mechanical and surface properties of substrates. Carbon films with varying diamond phase contents are widely used on the surfaces of cutting tools, molds, and other similar products. However, during the process of using DLC ​​films as surface modifiers for tools and molds, they are exposed to high temperatures and even pressure environments. These high temperatures promote the formation of poly(carbonyl) bonds. 3 -C structure towards sp 2 The transformation of the -C structure, coupled with thermal stress, further pushes the film structure towards an unstable state, ultimately leading to rupture and detachment. Therefore, it is necessary to improve the heat resistance and mechanical properties of diamond-like carbon films to meet application requirements.

[0003] Currently, low sp 3 Graphite-like carbons with high -C bond content are limited in application in high-temperature, high-pressure, and corrosive environments due to their poor heat resistance and mechanical properties. However, increasing sp... 3 Carbon films with low -C bond content are due to sp 3 The higher the -C bond content, the greater the internal stress of the film, and the easier it is to break down under internal stress, which limits the film thickness. 3 Hydrogen-free diamond-like carbon (DLC) films with -C bond density greater than 70% exhibit insufficient bonding with the substrate beyond 500 nm to offset internal stress, making them prone to cracking at large dimensions, corners, and locations with abrupt curvature changes under thermal stress. Therefore, while improving the high-temperature resistance of DLC films, it is also necessary to ensure the film-substrate adhesion and reduce internal stress. Summary of the Invention

[0004] The main objective of this application is to provide a high-temperature resistant and thermally conductive diamond-like carbon film and its preparation method, aiming to solve the technical problem that existing diamond-like carbon films are difficult to balance in terms of heat resistance, film-substrate adhesion, thermal conductivity, and internal stress.

[0005] To achieve the above objectives, this application proposes a high-temperature resistant and thermally conductive diamond-like film, wherein the diamond-like film is an allotropic interface structure deposited on the surface of a substrate.

[0006] sp in the diamond-like film 3 -C bond content varies continuously along the thickness direction of the diamond-like carbon film;

[0007] The average sp in the diamond-like carbon film 3 -C bond content accounts for more than 40% of the total carbon-carbon bond content in the diamond-like carbon film.

[0008] Optionally, the sp 3 The -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0009] c[sp 3 -C]=f(z)

[0010] Where z is the coating thickness of the diamond-like carbon film starting from the substrate, and the value of z ranges from 20nm to 2000nm; f(z) represents a continuous function; c[sp 3 -C] represents the sp in the diamond-like film. 3 The content of -C bonds ranges from 20% to 100%.

[0011] Optionally, the continuous function may be of the following types: linear function, trigonometric function, exponential function, and power function.

[0012] Optionally, along the thickness direction of the diamond-like carbon film, the sp 3 The area with the highest C-C bond content accounts for more than 60% of the carbon-carbon bond content in the diamond-like carbon film at that thickness location.

[0013] Optionally, the diamond-like carbon film is deposited near the initial coating location on the substrate surface, where the sp... 3 -C bond content accounts for 20%-40% of the carbon-carbon bond content in diamond-like carbon films at this thickness location.

[0014] This application also proposes a method for preparing a high-temperature resistant, thermally conductive diamond-like thin film, comprising the following steps:

[0015] A layer of the sp is deposited on the surface of the substrate using a physical deposition method or a chemical deposition method. 3 Diamond-like films with -C bond content that varies continuously along the thickness direction.

[0016] Optionally, a layer of the sp is deposited on the surface of the substrate using a physical deposition method or a chemical deposition method. 3Diamond-like carbon films with continuously varying -C bond content along the coating direction include:

[0017] During the deposition of a diamond-like carbon (DLC) film on the surface of the substrate, the temperature of the substrate and the bias voltage of the substrate are continuously varied within a preset temperature range and a preset bias voltage range, respectively, through programming based on the continuous function, so as to deposit the DLC film on the surface of the substrate. 3 Diamond-like carbon films with -C bond content that varies continuously along the coating direction.

[0018] Optionally, the preset bias voltage range is -1800V to 0V, and the continuous change accuracy of the bias voltage is ±0.1V / s; the preset temperature range is 25℃ to 300℃, and the change accuracy of the temperature is ±0.05℃ / s.

[0019] Optionally, the sp 3 The -C bond content is related to the temperature of the matrix and the bias voltage of the matrix by the following formula:

[0020] BiasV = f(c[sp] 3 -C])+a×Δt

[0021] Where BiasV is the bias voltage; f(c[sp 3 -C]) is the sp 3 -C bond content is a monotonic function; Δt is the temperature change rate of the substrate detected in real time during coating; a is a correction factor, obtained experimentally.

[0022] Optionally, the physical deposition method includes magnetron sputtering, cathodic arc deposition, ion plating, and electron beam deposition; the chemical deposition method includes thermal decomposition.

[0023] This application aims to eliminate interfacial thermal resistance, reduce internal stress, and improve film-substrate adhesion by depositing a layer of SP on the substrate surface. 3 Diamond-like carbon (DLC) films exhibiting a continuous variation in -C bond content, with an average spc content of [missing information]. 3 -C bonds account for more than 40% of the total carbon-carbon bonds in diamond-like carbon films, providing basic heat resistance and hardness properties, and the sp... 3 The -C bonds exhibit a continuous transition, with minimal compositional variation near any location within the diamond-like carbon film. There is no multilayer film interface structure. 3 The -C bond content does not change abruptly, thus weakening the sp 3The abrupt change in phonon oscillation caused by the change in -C bond content reduces internal stress and interfacial thermal resistance, allowing the bonding force between the internal stress of the diamond-like carbon (DLC) film and the substrate to reach a good balance. The DLC film can not only meet the requirements of high hardness, but also take into account the coating thickness. The continuous internal structure of the film layer greatly alleviates the interfacial thermal resistance and improves the heat transfer performance of the entire film layer, thereby greatly improving the thermal stress resistance. Furthermore, by controlling the structure of the outermost surface of the film layer, the surface friction performance can be controlled, thus matching different contact materials. This application improves the high temperature resistance of the DLC film while ensuring a balanced state of film-substrate bonding force, internal stress, interfacial thermal resistance, and surface lubricity, giving the film excellent comprehensive performance and further improving the applicable environment of the DLC material. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 sp as described in Embodiment 1 of this application 3 A schematic diagram illustrating the continuous variation of -C bond content with the thickness of the diamond-like carbon film.

[0026] Figure 2 sp as described in Embodiment 2 of this application 3 A schematic diagram illustrating the continuous variation of -C bond content with the thickness of the diamond-like carbon film.

[0027] Figure 3 The sp described in Embodiment 3 of this application 3 A schematic diagram illustrating the continuous variation of -C bond content with the thickness of the diamond-like carbon film.

[0028] Figure 4 The sp described in Embodiment 4 of this application 3 A schematic diagram illustrating the continuous variation of -C bond content with the thickness of the diamond-like carbon film.

[0029] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0031] Currently, hydrogen-containing diamond-like carbon (DLC) films contain hydrogen, which reduces internal stress and allows for higher deposition thicknesses, but the hardness is difficult to exceed 30 GPa; low sp... 3 Graphite-like carbons with high -C bond content are limited in high-temperature applications due to their poor heat resistance and mechanical properties. 3 Methods for preparing hydrogen-free diamond-like carbon films with low -C bond content typically yield films with thicknesses rarely exceeding 1 μm, and sp 3 The higher the -C bond content, the greater the internal stress of the film, and the easier it is to break down under internal stress, resulting in a lower achievable deposition thickness. 3 When the thickness of hydrogen-free diamond-like carbon (DLC) with -C bond density >70% exceeds 500 nm, the bonding degree with the matrix is ​​insufficient to offset internal stress, making it prone to cracking at large dimensions, corners, and locations with abrupt curvature changes under thermal stress.

[0032] In existing technologies, the internal stress of the film layer can be improved by doping, but this requires highly complex hardware. To improve the film-substrate adhesion and reduce internal stress in high-hardness carbon films, existing technologies also employ allotropic multilayer film deposition designs in the coating process. For example, the paper "The Influence of Modulation Comparison on the Performance of Multilayer DLC Thin Films" uses a soft-hard multilayer gradient transition film structure to increase film-substrate adhesion. The transition method used involves different concentrations of sp... 3 The multilayer structure is composed of -C bonds; in addition, Chinese patent CN113061845B discloses a preparation process of ultra-black high-performance Ti-DLC coating, which adds a metal transition layer between the carbon film and the substrate to improve the adhesion. However, the multilayer diamond-like films prepared above have large differences in properties between the film layers. In addition to the substrate surface and the coating surface, there are also positions in the film layer where the composition and properties change abruptly, which can easily generate interfacial thermal resistance, reduce the heat transfer effect, and generate thermal stress accumulation.

[0033] Interfacial thermal resistance is the obstruction encountered by heat flow when passing through the interface between different materials. It is the phonon reflection, refraction, and scattering caused by the interaction of different hot carriers on both sides of the interface within the phonon free path range at the nanoscale. When the material scale is close to or even smaller than the phonon free path (1nm-100nm), the thermal conductivity of the material will decrease significantly compared to the thermal conductivity of bulk natural materials. At this time, the interfacial thermal resistance becomes non-negligible. Interfacial thermal resistance can reduce the thermal conductivity of micro / nano film materials by orders of magnitude. The thinner the film and the more interfaces, the stronger the reduction in interfacial thermal resistance and the stronger the heat transfer effect between film layers. In unsteady heat transfer environments above 600℃, conventional multilayer diamond-like carbon films can still experience structural instability and failure.

[0034] To address the technical problems existing in existing diamond-like carbon films, embodiments of this application provide a high-temperature resistant and thermally conductive diamond-like carbon film, wherein the diamond-like carbon film is an allotropic interface structure deposited on the surface of a substrate.

[0035] sp in the diamond-like film 3 -C bond content varies continuously along the thickness direction of the diamond-like carbon film;

[0036] The average sp in the diamond-like carbon film 3 -C bond content accounts for more than 40% of the total carbon-carbon bond content in the diamond-like carbon film.

[0037] This application aims to reduce internal stress and improve the adhesion between the film and the substrate by depositing a layer of SP on the substrate surface. 3 Diamond-like carbon (DLC) films exhibiting a continuous variation in -C bond content, with an average spc content of [missing information]. 3 -C bonds account for more than 40% of the total carbon-carbon bonds in diamond-like carbon films, providing basic heat resistance and hardness properties, and the sp... 3 The -C bonds exhibit a continuous transition, with minimal compositional variation near any location within the diamond-like carbon film. There is no multilayer film interface structure. 3 The -C bond content does not change abruptly, thus weakening the sp 3The abrupt change in phonon oscillation caused by the change in -C bond content reduces internal stress and interfacial thermal resistance, allowing the bonding force between the internal stress of the diamond-like carbon (DLC) film and the substrate to reach a good balance. The DLC film can not only meet the requirements of high hardness, but also take into account the coating thickness. The continuous internal structure of the film layer greatly alleviates the interfacial thermal resistance and improves the heat transfer performance of the entire film layer, thereby greatly improving the thermal stress resistance. Furthermore, by controlling the structure of the outermost surface of the film layer, the surface friction performance can be controlled, thus matching different contact materials. This application improves the high temperature resistance of the DLC film while ensuring a balanced state of film-substrate bonding force, internal stress, interfacial thermal resistance, and surface lubricity, giving the film excellent comprehensive performance and further improving the applicable environment of the DLC material.

[0038] As one possible implementation method of this application, the sp 3 The -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0039] c[sp 3 -C]=f(z)

[0040] Where z is the coating thickness of the diamond-like carbon film starting from the substrate, and the value of z ranges from 20nm to 2000nm; f(z) represents a continuous function; c[sp 3 -C] represents the sp in the diamond-like film. 3 The content of -C bonds ranges from 20% to 100%.

[0041] In the specific implementation process, sp 3 The variation in -C bond content follows a continuous function distribution. A continuous function means that when the change in the independent variable is small, the resulting change in the dependent variable is also small. Therefore, the dependent variable changes continuously with respect to the independent variable. 3 The -C bond content varies with the coating thickness. The composition changes very little near any position in the film, and the overall transition is continuous. The continuous function satisfies f(z)→f(z0) when z→z0, which makes the internal structural composition of the film layer continuous and there are no abrupt changes.

[0042] As one possible implementation of this application, the function type of the continuous function includes linear functions, trigonometric functions, exponential functions, and power functions. Specifically, any function type that conforms to the definition of a continuous function can be used as a power function. 3 -C bond content is a function type with a continuous distribution.

[0043] As one possible implementation of this application, along the thickness direction of the diamond-like carbon film, the sp 3The area with the highest C-C bond content accounts for more than 60% of the carbon-carbon bond content in the diamond-like carbon film at that thickness location.

[0044] This application aims to satisfy the hardness and heat resistance properties of diamond-like carbon (DLC) films while also considering the adhesion between the internal stress of the DLC film and the matrix. 3 The -C bond content in diamond-like carbon films is determined to be above 60% of the total carbon-carbon bond content in the films.

[0045] As one possible implementation of this application, the diamond-like carbon film, at the initial coating location near the substrate surface, the sp 3 -C bond content accounts for 20%-40% of the carbon-carbon bond content in diamond-like carbon films at this thickness location.

[0046] In the specific implementation process, when starting the coating process at the initial coating point on the substrate surface, it is necessary to control the stress distribution (sp) to avoid excessive stress difference between the initial film layer and the substrate. 3 With a moderate -C bond content, this application determines the sp at the initial coating location. 3 -C bonds account for 20%-40% of the total carbon-carbon bonds in diamond-like carbon films, which can ensure basic film-substrate bonding and avoid excessive internal stress differences that could lead to cracking.

[0047] Embodiments of this application also provide a method for preparing a high-temperature resistant, thermally conductive diamond-like thin film, comprising the following steps:

[0048] A layer of the sp is deposited on the surface of the substrate using a physical deposition method or a chemical deposition method. 3 Diamond-like films with -C bond content that varies continuously along the thickness direction.

[0049] As one possible implementation of this application, the method of depositing a layer of the sp on the surface of the substrate using a physical deposition method or a chemical deposition method is described. 3 Diamond-like carbon films with continuously varying -C bond content along the coating direction include:

[0050] During the deposition of a diamond-like carbon (DLC) film on the surface of the substrate, the temperature of the substrate and the bias voltage of the substrate are continuously varied within a preset temperature range and a preset bias voltage range, respectively, through programming based on the continuous function, so as to deposit the DLC film on the surface of the substrate. 3 Diamond-like carbon films with -C bond content that varies continuously along the coating direction.

[0051] Specifically, the deposition method for diamond-like carbon films with continuous function distribution is such that the bias voltage and substrate temperature are continuously adjustable within the required range and can be controlled by programming the continuous function.

[0052] As one possible implementation of this application, the preset bias voltage range is -1800V to 0V, and the continuous change accuracy of the bias voltage is ±0.1V / s; the preset temperature range is 25℃ to 300℃, and the change accuracy of the temperature is ±0.05℃ / s.

[0053] Specifically, the initial substrate temperature and initial bias voltage are determined based on the status of the coating equipment. The continuous variation range of the bias voltage and the continuous variation range of the substrate temperature are based on the designed SP. 3 It changes with the content of -C bonds.

[0054] As one possible implementation method of this application, the sp 3 The -C bond content is related to the temperature of the matrix and the bias voltage of the matrix by the following formula:

[0055] BiasV = f(c[sp] 3 -C])+a×Δt

[0056] Where BiasV is the bias voltage; f(c[sp 3 -C]) is the sp 3 -C bond content is a monotonic function; Δt is the temperature change rate of the substrate detected in real time during coating; a is a correction factor, obtained experimentally.

[0057] This application calculates the result of differentiating the bias function by sp. 3 The amount of bias voltage change due to the change in -C bond content is corrected through experiments, and the rate of change of matrix temperature is detected in real time through experiments to ensure that both bias voltage and matrix temperature are continuously adjustable within the required range.

[0058] As one possible implementation of this application, the physical deposition method includes magnetron sputtering, cathodic arc deposition, ion plating, and electron beam deposition; the chemical deposition method includes thermal pyrolysis.

[0059] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0060] Example 1

[0061] A method for preparing a high-temperature resistant, thermally conductive diamond-like carbon film includes the following steps:

[0062] A layer of sp is deposited on the surface of a tungsten carbide substrate using magnetron sputtering. 3 A diamond-like carbon film with a total thickness of 500 nm, in which the -C bond content varies continuously along the thickness direction.

[0063] Based on the equipment status, the initial bias voltage was determined to be -1000V, and the substrate temperature was 200℃. The correction relationship was fitted through univariate experiments.

[0064] BiasV = f(c[sp] 3 -C])+a×Δt

[0065] The temperature and bias voltage of the substrate are continuously controlled by programming continuous functions with second-level time precision.

[0066] Where, the continuous function is represented as sp 3 -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0067] c[sp 3 -C]=f(z)

[0068] Here, f(z) is designed as a monotonically increasing linear function, and f(z) is expressed as:

[0069] f(z) = (0.1 × z + 30)%

[0070] That is, sp 3 The relationship between the -C bond content and the thickness direction of the diamond-like carbon film is expressed as follows:

[0071] c[sp 3 -C]=(0.1×z+30)%

[0072] The bias voltage change rate is 1V / 5s, and the temperature change rate is -1℃ / 30s.

[0073] That is, to obtain Figure 1 The diagram showing the continuous change, sp 3 -C bond content monotonically increases with the thickness of the diamond-like carbon film, exhibiting a continuous variation characteristic. At any thickness position in the thickness direction, sp 3 There is no mutation in the -C bond content;

[0074] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 1 below.

[0075] Table 1

[0076] Nano hardness 56GPa Nanoscale scratches (tungsten carbide substrate, 20µm needle tip) 3.5N internal stress 2.6 GPa thermal conductivity 12W / (m·K) Coefficient of friction (for ZK3 glass) 0.12 <![CDATA[Heat-resistant temperature (N₂ atmosphere, 10h)]]> 650℃

[0077] Example 2

[0078] A method for preparing a high-temperature resistant, thermally conductive diamond-like carbon film includes the following steps:

[0079] A layer of sp is deposited on the surface of a titanium alloy substrate using the cathodic arc method. 3 A diamond-like carbon film with a total thickness of 2000 nm, in which the -C bond content varies continuously along the thickness direction.

[0080] Based on the equipment status, the initial bias voltage was determined to be -1100V, and the substrate temperature was 80℃. The correction relationship was fitted through univariate experiments.

[0081] BiasV = f(c[sp] 3 -C])+a×Δt

[0082] The temperature and bias voltage of the substrate are continuously controlled by programming continuous functions with second-level time precision.

[0083] Where, the continuous function is represented as sp 3 -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0084] c[sp 3 -C]=f(z)

[0085] Here, f(z) is designed as a sine function, and f(z) is expressed as:

[0086] f(z)=(60×∣sin(0.0012z+60)∣+20)%

[0087] That is, sp 3 The relationship between the -C bond content and the thickness direction of the diamond-like carbon film is expressed as follows:

[0088] c[sp 3 -C]=(60×∣sin(0.0012z+60)∣+20)%

[0089] The bias voltage change rate is calculated to be 0.72cos(0.003t+60) / s, and the temperature change rate is ≤±2℃ / 30s.

[0090] That is, to obtain Figure 2 The diagram showing the continuous change, sp 3 The -C bond content first increases and then decreases along the thickness direction of the diamond-like carbon film, exhibiting a continuous variation. At any thickness position along the thickness direction, sp 3 There is no mutation in the -C bond content;

[0091] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 2 below.

[0092] Table 2

[0093]

[0094] Example 3

[0095] A method for preparing a high-temperature resistant, thermally conductive diamond-like carbon film includes the following steps:

[0096] A layer of SP is deposited on the surface of a stainless steel substrate using ion plating. 3 A diamond-like carbon film with a total thickness of 1000 nm, in which the -C bond content varies continuously along the thickness direction.

[0097] Based on the equipment status, the initial bias voltage was determined to be -1150V, and the substrate temperature was 50℃. The correction relationship was fitted through univariate experiments.

[0098] BiasV = f(c[sp] 3 -C])+a×Δt

[0099] The temperature and bias voltage of the substrate are continuously controlled by programming continuous functions with second-level time precision.

[0100] Where, the continuous function is represented as sp 3 -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0101] c[sp 3 -C]=f(z)

[0102] Here, f(z) is designed as a multi-segment continuous function combining linear increasing and cosine functions, and f(z) is expressed as:

[0103] f(z1)=(0.0005×z1+0.3)×100%, z1∈[0, 500);

[0104] f(z2)=0.6×∣cos(0.002z2+30)∣×100%, z2∈[500, 1000];

[0105] That is, sp 3 The relationship between the -C bond content and the thickness direction of the diamond-like carbon film is expressed as follows:

[0106] c1[sp 3 -C]=(0.0005×z1+0.3)×100%, z1∈[0, 500);

[0107] c2[sp 3 -C]=0.6×∣cos(0.002z2+30)∣×100%, z2∈[500, 1000];

[0108] The plated bias voltage change rate for segment c1 is 0.2V / s, and the temperature change rate is ≤0.1℃ / min; the plated bias voltage change rate for segment c2 is 1.2sin(0.02t+30) / s, and the temperature fluctuation rate is ≤±10℃.

[0109] That is, to obtain Figure 3 The diagram showing the continuous change, sp 3The -C bond content first increases and then decreases along the thickness direction of the diamond-like carbon film, exhibiting a continuous variation. At any thickness position along the thickness direction, sp 3 There is no mutation in the -C bond content;

[0110] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 3 below.

[0111] Table 3

[0112]

[0113]

[0114] Example 4

[0115] A method for preparing a high-temperature resistant, thermally conductive diamond-like carbon film includes the following steps:

[0116] Electron beam deposition of a layer of SP on the surface of a stainless steel substrate 3 A diamond-like carbon film with a total thickness of 800 nm, in which the -C bond content varies continuously along the thickness direction.

[0117] Based on the equipment status, the initial bias voltage was determined to be -1100V, and the substrate temperature was 100℃. The correction relationship was fitted through univariate experiments.

[0118] BiasV = f(c[sp] 3 -C])+a×Δt

[0119] The temperature and bias voltage of the substrate are continuously controlled by programming continuous functions with second-level time precision.

[0120] Where, the continuous function is represented as sp 3 -C bond content exhibits a continuous functional distribution along the thickness direction of the diamond-like carbon film, satisfying the following relationship:

[0121] c[sp 3 -C]=f(z)

[0122] Here, f(z) is designed as a multi-segment continuous function, and f(z) is expressed as:

[0123] f(z1)=0.3×100%, z1∈[0, 100);

[0124] f(z2)=0.003z×100%∣, z2∈[100, 200);

[0125] f(z3)=0.6×100%, z3∈[200, 500);

[0126] f(z4)=(-0.001z+1.1)×100%, z4∈[500, 600);

[0127] f(z5)=0.5×100%, z3∈[600, 800);

[0128] That is, sp 3 The relationship between the -C bond content and the thickness direction of the diamond-like carbon film is expressed as follows:

[0129] c1[sp 3 -C]=0.3×100%, z1∈[0, 100);

[0130] c2[sp 3 -C]=0.003z×100%∣, z2∈[100, 200);

[0131] c3[sp 3 -C]=0.6×100%, z3∈[200, 500);

[0132] c4[sp 3 -C]=(-0.001z+1.1)×100%, z4∈[500, 600);

[0133] c5[sp 3 -C]==0.5×100%, z3∈[600, 800);

[0134] The results show that the bias voltage change rate for segment c2 is 0.25V / s, and the temperature change rate is -1℃ / min; the bias voltage fluctuation rate for segment c3 is ≤±2V, and the temperature fluctuation rate is ≤±3℃; the bias voltage change rate for segment c4 is 0.2V / s, and the temperature fluctuation rate is ≤±5℃; and the bias voltage fluctuation rate for segment c5 is ≤±4V, and the temperature fluctuation rate is ≤±5℃.

[0135] That is, to obtain Figure 4 The diagram showing the continuous change, sp 3 The -C bond content first increases and then decreases along the thickness direction of the diamond-like carbon film, exhibiting a continuous variation. Except for the initial deposition location and the outer surface, the content of sp... 3 There is no mutation in the -C bond content;

[0136] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 4 below.

[0137] Table 4

[0138]

[0139] Comparative Example 1

[0140] Compared to Example 4, the continuous function is designed as a multi-layered discontinuous structure, with sp at thicknesses of 200 nm and 600 nm. 3 A mutation in the -C bond content, sp 3 The relationship between the -C bond content and the thickness direction of the diamond-like carbon film is expressed as follows:

[0141] c1[sp 3 -C]=0.3×100%, z1∈[0, 200);

[0142] c2[sp 3 -C]=0.7×100%∣, z2∈[200, 600);

[0143] c3[sp 3 -C]=0.5×100%, z3∈[600, 800);

[0144] The bias voltage for segment C1 is -1200V and the temperature is 50℃; the bias voltage for segment C2 is -130V and the temperature is 150℃; and the bias voltage for segment C3 is -330V and the temperature is 120℃.

[0145] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 5 below.

[0146] Table 5

[0147]

[0148] As shown in Table 5, multilayer film systems without continuous transitions have lower thermal conductivity and heat resistance than continuous film systems. They are also prone to mismatch between internal stress and bonding strength, making them susceptible to cracking under external stress.

[0149] Comparative Example 2

[0150] The diamond-like carbon (DLC) film is designed to be 400 nm thick. As a single-layer film, there are no splines in the thickness direction. 3 Changes in -C bond content;

[0151] sp 3 The relationship for -C bond content is expressed as follows:

[0152] c[sp 3 -C] = 65%;

[0153] By calibrating the equipment status, set the bias voltage during coating to -200V and the temperature to 50℃.

[0154] The properties of the obtained diamond-like carbon film were tested, and the test results are shown in Table 6 below.

[0155] Table 6

[0156]

[0157] As can be seen from Table 6, there is no sp 3 Diamond-like carbon films with varying -C bond content are difficult to balance with substrate adhesion and internal stress simultaneously, making it hard to increase the deposition thickness. After a certain thickness, the internal stress increases sharply and may even disintegrate during the preparation process.

[0158] In summary, as can be seen from Examples 1-4, SP plating can be applied to different substrates. 3 Diamond-like carbon (DLC) films with continuously varying -C bond content along the thickness direction can all achieve heat resistance temperatures above 600℃, maintain high hardness, high thermal conductivity, and high lubrication effect, and balance internal stress and film-substrate bonding force, making them less prone to cracking under stress. Compared with the comparative example, the DLC films with continuously varying film-substrate bonding force and internal stress are better matched, resulting in better heat resistance and thermal conductivity.

[0159] The above description is merely an optional embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A high-temperature resistant, thermally conductive diamond-like carbon film, characterized in that, The diamond-like carbon film is an allotropic interface structure deposited on the surface of a substrate; the sp in the diamond-like carbon film 3 The content of -C bonds follows a continuous function distribution along the thickness direction of the diamond-like carbon film, and satisfies the following relationship: c[sp 3 -C]=f(z) Where z is the coating thickness of the diamond-like carbon film starting from the substrate, and the value of z ranges from 20nm to 2000nm; f(z) represents a continuous function; c[sp 3 -C] represents the sp in diamond-like films. 3 The content of -C bonds ranges from 20% to 100%. Average sp in diamond-like carbon films 3 -C bond content accounts for more than 40% of the total carbon-carbon bond content in the diamond-like carbon film; At the initial deposition site near the substrate surface, the diamond-like carbon film... 3 -C bond content accounts for 20%-40% of the carbon-carbon bond content in diamond-like carbon films at this thickness location.

2. The high-temperature resistant, thermally conductive diamond-like carbon film according to claim 1, characterized in that, The continuous functions include linear functions, trigonometric functions, exponential functions, and power functions.

3. The high-temperature resistant, thermally conductive diamond-like carbon film according to claim 1, characterized in that, Along the thickness direction of the diamond-like carbon film, the sp 3 The area with the highest C-C bond content accounts for more than 60% of the carbon-carbon bond content in the diamond-like carbon film at that thickness location.

4. A method for preparing a high-temperature resistant, thermally conductive diamond-like carbon film as described in any one of claims 1-3, characterized in that, Includes the following steps: A layer of the sp is deposited on the surface of the substrate using physical deposition or chemical deposition methods. 3 Diamond-like carbon films with continuously varying -C bond content along the thickness direction; The surface of the substrate is coated with a layer of the sp using a physical deposition method or a chemical deposition method. 3 Diamond-like carbon films with continuously varying -C bond content along the coating direction include: During the deposition of a diamond-like carbon (DLC) film on the substrate surface, the substrate temperature and bias voltage are continuously varied within a preset temperature range and a preset bias voltage range, respectively, through programming based on the aforementioned continuous function, in order to deposit the DLC film on the substrate surface. 3 Diamond-like carbon films with -C bond content continuously varying along the coating direction; The sp 3 The -C bond content is related to the temperature of the matrix and the bias voltage of the matrix by the following formula: BiasV=f(c[sp 3 -C])+a×Δt Where BiasV is the bias voltage; f(c[sp 3 -C]) is for sp 3 -C bond content is a monotonic function; Δt is the temperature change rate of the substrate detected in real time during coating; a is a correction factor, obtained experimentally.

5. The method for preparing high-temperature resistant, thermally conductive diamond-like carbon thin films according to claim 4, characterized in that, The preset bias voltage range is -1800V to 0V, and the continuous change accuracy of the bias voltage is ±0.1V / s; the preset temperature range is 25℃ to 300℃, and the change accuracy of the temperature is ±0.05℃ / s.

6. The method for preparing high-temperature resistant, thermally conductive diamond-like carbon thin films according to claim 4, characterized in that, The physical deposition methods include magnetron sputtering, cathodic arc deposition, ion plating, and electron beam deposition; the chemical deposition methods include thermal pyrolysis.

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