阅读说明：本技术 一种获取复合材料氧化膜层厚度的方法、装置及电子设备 (method and device for obtaining thickness of composite material oxide film layer and electronic equipment ) 是由 国义军 曾磊 刘骁 周述光 石友安 邱波 代光月 朱言旦 于 2019-08-16 设计创作，主要内容包括：本发明涉及一种获取复合材料氧化膜层厚度的方法、装置及电子设备,该方法从烧蚀过程的基本原理出发,通过理论分析和公式推导,给出了该类材料在惰性氧化阶段的通用表达式,建立了不同组分之间热物性数据的关系,从而根据纯物质的测量结果,通过简单计算得到复合材料的热物性参数,进而获得复合材料的氧化膜层厚度,根据复合材料氧化膜层厚度对飞行器的热防护性能进行判断,可使问题得到大大简化,并且避开工艺和杂质的影响,获得准确的数据,并可极大地缩短设计周期,此外,本发明方法具有通用性,适用范围广,实用性强。(The invention relates to a method, a device and electronic equipment for obtaining the thickness of an oxide film layer of a composite material, wherein the method starts from the basic principle of an ablation process, gives a general expression of the material in an inert oxidation stage through theoretical analysis and formula derivation, establishes the relation of thermophysical property data among different components, obtains thermophysical property parameters of the composite material through simple calculation according to the measurement result of a pure substance, further obtains the thickness of the oxide film layer of the composite material, judges the thermal protection performance of an aircraft according to the thickness of the oxide film layer of the composite material, greatly simplifies the problem, avoids the influence of the process and impurities, obtains accurate data, and can greatly shorten the design period.)

1. A method for obtaining the thickness of an oxide film layer of a composite material is characterized by comprising the following steps: the method comprises the following steps:

obtaining physical property parameters of pure substances;

Obtaining physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material;

And obtaining the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

2. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 1, wherein: the physical property parameters of the pure substances are obtained by measurement or calculation.

3. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 2, wherein: the composite material is C/SiC, and the physical parameter of the composite material C/SiC is ablation characteristic parameter B of the C/SiC_C/SiCAnd A_C/SiC(ii) a The physical property parameter of the pure substance is an ablation characteristic parameter B of the pure substance SiC_SiCand A_SiCor ablation characteristic B of pure Si_SiAnd A_Si。

4. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 3, wherein: ablation characteristic parameter B of the composite material C/SiC_C/SiCablation characteristic parameter B of pure SiC_SiCablation characteristic parameter B of pure substance Si_SiThe relationship of (a) to (b) is as follows:

B_C/SiC＝(3γ/2)B_SiC＝γB_Si

Wherein: gamma is the element content of the composite material C/SiC, and the specific expression is as follows:

f_C＝F_C+F_SiCM_C/M_SiC

f_Si＝F_SiCM_Si/M_SiC

wherein: f. of_CIs the mass fraction of carbon element, f_SiIs the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCis the mass fraction of SiC component in the composite material C/SiC, M_SiIs the molecular weight of the constituent Si, M_SiCIs the molecular weight of the SiC component.

5. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 3, wherein: ablation characteristic parameter A of the composite material C/SiC_C/SiCAblation characteristic parameter A of pure SiC_SiCAblation characteristic parameter A of pure substance Si_SiThe relationship of (a) to (b) is as follows:

A_C/SiC＝A_SiC＝A_Si。

6. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 1, wherein: the thickness calculation formula of the oxide film layer of the composite material is as follows:

Wherein: x is the number of₀The oxide film thickness of the composite material is shown as A, B, the physical property parameter of the composite material is shown as t, t is time, and tau is an integral initial value, namely:

x_iIs an assumed initial thickness.

7. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 6, wherein: when the composite material is C/SiC, the thickness calculation formula of the oxide film layer of the composite material C/SiC is as follows:

Wherein: x is the number of₀oxide film thickness of composite C/SiC, A_C/SiC、B_C/SiCThe ablation characteristic parameter of the composite material C/SiC is shown, t is time, and tau is an integral initial value, namely:

x_iIs an assumed initial thickness.

8. The method for obtaining the thickness of the oxide film layer of the composite material according to claim 7, wherein: the thickness calculation formula of the oxide film layer of the composite material C/SiC is obtained by the following method:

(1) the inert oxidation reaction and the evaporation reaction process of the composite material C/SiC are as follows:

(2) if the mass fraction of the C component in the composite material C/SiC is F_Cthe mass fraction of SiC component is F_SiCand then the mass fractions of the carbon element and the silicon element are as follows:

f_C＝F_C+F_SiCM_C/M_SiC

f_Si＝F_SiCM_Si/M_SiC

wherein: f. of_CIs the mass fraction of carbon element, f_Siis the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCis the mass fraction of SiC component in the composite material C/SiC, M_SiIs the molecular weight of the constituent Si, M_SiCIs the molecular weight of the SiC component;

Setting the ablation mass flow rate of the composite material C/SiC to beAccording to the reaction process in the step (1), the mass flow rates of the components have the following relations:

Or is rewritten as

Wherein:Is the molar flow rate of component i, i represents each of the above components;

According to the reaction equation in the step (1), SiO is generated₂The formula for the layer thickness is as follows:

Wherein: x is the number of₀Is the thickness of the oxide film, t is the time,Is SiO₂the density of the liquid layer is higher than that of the liquid layer,Is SiO₂the molecular weight of the constituent elements, γ, is defined as:

(3) Oxygen in SiO₂diffusion in (b) is described by Fick's law as follows:

wherein: d is oxygen in SiO₂the diffusion coefficient of (1) is,Is the oxygen mass concentration;

boundary conditions:

a) Outer surface: the oxygen concentration is determined by the presence of oxygen in SiO₂obtained by dissolving

Wherein: h is the Henry constant of the Henry,The partial pressure of oxygen on the wall surface;

b) Inner surface: presumably through SiO₂The oxygen of the film is all reacted with the C/SiC material, then

Wherein:Is the rate constant of the oxidation reaction of C/SiC, C_iis O₂in SiO₂-concentration of the C/SiC interface;

For the above differential equationIntegration was performed to obtain the concentration of oxygen in the oxide film as

when the entire oxidation process is controlled by diffusion,The reaction rate is fast enough, thenIs large enough to be used for the purpose of,This gives:

Substituting (formula 14) for formula (8) yields:

Integration yields:

the rewrite is:

9. The utility model provides an obtain device of combined material oxidation film thickness which characterized in that: the device comprises a pure substance parameter acquisition module, a composite material parameter acquisition module and a film thickness calculation module, wherein:

pure substance parameter acquisition module: the composite material parameter acquisition module is used for acquiring physical parameters of pure substances and sending the acquired physical parameters of the pure substances to the composite material parameter acquisition module;

A composite material parameter acquisition module: receiving the physical parameters of the pure substances, obtaining the physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material, and sending the physical parameters of the composite material to a film layer thickness calculation module;

A film thickness calculating module: and receiving the physical parameters of the composite material, and calculating to obtain the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

10. An electronic device, characterized in that: comprising a memory and a processor:

The memory is to store one or more computer instructions;

The processor is to execute the one or more computer instructions to:

Obtaining physical property parameters of pure substances;

Obtaining physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material;

and obtaining the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

Technical Field

The invention relates to a method and a device for obtaining the thickness of an oxide film layer of a composite material and electronic equipment, and belongs to the technical field of thermal protection of aerospace vehicles.

Background

The ultrahigh-temperature ceramic composite material represented by the C/SiC composite material has the characteristics of high temperature resistance, oxidation resistance and low/non-ablation, is favored by aerospace type designers in recent years, and is widely used for thermal protection of key parts of a new generation of hypersonic aircraft. Under the condition that the temperature of the material is lower than 2600 ℃ (the highest allowable temperature of the surface of the adjacent space vehicle), two damage mechanisms of active oxidation and inert oxidation can occur, and the SiC ablation depends on the partial pressure of oxygen, the surface temperature and the microstructure and the composition of the material. Under low pressure and high temperature, the active oxidation is performed, the exposed SiC and oxygen directly react to generate gaseous products SiO and CO, and the reaction can be diffusion control, reaction speed control or mixing control. Gradually increasing the oxygen concentration (or partial pressure) to form SiO in a certain state₂An oxidation resistant film, the presence of which prevents direct reaction of oxygen with the surface material, oxygen must pass through the oxidation resistant film by diffusion to reach the SiC surface for oxidation reactions, a process known as inert oxidation. In the design of the type of the adjacent space vehicle, the material is expected to be in the inert ablation range during the process of flying along the trajectory, so the determination of the thickness of the oxide film becomes the key for judging whether the oxidation process is in the inert ablation or not. If the thickness is gradually reduced and approaches zero, a transition from inert to reactive oxidation will occur and the amount of ablation will increase substantially.

when the oxide film thickness is calculated, the oxidation kinetic data of the material must be known in advance, but the materials manufactured by different material development units through different processes and different impurities are very different, even if the same material is manufactured in different batches, the materials are not completely the same, if the thermophysical property and chemical kinetic data of the measured material are measured every time, time and labor are wasted, the measurement result cannot be suitable for the next batch of materials, and if the time is inaccurate, the situation that the ablation is changed from a non-ablation state into rapid ablation is likely to be serious.

disclosure of Invention

the invention aims to overcome the defects in the prior art and provides a method for acquiring the thickness of an oxide film layer of a composite material, which starts from the basic principle of an ablation process, gives a general expression of the material in an inert oxidation stage through theoretical analysis and formula derivation, establishes the relation of thermophysical property data among different components, obtains thermophysical property parameters of the composite material through simple calculation according to the measurement result of a pure substance, further acquires the thickness of the oxide film layer of the composite material, greatly simplifies the problem, avoids the influence of the process and impurities, acquires accurate data and can greatly shorten the design period.

Another object of the present invention is to provide an apparatus for obtaining the thickness of the oxide film layer of the composite material.

it is a further object of the invention to provide an electronic device.

The above purpose of the invention is mainly realized by the following technical scheme:

A method for obtaining a thickness of an oxide film layer of a composite material, comprising:

Obtaining physical property parameters of pure substances;

obtaining physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material;

And obtaining the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

In the method for obtaining the thickness of the oxide film layer of the composite material, the physical property parameters of the pure substances are obtained through measurement or calculation.

in the method for obtaining the thickness of the oxide film layer of the composite material, the composite material is C/SiC, and the physical parameter of the composite material C/SiC is the ablation characteristic of the C/SiCparameter B_C/SiCAnd A_C/SiC(ii) a The physical property parameter of the pure substance is an ablation characteristic parameter B of the pure substance SiC_SiCAnd A_SiCOr ablation characteristic B of pure Si_SiAnd A_Si.

In the method for obtaining the thickness of the oxide film layer of the composite material, the ablation characteristic parameter B of the composite material C/SiC_C/SiCAblation characteristic parameter B of pure SiC_SiCAblation characteristic parameter B of pure substance Si_SiThe relationship of (a) to (b) is as follows:

B_C/SiC＝(3γ/2)B_SiC＝γB_Si

wherein: gamma is the element content of the composite material C/SiC, and the specific expression is as follows:

f_C＝F_C+F_SiCM_C/M_SiC

f_Si＝F_SiCM_Si/M_SiC

Wherein: f. of_CIs the mass fraction of carbon element, f_SiIs the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCIs the mass fraction of SiC component in the composite material C/SiC, M_SiIs the molecular weight of the constituent Si, M_SiCIs the molecular weight of the SiC component.

in the method for obtaining the thickness of the oxide film layer of the composite material, the ablation characteristic parameter A of the composite material C/SiC_C/SiCAblation characteristic parameter A of pure SiC_SiCAblation characteristic parameter A of pure substance Si_Sithe relationship of (a) to (b) is as follows:

A_C/SiC＝A_SiC＝A_Si。

In the above method for obtaining the thickness of the oxide film layer of the composite material, the thickness calculation formula of the oxide film layer of the composite material is as follows:

Wherein: x is the number of₀The oxide film thickness of the composite material is shown as A, B, the physical property parameter of the composite material is shown as t, t is time, and tau is an integral initial value, namely:

x_iis an assumed initial thickness.

in the method for obtaining the thickness of the oxide film layer of the composite material, when the composite material is C/SiC, the thickness calculation formula of the oxide film layer of the composite material C/SiC is as follows:

Wherein: x is the number of₀Oxide film thickness of composite C/SiC, A_C/SiC、B_C/SiCThe ablation characteristic parameter of the composite material C/SiC is shown, t is time, and tau is an integral initial value, namely:

x_iIs an assumed initial thickness.

In the method for obtaining the thickness of the oxide film layer of the composite material, the thickness calculation formula of the oxide film layer of the composite material C/SiC is obtained by the following method:

(1) The inert oxidation reaction and the evaporation reaction process of the composite material C/SiC are as follows:

(2) if the mass fraction of the C component in the composite material C/SiC is F_Cthe mass fraction of SiC component is F_SiCand then the mass fractions of the carbon element and the silicon element are as follows:

f_C＝F_C+F_SiCM_C/M_SiC

f_Si＝F_SiCM_Si/M_SiC

wherein: f. of_Cis the mass fraction of carbon element, f_SiIs the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCis the mass fraction of SiC component in the composite material C/SiC, M_SiIs the molecular weight of the constituent Si, M_SiCis the molecular weight of the SiC component;

Setting the ablation mass flow rate of the composite material C/SiC to beaccording to the reaction process in the step (1), the mass flow rates of the components have the following relations:

Or is rewritten as

wherein:Is the molar flow rate of component i, i represents each of the above components;

According to the reaction equation in the step (1), SiO is generated₂the formula for the layer thickness is as follows:

Wherein: x is the number of₀Is the thickness of the oxide film, t is the time，Is SiO₂The density of the liquid layer is higher than that of the liquid layer,is SiO₂the molecular weight of the constituent elements, γ, is defined as:

(3) Oxygen in SiO₂Diffusion in (b) is described by Fick's law as follows:

wherein: d is oxygen in SiO₂The diffusion coefficient of (1) is,is the oxygen mass concentration;

boundary conditions:

a) outer surface: the oxygen concentration is determined by the presence of oxygen in SiO₂obtained by dissolving

Wherein: h is the Henry constant of the Henry,The partial pressure of oxygen on the wall surface;

b) inner surface: presumably through SiO₂the oxygen of the film is all reacted with the C/SiC material, then

wherein:Is the rate constant of the oxidation reaction of C/SiC, C_iIs O₂in SiO₂-concentration of the C/SiC interface;

for the above differential equationIntegration was performed to obtain the concentration of oxygen in the oxide film as

When the entire oxidation process is controlled by diffusion,The reaction rate is fast enough, thenIs large enough to be used for the purpose of,This gives:

substituting (formula 14) for formula (8) yields:

Integration yields:

The rewrite is:

The utility model provides an obtain device of combined material oxidation film thickness, includes pure material parameter acquisition module, combined material parameter acquisition module and film thickness calculation module, wherein:

pure substance parameter acquisition module: the composite material parameter acquisition module is used for acquiring physical parameters of pure substances and sending the acquired physical parameters of the pure substances to the composite material parameter acquisition module;

a composite material parameter acquisition module: receiving the physical parameters of the pure substances, obtaining the physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material, and sending the physical parameters of the composite material to a film layer thickness calculation module;

a film thickness calculating module: and receiving the physical parameters of the composite material, and calculating to obtain the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

an electronic device comprising a memory and a processor:

the memory is to store one or more computer instructions;

the processor is to execute the one or more computer instructions to:

obtaining physical property parameters of pure substances;

obtaining physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material;

and obtaining the thickness of the oxide film layer of the composite material according to the physical parameters of the composite material and the thickness calculation formula of the oxide film layer of the composite material.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention provides a method for obtaining the thickness of an oxide film layer of a composite material, which can obtain the ablation characteristic parameters of the composite material by utilizing the ablation characteristic parameters of the existing single-component pure material through a theoretical relation without directly measuring the composite material, and further obtain the thickness of the oxide film layer of the composite material, thereby being capable of quickly carrying out calculation and analysis on the thermal protection design of a new generation of hypersonic aircraft, greatly saving the resources and time of people, improving the accuracy of the parameters and greatly shortening the design period.

(2) The method of the invention obtains the thermophysical property parameters of another composite material by establishing the relationship of thermophysical property data among different components and converting according to the measurement result of one material, thereby greatly simplifying the problem, avoiding the influence of the process and impurities and obtaining accurate data.

(3) The invention provides a relation between pure substance physical property parameters and composite material physical property parameters and a calculation formula of the composite material oxide film layer thickness, has obvious innovativeness, has universality, can cover the same type of substances with different components, can determine the multiple relation of ablation rates between the substances, can obtain accurate oxide film layer thickness, and has wide application range and strong practicability.

(4) The invention theoretically provides a relational expression between B and B/A of different materials, can determine the corresponding parameter of another related material according to the ablation characteristic parameter of a certain component, simplifies the complex problem, has the advantages of accurate measurement, low cost, short period, simple and convenient operation and the like, judges the thermal protection performance of the aircraft according to the thickness of the composite material oxide film layer obtained by calculation, and if the thickness tends to 0, shows that the composite material can be rapidly ablated, thus achieving the purpose that the aircraft can not keep the shape unchanged; if the thickness is not zero (obviously larger than the initial value), the composite material is in an inert oxidation area, rapid ablation cannot occur, and the purpose that the shape of the aircraft is kept unchanged is met.

Drawings

FIG. 1 is a flow chart of a method for obtaining the thickness of an oxide film layer of a composite material according to the present invention;

FIG. 2 shows the present invention F_SiCAnd temperature on rate constant, where FIG. 2a is a parabolic rate constant B; FIG. 2B is a linear rate constant B/A;

FIG. 3 is a graph showing the thickness of an oxide film according to the present invention with time at different temperatures, wherein F is shown in FIG. 3a_SiC0.1; FIG. 3b is F_SiC＝1.0。

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

as shown in fig. 1, a flowchart of the method for obtaining the thickness of the oxide film layer of the composite material of the present invention is shown, and the method for obtaining the thickness of the oxide film layer of the composite material of the present invention specifically includes the following steps, taking the composite material C/SiC as an example:

and (I) determining the inert oxidation reaction process and reaction equation of the C/SiC composite material. Inert oxidation means that a layer of SiO is formed on the surface of C/SiC₂The protective film, oxygen must diffuse through the oxide film to reach and react with the C/SiC, the interface reaction equation is

the inert oxidation process comprises the following processes:

1) Oxygen diffuses to SiO through the boundary layer₂Surface and dissolving;

2) Oxygen diffusion through SiO₂The liquid layer reaches SiO₂-a C/SiC interface;

3) in SiO₂chemical reaction of oxygen with C/SiC at the C/SiC interface to form SiO₂And CO, increasing the oxide film thickness;

4) the reaction product CO passes through SiO₂The oxide film is diffused outwards;

5) Evaporation reaction occurs on the outer surface of the oxide film, SiO₂decomposition into SiO and O₂I.e. by

The oxide film is thinned.

(II) according to reaction kineticsin principle, an ablation rate differential equation is determined. In order to obtain a general relational expression, the mass fraction of the C component in the C/SiC is set as F_CThe mass fraction of SiC component is F_SiCAnd then the mass fractions of the carbon element and the silicon element are as follows:

f_C＝F_C+F_SiCM_C/M_SiC (4)

f_Si＝F_SiCM_Si/M_SiC (5)

In the formula: f. of_CIs the mass fraction of carbon element, f_Siis the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCIs the mass fraction of SiC component in the composite material C/SiC, M_iThe molecular weight of the component i is specifically as follows: m_SiIs the molecular weight of the constituent Si, M_SiCIs the molecular weight of the SiC component.

Setting the ablation mass flow rate of the composite material C/SiC to beaccording to the reaction equations (1) and (2), the mass flow rates of the respective constituent elements have the following relationships

Or is rewritten as

here, theIs the molar flow rate of component i, i representing each of the above components, e.g. J_COThe molar flow rate of the reaction product CO diffusing from the surface out of the boundary layer,is the flow rate of oxygen diffused from the boundary layer to the surface of the C/SiC.

According to the reaction equation (1)to form SiO₂The layer thickness is determined by

In the formula: x is the number of₀is the thickness of the oxide film, t is the time,Is SiO₂Density of liquid layer, where gamma is defined as

for pure SiC (i.e. F)_SiC1), then γ is 2/3; for pure C (i.e. F)_C1), γ is 0; for pure Si, γ ═ 1. The formula of the four materials of C, Si, SiC and C/SiC are unified, the C and SiC in the composite material C/SiC can have different mixing ratios, and the values of gamma are different when the mixing ratios of the C and SiC in the composite material C/SiC are different.

and (III) solving an ablation rate equation by integration to obtain an oxide film thickness theoretical formula. Oxygen in SiO₂The diffusion in (1) is described by Fick's law

Wherein: d is oxygen in SiO₂The diffusion coefficient of (1) is,Is the oxygen mass concentration.

boundary conditions:

1) outer surface: the oxygen concentration is determined by the presence of oxygen in SiO₂Obtained by dissolving

Wherein H is a Henry constant and,The partial pressure of oxygen on the wall surface.

2) Inner surface: presumably through SiO₂The oxygen of the film is all reacted with the C/SiC material, then

In the formulais the rate constant of the oxidation reaction of C/SiC, C_iis O₂In SiO₂-concentration of the C/SiC interface.

the above differential equation (10) is integrated to obtain the concentration of oxygen in the oxide film of

When the entire oxidation process is controlled by diffusion,The reaction rate is fast enough, thenIs large enough to be used for the purpose of,Thereby the device is provided with

substituting the formula (14) into the formula (8) to obtain

integration yields:

Wherein:

In the formulam＝1/γ。

(17) can be rewritten as

Since some of the physical quantities in the coefficients A and B are difficult to obtain directly, A and B/A are usually determined directly by experiments.

And (IV) determining the relationship of chemical kinetic parameters among different components. At present, a plurality of manufacturers of C/SiC composite materials exist, and the processes adopted by different manufacturers are different, wherein the matrix SiC can be divided into single crystal SiC, chemical vapor deposition SiC (CVD-SiC), sintered SiC, hot pressed SiC and the like according to different preparation methods, and can be roughly divided into two types of alpha-SiC and beta-SiC according to crystal structures. The oxidation behavior of crystalline SiC has directionality, and whether or not impurities are contained in the material also has a great influence on the oxidation rate. If the measurement is carried out on each batch of materials, not only the financial and material resources and the time are wasted, but also the problem is greatly simplified if the relation between B and B/A of different materials can be theoretically given, and the corresponding parameter of another material can be determined according to the ablation characteristic parameter of a certain component.

Obtaining the ablation characteristic parameter B of the composite material C/SiC according to the formula given above_C/SiCablation characteristic parameter B of pure SiC_SiCablation characteristic parameter B of pure substance Si_SiThe relationship of (a) to (b) is as follows:

B_C/SiC＝(3γ/2)B_SiC＝γB_Si (23)

Thus, the data of pure Si or SiC can be used to obtain the corresponding physical property data of the composite material C/SiC through calculation. The pure substance does not contain impurities, the implementation is convenient, the measurement result is accurate and reliable, and gamma is a parameter related to the element content of the composite material C/SiC.

and (V) measuring ablation characteristic parameters of the pure substances. In the laboratory, the measurement of ablation characteristic parameters of pure substances belongs to the mature technology, and the specific test equipment and the measurement method can adopt relevant literature documents, and are not described in detail here. For pure SiC, the following measurements are reported

Wherein B is₀＝524.19μm²/hr，B_p＝119244；B₀′＝1.505×10⁶μm²/hr，B′_p＝230000；(B/A)₀＝5.8087×10⁶μm/hr，B_L195800. Note that the activation energy at high and low temperatures is different, with 1673K as the dividing line, when T is<1673K, the activation energy is low, about 120-140 KJ/mol, mainly oxygen molecules in amorphous SiO₂Diffusion of (2); when T is>1673K, oxygen ion diffusion occurs, and SiO is added₂the transition from the amorphous state to the polycrystalline state slows the oxygen transport.

as shown in FIG. 1, taking the composite material C/SiC as an example, the method for obtaining the thickness of the composite material C/SiC oxide film layer specifically comprises the following steps:

Firstly, pure Si or SiC materials are prepared in a laboratory, and the physical parameters B and B/A are measured, and the two data can be searched from the literature.

secondly, obtaining the physical parameters of the composite material according to the relationship between the physical parameters of the pure substances and the physical parameters of the composite material, namely:

According to the ablation characteristic parameter B of the composite material C/SiC_C/SiCAblation characteristic parameter B of pure SiC_SiCablation characteristic parameter B of pure substance Si_SiCalculating to obtain the ablation characteristic parameter B of the composite material C/SiC according to the following relational expression_C/SiC：

B_C/SiC＝(3γ/2)B_SiC＝γB_Si

wherein: gamma is the element content parameter of the composite material C/SiC, and the specific expression is as follows:

f_C＝F_C+F_SiCM_C/M_SiC

f_Si＝F_SiCM_Si/M_SiC

Wherein: f. of_CIs the mass fraction of carbon element, f_Siis the mass fraction of silicon element, F_CIs the mass fraction of C component in the composite material C/SiC, F_SiCIs the mass fraction of SiC component in the composite material C/SiC, M_SiIs the molecular weight of the constituent Si, M_SiCIs the molecular weight of the SiC component.

Ablation characteristic parameter A according to composite material C/SiC_C/SiCAblation characteristic parameter A of pure SiC_SiCAblation characteristic parameter A of pure substance Si_SiCalculating to obtain the ablation characteristic parameter A of the composite material C/SiC according to the following relational expression_C/SiC：

A_C/SiC＝A_SiC＝A_Si。

Thirdly, ablation characteristic parameter B of the composite material C/SiC_C/SiCAnd A_C/SiCSubstituting the thickness into the following calculation formula of the thickness of the oxide film layer of the composite material C/SiC to obtain the thickness x of the oxide film layer₀。

wherein: x is the number of₀Oxide film thickness of composite C/SiC, A_C/SiC、B_C/SiCThe ablation characteristic parameter of the composite material C/SiC is shown, t is time, tau is the small integral initial value and is defined as:

x_iIs assumed to be of initial thickness (small amount), and is desirable here

Judging the thermal protection performance of the aircraft according to the calculated thickness of the composite material oxide film layer, and if the thickness is gradually reduced and tends to 0, indicating that the composite material is quickly ablated so as not to achieve the purpose of keeping the shape of the aircraft unchanged; if the thickness is not zero (obviously larger than the initial value), the composite material is in an inert oxidation area, rapid ablation cannot occur, and the purpose that the shape of the aircraft is kept unchanged is met.

In the present invention, the temperature and the component content have an influence on the coefficients A and B, and F is shown in FIG. 2_SiCand the effect of temperature on the parabolic rate constant B and the linear rate constant B/a. The effect of the crystalline structure on oxygen diffusion is considered here. As shown in FIG. 3, F is given_SiC0.1 and F_SiCThe thickness of the oxide film varied with time at different temperatures as 1.

the above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Those skilled in the art will appreciate that the invention may be practiced without these specific details.