阅读说明：本技术 一种采用化学气相沉积工艺在钛合金表面沉积非晶SiOC涂层的方法 (Method for depositing amorphous SiOC coating on titanium alloy surface by adopting chemical vapor deposition process ) 是由 唐明强 刘厚盛 崔新宇 王吉强 杨颖� 熊天英 于 2021-07-26 设计创作，主要内容包括：本发明属于涂层制备技术领域,具体涉及一种采用化学气相沉积工艺在钛合金表面沉积非晶SiOC涂层的方法。采用热激发式化学气相沉积系统,选择六甲基二硅氧烷(HMDSO)或六甲基二硅烷(HMDS)或四乙氧基硅烷(TEOS)、无水乙醇(C-(2)H-(5)OH)、氢气(H-(2))和氩气(Ar)气体体系并控制有机硅烷和无水乙醇的比例,在工作压强100～1000Pa和温度为1000～1200℃条件下,在钛合金表面沉积出结构致密、厚度1～5μm的非晶SiOC涂层。该非晶SiOC涂层化学稳定性好、耐磨性好,抗氧化能力强,耐蠕变能力强,与钛合金基体之间具有良好的结合力。非晶SiOC涂层能够显著提高钛合金在高温下的使用性能,如蠕变性能、抗热抗冲击性能和抗氧化性能等等。(The invention belongs to the technical field of coating preparation, and particularly relates to a method for depositing an amorphous SiOC coating on the surface of a titanium alloy by adopting a chemical vapor deposition process. Selecting Hexamethyldisiloxane (HMDSO), Hexamethyldisilane (HMDS), Tetraethoxysilane (TEOS), and anhydrous ethanol (C) by using thermal excitation type chemical vapor deposition system 2 H 5 OH), hydrogen (H) 2 ) And an argon (Ar) gas system, controlling the proportion of organosilane to absolute ethyl alcohol, and depositing an amorphous SiOC coating with a compact structure and a thickness of 1-5 mu m on the surface of the titanium alloy under the conditions that the working pressure is 100-1000 Pa and the temperature is 1000-1200 ℃. The amorphous SiOC coating has the advantages of good chemical stability, good wear resistance, strong oxidation resistance, strong creep resistance and good binding force with a titanium alloy matrix. The amorphous SiOC coating can obviously improve the service performance of the titanium alloy at high temperature, such as creep property, heat and impact resistance and resistanceOxidation performance, and the like.)

1. A method for depositing amorphous SiOC coating on the surface of titanium alloy by chemical vapor deposition process is characterized in that organosilane-C is selected as the gas system introduced into the reaction cavity₂H₅OH-H₂-Ar system, the organosilane being Hexamethyldisiloxane (HMDSO) or Hexamethyldisilane (HMDS) or Tetraethoxysilane (TEOS), comprising the following steps:

(1) sequentially using 400# sand paper, 800# sand paper and 2000# sand paper to polish off oxide skins on the surface of the titanium alloy, so that the surface is smooth and has no burrs;

(2) ultrasonically cleaning the titanium alloy with the polished surface by respectively adopting isopropanol and ethanol for 10-20 minutes, and drying the titanium alloy with nitrogen for later use;

(3) mixing organosilane and absolute ethyl alcohol according to the volume ratio of 0.5-2, and uniformly stirring to obtain a precursor raw material;

(4) when the amorphous SiOC coating is deposited on the titanium alloy substrate, the flow rate of a mixed solution of organic silane and absolute ethyl alcohol is 0.3-1 g/min, the flow rate of argon gas is 1000-5000 sccm, the flow rate of hydrogen is 100-600 sccm, the deposition temperature is 1000-1200 ℃, the working pressure is 100-1000 Pa, and the deposition time is 0.5-4 h.

2. The method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapor deposition process according to claim 1, wherein, preferably, in the step (3), the volume ratio of the organosilane to the absolute ethyl alcohol is 1: 1, the mixture of organosilane and absolute ethyl alcohol is stirred evenly before use.

3. The method for depositing an amorphous SiOC coating on the surface of a titanium alloy by chemical vapor deposition according to claim 1, wherein the flow rate of the mixture of the organosilane and the absolute ethyl alcohol in step (4) is preferably 0.8 g/min.

4. The method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapor deposition process according to claim 1, wherein, preferably, in the step (4), the flow rate of the argon gas is 3000 seem.

5. The method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapor deposition process according to claim 1, wherein, preferably, in the step (4), the hydrogen flow rate is 200 seem.

6. Method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapour deposition process according to claim 1, characterized in that, preferably, in step (4), the deposition temperature is chosen to be 1100 ℃.

7. Method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapour deposition process according to claim 1, characterized in that, preferably, in step (4), the working pressure is 600 Pa.

8. The method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapor deposition process according to claim 1, wherein, preferably, in step (4), the deposition time is 2 h.

9. The method for depositing an amorphous SiOC coating on a titanium alloy surface using a chemical vapor deposition process according to claim 1, wherein preferably, in step (4), the deposition is ended and furnace cooling is performed.

10. The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process as claimed in claim 1, wherein the thickness of the amorphous SiOC coating deposited on the surface of the titanium alloy is 1-5 μm, and the amorphous SiOC coating is dense and well combined with a substrate.

Technical Field

The invention belongs to the technical field of coating preparation, and particularly relates to a method for depositing an amorphous SiOC coating on the surface of a titanium alloy by adopting a chemical vapor deposition process.

Background

With the continuous development of industries such as automobiles, aerospace, mechanical equipment, chemical engineering and the like, light high-temperature structural materials with high temperature oxidation resistance, high temperature corrosion resistance and excellent mechanical properties are receiving more and more attention.

The titanium alloy (TiAl-based intermetallic compound) has high strength, good corrosion resistance and high heat resistance, the high-temperature titanium alloy for the aircraft engine and the structural titanium alloy for the aircraft body are developed in the fifty-sixty years of the 20 th century, the corrosion-resistant titanium alloy and the high-strength titanium alloy are further developed in the next decades, and the titanium alloy is mainly used for manufacturing parts of the compressor of the aircraft engine and is also used as structural parts of rockets, missiles and high-speed aircrafts. However, titanium alloys remain limited in application under certain conditions, and TiAl alloys have low room temperature plasticity, low ductility, and low thermal variability. More seriously, when the temperature is higher than 700 ℃, the TiAl alloy surface forms a loose-structure oxide film (TiO)₂And Al₂O₃Mixed oxide film of composition) resulting in a decrease, or even failure, of the high temperature performance of the TiAl alloy.

Disclosure of Invention

The invention aims to provide a method for depositing an amorphous SiOC coating on the surface of a titanium alloy by adopting a chemical vapor deposition process, which solves the problem that the titanium-based alloy fails due to oxidation at high temperature, thereby effectively improving the high-temperature oxidation resistance of the titanium-based alloy.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for depositing amorphous SiOC coating on the surface of titanium alloy by chemical vapor deposition process, wherein the gas system introduced into the reaction cavity is organosilane-C₂H₅OH-H₂-Ar system, the organosilane being Hexamethyldisiloxane (HMDSO) or Hexamethyldisilane (HMDS) or Tetraethoxysilane (TEOS), comprising the following steps:

(1) sequentially using 400# sand paper, 800# sand paper and 2000# sand paper to polish off oxide skins on the surface of the titanium alloy, so that the surface is smooth and has no burrs;

(2) ultrasonically cleaning the titanium alloy with the polished surface by respectively adopting isopropanol and ethanol for 10-20 minutes, and drying the titanium alloy with nitrogen for later use;

(3) mixing organosilane and absolute ethyl alcohol according to the volume ratio of 0.5-2, and uniformly stirring to obtain a precursor raw material;

(4) when the amorphous SiOC coating is deposited on the titanium alloy substrate, the flow rate of a mixed solution of organic silane and absolute ethyl alcohol is 0.3-1 g/min, the flow rate of argon gas is 1000-5000 sccm, the flow rate of hydrogen is 100-600 sccm, the deposition temperature is 1000-1200 ℃, the working pressure is 100-1000 Pa, and the deposition time is 0.5-4 h.

Preferably, in the step (3), the volume ratio of organosilane to absolute ethyl alcohol is 1: 1, the mixture of organosilane and absolute ethyl alcohol is stirred evenly before use.

According to the method for depositing the amorphous SiOC coating on the titanium alloy surface by adopting the chemical vapor deposition process, preferably, in the step (4), the flow rate of the mixed solution of organosilane and absolute ethyl alcohol is 0.8 g/min.

Preferably, in the step (4), the flow rate of the argon gas is 3000 sccm.

In the method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process, preferably, in the step (4), the hydrogen flow is 200 sccm.

The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process preferably selects the deposition temperature to be 1100 ℃ in the step (4).

The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process preferably has the working pressure of 600Pa in the step (4).

The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process preferably has the deposition time of 2h in the step (4).

The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process preferably comprises the step (4) of finishing deposition and cooling along with a furnace.

The method for depositing the amorphous SiOC coating on the surface of the titanium alloy by adopting the chemical vapor deposition process has the advantages that the thickness of the amorphous SiOC coating deposited on the surface of the titanium alloy is 1-5 mu m, and the amorphous SiOC coating is compact and is well combined with a substrate.

The design idea of the invention is as follows:

in order to improve the high-temperature service performance of the TiAl alloy and enhance the oxidation resistance of the TiAl alloy, the research directions mainly focus on two directions, namely TiAl alloying and surface modification, the invention mainly aims at the TiAl surface modification and provides that a micron-sized oxidation resistant layer and a micron-sized barrier layer are prepared on the surface of the TiAl alloy by adopting a chemical vapor deposition method, thereby improving the high-temperature oxidation resistance of the TiAl alloy. The amorphous SiOC coating has excellent performance, good barrier property, good corrosion resistance, and excellent high-temperature stability and oxidation resistance, so the surface modification of the TiAl alloy is carried out by selecting the amorphous SiOC coating.

The invention provides a method for depositing an amorphous SiOC coating on the surface of a titanium alloy by adopting a chemical vapor deposition method, wherein the surface of the titanium alloy (TiAl-based intermetallic compound) is easy to generate an oxide with a loose structure in a high-temperature aerobic environment, in order to improve the high-temperature oxidation resistance of the titanium alloy, a compact amorphous SiOC coating with the thickness of 1-5 mu m is deposited on the surface of the titanium alloy, the O atom part in the Si-O network structure of the amorphous SiOC coating is replaced by the C atom to form a Si-C bond, and the C atom which is not bonded forms free C to be distributed in the Si-O network structure to form a compact structure, so that the amorphous SiOC coating has excellent corrosion resistance, mechanical property, oxidation resistance and the like.

The invention has the advantages and beneficial effects that:

(1) the amorphous SiOC coating prepared by the method can effectively improve the high-temperature oxidation resistance of the titanium alloy.

(2) The amorphous SiOC coating prepared by the method has a compact structure and is well combined with a substrate.

(3) The amorphous SiOC coating prepared by the method has excellent mechanical property, and the performance of the amorphous SiOC coating can be adjusted within a certain range, so that the wear resistance of the titanium alloy is enhanced.

(4) The precursor raw material adopts hexamethyldisiloxane, hexamethyldisilane or tetraethoxysilane, and the selected precursor raw material has low gasification temperature, no toxicity, no harm and no corrosive waste gas; hexamethyldisiloxane is preferred and is relatively low cost.

Drawings

FIG. 1 is a surface topography of an amorphous SiOC coating deposited on the surface of a titanium alloy for 2h by a chemical vapor deposition process.

FIG. 2 is a cross-sectional view of an amorphous SiOC coating deposited by a chemical vapor deposition process on a titanium alloy surface for 2h, the coating having a thickness of about 2 μm.

The specific implementation mode is as follows:

in the specific implementation process, the invention adopts a thermal excitation type chemical vapor deposition system, and Hexamethyldisiloxane (HMDSO), Hexamethyldisilane (HMDS), Tetraethoxysilane (TEOS) and absolute ethyl alcohol (C) are selected₂H₅OH), hydrogen (H)₂) And an argon (Ar) gas system, controlling the proportion of organosilane to absolute ethyl alcohol, and depositing an amorphous SiOC coating with a compact structure and a thickness of 1-5 mu m on the surface of the titanium alloy under the conditions that the working pressure is 100-1000 Pa and the temperature is 1000-1200 ℃.

The following further describes the embodiments of the present invention, and it should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The experimental procedures in the following examples were carried out by conventional methods unless otherwise specified, and the experimental materials used in the following examples were commercially available by conventional methods unless otherwise specified.

Example 1

In this embodiment, the method for depositing the amorphous SiOC coating on the surface of the titanium alloy by using the chemical vapor deposition process is as follows:

(1) TiAl alloy (TC4) is selected as a substrate, and 400#, 800# and 2000# sandpaper are used for sequentially polishing away oxide skin on the surface of the TiAl alloy, so that the surface is smooth and has no burrs.

(2) Ultrasonically cleaning the TiAl titanium alloy with polished surface by respectively adopting isopropanol and ethanol for 15 minutes, and drying by using nitrogen for later use.

(3) Mixing Hexamethyldisiloxane (HMDSO) and absolute ethyl alcohol according to a certain volume ratio of 1, and uniformly stirring to obtain a precursor raw material.

(4) When the amorphous SiOC coating is deposited on the TiAl titanium alloy substrate, the flow rate of a mixed solution of hexamethyldisiloxane and absolute ethyl alcohol is 0.5g/min, the flow rate of argon gas is 3000sccm, the flow rate of hydrogen is 200sccm, the deposition temperature is 1000 ℃, the working pressure is 600Pa, and the deposition time is 2 h. And (5) after the deposition is finished, cooling along with the furnace.

(5) The TiAl alloy with the surface not deposited with the amorphous SiOC coating and the TiAl alloy with the surface deposited with the amorphous SiOC coating are oxidized for 1000 hours at constant temperature in an air environment at 800 ℃, the high-temperature oxidation resistance is evaluated by the weight increment condition of a unit area, the final weight increment condition is shown in Table 1, and after the high-temperature oxidation is carried out for 1000 hours, the weight increment of the TiAl alloy with the surface deposited with the amorphous SiOC coating is far lower than that of the TiAl alloy with the surface not deposited with the amorphous SiOC coating.

TABLE 1 weight gain of samples after 1000h high temperature oxidation of TiAl alloys with surface deposited and non-deposited amorphous SiOC coatings

Sample (I)	Weight gain (mg/cm)2)
		TiAl alloy without amorphous SiOC coating deposited on surface	5.33
TiAl alloy with amorphous SiOC coating deposited on surface	0.16

Example 2

In this embodiment, the method for depositing the amorphous SiOC coating on the surface of the titanium alloy by using the chemical vapor deposition process is as follows:

(1) TiAl alloy (TC4) is selected as a substrate, and 400#, 800# and 2000# sandpaper are used for sequentially polishing away oxide skin on the surface of the TiAl alloy, so that the surface is smooth and has no burrs.

(2) Ultrasonically cleaning the TiAl titanium alloy with polished surface by respectively adopting isopropanol and ethanol for 15 minutes, and drying by using nitrogen for later use.

(3) Mixing Hexamethyldisilane (HMDS) and absolute ethyl alcohol according to a certain volume ratio, wherein the volume ratio is 1, and uniformly stirring the mixture to be used as a precursor raw material.

(4) When the amorphous SiOC coating is deposited on the TiAl titanium alloy substrate, the flow rate of a mixed solution of hexamethyldisilane and absolute ethyl alcohol is 0.8g/min, the flow rate of argon gas is 3000sccm, the flow rate of hydrogen is 400sccm, the deposition temperature is 1100 ℃, the working pressure is 600Pa, and the deposition time is 1.5 h.

(5) The TiAl alloy with the surface not deposited with the amorphous SiOC coating and the TiAl alloy with the surface deposited with the amorphous SiOC coating are oxidized for 100 hours at constant temperature in an air environment at 800 ℃, the high-temperature oxidation resistance is evaluated by the weight increment condition of a unit area, the final weight increment condition is shown in Table 2, and after the TiAl alloy with the surface deposited with the amorphous SiOC coating is oxidized for 100 hours at high temperature, the weight increment is far lower than that of the TiAl alloy with the surface not deposited with the amorphous SiOC coating.

TABLE 2 weight gain of samples after 100h high temperature oxidation of TiAl alloys with surface deposited and non-deposited amorphous SiOC coatings

Sample (I)	Weight gain (mg/cm)2)
		TiAl alloy without amorphous SiOC coating deposited on surface	1.18
TiAl alloy with amorphous SiOC coating deposited on surface	0.07

Example 3

In this embodiment, the method for depositing the amorphous SiOC coating on the surface of the titanium alloy by using the chemical vapor deposition process is as follows:

(1) the Ti-47Al-2Cr-2Nb alloy is selected as a matrix, and 400#, 800# and 2000# sandpaper is used for sequentially polishing away oxide skins on the surface of the Ti-47Al-2Cr-2Nb alloy, so that the surface is smooth and has no burrs.

(2) And ultrasonically cleaning the Ti-47Al-2Cr-2Nb titanium alloy with the polished surface for 15 minutes by respectively adopting isopropanol and ethanol, and drying by using nitrogen for later use.

(3) Tetraethoxysilane (TEOS) and absolute ethyl alcohol are mixed according to a certain volume ratio of 1, and the mixture is uniformly stirred to be used as a precursor raw material.

(4) When the amorphous SiOC coating is deposited on the Ti-47Al-2Cr-2Nb substrate, the flow rate of a mixed solution of tetraethoxysilane and absolute ethyl alcohol is 1g/min, the flow rate of argon gas is 5000sccm, the flow rate of hydrogen is 600sccm, the deposition temperature is 1050 ℃, the working pressure is 800Pa, and the deposition time is 1 h.

(5) The Ti-47Al-2Cr-2Nb alloy with the surface not deposited with the amorphous SiOC coating and the Ti-47Al-2Cr-2Nb alloy with the surface deposited with the amorphous SiOC coating are oxidized at the constant temperature for 100h in the air environment at 800 ℃, the high-temperature oxidation resistance is evaluated by the weight increment condition per unit area, the final weight increment condition is shown in Table 3, and after the high-temperature oxidation is carried out for 100h, the weight increment of the Ti-47Al-2Cr-2Nb alloy with the surface deposited with the amorphous SiOC coating is far lower than that of the Ti-47Al-2Cr-2Nb alloy with the surface not deposited with the amorphous SiOC coating.

TABLE 3 sample weight gain after 100h high temperature oxidation of Ti-47Al-2Cr-2Nb alloy with surface deposition and with no amorphous SiOC coating deposited

As shown in FIG. 1, it can be seen from the surface morphology of the amorphous SiOC coating deposited on the surface of the titanium alloy by the chemical vapor deposition process for 2h that the SiOC coating is formed by wrapping and tightly packing the amorphous balls without obvious growth orientation.

As shown in FIG. 2, the amorphous SiOC coating has a compact structure, can effectively isolate the titanium alloy substrate from air and prevent the titanium alloy substrate from being oxidized, and can be well combined with the substrate as can be seen from the cross-sectional morphology of the amorphous SiOC coating deposited on the titanium alloy surface for 2 hours by adopting a chemical vapor deposition process.

The embodiment result shows that the invention provides the preparation method for preparing the amorphous SiOC coating by adopting the chemical vapor deposition process, which is suitable for the titanium-based alloy, and the amorphous SiOC coating has the advantages of good chemical stability, good wear resistance, strong oxidation resistance, strong creep resistance and good bonding force with the titanium alloy matrix. The amorphous SiOC coating can obviously improve the service performance of the titanium alloy at high temperature, such as: creep properties, thermal shock resistance, oxidation resistance, and the like.