CN110261256B

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Info

Publication number: CN110261256B
Application number: CN201910502911.7A
Authority: CN
Inventors: 张丹; 李爱军; 方文放
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2019-06-11
Filing date: 2019-06-11
Publication date: 2022-04-05
Anticipated expiration: 2039-06-11
Also published as: CN110261256A

Abstract

The invention discloses a method for measuring intrinsic deposition rate of a precursor in a CVD/CVI process, the intrinsic deposition rate measured by the method is independent of a gas-phase intermediate product, the intrinsic deposition rate represents the deposition rate of a source gas, the deposition rate is determined by the mass difference of a porous ceramic wafer before and after an experiment, and the cost is low. The intrinsic deposition rate of the precursor can be obtained through simple data processing, and the method is convenient to operate, fast and efficient.

Description

Method for measuring intrinsic deposition rate of CVD/CVI process precursor

Technical Field

The invention relates to a method for measuring intrinsic deposition rate of a precursor of a CVD/CVI process.

Background

Chemical vapor deposition/infiltration (CVD/CVI) processes are the primary methods for preparing high performance coating materials, carbon-based and ceramic matrix composites. However, the method has the problems of long preparation period, high production cost and the like, and limits the large-scale industrial application of coating materials, carbon-based and ceramic-based composite materials. The pyrolysis and deposition mechanisms of different precursors are researched, and the deposition rates are measured, so that the further optimization of the CVD/CVI deposition process is facilitated.

The CVD/CVI process involves homogeneous reactions of various pyrolysis intermediates in the vapor phase with heterogeneous reactions of various pyrolysis products at the surface of the deposition substrate. Currently common methods of measuring deposition rate include optical, microbalance and electrical methods. However, both optical and electrical methods are difficult to adapt for use in CVD/CVI processes, and the measured deposition rates represent mixed deposition rates of various gaseous intermediates. The microbalance method can theoretically be integrated into the CVD/CVI process to measure the intrinsic deposition rate of the source gases, but the cost to achieve this is very high and is difficult to apply in practical engineering.

Disclosure of Invention

In order to solve the problems of the prior art, the invention provides a method for measuring the intrinsic deposition rate of a precursor in a CVD/CVI process, wherein the measured intrinsic deposition rate is independent of a gas phase intermediate product and represents the deposition rate of a source gas.

The invention can be realized by the following technical scheme:

a method of measuring intrinsic deposition rate of pyrolytic carbon precursor in a CVD/CVI process comprising the steps of:

1) preparation of a deposition substrate: a plurality of cylindrical porous ceramic plates, No. 1, 2, 3, 4, … …, were prepared and weighed to obtain the mass M₁₁，M₁₂，M₁₃，M₁₄，… …；

2) Assembling a mold: vertically placing the cylindrical porous ceramic plates into a graphite mold in sequence, and assembling the mold;

3) CVD/CVI deposition: placing the mold into a constant temperature area in a deposition furnace, introducing inert gas as protective gas, heating, controlling to a specified pressure by a vacuum pump after reaching a specified temperature, controlling the retention time of the source gas in the isothermal area, and performing CVD/CVI deposition;

4) weighing a deposition substrate: after deposition is finished, introducing inert gas to enable the pressure in the deposition furnace to be recovered to normal pressure, stopping introducing the inert gas after the temperature is cooled to room temperature, taking out the die from the deposition furnace, and weighing to obtain the mass M of the plurality of cylindrical porous ceramic plates in the die₂₁，M₂₂，M₂₃，M₂₄，… …；

5) Calculating the deposition rate: calculating the deposition rate of the source gas at each numbering position according to the measured mass difference of the plurality of cylindrical porous ceramic plates;

6) and (3) drawing an on-way deposition rate curve: sequencing the numbered porous ceramic plates from near to far according to the distance from the gas inlet of the isothermal zone, and drawing a graph of the in-process deposition rate by taking the distance from the gas inlet as an abscissa and the deposition rate as an ordinate;

7) calculating the intrinsic deposition rate: reversely extending the on-way deposition rate curve to a position with a distance of 0 from the gas inlet of the isothermal zone, wherein the obtained deposition rate is the intrinsic deposition rate of the source gas under the current process condition; the air inlet of the graphite mold is a conical hole, and the lower end of the conical hole is communicated with a cylindrical hole through an air passage; the diameter of the cylindrical hole is larger than that of the gas channel, and the diameter of the gas channel is equal to that of the inlet face of the conical hole.

The method for measuring the intrinsic deposition rate of the precursor of the CVD/CVI process has the specified temperature lower than 1200 ℃.

The method for measuring the intrinsic deposition rate of the precursor of the CVD/CVI process has the specified pressure less than 10 kPa.

According to the method for measuring the intrinsic deposition rate of the pyrolytic carbon precursor in the CVD/CVI process, the source gas is a micromolecular hydrocarbon gas or other micromolecular gas-phase precursors.

Advantageous effects

The deposition rate of the invention is determined by the quality difference of the porous ceramic plate before and after the experiment, and the cost is low. The intrinsic deposition rate of the precursor can be obtained through simple data processing, and the method is convenient to operate, fast and efficient.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a top view of a porous ceramic sheet according to the present invention;

FIGS. 3-1 and 3-2 are side and top views, respectively, of a graphite mold air scoop assembly;

FIG. 4 is a graph of in-process deposition rate;

FIG. 5 is a graph of deposition rate as a function of residence time.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification.

As shown in FIG. 1, the method for measuring the intrinsic deposition rate of the precursor of the CVD/CVI process comprises the following steps:

1) preparation of a deposition substrate: a plurality of cylindrical porous ceramic plates (shown in FIG. 2), numbered 1, 2, 3, 4, … …, were prepared and weighed to obtain masses M₁₁，M₁₂，M₁₃，M₁₄，… …；

2) Assembling a mold: vertically arranging a plurality of cylindrical porous ceramic plates into a graphite mold in sequence, and assembling the mold;

3) CVD/CVI deposition: filling the mold into a constant temperature area in a deposition furnace, introducing inert gas (nitrogen or argon or helium) as protective gas, heating to reach an appointed isothermal temperature lower than 1200 ℃, controlling to an appointed pressure lower than 10kPa by a vacuum pump, and introducing micromolecular hydrocarbon gas or other micromolecular gas phase precursors to carry out CVD/CVI deposition;

5) Calculating the deposition rate: calculating the deposition rate of the micromolecular hydrocarbon gas or other micromolecular gas-phase precursors at each numbering position according to the measured mass difference of the plurality of cylindrical porous ceramic plates;

6) and (3) drawing an on-way deposition rate curve: sequencing the numbered porous ceramic plates from near to far according to the distance from the air inlet, and drawing a graph of the in-process deposition rate by taking the distance from the air inlet as an abscissa and the deposition rate as an ordinate;

7) calculating the intrinsic deposition rate: the on-the-way deposition rate curve was reverse-extended to a distance of 0 from the gas inlet where the resulting deposition rate was the intrinsic deposition rate of the source gas under the current process conditions.

As shown in fig. 3-1 and 3-2, the gas inlet of the graphite mold is a tapered hole a, and the lower end of the tapered hole a is communicated with a cylindrical hole C through a gas passage; the diameter of the cylindrical hole is larger than that of the gas channel B, and the diameter of the gas channel B is equal to that of the inlet face of the conical hole A.

Example 1

1) preparation of a deposition substrate: preparing 7 cylindrical porous ceramic plates with numbers of 1, 2, 3, 4, 5, 6 and 7, and weighing to obtain masses of 2.6288 g, 2.5583 g, 2.5301 g, 2.5613 g, 2.5823 g, 2.5672 g and 2.5980 g;

2) assembling a mold: vertically arranging 7 porous ceramic plates into a graphite mold in sequence, and assembling the mold;

3) CVD/CVI deposition: loading the mold into a constant temperature area in a deposition furnace, introducing nitrogen as protective gas, heating to 950 ℃, controlling the pressure to 5 kPa by using a vacuum pump, and introducing propylene for CVD/CVI deposition;

4) weighing a deposition substrate: after deposition is finished, introducing nitrogen to restore the pressure in the deposition furnace to normal pressure, stopping introducing nitrogen after the temperature is cooled to room temperature, taking out the mold from the deposition furnace, and weighing to obtain the mass of the porous ceramic wafer in the mold, such as 2.6506 g, 2.5829 g, 2.5574 g, 2.5895 g, 2.6114 g, 2.5966 g and 2.6290 g;

5) calculating the deposition rate: calculating the deposition rate of propylene at each numbering position according to the measured mass difference of the porous ceramic sheet of 0.0218 g, 0.0246 g, 0.0273 g, 0.0282 g, 0.0291 g, 0.0294 g and 0.031 g;

6) and (3) drawing an on-way deposition rate curve: sequencing the numbered porous ceramic plates from near to far according to the distance from the air inlet, and drawing a graph (shown in figure 4) of the deposition rate along the way by taking the distance from the air inlet as a horizontal coordinate and the deposition rate as a vertical coordinate;

7) calculating the intrinsic deposition rate: and (3) reversely extending the on-way deposition rate curve to a position with the distance of 0 from the air inlet of the isothermal zone, wherein the obtained deposition rate is the intrinsic deposition rate of the propylene under the current process condition.

The distance from the gas inlet may be replaced by residence time, and plotting the in-line deposition rate may be replaced by plotting the deposition rate as a function of residence time, and back-extending the plot to 0 s may also give an intrinsic deposition rate as a function of residence time.

Example 2

1) preparation of a deposition substrate: preparing 1 cylindrical porous ceramic plate, and weighing to obtain 2.9867 g of mass;

2) assembling a mold: putting the ceramic wafer into a graphite mold, and assembling the mold;

3) CVD/CVI deposition: loading the mold into a constant temperature region in a deposition furnace, controlling the retention time to be 0.125 s, introducing nitrogen as protective gas, heating to 975 ℃, controlling the pressure to be 5 kPa by using a vacuum pump, and introducing propylene for CVD/CVI deposition;

4) weighing a deposition substrate: after deposition is finished, introducing nitrogen to restore the pressure in the deposition furnace to normal pressure, stopping introducing the nitrogen after the temperature is cooled to room temperature, taking out the mold from the deposition furnace, and weighing to obtain 3.0195 g of porous ceramic plates in the mold;

5) repeat steps 1-4 a total of 6 times. Replacing the porous ceramic plate in thestep 1 each time, weighing to obtain the mass (2.8967 g, 3.0096 g, 2.9575 g, 2.9092 g, 2.8936 g and 2.9374 g), correspondingly changing the residence time (0.25 s, 0.375 s, 0.5 s, 0.625 s, 0.75 s and 0.875 s) in thestep 3 one by one, and obtaining the mass (2.9305 g, 3.0458 g, 2.9946 g, 2.9474 g, 2.9333 g and 2.9791 g) of the deposited porous ceramic plate in thestep 4

6) Calculating the deposition rate: according to the measured mass difference (0.0328 g, 0.0338 g, 0.0362 g, 0.0371 g, 0.0382 g, 0.0397 g and 0.0417 g) of the porous ceramic sheet, calculating the deposition rate of propylene at each residence time;

7) the deposition rate was plotted as a function of residence time: with the residence time as abscissa and the deposition rate as ordinate, a graph of the deposition rate as a function of the residence time is plotted, as shown in fig. 5;

8) calculating the intrinsic deposition rate: the deposition rate profile was reverse-extended to a residence time of 0 seconds, where the resulting deposition rate was the intrinsic deposition rate of propylene under the current process conditions.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

Translated fromChinese

1.一种测量CVD/CVI工艺前驱体本征沉积速率的方法，其特征在于，包括以下步骤：1. a method for measuring the intrinsic deposition rate of CVD/CVI process precursor, is characterized in that, comprises the following steps:

1）沉积基底准备：准备多块圆柱形多孔陶瓷片，编号1，2，3，4，… …，并分别称量得其质量M₁₁，M₁₂，M₁₃，M₁₄，… …；1) Preparation of deposition substrate: prepare a plurality of cylindrical porous ceramic sheets, numbered 1, 2, 3, 4, ..., and weigh them to obtain their masses M₁₁ , M₁₂ , M₁₃ , M₁₄ , ... ;

2）模具组装：将所述多块圆柱形多孔陶瓷片按顺序竖直装入石墨模具中，组装模具；2) Mold assembly: the plurality of cylindrical porous ceramic sheets are vertically loaded into the graphite mold in sequence, and the mold is assembled;

3）CVD/CVI沉积：将所述模具装入沉积炉内恒温区域，通入惰性气体作为保护气体升温，达到指定温度后通过真空泵控制到指定压力，控制源气体在等温区的滞留时间，进行CVD/CVI沉积；3) CVD/CVI deposition: put the mold into the constant temperature zone in the deposition furnace, pass in an inert gas as a protective gas to heat up, after reaching the specified temperature, it is controlled to the specified pressure by the vacuum pump, and the residence time of the source gas in the isothermal zone is controlled to carry out CVD/CVI deposition;

4）沉积基底称重：沉积结束后，通入惰性气体使沉积炉内压力恢复为常压，待温度冷却至室温后停止通入惰性气体，从沉积炉内取出所述模具，称量得模具内所述多块圆柱形多孔陶瓷片质量M₂₁，M₂₂，M₂₃，M₂₄，… …；4) Weighing of the deposition substrate: after the deposition is completed, pass in an inert gas to restore the pressure in the deposition furnace to normal pressure, stop feeding the inert gas after the temperature is cooled to room temperature, take out the mold from the deposition furnace, and weigh the mold The masses of the plurality of cylindrical porous ceramic sheets described in the inside are M₂₁ , M₂₂ , M₂₃ , M₂₄ , ...;

5）计算沉积速率：根据测得的所述多块圆柱形多孔陶瓷片的质量差，计算出该源气体在所述各编号位置处的沉积速率；5) Calculate the deposition rate: According to the measured mass difference of the plurality of cylindrical porous ceramic sheets, calculate the deposition rate of the source gas at the numbered positions;

6）绘制沿程沉积速率曲线：将所述各编号多孔陶瓷片按离进气口的距离由近及远排序，以离等温区进气口的距离为横坐标，沉积速率为纵坐标，绘制出沿程沉积速率曲线图；6) Draw the deposition rate curve along the process: sort the numbered porous ceramic sheets according to the distance from the air inlet to the farthest, take the distance from the air inlet in the isothermal zone as the abscissa and the deposition rate as the ordinate, draw Out of the deposition rate curve along the way;

7）计算本征沉积速率：将沿程沉积速率曲线反向外延至离等温区进气口距离为0处，此处得到的沉积速率就是该源气体在当前工艺条件下的本征沉积速率；所述石墨模具的进气口为锥形孔，锥形孔的下端通过气体通道连通一圆柱形孔；所述圆柱形孔的直径大于所述气体通道的直径，所述气体通道的直径和所述锥形孔入口面的直径相等。7) Calculate the intrinsic deposition rate: reversely extend the deposition rate curve along the process to a distance of 0 from the inlet of the isothermal zone, and the deposition rate obtained here is the intrinsic deposition rate of the source gas under the current process conditions; The air inlet of the graphite mold is a conical hole, and the lower end of the conical hole communicates with a cylindrical hole through a gas channel; the diameter of the cylindrical hole is larger than the diameter of the gas channel, and the diameter of the gas channel is the same as the diameter of the gas channel. The diameters of the inlet faces of the tapered holes are equal.

2.根据权利要求1所述的测量CVD/CVI工艺前驱体本征沉积速率的方法，其特征在于，所述指定温度低于1200 ℃。2 . The method for measuring the intrinsic deposition rate of a CVD/CVI process precursor according to claim 1 , wherein the specified temperature is lower than 1200° C. 3 .

3.根据权利要求1所述的测量CVD/CVI工艺前驱体本征沉积速率的方法，其特征在于，所述指定压力低于10kPa。3 . The method for measuring the intrinsic deposition rate of a CVD/CVI process precursor according to claim 1 , wherein the specified pressure is lower than 10 kPa. 4 .

4.根据权利要求1所述的测量CVD/CVI工艺前驱体本征沉积速率的方法，其特征在于，所述源气体为小分子烃类气体或者其它小分子气相前驱体。4 . The method for measuring the intrinsic deposition rate of a CVD/CVI process precursor according to claim 1 , wherein the source gas is a small-molecule hydrocarbon gas or other small-molecule gas-phase precursors. 5 .