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Preparation method of SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating

A technology of nanowire toughening and chemical vapor phase, which is applied in the field of preparation of nanowire toughened multiphase coatings, can solve the problems of limited coating resistance to oxidation, long diffusion free path, and decreased mechanical properties, and achieve excellent anti-burning corrosion performance, short reaction cycle, and low cost

Active Publication Date: 2019-03-19
NORTHWESTERN POLYTECHNICAL UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, there is a process of repeated heating in alternate deposition, which is prone to stress concentration.
At the same time, the alternate deposition of coatings cannot solve the problem of cracking of the coating during use, which makes the C / C matrix oxidized and the mechanical properties decline seriously.
In addition, during the anti-oxidation and anti-ablation process of alternately deposited coatings, due to the long diffusion free path of Hf, Si, and O elements, the Hf-Si-O glass phase can only be produced at the HfC / SiC interface, which limits the Antioxidant capacity of the layer
At the same time, the inherent brittleness of HfC and SiC ceramics is too high, which makes the coating very easy to crack under the influence of thermal stress.

Method used

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  • Preparation method of SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating
  • Preparation method of SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating
  • Preparation method of SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating

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preparation example Construction

[0027] Preparation method steps of SiC nanowire toughened chemical vapor co-deposition HfC-SiC composite coating:

[0028] (1) Before the coating preparation, the surface of the C / C composite material sample was polished and cleaned, and dried in an oven for use. SiO 2 , Si, C three kinds of powders with a particle size of 300 mesh are mixed evenly in the ratio of 6:1:2 and dried for use;

[0029] (2) Use a bunch of carbon fiber ropes to hang the C / C composite material in step 1 in the graphite crucible with prepared powder at the bottom, and put the crucible in the constant temperature zone of the argon protective atmosphere electric furnace, press 5°C Heat at a rate of 1 / min to 1600°C, keep the temperature constant for 2 hours, and then cool down with the furnace.

[0030] (3) Hang the C / C sample with SiC nanowires on the surface obtained in step 2 with a bundle of carbon fibers in an isothermal chemical vapor deposition (CVD) furnace. 4 The powder is placed in the powder ...

Embodiment 1

[0038] The selected density is 1.70g / cm 3 The C / C sample was ground with 320-mesh SiC water sandpaper and dried at 80°C for 4 hours for later use; the particle size was minus 300-mesh SiO 2 , Si, and C are put into a planetary ball mill and stirred for 3 hours according to the ratio of about 6:1:2, and dried for later use. Choose HfCl 4 , SiCl 3 CH 3 , CH 4 As a precursor, H 2 As a reducing gas, Ar as a protective gas.

[0039] Suspend the prepared C / C matrix with carbon fiber and install the prepared SiO 2 , Si, C mixed powder graphite crucible, heated to 1500 ° C, heat preservation 2h, to obtain the surface of the C / C matrix with SiC nanowires, and then suspended in the chemical vapor deposition furnace (isothermal vertical vacuum furnace) isothermal zone . Under the protection of the Ar gas flow rate of 600ml / min, the temperature was raised at 7°C / min, and the pressure of the furnace body was kept at about 30kpa. After the temperature was raised to 1300°C, the pow...

Embodiment 2

[0041] The selected density is 1.70g / cm 3 The C / C sample was ground with 320-mesh SiC water sandpaper and dried at 80°C for 4 hours for later use; the particle size was minus 300-mesh SiO 2 , Si, and C are put into a planetary ball mill and stirred for 3 hours according to the ratio of about 6:1:2, and dried for later use. Choose HfCl 4 , SiCl 3 CH 3 , CH 4 As a precursor, H 2 As a reducing gas, Ar as a protective gas.

[0042] Suspend the prepared C / C matrix with carbon fiber and install the prepared SiO 2 , Si, C mixed powder graphite crucible, heated up to 1600 ° C, and kept for 2 hours to obtain a C / C matrix with SiC nanowires on the surface, and then hung it in the isothermal zone of a chemical vapor deposition furnace (isothermal vertical vacuum furnace) . Under the protection of the Ar gas flow rate of 600ml / min, the temperature was raised at 7°C / min, and the pressure of the furnace body was kept at about 30kpa. After the temperature was raised to 1400°C, the po...

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Abstract

The invention relates to a preparation method of a SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating. The preparation method comprises the following steps: first, preparing a SiC nanowire on the surface of a C / C composite material by means of a chemical vapor deposition technique; and then depositing an HfC-SiC compound phase coating by means of the chemical vapor deposition technique to further obtain the SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating on the surface of the C / C composite material. By controlling the tissue componentsand the uniform degree of the SiC nanowire toughened chemical gas codeposited HfC-SiC compound phase coating, mismatching of coefficients of thermal expansion between the coating and the C / C composite material is alleviated. Crack generation and expansion are inhibited by means of a nanowire bridging and pulling out mechanism, so that the cracking condition of an HfC-based ceramic coating in an ablating process is inhibited effectively. The prepared coating is uniform in thickness, controllable in tissue, short in process preparation period, simple in process course and low in cost.

Description

technical field [0001] The invention belongs to a method for preparing a nanowire-toughened composite coating, and relates to a method for preparing a SiC nanowire-toughened chemical vapor co-deposition HfC-SiC composite coating. Background technique [0002] Carbon / carbon (C / C) composites have broad application prospects in aerospace materials due to their low density and excellent high-temperature mechanical properties. However, under the ablative environment of oxygen-containing atmosphere, C / C composites will undergo severe oxidation and mechanical erosion, which severely limits their application in key parts of aircraft and spacecraft. In order to solve this problem and after a lot of research by domestic and foreign scholars, coating technology is a technology that can effectively protect C / C composite materials in extreme ablation environments. [0003] Refractory ceramics (HfC, ZrC, TaC, ZrB 2 , HfB 2 ...) has a higher melting point and is suitable as a material f...

Claims

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Application Information

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IPC IPC(8): C04B35/56C04B35/565C04B35/622C04B35/80C04B41/87
CPCC04B35/806C04B35/5607C04B35/565C04B35/62222C04B41/009C04B41/5059C04B41/87C04B2235/3817C04B2235/5244C04B35/83
Inventor 冯涛李贺军付前刚童明德
Owner NORTHWESTERN POLYTECHNICAL UNIV
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