Silicon carbide _w /SiC-Si-Y Preparation of composite materials and 1500 °C Study on Water-Oxygen Corrosion Performance

Digital Object Identifier ：10.1016/j.jmrt.2023.04.150

Laboratory of Thermal Structural Composite Materials Science and Technology, Northwestern Polytechnical University Professor Cheng Laifei’s team in the journal “ Journal of Materials Research and Technology 》published a paper titled “ Fabrication of SiC _w /SiC- Yes - Y composites and their   Resistance to water-oxygen corrosion at 1500 degrees Celsius ” of the paper. This study primarily investigates a novel silicon carbide-based composite material. Silicon carbide _w /SiC- Yes - Y ， and placed particular emphasis on evaluating its in 1500 Corrosion Resistance in High-Temperature Aqueous Oxygen Environments 。

Research Background

The hot-end components of aerospace engines are required to operate under extreme conditions of high temperature, high-velocity steam, and oxygen. Ceramic matrix composites, owing to their outstanding high-temperature performance, among which Silicon carbide w /SiC Composite material In high-temperature structural applications is particularly prominent. Previous studies have primarily focused on the mechanical properties of such materials, while research on their performance at high temperatures - Research on corrosion behavior in aqueous-oxygen environments is relatively limited. By employing a matrix modification strategy, yttrium is introduced Silicon carbide Within the matrix, this promotes the formation of a corrosion-resistant rare-earth silicate protective layer under high-temperature water–oxygen corrosion, fundamentally enhancing the intrinsic corrosion resistance of the composite material.

Research Methods

1. Silicon carbide _w /SiC- Yes - Y of the material Preparation method:

1. Silicon carbide _w (32 vol%), PEG (2 wt%), TMAH (4 wt%), AM (10 wt%), Bis (1 wt%) Ball mill in deionized water 6-10h。 APS (APS: AM 1 / 4 Quality ratio 1:60) Add to the slurry and stir rapidly. 30 s . Then pour into the mold and place in the muffle furnace. 80 Heating in ℃ 10-20min , then dry again.
2. PCS/ Xylene solution (mass ratio of 1:40 ) penetrate into SiCw Vacuum Infiltration in Preforms 1 h . Finally, we will SiCw The prefabricated components are placed in a tube furnace, and respectively at 220 °C and 900 at a temperature of ℃ PCS Perform curing and pyrolysis 2 h。
3. With a mass ratio of 1:2 phenolic resin / Ethanol solution is injected into the material via a vacuum impregnation process. SiCw in the precursor, and in 150 Curing at ℃ 3h . Then, under an argon atmosphere, the phenolic resin is 900 Pyrolysis is carried out at ℃. 2h . The above steps are repeated until the carbon volume fraction is approximately 30% , with a porosity of approximately 32% . Finally, in 1650 Under vacuum conditions of ℃, the Si-Y Alloy Melt Injection SiCw/C In the precursor 0.5h。

2. Water-oxygen experiment: Temperature is 1500 ℃, the partial pressure of this gas mixture is P(H ₂ O): P(O ₂ ): P(Ar)=30: 20: 50 , the gas flow rate is 50ml/min . Total corrosion time is 20h , respectively in 1h，5h，10h and 20h Take out the scale.
3. Corrosion Mechanism  ：

1. The introduced yttrium reacts with oxygen in the early stages of corrosion to form Y₂Si₂O₇ , and subsequently undergo further reaction with water vapor to transform into Y₂SiO₅ 。
2. Protective layer: Y₂SiO₅ It features a high melting point, low oxygen permeability, and high chemical stability. This protective layer effectively prevents the penetration of water and oxygen vapor into the material’s interior (with a penetration depth of only ~30 micrometer )
3. Corrosion resistance: generated during the corrosion process Y₂SiO₅ It filled some of the pores, reducing the open porosity of the composite material from 2.76% Decrease to 1.39% , with a denser structure.

Research Results

Combines excellent mechanical properties with extraordinary durability. 1500°C Water-oxygen corrosion performance SiCw/SiC–Si–Y Composite materials can in-situ self-generate stable Y₂SiO₅ Protective layer, achieved “ Proactive Protection ” , it holds tremendous application potential in the field of high-temperature thermal structural components for aerospace.

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