(C-SiC)f/C复合材料的烧蚀性能

doi:10.15541/jim20170012

摘要/Abstract

摘要：

将SiC纤维毡与C纤维毡交替层叠, 通过针刺工艺制备(C-SiC)_f/C预制体, 采用化学气相渗透与前驱体浸渍裂解复合工艺(CVI+PIP)制备(C-SiC)_f/C复合材料, 研究(C-SiC)_f/C复合材料H₂-O₂焰烧蚀性能。利用SEM、EDS和XRD对烧蚀前后材料的微观结构和物相组成进行分析, 探讨材料抗烧蚀机理。结果表明: (C-SiC)_f/C复合材料表现出更优异的耐烧蚀性能。烧蚀750 s后, (C-SiC)_f/C复合材料的线烧蚀率为1.88 μm/s, 质量烧蚀率为2.16 mg/s。与C/C复合材料相比, 其线烧蚀率降低了64.5%, 质量烧蚀率降低了73.5%; SiC纤维毡在烧蚀中心区表面形成的网络状保护膜可以有效抵御高温热流对材料的破坏; 在烧蚀过渡区和烧蚀边缘区形成的熔融SiO₂能够弥合材料的裂纹、孔洞等缺陷, 阻挡氧化性气氛进入材料内部, 使材料表现出优异的抗烧蚀性能。

关键词: (C-SiC)_f/C复合材料, SiC纤维, H₂-O₂焰烧蚀, SiO₂保护膜

Abstract:

(C-SiC)_f/C preform was prepared by needle-punching technology, which SiC fiber felts and C fiber felts were laminated alternately. Then (C-SiC)_f/C preform was densified by chemical vapor infiltration and impregnation with resin to prepare (C-SiC)_f/C composites. H₂-O₂ flame ablation behavior of (C-SiC)_f/C composites was investigated. Phase composition and microstructure of the (C-SiC)_f/C composites before and after ablation were characterized by XRD, SEM and EDS, respectively. The results indicate that (C-SiC)_f/C composites exhibit excellent anti-ablation resistance. After ablation for 750 s by H₂-O₂ flame, linear ablation and mass ablation rates of (C-SiC)_f/C composites are as low as 1.88 μm/s and 2.16 mg/s, respectively. Compared with C/C composites, linear ablation and mass ablation rates of (C-SiC)_f/C composites decrease by 64.5% and 73.5%, respectively. It is found that in the high temperature ablation process, the networking-shaped protective film formed by SiC fiber felts on the surface of the ablation center zone effectively protects materials from high temperature thermal damage. Molten SiO₂ in the ablation transitional and marginal zone can heal cracks, holes and other defects, and effectively prevent oxidizing atmosphere into the materials, leading to excellent anti-ablation performance.

Key words: (C-SiC)_f/C composites, SiC fiber, H₂-O₂ flame ablation, SiO₂ protective film

中图分类号:

TB332

左亚卓, 李红, 王少雷, 杨敏, 任慕苏, 孙晋良. (C-SiC)_f/C复合材料的烧蚀性能[J]. 无机材料学报, 2017, 32(11): 1141-1146.

ZUO Ya-Zhuo, LI Hong, WANG Shao-Lei, YANG Min, REN Mu-Su, SUN Jin-Liang. Ablation Behavior of (C-SiC)_f/C Composites[J]. Journal of Inorganic Materials, 2017, 32(11): 1141-1146.

图/表 14

图1 (C-SiC)f/C复合材料制备流程图

Fig. 1 Processing scheme of manufacturing (C-SiC)f/C composites

表1 (C-SiC)f/C复合材料与C/C复合材料基本参数

Table 1 Basic parameters of (C-SiC)f/C and C/C composites

Sample	Structure	Density/ (g•cm^-3)	Open porosity	Mass fraction of SiC/%
(C-SiC)_f/C	CF felt/ SiCF felt	1.80	8.0%	5%-6%
C/C	CF felt	1.80	5.1%	0

图2 (C-SiC)f/C复合材料烧蚀测试图

Fig. 2 Illustrations of the (C-SiC)f/C composites ablation test

图3 (C-SiC)f/C复合材料的XRD图谱

Fig. 3 XRD pattern of (C-SiC)f/C composites

图4 (C-SiC)f/C复合材料截面形貌照片和EDS谱图(插图)

Fig. 4 Cross-sectional morphologies and EDS spectrum (insert) of (C-SiC)f/C composites (a) Low magnification; (b) High magnification

表2 (C-SiC)f/C与C/C复合材料的线烧蚀率与质量烧蚀率

Table 2 Linear and mass ablation rates of (C-SiC)f/C and C/C

Samples	Ablation time/s	Linear ablation rate/(μm·s^-1)	Mass ablation rate/(mg·s^-¹)
(C-SiC)_f/C	750	1.88	2.16
C/C	750	5.29	8.14

图5 复合材料烧蚀后宏观形貌照片

Fig. 5 Surface macrographs of (C-SiC)f/C composites after ablation (a) (C-SiC)f/C; (b) C/C

图6 (C-SiC)f/C复合材料烧蚀中心区SEM照片和EDS谱图(插图)

Fig. 6 SEM images and EDS spectrum (insert) of the ablation center zone in (C-SiC)f/C composites (a) Low magnification; (b,d) High magnification

图7 (C-SiC)f/C复合材料烧蚀过渡区的SEM照片和EDS谱图(插图)

Fig. 7 SEM image and EDS spectrum (insert) in ablation transitional zone in (C-SiC)f/C composites

图8 (C-SiC)f/C复合材料烧蚀边缘区不同位置SEM照片和EDS谱图(插图)

Fig. 8 SEM images and EDS spectrum (insert) of ablation marginal zone at different places in (C-SiC)f/C composites (a) Near the transitional zone; (b) Edge of the marginal zone

图9 (C-SiC)f/C复合材料烧蚀样品元素分析结果

Fig. 9 Element analysis of (C-SiC)f/C composite ablation sample

表3 C和SiC在烧蚀过程中主要发生的反应

Table 3 Main reactions occured in thermo-chemical ablation process

No.	Reaction
1	SiC(s) → SiC(l)
2	2/3SiC(s) + O₂(g) → 2/3SiO₂(s) + 2/3CO(g) 2/3SiC(s) + O₂(g) → 2/3SiO₂(l) + 2/3CO(g) 2/3SiC(l) + O₂(g) → 2/3SiO₂(g) + 2/3CO(g)
3	1/2SiC(s) + O₂(g) → 1/2SiO₂(s) + 1/2CO₂(g) 1/2SiC(s) + O₂(g) → 1/2SiO₂(l) + 1/2CO₂(g) 1/2SiC(l) + O₂(g) → 1/2SiO₂(g) + 1/2CO₂(g)
4	SiC(s) + O₂(g) → SiO(g) + CO(g)
5	2/3SiC(s) + O₂(g) → 2/3SiO(g) + 2/3CO₂(g)
6	SiO₂(l) → SiO₂(g)
7	SiO₂(l) + CO(g) → SiO(g) + CO₂(g)
8	SiO₂(l) + C(s) → SiO(g) + CO(g)
9	1/3SiO₂(l) + C → 1/3SiC(s) + 2/3CO(g) 1/3SiO₂(g) + C → 1/3SiC(s) + 2/3CO(g) 1/3SiO₂(g) + C → 1/3SiC(l) + 2/3CO(g)
10	1/2SiO₂(l) + C → 1/2SiC(s) + 1/2CO₂(g) 1/2SiO₂(g) + C → 1/2SiC(s) + 1/2CO₂(g) 1/2SiO₂(g) + C → 1/2SiC(l) + 1/2CO₂(g)
11	SiC(s) + 2SiO₂(l) → 3SiO(g) + CO SiC(l) + 2SiO₂(g) → 3SiO(g) + CO
12	C(s) + O₂(g) → CO₂(g)
13	2C(s) + O₂(g) → 2CO(g)
14	C(s) + H₂O(g) → CO(g) + H₂(g)

图10 C和SiC氧化过程中吉布斯自由能随温度变化

Fig. 10 Changes of Gibbs-free-energy for the oxidation of SiC and C

图11 (C-SiC)f/C复合材料烧蚀模型

Fig. 11 Ablation model of (C-SiC)f/C composites

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