Preparation of 3D orthogonal woven C–SiC composite and its characterization for thermo-mechanical properties

https://doi.org/10.1016/j.msea.2011.04.063Get rights and content

Abstract

3D-orthogonal-woven-C–SiC composite blocks were fabricated using liquid–silicon-infiltration and were characterized for thermal and mechanical properties. Coefficient of thermal expansion (CTE) and thermal-diffusivity of the blocks were determined in the three mutually perpendicular directions. CTE was found to lie in the range −0.5 × 10−6 to 0.9 × 10−6/°C over the temperature range 25–1050 °C while thermal diffusivity was found to be in the range 37.0–7.0 mm2/s over the temperature range 25–1200 °C. The composites were subjected to sudden heating at a heat flux of 0.9 W/mm2 for 20 s and cooling by a blast of air, upto 5 times. Three point bend test of the specimens was carried out. After five thermal shocks the composites retained about 59% of the initial strength (190 MPa); after each thermal shock, the composite retained 85–90% of the previous strength. The composites showed excellent resistance to thermal shock and chemical erosion necessary for re-usable aerospace applications.

Highlights

► 3D orthogonal C–SiC using LSI having uniform properties have been fabricated. ► CTE in all the direction varies from −0.5 × 10−6 to 0.9 × 10−6/°C over 25–1050 °C. ► Thermal diffusivity in all the direction varies from 37.0 to 7.0 mm2/s over 25–1200 °C. ► Mean flexural strength at room temperature in all the direction is about 190 MPa. ► After five thermal shocks, the residual flexural strength is about 112 MPa.

Introduction

Multidirectional carbon-fiber reinforced silicon-carbide matrix composites (C–SiC) have received considerable attention for the fabrication of reusable aerospace products like leading edges and nose tip of a hypersonic vehicle [1], [2], [3], [4], [5], [6]. To develop thicker products liquid–silicon-infiltration (LSI) has been reported to be a better process as compared to chemical vapor deposition and polymer impregnation [3], [4]. Fabric reinforcement based bi-directional and 3D stitched C–SiC composites using LSI have been reported in literature [3], [4], [7], [8]. In LSI based C–SiC composites, the molten silicon metal infiltrates into the pores of carbon–carbon (C–C) preform by capillary action and reacts with its carbon matrix to form the matrix of SiC (the carbon fibers provide excellent mechanical strength to the composite if the reaction is restricted to the carbon matrix). The hard SiC matrix provides excellent resistance to oxidation and erosion of the structure used, for the intended purpose i.e. propulsion systems, hypersonic environment and for thermal protection systems for re-entry [7], [8], [9].

Large thermal stresses generated in such applications lead to surface cracks on the structure. To prevent this the structure requires uniform properties in all the directions in addition to high thermal diffusivity, low CTE, low elastic modulus and high tensile strength. Fiber reinforced composites may be tailored made to achieve a combination of all the desirable properties by controlling fiber volume fraction (Vf) in different directions. Bi-directional C–SiC composites have good thermal and mechanical properties in XY directions but these are much inferior in the through thickness direction [7], [8], [9].

Three-dimensional fiber-reinforced ceramic composites are potential structural materials for sudden heating and cooling environment [10], [11], [12], [13], [14]. 3D-stitched C–SiC composites show still better behavior along the length and width of the fabric (X, Y directions) but mechanical properties in the through thickness direction are not as good due to very low Vf in the Z-direction [3], [4]. It is expected that 3D orthogonal woven C–SiC composites would have uniform properties in all the directions due to controlled and equal Vf in all the directions.

Aim and scope: The aim of the present work is to develop a 3D-orthogonal woven C–SiC composite material having low CTE, high thermal diffusivity and good mechanical properties in all the directions. Effect of thermal shock on flexural strength also needs to be studied to establish its usefulness for the reusable applications.

Section snippets

Raw materials

T-300 (high-strength) 3k carbon fiber tows were used to fabricate 3D-woven carbon fibrous preforms. Low quinoline soluble coal-tar pitch was used for densification of the preforms and high purity silicon metal was used for siliconization of the densified C–C preforms.

Preforming

3D orthogonal fibrous preforms in the size range 50 mm × 50 mm × 100 mm–75 mm × 100 mm × 200 mm were made manually using an indigenously developed fixture. The fiber tows were woven in the mutually perpendicular (X, Y and Z) directions (Fig. 1).

Composition

Weight of the composite blocks was noted at each stage of processing (Table 1). The density of the fibrous preforms and that of C–C preforms are 0.44 and 1.55 g/cm3 respectively; after siliconization it is about 2.30 g/cm3. From chemical analysis it is observed that 12% of the total mass of the composite is residual silicon which is entrapped in the pores of the siliconized blocks. It is also evident that SiC is about 44%. Carbon, which includes fibers and un-reacted matrix, is also about 44%. It

Conclusions

  • 1.

    Using coal-tar pitch as carbon matrix precursor 3D orthogonal woven C–C preform can be fabricated; further, using LSI, C–SiC composites of density 2.3 g/cm3 can be fabricated.

  • 2.

    Thermal and mechanical properties of 3D orthogonal woven C–SiC are uniform in all the three directions.

  • 3.

    CTE of the composites varies in the range −0.5 × 10−6 to 0.9 × 10−6/°C over 25–1050 °C. It is almost equal to the CTE of carbon fibers in the axial direction.

  • 4.

    The thermal-diffusivity of the composites varies in the range of

References (26)

  • J. Schulte-Fischedick et al.

    Mater. Sci. Eng. A

    (2002)
  • Y.D. Xu et al.

    Carbon

    (1998)
  • Y. Xu et al.

    Mater. Sci. Eng. A

    (2001)
  • F.H. Gern et al.

    Compos. Part A

    (1997)
  • C. Pradere et al.

    Carbon

    (2008)
  • D.K.L. Tsang et al.

    Carbon

    (2005)
  • C. Pradere et al.

    Carbon

    (2009)
  • R.J. Bruls et al.

    J. Eur. Ceram. Soc.

    (2005)
  • H. Qingwei et al.

    J. Mater. Process. Technol.

    (2001)
  • H. Kodama et al.

    J. Am. Ceram. Soc.

    (1989)
  • K. Nakano et al.

    J. Ceram. Soc. Jpn.

    (1992)
  • K. Suresh, K. Sweety, K. Anil, S. Anupam, G.R. Devi, A.K. Gupta, J. Mater. Sci....
  • K. Suresh, Preparation and characterization of continuous fiber reinforced multidirectional C–SiC composites using...
  • Cited by (17)

    • Image-based numerical modeling for the effective thermo-elastic property of 4D carbon/carbon composite at high temperatures

      2021, Composite Structures
      Citation Excerpt :

      Experimental studies have explored various factors which directly affect the CTE of c/c composites. These factors include morphology of constituents [4], porosity [5], preform architectures [5,6], heat treatment temperature [5,7], and environmental temperature [5,8–10]. Farhan et al. [8] measured the effective CTE of 4D in-plane (4DIN) c/c composite in in-plane and out of plane directions.

    • Advanced textile technology for fabrication of ramie fiber PLA composites with enhanced mechanical properties

      2021, Industrial Crops and Products
      Citation Excerpt :

      Furthermore, the interfacial bonding performance of RF/PLA in 50/50 composite is better than that of the other composites. Enhanced interface adhesion also contributes to improved flexural performances (Kumar et al., 2011). Therefore, 50/50 composite exhibited the highest flexural strength and modulus.

    • Continuous fiber reinforced ceramic matrix composites

      2021, Fiber Reinforced Composites: Constituents, Compatibility, Perspectives and Applications
    View all citing articles on Scopus
    View full text