Preceramic Paper-Derived SiCf/SiCp Composites Obtained by Spark Plasma Sintering: Processing, Microstructure and Mechanical Properties

Abstract

Ceramic matrix composites (CMCs) based on silicon carbide (SiC) are promising materials for applications as structural components used under high irradiation flux and high temperature conditions. The addition of SiC fibers (SiCf) may improve both the physical and mechanical properties of CMCs and lead to an increase in their tolerance to failure. This work describes the fabrication and characterization of novel preceramic paper-derived SiCf/SiCp composites fabricated by spark plasma sintering (SPS). The sintering temperature and pressure were 2100 °C and 20–60 MPa, respectively. The content of fibers in the composites was approx. 10 wt.%. The matrix densification and fiber distribution were examined by X-ray computed tomography and scanning electron microscopy. Short processing time avoided the destruction of SiC fibers during SPS. The flexural strength of the fabricated SiCf/SiCp composites at room temperature varies between 300 and 430 MPa depending on the processing parameters and microstructure of the fabricated composites. A quasi-ductile fracture behavior of the fabricated composites was observed.

Microstructural Analysis of Novel Preceramic Paper-Derived SiCf/SiC Composites

“…The SiC f /SiC composites made of preceramic papers were fabricated using SPS. The manufacturing process of these specimens was presented in detail in [1]. The fabricated SiC f /SiC composites consist of the SiC layers derived from preceramic papers [9,10] and the layers of oxygen-free SiC-Nicalon™ fibers (Nippon Carbon Co., Tokyo, Japan).…”

“…The organic components in the preceramic paper decompose during sintering, and thus the porosity can be formed. In addition, during sintering a necking is formed between SiC particles, resulting in a uniform porous structure [1].…”

“…Silicon carbide (SiC) has excellent properties-such as low density, high specific strength, high specific modulus, resistance to thermal shock, low coefficient of thermal expansion, radiation tolerance, and chemical inertness [1,2]. Due to the high radiation resistance at elevated temperature, low activation and decay heat properties, low thermal neutron cross section and low tritium permeability, SiC is of particular interest for applications in nuclear reactors [3].…”

“…Another design based on the formation of a laminated structure layer-by-layer reinforced with SiC fibers was suggested in the previous study, in which the novel preceramic paper-derived SiC f /SiC composites were successfully fabricated using spark plasma sintering (SPS) [1], which has the advantage of being faster than other processes-such as reactive melt infiltration (RMI) [7], chemical vapor infiltration (CVI), polymer infiltration pyrolysis (PIP) [8], etc. Preceramic paper, as a feedstock for sintering SiC, is a paper with a thickness of 0.5 mm that incorporates SiC powder with a size of about 4.5 µm, can be used as a raw for manufacturing ceramic substrates with complex geometric shapes.…”

“…The 'nature' of the layered-structure can also lead to the improvement of the mechanical properties such as flexural strength and fracture toughness of these composites [11]. It has been shown that the SiC f /SiC composites have obvious advantages as a structural material for nuclear reactors, such as high strength and quasi-ductility in comparison with SiC bulk materials, the improved mechanical properties are attributed to a combination of distinct toughening mechanisms-such as crack deflection, crack bridging, crack branching and delamination, pull-out, and layer rupture [1]. The main goal of this study was to analyze the microstructure of the paper-derived SiC f /SiC composites fabricated by SPS.…”