Abstract
Ceramic matrix composites made of carbon fibres and carbon matrix (C/C) are generally used for aircraft structures and brake discs due to their low density, and good thermal, mechanical, and tribological properties. Silicon carbide (SiC) can be introduced to the matrix to improve the performance of C/C composites, because it increases the hardness and thermal stability, and decreases the chemical reactivity, which leads to the improvement of tribological properties of C/C composites. Thus carbon–carbon silicon carbide (C/C–SiC) composites can be used at high temperature for the application of brake discs, friction clutches, etc. C/C–SiC composites are fabricated by three different methods: (i) chemical vapour infiltration (CVI), (ii) polymer infiltration and pyrolysis (PIP), and (iii) liquid silicon infiltration (LSI), among which LSI method is widely used for the fabrication of C/C–SiC composites due to higher mechanical and thermal properties.
Highlights
Carbon fibre reinforced carbon (C/C) composites have unique properties like high melting point, high stiffness and toughness, better thermal shock properties, low coefficient of thermal expansion, etc., due to which C/C composites are used in aircraft brake applications, racing cars, and motorcycles [1,2,3,4,5]
Several industries and institutions are working on C/C–silicon carbide (SiC) composites to investigate them as friction materials for brake discs and brake pads [11,12,13,14]
These two approaches successfully meet the requirement, but due to higher coefficient of thermal expansion of ceramic rich surface than that of carbon–carbon silicon carbide (C/C–SiC) substrate, tensile stress develops in the surface during cooling after processing leading to micro cracking of the surface
Summary
Carbon fibre reinforced carbon (C/C) composites have unique properties like high melting point, high stiffness and toughness, better thermal shock properties, low coefficient of thermal expansion, etc., due to which C/C composites are used in aircraft brake applications, racing cars, and motorcycles [1,2,3,4,5]. The presence of SiC in the composite matrix results in increase in coefficient of friction, but wear rate increases due to abrasive action of silicon carbide [9]. Gradual increase of SiC from the centre to the outer region (i.e., friction surface); homogeneous C/C–SiC composites with Si–SiC coating on the outer region These two approaches successfully meet the requirement, but due to higher coefficient of thermal expansion of ceramic rich surface than that of C/C–SiC substrate, tensile stress develops in the surface during cooling after processing leading to micro cracking of the surface. C/C–SiC composites have high porosity due to which it possess high wear rate This is attributed to the fact that due to higher porosity, SiC particle framework does not form and the hard SiC particles plough and micro-cut the friction surface resulting in grain abrasion [17].
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