Preparation, microstructure and properties of C/Ta4HfC5-SiC composite fabricated by PIP method based on a new liquid precursor

Abstract

A novel liquid Ta₄HfC₅ precursor was produced by modified citric acid complexation method and C/Ta₄HfC₅-SiC composite was manufactured by precursor impregnation and pyrolysis (PIP) process. The powder obtained after 1800 ℃ heat treatment of the precursor has a diameter range of 50–300 nm, with a median diameter of ∼110 nm. The density and porosity of C/Ta₄HfC₅-SiC composite are 2.43 g/cm³ and 13.2 %, respectively. Due to the toughening of fibers and the addition of SiC, the overall integrity of C/Ta₄HfC₅-SiC is improved, achieving high bending strength and fracture toughness of 392.6 MPa and 10.4 MPa·m^1/2, respectively. After oxyacetylene ablation assessment of 60 s, the measured mass ablation rate and linear ablation rate of the composite were 11.6 mg/s and 9.1 µm/s, respectively. A complete oxide layer based on the joint effort of oxides of Ta(Hf) and Si was formed on the surface of the composite, with no exposed fibers observed.