Microstructure and Properties of DCP-Derived W-ZrC Composite Using Nontoxic Sodium Alginate to Fabricate WC Preform

Abstract

In the present work, tungsten carbide (WC) preforms were fabricated by gel-casting process, using different nontoxic Na-alginate to tertiary calcium phosphate ratios and different loadings of WC powder in the initial slurries. The gel-cast green bodies were dried and pre-sintered at 1723 K for 4 h and then reactively infiltrated by molten Zr2Cu at 1623 K for 0.5 h, to produce W-ZrC composite via displacive compensation of porosity process. The phases, microstructures, and mechanical properties of the preforms and the W-ZrC composites were investigated by Fourier transform infrared spectroscope, x-ray diffractometer (XRD), scanning electron microscope (SEM), image analyzer, and universal mechanical testing machine. XRD results, SEM micrographs, and elemental maps indicated uniform distribution of phases (W and ZrC) and elements (W, Zr, and C). Flexural strengths and hardness of the fabricated composites were in the ranges of 429-460 MPa and 7.5-9.5 GPa, respectively. Fractography studies revealed two types of dimple rupture and cleavage fracture modes in different composite samples. The W-ZrC composite was ablated by an oxyacetylene flame for 60 s. The mean value of mass and linear ablation rates of the composite were 2.1 ± 0.1 mg/s and 3.6 ± 0.5 µm/s, respectively.