Effect of W content on the ablation properties of W-ZrC composites synthesized by reactive melt infiltration under oxyacetylene flame

Abstract

W-ZrC composites with different W contents from 48 to 68 vol% have been produced by reactive melt infiltration of molten Zr2Cu alloy into porous preforms from partially-carburized W powders at 1300 °C for 1 h in vacuum. The influence of W content on ablation behavior and properties was evaluated under oxyacetylene flame conditions. When W content is above 50 vol%, the W-ZrC composites withstood the thermal shock at the early ablation stage. The linear and mass ablation rates of the 68 vol% W-ZrC composite without residual tungsten carbides are 0.8 μm·s−1 and 3.5 mg·s−1, respectively, tested at 2600 °C for 120 s. Such a performance is attributed to the evaporation of WO3 and residual Cu and the formation of protective ZrO2-rich oxide layers on the ablated surfaces of the composites. The ablation of W-ZrC composites is mainly caused by the thermo-chemical oxidation as well as thermo-mechanical erosion of the formed oxides.