Effect of Microstructure, Chemical Composition, and Open Porosity on Oxidation Resistance of ZrB2-Based Composites

In this research, the effect of microstructure, chemical composition, and open porosity on the oxidation resistance of ZrB2-based composites was investigated. To this end, four composites with different chemical compositions were consolidated by Spark Plasma Sintering (SPS) method in different conditions, namely different temperature, time, and pressure. The open porosity was measured using the Arashmidouse method. Image Analysis Tools (IAT) were also utilized to determine the grain size of all composites through SEM images. For oxidation test, the samples were put on the box furnace and oxidized at 1400 C at different holding times of 20, 40, 60, and 120 minutes. The oxidation resistance was evaluated by weighing the samples before and after oxidation and the 𝛥w was considered as the oxidation criterion. In addition, EDS analysis was used to identify the phases. The results showed that chemical composition was the most significant factor in terms of the oxidation resistance, least affected by open porosity. Sample 9, with a grain size of 2.5 µm and open porosity of 1.5%, had the least oxidation value of 0.0026 gr; however, Sample 4 with a grain size of 12 µm and open porosity of 0.68% had the highest oxidation value of 0.0176 gr.