A typical TGA profile recorded in static air is shown in Fig. 4. During the initial heating between 30 and 180 °C, water is removed from the sample corresponding to an initial weight loss of 13.31%. There is a weight gain starting at 195 °C. The weight of the sample increases slowly by 4.95% from 195 to 525 °C. With the temperature increasing, the remaining ZrB2 nanocrystallites are further oxidized by O2 in air and the weight gain increases rapidly. The weight gain can be ascribed to the oxidation of ZrB2 forming ZrO2 and B2O3[11]. Around 1000 °C B2O3 evaporates extensively [12], which counteracts the weight gain due to the oxidation of ZrB2, so the weight change begins to decrease. In addition, B2O3 evaporation results in the final weight gain being less than the theoretical value (149%)