Oxidation and laser ignition characteristics of Mn, Mo, Ta, and W powders in oxygen-rich environments

Manganese (Mn), molybdenum (Mo), tantalum (Ta), and tungsten (W) powders offer exceptional properties such as high strength, combustibility, and substantial volumetric combustion enthalpy, making them valuable for aerospace and industrial applications. This study investigates their oxidation and burning characteristics through thermogravimetric-differential scanning calorimetry and high-pressure combustion tests. Onset oxidation temperatures were determined as 340.23 °C, 475.01 °C, 523.90 °C, and 535.70 °C for Mn, Mo, Ta, and W, respectively. Mn forms Mn₂O₃ and Mn₃O₄, with combustion products exhibiting surface holes as substance migration channels. Mo and W form volatile oxides (MoO₃, WO₃) sublimating above 800 °C and 1200 °C, respectively, while Ta forms stable Ta₂O₅. Luminous intensity measurements quantified combustion evolution, revealing ignition delay times of 64 ms, 77.5 ms, 97.8 ms, and 128 ms for Mn, Mo, Ta, and W under 0.5 MPa oxygen, with Mn and Ta showing intense flames and faster reaction rates. Scanning electron microscope and X-ray diffraction analyses identified Mn₃O₄, MoO₃, Ta₂O₅, and WO₃ as primary combustion products. This study provides insights into the oxidation and combustion behaviors of high-density metal powders, supporting improved safety in powder metallurgy, 3D printing, and energetic material design.