การหาค่าสัมประสิทธิ์การแพร่ของเงินในเซอร์โคเนียมคาร์ไบต์ในช่วงอุณหภูมิ 1400 °ซ - 1600 °ซ / ฉัตรชัย สัมฤทธิ์ศุภผล = Evaluating silver diffusion coefficient in zirconium carbide in the temperature range of 1400 °c – 1600 °c / Chatchai Sumritsupapon
This research work aimed to evaluate the silver diffusivity in zirconium carbide (ZrC) at 1400 °c – 1600 °c. High temperature gas cooled-reactors (HTGR) use TRISO fuel microspheres and Ag is the only element that can diffuse out of the TRISO fuel to the coolant. 110mAg is considered to be the most dangerous radioisotope of silver, as it releases high intensity gamma ray to the environment. Therefore, it is essential to study the diffusivity of silver in ZrC. In this research work, ZrC was prepared with a thickness of 1 centimeter and was coated with silver by a sputtering method. Specimens were placed in containers made of stainless steel and ceramic. Thirty grams of silver was poured onto ZrC in the containers, and each container was heated for 20 hours. ZrC specimens were line-scanned by scanning electron microscope. The distances that silver was able to penetrate into ZrC were as follows: 5 microns at 1350 °c, 15 microns at 1500 °c and 20 microns at 1550 °c. Calculated diffusivities were as follows: D₁₃₅₀ = 2.17 x 10⁻¹⁷ m²/s, D₁₅₀₀ = 1.95 × 10-16 m²/s and D₁₅₅₀ = 3.47 × 10⁻¹⁶ m²/s. The activation energy was evaluated to be 74.03 kcal/mol or 309.74 kJ/mol and D₀ was evaluated to be 2.604 x 10⁻¹⁷ m²/s