Cold Sintering Dwell Time Effects on Gadolinium Doped Ceria
Gadolinium doped nanocrystalline cerium dioxide (GDC) powder samples were effectively densified using the developing process known as “cold sintering” with adjustments to dwell time investigated. Ceria was chosen due to its application as an electrolyte in solid oxide fuel cells. Trials of 3, 6, and 12 hours were completed with the peak dwell temperature of 350˚C through die jacket heaters within a Carver press applying 500 MPa. The mixed NaOH-KOH molten hydroxide flux facilitated densification to approximately 61, 76, and 79% relative density for sintering durations 3, 6, and 12 hours, respectively. Although density increased, grain growth was not directly affected by sintering time. Measurements found the average grain size in the 3- and 12-hour samples to be greater than that of the 6-hour, with large standard deviations in all samples. Following cold sintering, samples were annealed at 800˚C for 6 hours, in order to burn off the remaining hydroxides. Traces of flux were found between layers of delamination, and striations heavier in sodium were identified on a 12-hour sample. Chemical analysis of 3 different duration samples showed that the plateau of flux removal is reached after 6 hours of sintering. The sodium and potassium concentrations were higher in the 3-hour sample, as compared to the similar values of the 6- and 12-hour samples. Significant data was collected which contributes to the progress of cold sintering development.
Thesis completed in partial fulfillment of the requirements for the Alfred University Honors Program.
Honors thesis, Material Science, Ceramics, Chemical Analysis