Low Temperature Sintering of Silicon Carbide through a Liquid Polymer Precursor
There exists a need for a more developed and advanced cladding material for operational nuclear reactors. The current cladding, a Zirconium-alloy, is quickly approaching the pinnacle of its ability to handle the increasing fuel load demands. Also, as evidenced by the incident at Fukushima, it reacted violently with water steam at high temperatures, which created hydrogen gas and lead to subsequent explosions. Therefore, the material leading the investigation to replace the alloy is silicon carbide. Silicon carbide has been processed and manufactured through several techniques; however, this study focuses on the development of silicon carbide through the use of the polymer infiltration and pyrolysis (PIP) technique. This technique utilizes a polymer precursor, AHPCS, in accordance with low temperature sintering to enhance the density of silicon carbide. This procedure is environmentally friendly and makes use of low temperature and pressure processing parameters. The density achieved through this study was found to be 95 percent of fully dense silicon carbide. In an effort to enhance sintering and further increase density, nickel nanoparticles were added to the polymer precursor in two different proportions, 5 and 10 weight percent. The obtained densities were 96 and 97 percent, respectively. Hardness values were also obtained for the pure silicon carbide sample, 5 and 10 weight percent nickel samples. They were 2600, 2700 and 2730 HV, respectively. In addition to the recorded densities and hardness values, scanning electron and optical microscopy images were also utilized to properly characterize the samples. From the images obtained through these instruments, it is seen that the samples appear quite dense with minimal open pores. Lastly, x-ray diffraction patterns were recorded to appropriately characterize the phase of each sample and assess any additional product formation with the addition of the nickel nanoparticles. It is apparent that the pure silicon carbide samples are crystalline in phase from the XRD examination. As for the nickel added samples, there appears to be a formation of nickel carbide. The obtained results are a promising outlook on the advancement of silicon carbide as a potential cladding material for operational nuclear reactors.