The Effect of the Addition of Aluminum Nitride to the Composition of NiAl2O4 Ceramics on Hydrogenation Processes and the Increase in Resistance to Swelling and Degradation

Abstract

This work examines the effects of the formation of impurity inclusions in the structure of NiAl2O4 ceramics when aluminum nitride is added to them and the occurrence of a reinforcement effect that prevents hydrogenation processes and the subsequent destruction of conductive and thermophysical characteristics. The appeal of ceramics possessing a spinel crystal structure lies in their potential use as ceramic fuel cells for both hydrogen generation and storage. Simultaneously, addressing the challenges related to ceramic degradation during hydrogenation, a critical aspect of hydrogen production, can enhance the efficiency of these ceramics while lowering electricity production costs. The selection of aluminum nitride as an additive for ceramic modification is based on its remarkable resistance to structural damage accumulation, its potential to enhance resistance to high-temperature degradation, and its ability to bolster strength properties. Moreover, an examination of the alterations in the strength characteristics of the examined samples subjected to hydrogenation reveals that the stability of two-phase ceramics is enhanced by more than three to five times compared to the initial ceramics (those without the addition of AlN). Additionally, it was noted that the most significant alterations in both structure and strength become apparent at irradiation fluences exceeding 1014 proton/cm2, where atomic displacements in the damaged ceramic layer reach over 5 dpa. During the evaluation of thermophysical properties, it was discerned that ceramics featuring an impurity phase in their composition exhibit the highest stability. These ceramics demonstrated a reduction in the thermal conductivity coefficient of less than 1% at the peak irradiation fluence.

Tudy of the Influence of the Accumulated Dose of Damage in the Near-Surface Layer on Resistance to External Influences Associated With Corrosion Processes During High-Temperature Annealing

“…The significant improvement in the resistance to strength property destruction observed in stabilized ceramics with a dopant concentration of 0.15 M is primarily linked to the emergence of inclusions in the shape of an impurity phase, Al 7 O 3 N 8 . As demonstrated in work [16], these inclusions fill the intergranular space in the form of a fine fraction, thereby enhancing degradation resistance. The observed softening for irradiated samples stems from the accumulation of deformation distortions of the crystal structure, alongside the formation of gas-filled inclusions in the pores, a growth in the concentration of which, alongside their combination into larger agglomerates, results in deformation of the near-surface damaged layer, as a consequence of a rise in internal pressure in the gas-filled cavities.…”

“…The choice of AlN dopant concentrations was determined by the possibility of obtaining ceramics exhibiting a significant structural ordering degree (exceeding 95% at a dopant concentration of 0.05 M) and ceramics containing impurity inclusions in the form of Al 7 O 3 N 8 impurity phases, characterized by an orthorhombic crystal lattice. A detailed study of the structural features of NiAl 2 O 4 ceramics depending on the AlN stabilizing additive concentration was presented in the work [16]. The samples were irradiated at the UKP-2.1 accelerator (Institute of Nuclear Physics of the Ministry of Energy of the Republic of Kazakhstan, Almaty, Kazakhstan) with protons with an energy of 1.5 MeV and a fluence of 5×10 15 ion/cm 2 (which, according to SRIM Pro 2013 calculations, corresponds to a displacement value of about 50 dpa).…”