Study on Deterioration Law and Mechanism of Pottery Culture Relics Due to Salt Crystallization

To investigate the deterioration patterns and damage mechanisms of pottery relics caused by soluble salts, this study used soil from the Qin Eastern Mausoleum to prepare simulated pottery samples. Sodium chloride, sodium sulfate, and sodium nitrate were selected as representative soluble salts. A three-factor, three-level orthogonal experimental design was employed to examine the effects of salt type, concentration (1%, 5%, 10%), and dry-wet cycles (10, 20, 30 cycles) on pottery deterioration. Changes in mass, hardness, color difference, and microstructure were analyzed using XRD, IC, XRF, and SEM-EDS. The results showed significant differences among salt types. The Na2SO4 group exhibited the most severe surface powdering, the NaCl group mainly showed salt crystallization, while the NaNO3 group caused the least visible damage. After 30 cycles, the 5% Na2SO4 group showed a hardness decrease of 206.66 HL and a color difference of 14.53, indicating serious structural deterioration. The 10% NaCl group showed a Cl− content increase to 115.51 mg/g, whereas the 1% NaNO3 group maintained relatively stable structure with only a 13.00 HL hardness decrease. The deterioration mechanisms mainly involved Na2SO4 phase transformation, NaCl pore crystallization and ion exchange, and the high solubility of NaNO3. These findings provide experimental and theoretical support for the protection of salt-damaged pottery relics.