Preliminary research on the multi-hierarchy structure and water loss process of excavated ivories at Sanxingdui
The high moisture content of excavated ivories excavated from Sanxingdui sacrificial pits is due to their long-term burial in the wet underground environment.There are also such problems as body fracture,glaze cracking and peeling,resulting from poor preservation conditions.It is very easy for excavated ivories to lose water quickly and suffer irreversible damages such as cracking and pulverization.To clarify the preservation status of excavated ivories from Sanxingdui site,the composition,structure and water loss process of ivories at Pits No.3,4,7 and 8(K3,K4,K7 and K8)of Sanxingdui site excavated in 2021 were analyzed by means of spectrometry,electron microscopy and nano-indentation,etc.The results show that the main phase of the excavated ivories from the four sacrificial pits was hydroxyapatite[Ca10(PO4)3(CO3)3(OH)2].The organic components had largely dis-appeared,forming a mainly mesoporous pore structure(pore size distribution in the range of 3-50 nm).These pore structures were occupied by a large amount of adsorbed water and bound water,showing high adsorbent water contents.The moisture contents of K3-excavated ivory(K3XY-54)and K4-excavated ivory(K4YW-289)were 43.8％and 43.4％,respectively.All the four sacrificial pits had flake and needle-like crystal structures,among which,K3XY-54 showed obvious orientation growth with needle-like crystal structures,while K4YW-289 showed crystal aggregation and significant increase in thickness.The internal stress of microstructure caused by the volatilization of adsorbed water on the surface and inside of excavated ivories,resulted in irreversible damages such as cracking and pulverization.The surface micro-hardness changes of excavated ivories in the rotten state were preliminarily explored by nano-indentation.The surface micro-hardness difference of K4YW-289 before and after water loss was the largest(0.090±0.049 GPa in the waterlogged state,1.55±0.31 GPa after water loss),which may be related to the low adsorbed water content in the component structure and high argillation phenomenon.In combination with the studies of K3XY-54,K7XY-43 and K8XY-11-13,it was found that the micro-hardness and elasticity modulus of excavated ivories before and after water loss was largely affected by the relationship between the component structure and water loss rate.These research results provide a powerful scientific basis and reference data for the subsequent effective implementation of preservation and reinforcement of excavated ivories.
Sanxingdui site sacrificial areaExcavated ivoryMulti-hierarchy structureWater loss
万方数据
维普
