Biomimetic fluorapatite films for conservation of historic calcareous stones

Fuwei Yang,Yan Liu,Yuancheng Zhu,Pingning Hua,Bingjian Zhang,Guofang Zuo

doi:10.1007/s11434-012-5026-1

Fuwei Yang, Yan Liu + Show 4 more

Open Access

https://doi.org/10.1007/s11434-012-5026-1

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Abstract

Fluorapatite protective films were prepared on marble substrates using a biomimetic method. By mimicking the mineralization mechanism of enamel, phosphorus and fluorine were introduced on the surface of the marble substrate. In the presence of a biological template, namely collagen, an integrated fluorapatite film was produced and the marble substrate was entirely covered. The prepared fluorapatite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) spectroscopy. The performances of the fluorapatite films were evaluated by color changes, capillary water absorption, and acid resistance tests. The results revealed that the fluorapatite films had good compatibility with the marble substrate; the physical properties such as color and capillary water adsorption of the marble substrates were unchanged. The fluorapatite films also had good acid resistance and were stable even in heavy acid rain.

Highlights

Sample preparationAbsorbent cotton was immersed in a solution of ammonium phosphate (0.0–5.0 g/L), ammonium fluoride (0.0–0.6 g/L), and Type I collagen (0.0–0.1 g/L)
Calcareous stone is the most widely used material in historic statues and monuments
Stone relics treated with organic materials can be attacked by microorganisms which feed on the protective organic materials [12]

Summary

Sample preparation

Absorbent cotton was immersed in a solution of ammonium phosphate (0.0–5.0 g/L), ammonium fluoride (0.0–0.6 g/L), and Type I collagen (0.0–0.1 g/L). The final mixtures were packed onto white marble specimens (2.5 cm × 2.5 cm × 0.5 cm) by pressing for 48 h. The molar ratio of ammonium phosphate to ammonium fluoride was fixed at 3:1. The specimens were washed with deionized water and dried in an oven at 60°C for 24 h. Ammonium phosphate, ammonium fluoride (Sinopharm Chemical Reagent Co., Ltd, China) and Type I collagen (Elastin Products Company, Inc., USA) were used without purification

Characterization

Biomimetic treatment of white marble

Conclusion