Quantitative measurement of cast metal relics by pulsed thermal imaging

ABSTRACT

Corrosion in cast metal relics has always been a concern for the conservation and restoration of ancient culture relics. In recent years, there is an increased interest in the determination of the corrosion/rust thickness and the substrate thickness of bronze and iron cultural relics. The solution of this problem is of great significance in the evaluation of the corrosion status, rust cleaning, and the restoration and conservation of metal cultural relics. This paper presents a new method for the measurement of the rust thickness and the substrate thickness of a replica cast-iron Buddha head by one-sided pulsed thermal imaging. In this method, the rust thickness and the substrate thickness of cast-iron Buddha head were determined simultaneously by a non-linear fitting of a theoretical solution with experimental values. The finite flash duration effect and the finite substrate thickness effect on the rust thickness measurement are analysed and discussed. Besides the new method, the conventional Flash method for single-layer materials was also used to estimate the wall thickness. The measurement results show that this new method has great potential and capability in the quantitative measurement of ancient iron and bronze cultural relics.

KEYWORDS:

• Pulsed thermal imaging
• rust thickness
• substrate thickness
• cast metal relics
• thermal diffusivity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Ning Tao

Ning Tao received her PhD in Physical Electronics from University of Science and Technology of China, Hefei, China, in 2005. She is currently an Associate Professor of Nondestructive testing, Optical Engineering with the Department of Physics, Capital Normal University, China. Her research interests include Infrared nondestructive testing and quantitative evaluation method and its application in composite materials and cultural heritage.

Congsi Wang

Congsi Wang received his B.Sc. degree in Optoelectronic Information Science and Engineering from Capital Normal University, Beijing, China, in 2018. He is currently working toward the M.Sc. degree in Optics with the Capital Normal University, Beijing, China. His research interests include Nondestructive testing and evaluation by Pulse thermography and step heating thermography.

Cunlin Zhang

Cunlin Zhang received his PhD in Optical Engineering from Beijing Institute of Technology, China, in 1992. From 1992 to 1996, he was an Assistant professor with Beijing Institute of Technology. Since 1992, he has been a Professor of Optics and Optical Engineering with the Department of Physics, Capital Normal University, China. He is currently a director of Key Lab of Terahertz Optoelectronics, Ministry of Education. His research interests include terahertz spectrum and imaging theory and basic research of functional devices, and nondestructive testing and evaluation.

Jiangang Sun

Jiangang Sun received his PhD in Mechanical Engineering from University of Illinois at Urbana-Champaign, USA. He previously worked as a Mechanical Engineer at Argonne National Laboratory. He is now an Adjunct Professor with the Department of Physics, Capital Normal University, Beijing, China. His research interests include infrared thermal imaging for the characterization of advanced ceramic and composite materials, multiphase flow and heat transfer.