SPring-8, the large synchrotron radiation facility

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Understanding the UPD (Under-Potential Deposition) on the surface of industrial metal materials for the first time in the world: a problem that had not been previously solved (Press Release)

Release Date
11 Jul, 2012
- Results of Industrial Uses of SPring-8 (a large synchrotron radiation facility) -

Kobe Steel, Ltd.

Kobe Steel, Ltd.,*1 in conjunction with a group led by Masahiro Seo and Hiroki Habazaki*2 (professor emeritus and professor, respectively, of the Graduate School at Hokkaido University), and Kobelco Research Institute, Inc.,*3 which is an affiliate of Kobe Steel, Inc., have developed original technology that performs, on the atomic level, in-situ XAFS*6 measurements of electro-chemical adsorption phenomena on corrosive metal material surfaces, using a beam line*5 dedicated to industrial usage at SPring-8,*4 a facility in which Kobe Steel, Ltd. is involved. For the first time in the world, the under-potential deposition (UPD)*7 phenomenon of a miniscule amount of Pb on a Ni surface, a topic previously unsolved, was studied, and the chemical conditions and the surface adsorption mechanism of the adsorbed monolayer of Pb were made clear.

This result is a new discovery contributing to a new understanding of the mechanism of stress corrosion cracking*9 by UPD of a miniscule amount of Pb, a problem that had arisen on steam generator tubes made with a Ni-alloy*8 at PWR-type nuclear power plants. Further, the results will help us understand other industrial problems caused by UPD, such as hydrogen embrittlement (delayed fracture) of high-tension steel and plating failures. This research, therefore, has significant implications both industrially and academically.

These results have already been published in the April issue of The Journal of Electroanalytical Chemistry, an international journal in this field. They were also presented at the lecture conference “Materials and Environment 2012” of the Japan Society of Corrosion Engineering, held on April 27 in Tokyo.

Kobe Steel, Ltd., together with the Graduate School of Hokkaido University, plans to use these research results to help solve the industrial problem of corrosion-related failures caused by UPD and to continue its research on structural materials at SPring-8.


The group in charge of this project was the Materials Research Laboratory of the Technical Development Group (Takenori Nakayama, board member and chief researcher).

Laboratory of Interfacial Electrochemistry, Research Group of Functional Materials Chemistry, Division of Materials Chemistry, Faculty of Engineering

A comprehensive testing and research firm founded when the analysis and testing work was separated and became independent from Kobe Steel, Ltd. The firm’s experiments at SPring-8 were commissioned by Kobe Steel, Ltd. The group in charge of this project was the Surface and Property Analysis Laboratory, Physical Analysis Center, Electronics Business Division (Masayuki Inaba, et. al., chief engineers).

*4 SPring-8
A RIKEN facility located in Harima Science Garden City (Hyogo prefecture) is capable of producing the world's highest intensity synchronous radiation. The management and promotion of utilization of this facility are undertaken by JASRI. The name “SPring-8” comes from “Super Photon ring-8 GeV.” An electron flying at nearly the speed of light, if deflected from its original trajectory through the effect exerted by a magnet, emits an electromagnetic wave in a direction tangential to its trajectory, which is called radiation light (or synchrotron radiation). At present, there are three “3rd Generation” large scale synchronous radiation facilities in the world: SPring-8 (Japan), APS (USA) and ESRF (France). The acceleration energy available at SPring-8 (8 billion electron volts) enables the provision of an extremely wide spectrum of radiation light: from far infrared to visible, vacuum ultraviolet, and soft X-ray up to hard X-ray. SPring-8 provides a theater for collaborative works involving researchers inside and outside Japan, and the research conducted at this facility cover such diverse areas as material science, geoscience, life science, environmental science, and various applications in industrial sectors.

*5 Beam line dedicated to industrial usage
The beam line established, used, and operated by the Consortium for Building and Using a Beam Line Dedicated to Industrial Usage (“Sangyokai senyo beamline kensetsu riyo kyodotai,” nicknamed “Sunbeam Consortium”). Actually there are two beam lines, BL16XU and BL16B2; the latter was used in this research. The Sunbeam Consortium consists of 13 companies and groups, including Kobe Steel, Ltd., Sumitomo Electric, Ltd., Sony, Ltd., and Hitachi, Ltd. and has been using SPring-8 for industrial purposes since 1998.

An abbreviation for X-ray Absorption Fine Structure; in Japanese, it is called “X-sen kyushu bisai kozo.” When an X-ray is applied to an object, it interacts with various motions of the atomic nucleus and electrons in the object, resulting in part of the incident X-ray being absorbed by the object and losing some energy. Hence, by continuously changing the energy level of the X-ray applied and measuring the level of X-ray absorbed by the object, one can obtain information on the structure around the central atom, such as the (1) neighboring atomic species, (2) distance between atoms, and (3) coordination number.

fig*7 Under-Potential Deposition
UPD is an abbreviation for “under-potential deposition,” an electro-chemical phenomenon in which a miniscule amount of ions is adsorbed on a different type of metal with a positive electric potential higher than the equilibrium potential at which the metal deposits. Although it is not yet well-understood, this phenomenon contributes not only to stress corrosion cracking of Ni-based alloys at nuclear plants but also to hydrogen embrittlement of high-tension steel and plating failures. A dramatic measure through clear understanding of its mechanism is being sought.

UPD Extraction
Mn+ + ne- (M’) → Mad (M’)
M’ indicates a different metal species; Mad indicates an atom of metal M adsorbed on metal M’ of different metal species.

*8 Steam generator
A gigantic heat exchanger that collects heat from a nuclear reactor and transfers it from the primary system to the secondary system at a pressurized water reactor (PWR), a type of light-water power-generating reactor. Ni-based alloys (Alloy 600, 690) are often used as heat-conducting small-tube materials. If these small tubes are damaged due to stress corrosion cracking, etc., the primary coolant leaks into the secondary system, possibly causing a serious accident.

*9 Stress corrosion cracking
Corrosive damage of a metal material caused by certain combinations of three factors: material, environment, and tensile stress. Because the damage could occur even below a tensile stress level where damage is almost unthinkable from the standpoint of the mechanical strength of the material, this is a serious phenomenon which requires a drastic solution industrially.

For more information, please contact:
  Dr. Takenori Nakayama (Kobe Steel, Ltd.)
    E-mail :

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