実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report

課題番号 Project No.

装置責任者 Name of responsible person

2014B0134

Kenichi Oikawa

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Direct observation of water motion under blister of under-film

Noboru (BL-10)

corroded steels by ultra-bright neutron imaging technique

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2016/3/28- 3/31

Atsushi Taketani
所属 Affiliation
RIKEN
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
Organic Film-coated steel samples with under-film corrosion.
Chemical components: Fe, C, H, O
Solid. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

Sample preparation

Plates of normal steels and corrosion-resistant steels were prepared. These were coated with epoxy paintsand scratched by the sharp-edged knife. And then they were subjected to cyclic corrosion test (CCT)，topromote under-film corrosions, which repeated salt water spraying and drying process cyclically. List ofsamples are shown in a table.
Sample Name

Normal/Alloy

CCT days ( 4cycle/day)

Size

F5

Normal0 day

18*70.5*6mm3F1

19 day24.6*70.5*6.5

F2

30 dayF3

46 dayG3Alloy

46 dayS18Normal

6 monthE16Alloy

170*140*62. 実験方法及び結果（つづき） Experimental method and results (continued)
The samples were dried in the air environment. For the wet samples, they were soaked in the water until
saturation, salvaged and then wiped the surface water.
Experimental setup
A top view of an experimental setup is shown. Top in the picture was upstream of the beam line. From theupstream, a chamber box and a neutron cameras were settled.
A sample was set in the chamber box. Neutron radiography
images were taken by the neutron camera. For the computer
tomography imaging, a rotation stage was equipped in thechamber box. For the dry process continuous imaging, thechamber box was used for the maintain sample environment
with controlled humidity by flowing 2l/min dry air. Humidity andtemperature in the chamber box were monitored continuously.
The neutron camera was combination of a LiF/ZnS scintillator
and a cooled CCD sensor. The neutron camera, rotation stage and beam monitoring devices were controlled
together by single software in a PC.
Computer tomography Imaging. After drying or wetting,the sample was packed by thin polymer film to maintaindry or wet conditions. Neutron radiography images weretaken with 360 * 1deg rotation step and 12 sec exposure
time with 3 sec interval for the computer tomography.
Images of the E16 sample are shown. Left is dry andright is wet. Neutrons exposed from the front of thesample. All seven samples were taken dry and wet
images by same configuration. Texture of the dry image
might be caused by hydrogen in the under-film
corrosions. The difference between two images may indicate the water distribution.
Dry process continuous imaging. Samples were wetted by soaking in the water. The samples were set in thechamber box with dry air flow in order to maintain the controlled air environments. These images were taken
continuously by 12 sec exposure time with 3 sec interval to observe the water movement in the under-film
corrosion. F3, G3, E16, and S18 samples were measured by this method. Time decencies of the water
distribution in 2D will be obtained.
Expected Result
Spatial and time resolutions of the images were enough high as expected. Even thin film for packing material
was well imaged with 12 sec exposure time. By the quick analysis, waters in the regions which size were orderof a few mm disappeared within several minutes. It could be caused by voids and defects in the under-film
corrosions. The 3D images of the wet and dry will provide the information of the 3D distribution of thecorrosions and the water. These will be analyzed with time dependency of 2D water distributions in order tounderstand the water behaviors in the under-film corrosions.

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