23D01
Large-Area Coating of High functionality Oxide Thin Film through MOCVDProcessing
MOCVD法による高機能被覆の大面積化
Yoshimitsu Hishinuma, Teruya Tanaka, Takuya Nagasaka, Akio Sagara and Takeo Muroga
菱沼 良光, 田中 照也，長坂 琢也，相良 明男, 室賀 健夫
National Institute for Fusion Science322-6, Oroshi-cho, Toki, Gifu, 509-5292, Japan
核融合科学研究所 〒509-5292 岐阜県土岐市下石町322-6
The blanket system is one of the important components in order to realize the fusion power plant. In theliquid Lithium breeding blanket, reducing of the Magneto Hydrodynamic (MHD) pressure drop is keyissue to operate stably in the magnetic confinement fusion reactor. The electrical insulating coating on theblanket components such as ducts and large walls is an attractive concept to reduce MHD. We haveconstructed the Metal Organic Chemical Vapor Deposition (MOCVD) apparatus for the large area andcomplicatedly shaped erbium oxide (Er2O3) insulator coating. Furthermore, we also succeeded todemonstrate the Er2O3 coating into the interior surface of the stainless steel (SUS) pipe stably through theMOCVD process.

1. Introduction
The MHD pressure drop is a critical issue forliquid lithium fusion reactor blankets [1]. An
electrically insulating coating with oxide ceramics
is one of the attractive methods for reducing theMHD pressure drop. A ceramic coating would also
be necessary to suppress the hydrogen permeation
in a molten salt type blanket systems using Flibe orFlinak as the breeding and cooling fluid [2]. Someceramic materials such as CaO, Y2O3, CaZrO3, AlN
and Er2O3 have been studied as candidates for theinsulating coating [3,4]. Based on these studies,
Er2O3 was selected as one of the candidate materials
for MHD insulator coating because of highcompatibility with liquid Li and high electricalresistivity [4]. In the previous studies, Er2O3
coatings were developed by Physical Vapor
Deposition (PVD) methods. However, the PVD
methods have limited capability in coating on
complex surfaces expected in the blanketcomponents. It is important to develop new
methods of large area Er2O3 coating on the innerand outer surface of the complex shaped duct
tubing for the advanced liquid metal breeder
blanket application.
We investigated the MOCVD process as a newtechnology for large area coating on broad andcomplicated shaped components. MOCVD process
is a concise procedure to form homogeneous large
area coating layer which is synthesized via vapor
phase from a metal organic complex. It has thepossibility to form homogeneous coating layer into
the interior surface of the metal tube using vapor
flowing control.

2. Construction of large area MOCVD coatingapparatus
We constructed MOCVD apparatus to form large
area oxide coating in NIFS. Large area MOCVD
apparatus constructed in NIFS is shown in fig.1.
The MOCVD apparatus consists of three maincomponents; the metal organic complex supplying
line with a vaporizer, a gold furnace type quartz

Fig.1. Large area MOCVD apparatus in NIFS

tube reactor having long plateau temperature and anexhaust system [5]. The metal organic complex wasvaporized at 150℃in the vaporizer and introduced
into the reactor by the argon carrier gas. Allsupplying lines were heated at 250℃ by the ribbon
heater to prevent the metal organic complex
solidification. The vaporized complex reacted withoxygen gas via the other supplying line and theoxide coating layer was grown on the varioussubstrates. In this study, we used the Er(IBPM)3(isobutyrylpivaloylmethane) complex made in
Toshima MFG Co.,Ltd as the Er source material[5,6].
3. Er2O3 coating through MOCVD process
We confirmed clearly that Er2O3 coating layer
can be formed on various metal disk substrates such
as V, SUS and Ni, macroscopically. Transmission
Electron Microscope (TEM) and selected area
diffraction (SAD) images of the Er2O3 coating layer
is shown in fig.2. As dark field image and SAD
pattern are figs. a) and b). We found that Er2O3coating layer with about 800 nm thickness wasformed stably. In the boundary of Er2O3 and SUS
substrate, no macro defect such as crack andadhesion was also observed. In the SAD patterns, it
was clear that Er2O3 coating layer was crystallized
uniformly because the diffraction fleck arranged
like a ring shaped.
4. Large inner surface coating of metal tube pipe
We found that Er2O3 coating was able to form on
the metal substrates using MOCVD process. So, we
tried to form the Er2O3 insulator coating on thelarge interior surface area of a commercial SUS 316pipe. Typical photograph images of the interior
surface of a part of the SUS pipe before and after
MOCVD process is shown in fig. 3. We confirmedthat the green-colored homogeneous thin coating
was formed stably on the interior surface of theSUS pipe. In addition, Er2O3 coating was notremoved from the interior surface at all. This wascaused by the reduced surface roughness. It wassuggested that the surface conditions such asroughness and undulation were important factors toform coating layer into interior surface of the metal
pipe via MOCVD process.
Acknowledgments
This work was mainly supported by the NIFS
ProgramBudget(NIFS11UFFF026)
andCollaboration Research Program with Toshima
MFG Co.,Ltd: NIFS10PLFF401), in part by the
Grant-in-Aid for Scientific Research (A) 21246141(2009-2012).. In addition, we would like to thank to

500℃×1hFig.2. TEM and SAD images of Er2O3 coating layer
via MOCVD process(a)
10 mm

20 mm

SUS316 pipe

(b)

5 mm

Er2O3

SUS316 pipe
Fig.3. Typical photograph of the interior surface of
the SUS pipe before and after MOCVD Er2O3coating. (a) Before MOCVD coating, (b) After
MOCVD coating

Prof. K. Matsuda, University of Toyama, forproviding us with the microstructure analysis using
TEM observation.
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