In fast neutron reactors, some parts can be subjected to displacements between each other (as movable parts for example). On these parts, the contact areas usually need a hardfacing coating. The standard hardfacing alloy is a cobalt-base alloy (for example Stellite®6). Unfortunately, in the primary coolant circuit and on wear conditions, cobalt can be released. Under neutron flux, the stable 59Co can be transmuted into 60Co by radioactive capture of neutrons and, therefore, can contaminate the primary circuit. Therefore, it is desired to replace this cobalt based hardfacing alloy by a cobalt-free one. Previous presentations have shown the potential interest of some nickel base materials as Colmonoy® alloy. In parallel, laser cladding has been identified as a deposition process that could increase the performances of the hardfacing materials compared to the standard process (Plasma Transferred Arc Welding). In all the study, the base material is the stainless steel 316LN. In the first section of this article, the authors present previous results related to the selection of hardfacing materials and their evaluation in comparable tribology conditions. Then, Tribaloy® 700, another nickel based alloy that has been poorly investigated, is presented and evaluated. This nickel base has a completely different microstructure, and its tribological behavior related to the variation of the microstructure is not well known. First, the authors present the features of the selected materials. Then, the authors present various property characterization results obtained by changing several process parameters. The quality of the clad is considered, and the process window providing a good clad is determined (no crack, only a few porosities, etc.). The variation of the microstructure is analyzed, and solidification paths are proposed regarding the process parameters. Wear tests are performed on typical wear conditions. The movement is linear. Argon is used for the protection of the sample against oxidation. Tests are carried out at 200 °C. Wear tests are analyzed, and wear mechanisms are correlated with the microstructure of the material.

1.
P. M.
Dunckley
,
T. F. J.
Quinn
, and
J.
Salter
, “
Studies of the unlubricated wear of a commercial cobalt-base alloy at temperatures up to about 400 °C
,”
ASLE Trans.
19
,
221
231
(
1976
).
2.
H.
So
,
C. T.
Chen
, and
Y. A.
Chen
, “
Wear behaviours of laser-clad Stellite alloy 6
,”
Wear
192
,
78
84
(
1996
).
3.
J. T. M.
de Hosson
and
L.
de Mol van Otterloo
,
Surface Engineering with Lasers of Co-base Materials, Surface Treatment, Computer Methods and Experimental Measurements
(
Computational Mechanics Publications
,
Southampton, UK
,
1997
), pp.
341
359
.
4.
J. L.
de Mol van Otterloo
and
J. T. M.
de Hosson
, “
Microstructure and abrasive wear of cobalt-based laser coatings
,”
Scr. Mater.
36
,
239
245
(
1997
).
5.
D. H. E.
Persson
,
S.
Jacobson
, and
S.
Hogmark
, “
Effect of temperature on friction and galling of laser processed Norem 02 and Stellite 21
,”
Wear
255
,
498
503
(
2003
).
6.
D. H. E.
Persson
, “
Laser processed low friction surfaces
,”
Dissertation for the degree of Licentiate of Philosophy in Materials, Materials Science Division
, the Ångström Laboratory, Uppsala University, Sweden, March
2003
.
7.
C. B.
Bahn
,
B. C.
Han
,
J. S.
Bum
,
I. S.
Hwang
, and
C. B.
Lee
, “
Wear performance and activity reduction effect of Co free valves, in PWR environment
,”
Nucl. Eng. Des.
231
,
51
65
(
2004
).
8.
M.
Corchia
,
P.
Delogu
, and
F.
Nenci
, “
Microstructural aspects of wear-resistant Stellite and Colmonoy coatings by laser processing
,”
Wear
119
,
137
152
(
1987
).
9.
H.
Kashani
,
A.
Amadeh
, and
H.
Ghasemi
, “
Room and high temperature wear behaviors of nickel and cobalt base weld overlay coatings on hot forging dies
,”
Wear
262
,
800
806
(
2007
).
10.
Q.
Ming
,
L. C.
Lim
, and
Z. D.
Chen
, “
Laser cladding of nickel-based hardfacing alloys
,”
Surf. Coat. Technol.
106
,
174
182
(
1998
).
11.
D.
Kesavan
and
M.
Kamaraj
, “
The microstructure and high temperature wear performance of a nickel base hardfaced coating
,”
Surf. Coat. Technol.
204
,
4034
4043
(
2010
).
12.
V. D.
Tran
,
P.
Aubry
,
C.
Blanc
,
J.
Varlet
, and
T.
Malot
, “
Laser cladding and tribocorrosion testing of cobalt-free hardfacing coatings for fast neutron reactor
,” in
Proceeding of ICALEO 2014
(
2014
), Paper No. 203.
13.
C.
Navas
,
R.
Colaço
,
J.
Damborenea
, and
R.
Vilar
, “
Abrasive wear behaviour of laser clad and flame sprayed-melted NiCrBSi coatings
,”
Surf. Coat. Technol.
200
,
6854
6862
(
2006
).
14.
K.
Komvopoulos
and
K.
Nagarathnam
, “
Processing and characterization of laser-cladded coating materials
,”
J. Eng. Mater. Technol.
112
,
131
143
(
1990
).
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