Encyclopedie de la recherche sur l'aluminium au Quebec - Edition 2014 | Page 14
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Iron Aluminide-based Coatings:
PRODUCTION D’ALUMINIUM // ALUMINIUM PRODUCTION
Microstructure and Microhardness
REVÊTEMENTS À BASE D'ALUMINIURE DE FER : MICROSTRUCTURE ET MICRODURETÉ
Revêtements à base d'aluminiure de fer:
Microstructure et la microdureté
IRON ALUMINIDE-BASED COATINGS : MICROSTRUCTURE AND MICROHARDNESS
Mahdi Amiriyan1, Houshang D. Alamdari1, Carl Blais1 et Robert Schulz2
Department of Mining, Metallurgical and Materials Engineering, Université Laval, Québec (QC), Canada G1V 0A6
2 Hydro-Quebec Research Institute, 1800 Boul. Lionel Boulet, Varennes, QC, Canada J3X 1S1
Introduction
Results & Discussion
Feedstock Powder
(a)
Figure 1. XRD
patterns of the
Fe3Al-TiC
composite
powders milled
for 6 h and heat
treated at
1000°C for 2h
(a’)
(b)
12
Differential Volume (%)
Progressive degradation of metallic parts due to wear damages leads to loss of
efficiency and even failure.
Deposition of a proper wear resistant coating, even on damaged surfaces, can provide a
refurbished surface without replacing the part.
Aluminide coatings are attractive alternatives to improve tribological behavior of
hydroelectric power generation equipment in which wear has significant impact on
operating and maintenance costs, as well as efficiency.
Iron aluminide intermetallics have been recently identified as potential coatings for
steel substrates in sulfidation and corrosion resistant applications [1, 2].
Recent studies [3, 4] have demonstrated that incorporation of hard ceramic particles
could improve the mechanical properties of iron aluminide coatings.
It has been reported that iron aluminide coatings obtained by HVOF are characterized
with high relative density and adequate adhesion to substrate [5-7].
100
90
80
70
60
50
40
30
20
10
0
1000
10
8
6
4
2
0
In Fig.1 the main peak of iron aluminide is clearly
seen and for each composition, titanium carbide
peaks are also observed at different intensities. TiC is
formed by mechanochemical reaction between
graphite and titanium during milling and this ceramic
phase grows during the subsequent heat treatment.
Problem Statement
limited room temperature ductility (less than 5%)
poor mechanical properties and wear resistance at room temperature
Objectives
To in-situ synthesis of Fe3Al-TiC composite powders
To investigate the effect of in-situ TiC particle content on the microstructure and
mechanical properties of Fe3Al coatings
1
10
100
Particle Diameter (µm)
Figure 2. (a & aˈ) Morphology
at two magnifications and (b)
particle size distribution of the
Fe3Al-50 mol.% TiC
composite powder
Methodology & Analysis
Experimental Procedure
In-situ powder synthesis
High energy ball milling:
Fe3Al+Ti+C
1-12 h
Heat treatment:
900-1000 ºC for 2h
(a)
(d)
Fe3Al
Graphite
Milling
Ball
Collision
Equivalent
Fe3Al volume
fraction (%)
Pd
Cr
fraction (%)
Fe3Al
0
100
0
10
90
4
30
70
15
50
50
29
71
Fe3Al-70 TiC
70
30
49
Figure 4. Cross sectional SEM images of the (a) Fe3Al (b) 10,
(c) 30, (d) 50, and (e) 70 mol.% TiC deposited coatings
85
Fe3Al-50 TiC
(b)
96
Fe3Al-30 TiC
(a)
100
Fe3Al-10 TiC
51
The images in Fig. 4 show that the coatings are quite
dense. The porosity content is on the order of 3-6 %.
The deposition process leads to the development of a
lamellar microstructure consisting of melted and
partially melted particles that is typical of HVOF
coatings.
Vickers Microhardness
Titanium
Milling
Ball
Collision
PRIX // AWARD
(c)
Iron
Aluminide
Step II
Oxygen flow
rate, m3/h
54
Milling
Ball
Collision
Mahdi Amiriyan
Houshang D. Alamdari
Carl Blais
Département de génie des
mines, de la métallurgie
et des matériaux,
Université Laval
Robert Schulz
Institut de recherche
d’Hydro-Québec
Step III
Milling
Ball
Collision
Kerosene
flow rate,
m3/h
0.02
Carrier gas,
m3/h
Spraying
distance, m
0.56
0.38
Number of
deposition
passes
5
Hv300
Milling
Ball
Collision
Milling
Ball
Collision
Experimental Analyses
X-ray Analysis
P
Milling
Ball
Collision