desenvolvimento de aços sinterizados autolubrificantes a seco para a lubrificação sólida na...
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Desenvolvimento de aços sinterizados autolubrificantes a seco para a lubrificação sólida na Engenharia Mecânica / Development of self-lubricating sintered steels for solid lubrication applications in Mechanical Engineering Palestrante: Dr. Aloisio Nelmo Klein– Universidade Federal de Santa Catarina - UFSC / BrasilTRANSCRIPT
Development of dry self lubricating sintered steels for solid lubrication in
mechanical engineering
Aloisio
N. Klein (Depto
de Eng. Mecânica LabMat/UFSC)
Mechanical Engineering DepartmentFederal University of Santa CatarinaFlorianópolis, Brazil
Materials Laboratory
Pesquisa Cientifica X Inovação tecnológica
O Brasil atualmente produz 2,18% dos artigos científicos do
mundo em revistas indexadas, mas o percentual de patentes
encaminhadas, que de certa forma representa um Índice de
Inovação
é
apenas da ordem de 0,02%.
Uma das maiores preocupações que temos hoje no BRASIL é aprender a utilizar a ciência para fazer tecnologia no Brasil e
tornar esta tecnologia em inovação no setor produtivo.
Na área de materiais, por exemplo, não basta desenvolver no
novo material. Para que ele venha a constituir de fato uma
inovação é
necessário que venha a ser homologado na produção
industrial, na forma de um componente com função de
engenharia especifica.
Inovação em Materiais
De uma forma geral, um problema crônico dificulta a rápida
incorporação de novos materiais e novos componentes em
sistemas mecânicos. Isto se deve a inexistência da infra- estrutura e até
de ampla metodologia para levar o processo
até
a fase de produto inovador disponível no mercado.
Para INOVAÇÃO definitiva, além do novo material
, é necessário:
projeto de componente;
prototipagem para testes no sistema;
produção de lotes em escala piloto de componentes
(alguns milhares) para a homologação do material, do
componente e do seu processo de fabricação.
Development of dry self lubricating sintered steels for solid lubrication in mechanical
engineering
Aloisio
N. Klein (LabMat/UFSC)
José
Daniel B. de Mello (LTM/UFU)Roberto Binder
(Whirlpool-EMBRACO)
Cristiano Binder
(LabMat/UFSC)Gisele Hammes
(LabMat/UFSC)
Renan Schroeder
(LabMat/UFSC)
Mechanical Engineering DepartmentFederal University of Santa CatarinaFlorianópolis, Brazil
Materials Laboratory
Authorship:
+
Most of the results shown in this presentation are part of a research program whose main goal is: -to develop dry self lubricating sintered steels that combine a low friction coefficient with high mechanical and wear resistance for applying in solid lubrication solutions.
Financial support:
Whirlpool/Embraco
(Joinville-Brazil) hermetic compressors producer (34 million compressors/year). (www.embraco.com.br)
Steelinject
(Caxias
do Sul
–
Brazil) sintered parts producer (powder injection molding)
(www.steelinject.com.br)
FINEP -
Financiadora
de Estudos
e Projetos
Brazilian
funding agency (www.finep.gov.br)
BNDES -
Banco
Nacional
de Desenvolvimento
Econômico
e Social ( www.bndes.gov.br
)
CNPq
-
Conselho
Nacional
de desenvolvimento
Cientifico
e tecnológico
( www.cnpq.br
). 5
6
Some general observations:
About 1/3 of all energy used in industrial countries goes to
overcome friction. High friction often results in high wear
and more than 30% of the production in industry goes to
replace worn out products with new ones.
A better control of wear would result in longer product
lifetimes and less energy consumption for replacement
production.
Thus, to reduce
friction and wear is
one
important path for reducing the energy consumption
and
decreasing the human impact on climate
change”
OUTLINEOUTLINE
1)
Introduction
2)
Brief overview on self lubricating sintered bulk materials
3)
Microstructure and materials requirements for high strength and high tribological
performance .
4)
Process, experimental and materials in development
5)
Some Results on sintered steels (MIM and die pressing)
6)
Conclusions
7
8
1) Introduction
9
In most tribological
applications, mainly fluid and grease lubricants are used to reduce friction and minimize wear;
But, there are several situations where the use of solid lubricant is the best way or even the only viable option:
1)
When working conditions become too severe the use of solid lubricants may be the only option
to reduce friction and to
control wear (e.g., high or low temperatures, low pressure or even in vacuum, or by extreme high contact pressure)
2)
In Microelectromechanical
Systems (MEMS);
3)
In appliances and small office equipment, such as printers, electric shavers, mixers, drills, cameras, etc.
10
A combination of solid and liquid lubrication is
also feasible and may have a synergistic effect in
reducing friction and wear of the contact
surfaces;
The solid lubricants can also be dispersed in
water, oil and grease to improve the friction and
wear under conditions of extreme pressure and /
or temperatures
Solid lubricant can be applied to mechanical parts in two ways:
1)
on the surface of the net shaped mechanical components in form of coatings (films ), or
2)
in the volume of the material as dispersed particles (bulk dry self lubricating composite materials)
1) Introduction
11
Solid lubricant
Solid lubricant can be applied to mechanical parts in two ways:
1)
on the surface of the net shaped mechanical components in form of coatings (films ), or
2)
in the volume of the material as dispersed particles (bulk dry self lubricating composite materials)
1) Introduction
12
Solid lubricant
Vapor deposition techniques (Chemical, Physical and Plasma assisted vapor deposition (CVD, PVD and PACVD))
Other coating technologies (lamellar solids)
Solid lubricant can be applied to mechanical parts in two ways:
1)
on the surface of the net shaped mechanical components in form of coatings (films ), or
2)
in the volume of the material as dispersed particles (bulk dry self lubricating composite materials)
1) Introduction
13
Vapor deposition techniques (Chemical, Physical and Plasma assisted chemical vapor deposition (CVD, PVD and PACVD))
Other coating technologies (lamellar solids)
Powder metallurgy techniques like:- die compaction - powder injection molding- powder extrusion- powder rolling, etc.
19
Powder metallurgy techniques are low cost serial mechanical parts manufacturing techniques
By processing the parts via powder metallurgy techniques, the composition of material can easily be tuned for the particular application.
20
21
SiC particles dispersed in Al: a) Mean particle size of SiC = 14,5 µm; b) Mean particle size of SiC= 1,5 µm
a b
22
UO2
+ 11Wt% Mo
23
Ni + 5%FeCr + 5FeP + 10%hBN
24
Powder metallurgy techniques are low cost serial mechanical parts manufacturing techniques
By processing the parts via powder metallurgy techniques, the composition of material can easily be tuned for the particular application.
Self lubricating bulk materials can re-generate its tribolayer after demage by wear or when even when it peels away (self healing effect)
Self healing effect of dry self lubricating sintered materials
Coefficient of friction
Load Electrical resistance of contact
Resistência elétrica do contato
25
OUTLINEOUTLINE
1)
Introduction
2)
Brief overview on self lubricating sintered bulk materials
3)
Microstructure and materials requirements for high strength and high tribological performance .
4)
Process, experimental and materials in development
5)
Some Results on sintered steels (MIM and die pressing)
6)
Conclusions
26
Solid lubricant particles dispersed in the volume
of the material
Porous bearings: Pores are lubricant
reservoirs (fluid lubricants and solid
lubricants27
2) Self lubricating sintered bulk materials
28
Dry self lubricating bearings:
Used for decades in households equipments and in office slight equipments (printers, electric shavers, drills, blenders, among others)
Solid lubricants phases mostly used include:
•
graphite, hexagonal boron Nitride (h-BN), molybdenum disulfide (MoS2
), tungsten disulfide (WS2
) and other dichalcogenides (lamellar solids)
•
Low melting metals (silver, tin, lead, others), halides, oxides, among others.
The most used metallic matrixes are:
copper alloys, ferrous alloys and nickel alloys.
2) Self lubricating sintered bulk materials
29
Usually these materials have a high content of solid lubricant (15 to 35 v/o). This results in a high degree of discontinuity of the metallic matrix leading to poor mechanical strength of composite.
Thus, these materials cannot be used for a lot of typical mechanical applications where we need higher mechanical and wear resistance of the self lubricating sintered material.
So we need to develop bulk dry self lubricating materials that combine a low friction coefficient with high mechanical strength, tuned for each particular application
OUTLINEOUTLINE
1)
Introduction
2)
Brief overview on self lubricating sintered bulk materials
3)
Microstructure and materials requirements for high strength and high tribological performance .
4)
Process, experimental and materials in development
5)
Some Results on sintered steels (MIM and die pressing)
6)
Conclusions
30
1)
optimization of microstructure parameters of the composite material (content of solid lubricant,
lubricant particle size and size distribution, mean free path between lubricant particles)
By designing dry self lubricating composites with improved mechanical properties and low friction coefficient, we have to consider some specific requirements :
3) Microstructure and materials requirements for high strength and high tribological performance
Binder, C.; Hammes, G.; Schroeder, R.; Klein, A. N. ; De Mello, J.D.B.; BInder, R. ; Ristow Jr, W. . “Fine tuned”
steels point the way to a
focused future. Metal Powder Report, v. 65, p. 29-37, 2010.31
32
“regular distribution each particle has to provide lubricant for a well defined area of the interface”.
Ideal situation -
model
Area on thesurfaces to be lubricated by each lubricant
particle
Solid lubricant particles
dispersed in the composite
material
3) Microstructure and materials requirements for high strength and high tribological performance
1)
optimization of microstructure parameters of the composite material (content of solid lubricant,
lubricant particle size and size distribution, mean free path between lubricant particles)
2)
mechanical properties of the metallic matrix tuned for specific application (hardness, strength and toughness)
By designing dry self lubricating composites with improved mechanical properties and low friction coefficient, we have to consider some specific requirements :
Binder, C.; Hammes, G.; Schroeder, R.; Klein, A. N. ; De Mello, J.D.B.; BInder, R. ; Ristow Jr, W. . “Fine tuned”
steels point the way to a
focused future. Metal Powder Report, v. 65, p. 29-37, 2010.
3) Microstructure and materials requirements for high strength and high tribological performance
33
The metallic matrix of the composite must be hard enough
to avoid occurrence of micro plastic deformation by friction
and wear under operation. The mass flow of plastic
deformation covers gradually the lubricant particles,
breaking replacement of lubricant to the interface.
3) Microstructure and materials requirements for high strength and high tribological performance
34
OUTLINEOUTLINE
1)
Introduction
2)
Brief overview on self lubricating sintered bulk materials
3)
Microstructure and materials requirements for high strength and high tribological performance .
4)
Process, experimental and materials in development
5)
Some results withn sintered steels (MIM and die pressing)
6)
Conclusions
35
36
1)
mix particles of solid lubricant with the metal matrix powders by any mixing process
2)
generate particles of solid lubricant “in situ”
during the sintering by reaction between components (for example, dissociation of a carbide).
There are two different ways to get solid lubricant particles dispersed in the volume of the matrix:
Binder, C.; Hammes, G.; Schroeder, R.; Klein, A. N. ; De Mello, J.D.B.; BInder, R. ; Ristow Jr, W. . “Fine tuned”
steels point the way to a focused
future. Metal Powder Report, v. 65, p. 29-37, 2010.
3) Microstructure and materials requirements for high strength and high tribological performance
Undesirable distribution
(Iron + Graphite) powder mixture(after sintering)
(Iron + h-BN) powder mixture(after sintering)
Mixing process: mechanical stresses leads to spreading of lamellar solid lubricant by shearing
50 m50 m
solid lubricant phase
We need solid lubricant nodules with rounded shape in order to avoid stress concentration.
37
3) Microstructure and materials requirements for high strength and high tribological performance
Shape and distribution of h-BN dispersed in nickel alloys after sintering: a) Ni + 10%hBN ; b) Ni + 5%FeCr (wt%) + 5%FeP(wt%) + 10%hBN (vol%).
b) Liquid phase assisted sintering
a) Sintering without liquid phase
38
Method used for the measurement of the length of segments along the matrix phase.
39
20m
Mean free path lengths between solid lubricant particles along the matrix [m]
Fre
quen
cy o
f occ
urre
nce
[%]
0
5
10
15
20
25
0 50 100 150 200
Ni + 10%hBN (without liquid phase)
Ni + 10%hBN + 5%FeCr + 5%FeP (liquid phase sintering)
Mean free paths lengths between solid lubricant particles measured along matrix of sintered composite material. a) Sintering without liquid phase; b) Sintering in presence of liquid phase.
m
= 19,5
1,6 m
m
= 65,5
4,8 m
40
41
1)
mix particles of solid lubricant with the metal matrix powders by any mixing process
2)
generate particles of solid lubricant “in situ”
during the sintering by reaction between components (for example, dissociation of a carbide).
There are two different ways to get solid lubricant particles disperse in the volume of the matrix:
Binder, C.; Hammes, G.; Schroeder, R.; Klein, A. N. ; De Mello, J.D.B.; BInder, R. ; Ristow Jr, W. . “Fine tuned”
steels point the way to a
focused future. Metal Powder Report, v. 65, p. 29-37, 2010.
3) Microstructure and materials requirements for high strength and high tribological performance
g(T)sol
= nA
RTlnaA
+ nB
RTlnaB
+ ... +
nM
RTlnaM
(1)
Example: Will compound AB dissociate ain a matrix M ? In this case we have to compare the values for Gibbs free energy for formation of solid solution between A
and B at temperature T
(equation 1), and the Formation Gibbs free energy of compound AB at the same temperature T (equation 2) .
G0(T)AB
= C1
+ C2
TlogT + C3
T (2)
Dissolution will occur up to activity values (corresponding to concentrations values via relation ai
= xi
i
) for which relation 3 is satisfied: |AG(T)sol
|
≥
|G0(T)AB
|
g(T) = [nA
RTlnaA
+ nB
RTlnaB
+ nM
RTlnaM
] -
nG0T
(AB)
Using thermodynamic data for selecting the mixture components
42
(3)
1,0 0,1 0,01 0,001 0,0001
G0(T)TiC
G0(T)NbC
G0(T)Cr4C
- 10
- 20
0
- 30
- 40
- 50
Activity of alloying element Si dissolved in the matrix
G0 (
T) a
t 115
00 C [k
cal/
mol
]
RTlnaSi
RT lnaSi = G0(T)SiC
T = TS = 1150 OC
G0(T)SiC
G(T) = [nSi
RTlnaSi
+ nC
TlnaC
+ nM
RTlnaM
] -
nG0T
(SiC)
Example: Silicon carbide (SiC) in Iron, 11500C
43
+ 10
0
- 10
- 20
- 30
- 40
- 50 0 200 400 600 800 1000 1200 1400 1600
Temperatura (0C)
3/2Cr + C = 1/2Cr3C2
Mn + C = MnC
[ T(0K) = T(0C) + 273 ]
G0 (T
)kc
alm
ol
[
[
44
45
a)
Powder injection moulding (fine carbonyl powders)
Self lubricating sintered steels : Fe + C + SiC + Ni + Mo alloy system;
Self lubricating composites with Ni alloys as matrix
Solid lubricants used: h-BN, Graphite and mixtures of them
b)
Uniaxial die pressing (atomized powders from Höganäs)
Self lubricating sintered steels : Fe + C + SiC + Ni + Mo alloy system;
Solid lubricant used: h-BN, Graphite and mixtures of them
Test samples production
a
a)
Fe + 0.6%C + 4%Ni
Ferrite + perlite
b) Fe + 0.6%C + 4%Ni + 2%SiC Ferrite + Perlite + Graphite
nodules that are surrounded by a ferrite ring
Sintered steels produced by MIM (sintered in the PADS
furnace, TS
= 1150 C, 1h, H2
)
b
Solid lubricant nodules formed “in situ”
during the
sintering by dissociation of SiC
46
47
Line profile -
Microprobe analysis
graphitenodule
FEG-SEM image
of an graphite nodule (taken on a fractured surface)
48
FEG-SEM image of the interior of the graphite nodule: Graphite foils with 10 to 45 nm in thickness (about 30 to
100 atom planes)
49
Fe+0,6C+ 3SiC+4Ni Fe+0,6C+ 3SiC+4Ni+1Mo
Microstructure of Fe+C+SiC+Ni+Mo steels (1h, 1150C, H2
plasma assisted)
Fe + 0,6C + 3SiC Fe+0,6C+2SiC+4Ni
51
Graphite nodules formed “in situ”
during the sintering:
Tensile strength = 710 Mpa
Friction coefficient
= 0,06
3) Microstructure and materials requirements for high strength and high tribological performance
50 m50 m
solid lubricant phase
Sintered steel graphite as solid lubricant mixed to the feedstock
Tensile strength = 340 Mpa
Friction coefficient
= 0,11
20 m
Solid lubricant nodules
OUTLINEOUTLINE
1)
Introduction
2)
Brief overview on self lubricating sintered bulk materials
3)
Some considerations about microstructure and properties requirements.
4)
Process, experimental and materials in development
5)
Some Results on sintered steels (MIM and die pressing)
6)
Conclusions
52
4)Mechanical and tribologycal properties of dry self lubricating sintered MIM steels
53
1) Powders
Fe BASF (CL-OM)
carbonyl iron powder with a mean particle size of 7.8 m;
Mo elemental Mo (OMP HC Starck, d (mean) = 5,5 m,)
Ni element Ni powder (INCO 123, d (mean) = 8,86 m);
SiC
mean particle size of 10 m
2) Feedstock preparation
The feedstock for injection molding was prepared by mixing the powder (Haake Sigma mixer, 180C, 70 rpm, 90 min) with 8% (w/o) organic binders (binder system)
Binder system:
paraffin-wax, stearic acid (surfactant), amide wax,
EVA (ethylene vinyl acetate copolymer) and polypropylene (back bone). 54
4) A chemical debinding step
dissolution of the low molecular weight components of the binder system in hexane.
5) Thermal Debinding
and
Sintering (1100 to 1200 C, 1h, H2
plasma (low energy)
The thermal debinding, as well as the sintering , were performed in the same thermal cycle in a Hybrib Plasma Plasma ReactorReactor,
i.e., using the Plasma Assisted Debinding and
Sintering (PADS) process develop in Brazil.
3) Injection of the parts Arbourg 320S injection molding machine (pressure: 100 MPa).
55
Plasma Assisted Debiding (PAD)(using the reactive environment of a plasma)(using the reactive environment of a plasma)
Electron bombardment ofmacromolecules (inelastic collision)
Macromolecule dissociation
C C C C C C
HH H H H H
H H H H H H
n
polyethylene
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
C
H
H
C
H
HHH
HH
HH
HH
HH
HH
HHHH
A. N. Klein et all, US Patent Nr. US 6,579,493 B1 (2003)
A. N. Klein at all, European Patent No. EP 1 230 056 B1 (2003)
e + He + H
22
= H + H + e= H + H + e
56
vacuum chamber
energy supply for electrical heating
energy supplyfor the cathode
cathode
gas inlet
anode
electrical heating elements
thermocouples
vacuum system
Shielding
cooling system
Design (schematic) of the hybrid plasma DC reactor 57
Plasma Reactor: Pilot Plant at LabMat
R. Machado, A. N. Klein, …
“Industrial Plasma Reactor for Plasma Assisted Thermal
Debinding of Powder Injection-Molded Parts. US 7,718,919 B2 (2010) 58
Mechanical Engineering DepartmentFederal University of Santa CatarinaFlorianópolis, Brazil
Materials Laboratory
anode
cathode
Al2
O3
plate
Plasma Assisted Debinding and SinteringPlasma Assisted Debinding and Sintering (PADS) (PADS) in the same thermal cyclein the same thermal cycle
60
After debinding After debinding without without plasmaplasma: organic residues remain in the reactor: organic residues remain in the reactor
61
After debinding After debinding withoutwithout plasmaplasma: details of organic residues : details of organic residues
62
Processing time (h)
Tem
pera
ture
(0 C)
debinding plasma nitriding or carbonitriding
Debinding and sintering in the same equipment Debinding and sintering in the same equipment and same thermal cycleand same thermal cycle (single (single –– cycle)cycle)
sintering
Saving energy and processing
time!
63
Steelinject Industrial PADS Equipment Steelinject Industrial PADS Equipment
Properties of Fe + 0,6%C
+ SiC sintered steels
65
0
500
1000
1500
2000
2500
3000
3500
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
0,45
0,50
0 1 2 3 4 5
Fric
tion
Coe
ffici
ent
SiC Content (w/o)
Friction Coef f icient Durability
Dur
abili
ty (
N.m
)
Fe + 0.6%C + SiC
sintered steels (1150 C, 1h, H2
, PADS)66
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 1 2 3 4 5 6
Fric
tion
Coe
ffici
ent
SiC content ( % )
1100 °C
1150 °C
1200 °C
Friction coefficient as a function of sintering temperature
Fe + 0,6%C + SiC sintered steels (1h, H2
, PADS)
67
Mudar graficos
0
2
4
6
8
10
12
14
16
0 1 2 3 4 5 6SiC content ( % )
Scuf
fing
Res
istan
ce (
N.m
)103
1100 °C
1150 °C
1200 °C
68
De Mello & Klein. To be published69
Comparison of friction coefficient of materials containing distinct graphite types
Tensile strength, hardness and elongation measured on the sintered Fe + 0.6%C + increasing content of SiC (w/o).
0
3
6
9
12
15
18
0
100
200
300
400
500
600
700
800
0 1 2 3 4 5
Elo
ngat
ion
(%)
Yiel
d S
treng
th a
nd T
ensi
le S
treng
th(M
Pa)
Har
dnes
s (H
V)
SiC Content (w/o) in matriz Fe + 0.6C
HV 0,2 YS UTS % EL
SiC content (w/o) in the Fe + 0,6%C matrix
70
Properties of Fe + 0,6%C + Ni + Mo + SiC
sintered steels
71
Martensitic dry self lubricating sintered steels. Fe + 0,6C + 4Ni + 1Mo + 3SiC
Mechanical properties of some of sintered self lubricating steels
73
HV = 400UTS = 810 MpaElongation = 6%
74
75
Wear bahavior in sliding tests
Conclusions
1)
Self lubricating sintered steels produced by Powder Injection Molding with a wide range of mechanical properties (200-1000 MPa and 150-600HV) were obtained. The friction coefficient of this materials can be varied in a range from
= 0,04 to
= 0,21
2)
Compositions having at the same time Ni, Mo, Si and C generate a martensitic microstructure even under low cooling rates.
3)
It is suggested that graphite foils, removed from the “in situ” generated graphite nodules, remain at the interface, thus
contributing to the formation of the protective tribolayer.
76
Thanks for your attention!
77
Fe+0.6%C+3% SiC
Graphite
Fe3
CFe Fe
Fe
Angle
Inte
nsit
y
Dissociation of SiC in iron matrix
78
Fe+0.6% C+3% SiC Fe+0.6% C+3% SiC ––
1100 1100 °°C C
0 20 40 60 80 100 120
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400In
tens
idad
e
2(Graus)
240 min 120 min 60 min 30 min 10 min
Graphite
Fe3
C Fe Fe
Fe
Angle
Inte
nsit
y
In situ dissociation of precursorIn situ dissociation of precursor
79
Martensitic dry self lubricatiing sintered steels. Fe + 0,6C + 4Ni + 1Mo + 3SiC (verificar na tese cristiano
81
Self healing effect of the dry self lubricating sintered steel produced (composite material)
82
(a) (b)Reciprocating wear test (un-lubricated, in air). (a) equipment; (b) steel sphere (held on a pivoted arm) compressing against the
moving specimen surface (schematically)
5) Tribological characterization
2) Materials and experimental
500 1000 1500 2000 2500 3000
Raman shift / cm-1
0
1000
2000
3000
4000
5000
Cou
nts
1581.65
2727.42
Graphite powder UF4
500 1000 1500 2000 2500 3000
Raman shift / cm-1
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Cou
nts
1356.62
1582.3
2727.11
Graphite nodulenodular cast iron
Graphite noduleGraphite noduleSiC dissociationSiC dissociation
D b
and
(sp3
-dia
mon
d)
Graphite noduleSiC dissociation
Raman Spectroscopy
G’Ba
nd
G b
and
(sp2
–gr
aphi
te)
full-width at half peak height
83
MaterialBand D position
(cm-1)
Band G position
(cm-1)
Band D FWHPH
(cm-1)
Band G FWHPH
(cm-1)ID / IG
Crystallite size La
(Å)
Band G’ Position (cm-1)
Band G’ Shape
Graphite powder
1354.34 1581.65 8.0 14.71 0.050 880.00 2726,80Broad
Nodular cast iron
1356.62 1582.3 16.50 27.96 0.189 232.80 2727,10Broad
Fe+0.6C+3SiC 1351.55 1586.60 58.97 42.22 1.183 37.19 2709,17Peak
FWHPH-
full-width at half peak height
De Mello & Klein et al, 64th STLE Annual Meeting, Las Vegas, 2010
Turbostratic 2D graphite Higher interlamellar distances Lower friction coefficient
84
Results and discussionResults and discussion: : Tribological behaviourTribological behaviour
Fe+0.6%C+5%SiC, 14 N
It is reasonable to suppose that the graphite foils are removed from the in situ generated graphite nodules and remain at the interface thus contributing
to the formation of the protective tribo-layer;
On the other hand, the tribo- layers also degrade under the
sliding action.
Wear track
85
Fe
+ 0.6%C + 5%SiC(14 N, 11500C,1h,PADS)
500 1000 1500 2000 2500 3000
Raman shift / cm-1
0
1000
2000
3000
4000
5000
6000
7000
8000
Cou
nts
1350.15
1582.08
2698.25
2939.84
Wear scar
Before test
Turbostratic 2D graphite
Higher interlamellar
distances
Low friction coefficient
86
The Plasma Assisted Debinding
rate is a function of several variables:
type of polymer or binder system used (properties of the binders)
temperature and heating up rate (time)
energy and quantity of the reactive species generated in the plasma.
We need electrons with enough energy to cause the dissociation of de binder molecules, and
Atomic Hydrogen (H2
+ e = H + H + e ).
The reaction constant for any dissociation reaction promoted by energy transfer via inelastic collisions of electrons with binder molecules in the plasma may be given by
0
)()( dgK eer
Wherein:
)(eg energy distribution function of the electrons
)( e cross section of collision distribution function (cross section for the inelastic collision which promote the dissociation), as a function of the electrons energy
UFSCUFSC-- Mechanical Engineering DepartmentMechanical Engineering DepartmentMATERIALS LABORATORY MATERIALS LABORATORY
Team involved in the developments:Team involved in the developments:Joel L. R. Joel L. R. MuzartMuzart††,,
Antonio R. de Souza,Antonio R. de Souza,
Carlos Carlos SpellerSpeller, Ana M. , Ana M. MaliskaMaliska, Paulo , Paulo
A. P. A. P. WendhausenWendhausen, Marcio C. , Marcio C. FredelFredel, Cristiano , Cristiano BinderBinder, Davi Fusão, Roberto , Davi Fusão, Roberto BinderBinder, , WaldyrWaldyr
RistowRistow
Jr., Ricardo Machado, Paulo Alba, Maria A. dos Santos, Jr., Ricardo Machado, Paulo Alba, Maria A. dos Santos,
Rubens M. do Nascimento, Wagner da Silveira, Henrique C. Rubens M. do Nascimento, Wagner da Silveira, Henrique C. PavanatiPavanati, Gisele , Gisele HammesHammes, Vilson J. Batista, Ivani T. , Vilson J. Batista, Ivani T. LawallLawall...)....).
AloisioAloisio
N. KleinN. Klein
Plasma technology applied to powder Plasma technology applied to powder materials processingmaterials processing
1) 1) Plasma technology applied to powder materials Plasma technology applied to powder materials processingprocessing
c)c) ThermoThermo--chemical surface treatments chemical surface treatments -- via plasmavia plasma(cleaning, nitriding, cementation,…)
a) a) Plasma Assisted Plasma Assisted DebindingDebinding and Sintering (PADS)and Sintering (PADS) of PIM partsof PIM parts(dissociation of organic macromolecules)
b)b) Plasma Assisted Sintering: Surface modification via plasmaPlasma Assisted Sintering: Surface modification via plasma(surface morphology, chemical composition / surface enrichment ,cathodic sputtering, …).
OUTLINEOUTLINEOUTLINE
Plasma generation(abnormal DC glow discharge)
luminescent region
Cathode Anode
reactive species
- V
- V
++
00++
--
heat generation and sputtering
2) Inelastic collision
of
electrons with gaseous species in the plasma environment:
chemical reactions improvement
Important phenomena in the plasma environment:
1) Ionic and fast neutral atoms bombardment on the cathode:
Vp
1) 1) Plasma technology applied to powder materials Plasma technology applied to powder materials processingprocessing
c)c) ThermoThermo--chemical surface treatments chemical surface treatments -- via plasmavia plasma(cleaning, nitriding, cementation,…)
a) a) Plasma Assisted Debinding and Sintering (PADS)Plasma Assisted Debinding and Sintering (PADS) of PIM partsof PIM parts(dissociation of organic macromolecules)
b)b) Plasma Assisted Sintering: Surface modification via plasmaPlasma Assisted Sintering: Surface modification via plasma(surface morphology, chemical composition / surface enrichment ,cathodic sputtering, …).
OUTLINEOUTLINEOUTLINE
Plasma Assisted Debiding (PAD)(using the reactive environment of a plasma)(using the reactive environment of a plasma)
Electron bombardment ofmacromolecules (inelastic collision)
Macromolecule dissociation
C C C C C C
HH H H H H
H H H H H H
n
polyethylene
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
C
H
H
C
H
HHH
HH
HH
HH
HH
HH
HHHH
A. N. Klein et all, US Patent Nr. US 6,579,493 B1 (2003) A. N. Klein at all, European Patent No. EP 1 230 056 B1
(2003)
e + H2 = H + H + ee + H2 = H + H + e
b) The furnace remains clean
possibility for debinding and sintering in the same equipment in a single – cycle
Plasma Assisted Debinding of PIM parts
Advantages:
a) Increasing of the debinding rate
save processing time / improve the productivity
1)
Electrons impinging the surface of the parts causes dissociation of binder molecules to convert the binder into gas
molecules
2) A new portion of the molted binder flows up to the top via interconnected pores reducing the time needed for binder removal
Plasma Assisted DebindingPlasma Assisted Debinding
0 10 20 30 40 50 60
0
50
100
Po
lypr
opyl
ene
rem
oval
(%)
Time (min)
Anode-cathode Floating potential Anode/shield-cathode
Plasma Assisted Debinding: Plasma Assisted Debinding: Effect of the electrons on the debinding rateEffect of the electrons on the debinding rate(Experimental Results for Polypropylene in (Experimental Results for Polypropylene in hydrogen electrical discharge)hydrogen electrical discharge)
T = 400T = 400°°CC
Plasma Reactor: Pilot Plant at LabMat
R. Machado, A. N. Klein, …
“Industrial Plasma Reactor for Plasma Assisted Thermal
Debinding of Powder Injection-Molded Parts. US 7,718,919 B2 (2010)
After After Plasma Assisted DebindingPlasma Assisted Debinding: no organic residues : no organic residues remain in the reactorremain in the reactor
anode
cathode
Al2O3 plate
Parts after Parts after Plasma Assisted Debinding and SinteringPlasma Assisted Debinding and Sintering (PADS) (PADS) in the same thermal cyclein the same thermal cycle
Parts after Parts after Plasma Assisted Debinding and SinteringPlasma Assisted Debinding and Sintering (PADS) (PADS) in the same thermal cyclein the same thermal cycle
After debinding After debinding without without plasmaplasma: organic residues remain in the reactor: organic residues remain in the reactor
After debinding After debinding withoutwithout plasmaplasma: details of organic residues : details of organic residues
Processing time (h)
Temperature (0C)
debinding plasma nitriding or carbonitriding
Debinding and sintering in the same equipment Debinding and sintering in the same equipment and same thermal cycleand same thermal cycle (single (single –– cycle)cycle)
Sintering
Some resultsSome results
--
Fe+ 2Ni + 0,6C low alloy steel Fe+ 2Ni + 0,6C low alloy steel
--
316316--L stainless steel.L stainless steel.
Binder system:
polymer and wax. Wax debinding: organic solvent.
Thermal debinding and sintering: PADS furnace.
Alloy Debinding parameters
Sintering parameters
2NiFe0,6C(carbonyl powders)
Heating rate: 2,0 ºC/min.
Atmosphere: atomic hydrogen
1250 ºC, 60 min, argon partial
pressure
316-L(atomized powders)
1300 ºC, 90 min, H2 partial pressure
AlloyAlloy ConditioConditio nn
ProcesProces ss
DensitDensit y y
(g/cm(g/cm33))
Carbon Carbon content content
(% mass)(% mass)
Hardness Hardness (HV 0,2 (HV 0,2
kg)kg)
Ultimate Ultimate Strength Strength
(MPa)(MPa)
Yield Yield StrengtStrengt h (MPa)h (MPa)
ElongElong ation ation (%)(%)
Fe + Fe + 2% Ni 2% Ni + 0,6C+ 0,6C
sinteredsinteredPADSPADS 7,657,65 0,58 0,58 ––
0,620,62 170170 575575 480480 44
Conv.Conv. 7,507,50 0,6 0,6 –– 0,80,8 160160 500500 250250 33
temperedtemperedPADSPADS 7,657,65 0,58 0,58 ––
0,620,62 350350 12101210 11801180 22
Conv.Conv. 7,507,50 0,6 0,6 –– 0,80,8 340340 950950 800800 33
316316--LL sinteredsinteredPADSPADS 7,707,70 0,00150,0015 170170 505505 290290 5454
Conv.Conv. 7,857,85 0,03 m0,03 mááx.x. 120120 510510 180180 5050
Comparison of metallurgical variables of materials processed in PADS furnace and in a conventional route (catalytic
debinding)
PADS process x LupatechPADS process x Lupatech’’s actual processs actual process
ProcessProcess Lead time Lead time (h)(h)
Heating rate Heating rate during debinding during debinding
((ººC/min)C/min)
Energy Energy consumption consumption
(kW)(kW)
Gas Gas consumption consumption
(m(m33))
PADSPADS 77 2,02,0 500500 1212
LupatechLupatech 8080 0,070,07 800800 120120
Processed alloy: 316Processed alloy: 316--L stainless steel:L stainless steel:
–
Actual process: permeation controlled thermal + vacuum sintering.
–
PADS process: Plasma Assisted Debinding and Sintering.
Steelinject Industrial PADS Equipment Steelinject Industrial PADS Equipment
Industrial Plasma Reactor for Plasma Assisted Thermal Debinding of Powder Injection-Molded Parts. US Patent Office, number US 7,718,919 B2 (2010)
113
Resultados:Resultados:
Redução de custo (processo PADS): mínimo 20 %
Redução de energia (processo PADS): : 50%
Premio Medalha de desenvolvimento
114
Nestor Perini
http://medalha.desenvolvimento.gov.br/arquivos/agra ciados06.htm
Cargo: Presidente da Lupatech S/A
Indicação: Sr. Paulo Belini; Sr. Jorge Gerdau Johannpeter e Sr. Raul Anselmo Randon
Justificativa da
Indicação:
A Lupatech S/A., através de sua divisão Steelinject, é pioneira na América Latina na utilização da tecnologia MIM (Metal Injection Molding). Esta tecnologia é indicada para produção de peças em série de alta precisão e complexidade de forma. A Steelinject conseguiu reduzir em 20% os custos de produção e em 50% o de consumo de energia graças a uma tecnologia desenvolvida em parceria com o laboratório de materiais da Universidade Federal de Santa Catarina (UFSC). Com o invento, a empresa pretende deixar de ser importadora para se tornar exportadora de tecnologia. A patente nos Estados Unidos acabou de ser registrada e está em processo o registro na Europa. No Brasil, a patente já está no Instituto Nacional de Propriedade Industrial (INPI).
115
Processo de transferência da Processo de transferência da tecnologia para PADS para USAtecnologia para PADS para USA
Lupatech (Caxias)
+ LabMat (UFSC)
DSH Technologies, LLC, que através da associada -
Elnik
Systems vai produzir o equipamento e disponibilizar no mercado mundial.Primeiro equipamento em 3D foi exposto na PM2008 em Washington
(8 a 12 de Junho )
Forno PLASMIM projetado para a Empresa Elnik Systems (USA) pela Equipe do LabMat/UFSC + Steelinject (Caxias do sul)
Protótipo Forno Hibrido para extração térmica de ligantes orgânicos assistida por plasma seguida de sinterização assistida por plasma.
Possibilities:Possibilities:
A) Plasma reactor with an auxiliary resistive heatingA) Plasma reactor with an auxiliary resistive heating
B) Plasma reactor without auxiliary resistive heatingB) Plasma reactor without auxiliary resistive heating
The plasma is used only to promote the chemical reactions. Plasma works with low current density (at the exact current needed).
Heat is generated by the plasma, i.e., only by the bombardment of the cathode by ions and atoms of high energy.
Problem:Problem: high sputtering from cathode – surfacecontamination
Opportunity:Opportunity: this can be used for surface enrichment of unalloyed iron parts
Plasma reactors for materials processingPlasma reactors for materials processing
Modification of the chemical composition of parts during plasma assisted sintering
Surface enrichment of unalloyed iron with Chromium
0 5 10 15 20 25 300
1
2
3
4
5
6C
once
ntra
ção
de M
o (%
peso
)
Profundidade (m)
1150 °C 1000 °C 800 °C
Enrichment with Molybdenum: Temperature Influence Enrichment with Molybdenum: Temperature Influence (1Torr;(1Torr;
700V; 1h ; 700V; 1h ;
10%H2 + 90%Ar; Gas flow = 5 x 1010%H2 + 90%Ar; Gas flow = 5 x 10--66
mm33/s (300 sccm)/s (300 sccm)
Conc
entr
atio
n of
Mo
(%w
eigh
t)Co
ncen
trat
ion
of M
o (%
wei
ght)
Depth(Depth(µµm) m)
0 10 20 30 40 50 60 70 80 90 1000
1
2
3
4
5
6
7
8
Con
cent
raçã
o de
Mo
(%pe
so)
Profundidade (m)
3,5 Torr 1 Torr
Conc
entr
atio
n of
Mo
(%w
eigh
t)Co
ncen
trat
ion
of M
o (%
wei
ght)
Depth(Depth(µµm) m)
Enrichment with Molybdenum: Pressure Influence Enrichment with Molybdenum: Pressure Influence ( ( 1150 1150 °°CC
; ; 700V; 1h ; 10%H2 + 700V; 1h ; 10%H2 +
90%Ar; Gas flow = 5 x 1090%Ar; Gas flow = 5 x 10--66
mm33/s (300 sccm)/s (300 sccm)
800800°°C; 500 V C; 500 V
800800°°C; 700 V C; 700 V
Deposition of atoms/ions sputtered from the Deposition of atoms/ions sputtered from the cathode (clusters of size in the nanometer range)cathode (clusters of size in the nanometer range)
0,0 0,2 0,4 0,6 0,8 1,00
50
100
150
200
250
Con
tage
m
Tamanho de partícula (m)
500 V 700 V
Am
ount
Am
ount
Particle size (Particle size (µµm)m)
View of the lateral side which is exposed to ion bombardment
Base, which is in contact to the support and does not receive bombardment
Ion bombardmentIon bombardmentSputtering +Sputtering +
deposition anddeposition and
activated diffusionactivated diffusion
Dense surface layerDense surface layer
Surface dense layer in plasma assisted sintering Surface dense layer in plasma assisted sintering (parts placed on the cathode)(parts placed on the cathode)
The International Journal of Powder Metallurgy, Vol. 34, No. 8, 1998, pg.55–62.
Ionic bombardment of the surface improves diffusion rates;
As compactedAs compacted Afther sintering (on cathode)Afther sintering (on cathode)
Sintering of unalloyed iron samples produced by powder compaction
The densification is further enhanced by the The densification is further enhanced by the retrodeposition of atoms.retrodeposition of atoms.
Surface dense layer in plasma assisted sintering Surface dense layer in plasma assisted sintering (parts placed on the cathode)(parts placed on the cathode)
1) 1) Plasma technology applied to powder materials Plasma technology applied to powder materials processingprocessing
c)c) ThermoThermo--chemical surface treatments chemical surface treatments -- via plasmavia plasma(cleaning, nitriding, cementation,…)
a) a) Plasma Assisted Debinding and Sintering (PADS)Plasma Assisted Debinding and Sintering (PADS) of PIM partsof PIM parts(dissociation of organic macromolecules)
b)b) Plasma Assisted Sintering: Surface modification via plasmaPlasma Assisted Sintering: Surface modification via plasma(surface morphology, chemical composition / surface enrichment ,cathodic sputtering, …).
OUTLINEOUTLINEOUTLINE
Unalloyed iron: sintering followed by plasma nitriding
20 m 20 m
NITRIDE LAYERNITRIDE LAYER
Surface and Coatings Technology 141(2001) 128-134
c)c) ThermoThermo--chemical surface treatments chemical surface treatments -- via plasmavia plasma(nitriding, cementation, nitro cementation)(nitriding, cementation, nitro cementation)
Montagem parcial da carga a ser tratada.
Reator de nitretação por plasmaescala piloto (4 mil peças por
carregamento)
127
Desenho esquemático célula de limpeza e nitretação –
escala industrial 4,5
milhões peças/ano
Remoção do óleo de calibração dos poros residuais e nitretação por plasma de materiais sinterizados em único ciclo térmico (patente);
128
Foto da célula em operação na Empresa GKN (fornecedor de peças para a Embraco)
Remoção do óleo de calibração dos poros residuais e nitretação por plasma de materiais sinterizados em único ciclo térmico (patente);
129
Foto da célula em operação na
Empresa GKN (fornecedor de
peças para a Embraco)