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 / Brasil

1. Development of dry self lubricating
sintered steels for solid lubrication in
mechanical engineering
Aloisio N. Klein
(Depto de Eng. Mecânica LabMat/UFSC)
Materials Laboratory
Mechanical Engineering Department
Federal University of Santa Catarina
Florianópolis, Brazil

2. 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.

3. 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.

4. 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)
Authorship: Roberto Binder (Whirlpool-EMBRACO)
Cristiano Binder (LabMat/UFSC)
Gisele Hammes (LabMat/UFSC)
Renan Schroeder (LabMat/UFSC)
Materials Laboratory
Mechanical Engineering Department
Federal University of Santa Catarina
Florianópolis, Brazil
+

5. 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”
6

7. OUTLINE
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
8

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.
9

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
10

11. 1) Introduction
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 Solid
dispersed particles (bulk dry self lubricant
lubricating composite materials)
11

12. 1) Introduction
Solid lubricant can be applied to mechanical parts in two ways:
Vapor deposition techniques
1) on the surface of the net shaped (Chemical, Physical and Plasma
mechanical components in form  assisted vapor deposition (CVD,
of coatings (films ), or PVD and PACVD))
Other coating technologies
(lamellar solids)
2) in the volume of the material as Solid
dispersed particles (bulk dry self lubricant
lubricating composite materials)
12

13. 1) Introduction
Solid lubricant can be applied to mechanical parts in two ways:
Vapor deposition techniques
1) on the surface of the net shaped (Chemical, Physical and Plasma
mechanical components in form  assisted chemical vapor
of coatings (films ), or deposition (CVD, PVD and
PACVD))
Other coating technologies
(lamellar solids)
Powder metallurgy techniques
2) in the volume of the material as like:

dispersed particles (bulk dry self - die compaction
lubricating composite materials) - powder injection molding
- powder extrusion
- powder rolling, etc.
13

18.  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.
19

19. 20

20. a b
SiC particles dispersed in Al: a) Mean particle size of SiC = 14,5 µm; b) Mean
particle size of SiC= 1,5 µm
21

21. UO2 + 11Wt% Mo
22

22. Ni + 5%FeCr + 5FeP + 10%hBN
23

23.  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)
24

24. Self healing effect of dry self lubricating sintered materials
Electrical
Load resistance
of contact
Coefficient Resistência elétrica do contato
of friction
25

25. OUTLINE
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

26. 2) Self lubricating sintered bulk materials
Solid lubricant particles
dispersed in the volume
of the material
Porous bearings:
Pores are lubricant
reservoirs (fluid
lubricants and solid
lubricants
27

27. 2) Self lubricating sintered bulk materials
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.
28

28.  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
29

29. OUTLINE
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

30. 3) Microstructure and materials requirements for high strength and high
tribological performance
By designing dry self lubricating composites with improved
mechanical properties and low friction coefficient, we have to
consider some specific requirements :
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)
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

31. 3) Microstructure and materials requirements for high strength
and high tribological performance
Ideal situation - model
Area on the
surfaces to be
lubricated by
each lubricant
particle
Solid lubricant
particles
dispersed in
the composite
material
“regular distribution  each particle has
to provide lubricant for a well defined
area of the interface”.
32

32. 3) Microstructure and materials requirements for high strength
and high tribological performance
By designing dry self lubricating composites with improved
mechanical properties and low friction coefficient, we have to
consider some specific requirements :
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)
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.
33

33. 3) Microstructure and materials requirements for high strength
and high tribological performance
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.
34

34. OUTLINE
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

35. 3) Microstructure and materials requirements for high strength
and high tribological performance
There are two different ways to get solid lubricant
particles dispersed in the volume of the matrix:
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).
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.
36

36. 3) Microstructure and materials requirements for high strength
and high tribological performance
solid
lubricant
phase
We need solid lubricant nodules with rounded
shape in order to avoid stress concentration.
50 m
(Iron + h-BN) powder mixture (Iron + Graphite) powder mixture
(after sintering) (after sintering)
Mixing process: mechanical stresses leads to spreading of
lamellar solid lubricant by shearing
 Undesirable distribution
37

37. a) Sintering without b) Liquid phase
liquid phase assisted sintering
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%).
38

38.    
20m
Method used for the measurement of the length of
segments along the matrix phase.
39

39. 25
m = 19,5  1,6 m Ni + 10%hBN (without liquid
phase)
20
Frequency of occurrence [%] Ni + 10%hBN + 5%FeCr +
5%FeP (liquid phase sintering)
15
m = 65,5  4,8 m
10
5
0
0 50 100 150 200
Mean free path lengths between solid lubricant particles along the matrix [m]
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. 40

40. 3) Microstructure and materials requirements for high strength
and high tribological performance
There are two different ways to get solid lubricant
particles disperse in the volume of the matrix:
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).
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.
41

41. Using thermodynamic data for selecting the mixture components
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) .
g(T)sol = nARTlnaA + nBRTlnaB + ... + nMRTlnaM (1)
G0(T)AB = C1 + C2TlogT + C3T (2)
g(T) = [nARTlnaA + nBRTlnaB + nMRTlnaM ] - nG0T(AB)
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| (3)
42

42. Example: Silicon carbide (SiC) in Iron, 11500C
G(T) = [nSiRTlnaSi + nCTlnaC + nMRTlnaM ] - nG0T(SiC)
0 RTlna Si T = TS = 1150 OC
- 10 G 0 ( T ) Si C
G0(T) at 11500C [kcal/mol]
G 0 (T ) Cr 4C
- 20
RT l na Si = G 0 ( T ) SiC
- 30 G 0 (T) NbC
- 40 G 0 (T) TiC
- 50
1,0 0,1 0,01 0,001 0,0001
Activity of alloying element Si dissolved in the matrix
43

43. + 10
0
Mn + C = MnC
- 10
[
3/ Cr + C = 1/2Cr3C2
2
kcal
mol
[
G0(T)
- 20
- 30
- 40
- 50
0 200 400 600 800 1000 1200 1400 1600
Temperatura (0C) [ T(0K) = T(0C) + 273 ]
44

44. Test samples production
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
45

45. a
Sintered steels produced by
MIM (sintered in the PADS
furnace, TS = 1150 C, 1h, H2 )
a) Fe + 0.6%C + 4%Ni
 Ferrite + perlite
b b) Fe + 0.6%C + 4%Ni + 2%SiC
 Ferrite + Perlite + Graphite
nodules that are surrounded
by a ferrite ring
Solid lubricant nodules
formed “in situ” during the
sintering by dissociation of SiC
46

46. Line profile - Microprobe analysis
47

47. graphite
nodule
FEG-SEM image of an graphite nodule
(taken on a fractured surface)
48

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

49. Fe + 0,6C + 3SiC Fe+0,6C+2SiC+4Ni
Fe+0,6C+ 3SiC+4Ni+1Mo
Fe+0,6C+ 3SiC+4Ni
Microstructure of Fe+C+SiC+Ni+Mo steels (1h, 1150C, H2 plasma assisted)

50. 3) Microstructure and materials requirements for high strength
and high tribological performance
solid Solid
lubricant lubricant
phase nodules
50 m 20 m
Sintered steel  graphite as solid Graphite nodules formed “in
lubricant mixed to the feedstock situ” during the sintering:
Tensile strength = 340 Mpa Tensile strength = 710 Mpa
Friction coefficient  = 0,11 Friction coefficient  = 0,06
51

51. OUTLINE
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

52. 4)Mechanical and tribologycal
properties of dry self lubricating
sintered MIM steels
53

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, 180C, 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

54. 3) Injection of the parts  Arbourg 320S injection molding
machine (pressure: 100 MPa).
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
Reactor, i.e., using the Plasma Assisted Debinding and
Reactor
Sintering (PADS) process develop in Brazil.
55

55. Plasma Assisted Debiding (PAD)
(using the reactive environment of a plasma)
Electron bombardment of
Macromolecule
macromolecules
(inelastic collision)  dissociation
H H
H H
H H H H H H H H
C C
H C C H
C C C C C C n H H
H H
H H H H H H
H H
polyethylene H
H C C
H
e + H2 = H + H + e H C H
H H
H
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)
56

56. gas inlet
Shielding
cathode
energy supply for
electrical heating
anode
electrical
heating
elements
vacuum chamber
cooling system
thermocouples
energy supply
for the cathode vacuum system
Design (schematic) of the hybrid plasma DC reactor
57

57. Materials Laboratory
Plasma Reactor: Pilot Plant at LabMat Mechanical Engineering Department
Federal University of Santa Catarina
Florianópolis, Brazil
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

58. Al2O3 plate
anode
cathode
Plasma Assisted Debinding and Sintering (PADS)
in the same thermal cycle
60

59. After debinding without plasma: organic residues remain in the reactor
61

60. After debinding without plasma: details of organic residues
62

61. Debinding and sintering in the same equipment
and same thermal cycle (single – cycle)
Saving energy
and processing
Temperature (0C)
sintering
time!
plasma nitriding or
debinding carbonitriding
Processing time (h)
63

62. Steelinject Industrial PADS Equipment

63. Properties of Fe + 0,6%C + SiC
sintered steels
65

64. Friction Coef f icient Durability
0,50 3500
0,45
3000
0,40
0,35 2500
Friction Coefficient
Durability ( N.m )
0,30
2000
0,25
1500
0,20
0,15 1000
0,10
500
0,05
0,00 0
0 1 2 3 4 5
SiC Content (w/o)
Fe + 0.6%C + SiC sintered steels (1150 C, 1h, H2, PADS)
66

65. 0.40
0.35 Friction coefficient as a function 1100 °C
of sintering temperature 1150 °C
Friction Coefficient
0.30 1200 °C
0.25
0.20
0.15
0.10
0.05
0.00
0 1 2 3 4 5 6
SiC content ( % )
Fe + 0,6%C + SiC sintered steels (1h, H2, PADS)
67

66. 16
1100 °C
14 1150 °C
Scuffing Resistance ( N.m )103
1200 °C
12
10
8
6
4 Mudar
2 graficos
0
0 1 2 3 4 5 6
SiC content ( % )
68

67. Comparison of friction coefficient of materials
containing distinct graphite types
De Mello & Klein. To be published
69

68. HV 0,2 YS UTS % EL
Yield Strength and Tensile Strength (MPa)
800 18
700
15
600
Hardness (HV)
12
Elongation (%)
500
400 9
300
6
200
3
100
0 0
0 1 2 3 4 5
SiC content (w/o) (w/o) in Fe + 0,6%C matrix
SiC Content in the matriz Fe + 0.6C
Tensile strength, hardness and elongation measured on the sintered Fe
+ 0.6%C + increasing content of SiC (w/o).
70

69. Properties of
Fe + 0,6%C + Ni + Mo + SiC
sintered steels
71

70. Martensitic dry self
lubricating sintered steels. Fe
+ 0,6C + 4Ni + 1Mo + 3SiC

71. Mechanical properties of some of
sintered self lubricating steels
73

72. HV = 400
UTS = 810 Mpa
Elongation = 6%
74

73. Wear bahavior in sliding tests
75

74. 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

75. Thanks for your attention!
77

76. Dissociation of SiC in iron matrix
Fe+0.6%C+3% SiC
Graphite
Fe
Fe3C
Fe Fe
Intensity
Angle
78

77. In situ dissociation of precursor
Graphite Fe+0.6% C+3% SiC – 1100 °C
2400
2200 240 min
2000 120 min
Fe 60 min
1800
30 min
1600 10 min
Intensidade
Intensity
1400 Fe3C Fe Fe
1200
1000
800
600
400
200
0 20 40 60 80 100 120
2(Graus)
Angle
79

78. Martensitic dry self lubricatiing
sintered steels. Fe + 0,6C + 4Ni +
1Mo + 3SiC (verificar na tese
cristiano

79. Self healing effect of the dry self lubricating
sintered steel produced (composite material)
81

80. 2) Materials and experimental
5) Tribological characterization
(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)
82

81. (sp3 - diamond)
(sp2 – graphite)
Graphite nodule
G’ Band
Graphite nodule
D band
SiC dissociation
SiC dissociation
G band
Graphite nodule 10000 1582.3 full-width at half
nodular cast iron
9000
8000
peak height
7000
2727.11
6000
Counts
5000
4000
3000
1356.62
2000
1000
0
500 1000 1500 2000 2500 3000
Raman shift / cm-1
1581.65
Graphite powder 5000
UF4 4000
3000
2727.42
Counts
2000
1000
0
500 1000 1500 2000 2500 3000
Raman shift / cm-1
Raman Spectroscopy 83

82. Band D Band G Band D Band G Crystallite Band G’
Material position position FWHPH FWHPH ID / IG size La Position Band G’
(cm-1) (cm-1) (cm-1) (cm-1) (Å) (cm-1) Shape
Graphite Broad
1354.34 1581.65 8.0 14.71 0.050 880.00 2726,80
powder
Nodular cast Broad
1356.62 1582.3 16.50 27.96 0.189 232.80 2727,10
iron
Peak
Fe+0.6C+3SiC 1351.55 1586.60 58.97 42.22 1.183 37.19 2709,17
FWHPH- full-width at half peak height
 Turbostratic 2D graphite
 Higher interlamellar distances
 Lower friction coefficient
De Mello & Klein et al, 64th STLE Annual Meeting, Las Vegas, 2010
84

83. Results and discussion: Tribological behaviour
Fe+0.6%C+5%SiC, 14 N
Wear track
It is reasonable to suppose that
the graphite foils are removed
from the in situ generated
On the other hand, the tribo-
graphite nodules and remain at
layers also degrade under the
the interface thus contributing
sliding action.
to the formation of the
protective tribo-layer;
85

84. Fe + 0.6%C + 5%SiC
Before test (14 N, 11500C,1h,PADS)
 Turbostratic
2D graphite
 Higher
8000
1582.08
interlamellar
7000
1350.15
distances
6000
Wear scar  Low friction
5000
2698.25
coefficient
C o u n ts
4000
3000 2939.84
2000
1000
0
500 1000 1500 2000 2500 3000 86
Raman shift / cm-1

85. 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 ).

86. 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
 
Kr 

g
0
e (  ) e (  ) d 
Wherein:
g e ( )  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

87. UFSC- Mechanical Engineering Department
MATERIALS LABORATORY
Plasma technology applied to powder
materials processing
Aloisio N. Klein
Team involved in the developments:
Joel L. R. Muzart†, Antonio R. de Souza, Carlos Speller, Ana M. Maliska, Paulo
A. P. Wendhausen, Marcio C. Fredel, Cristiano Binder, Davi Fusão, Roberto
Binder, Waldyr Ristow Jr., Ricardo Machado, Paulo Alba, Maria A. dos Santos,
Rubens M. do Nascimento, Wagner da Silveira, Henrique C. Pavanati, Gisele
Hammes, Vilson J. Batista, Ivani T. Lawall...).

88. OUTLINE
1) Plasma technology applied to powder materials
processing
a) Plasma Assisted Debinding and Sintering (PADS) of PIM parts
(dissociation of organic macromolecules)
b) Plasma Assisted Sintering: Surface modification via plasma
(surface morphology, chemical composition / surface enrichment ,
cathodic sputtering, …).
c) Thermo-chemical surface treatments - via plasma
(cleaning, nitriding, cementation,…)

89. Plasma generation Important phenomena in
(abnormal DC glow discharge) the plasma environment:
1) Ionic and fast neutral
Cathode Anode atoms bombardment on
the cathode:
-V luminescent
region
heat generation and
sputtering
-
+ reactive species 2) Inelastic collision of
Vp - electrons with gaseous
species in the plasma
0
environment:
+
chemical reactions
-V improvement

90. OUTLINE
1) Plasma technology applied to powder materials
processing
a) Plasma Assisted Debinding and Sintering (PADS) of PIM parts
(dissociation of organic macromolecules)
b) Plasma Assisted Sintering: Surface modification via plasma
(surface morphology, chemical composition / surface enrichment ,
cathodic sputtering, …).
c) Thermo-chemical surface treatments - via plasma
(cleaning, nitriding, cementation,…)

91. Plasma Assisted Debiding (PAD)
(using the reactive environment of a plasma)
Electron bombardment of
Macromolecule
macromolecules
(inelastic collision)  dissociation
H H
H H
H H H H H H H H
C C
H C C H
C C C C C C n H H
H H
H H H H H H
H H
polyethylene H
H C C
H
e + H2 = H + H + e H C H
H H
H
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)

92. Plasma Assisted Debinding of PIM parts
Advantages:
a) Increasing of the debinding rate
 save processing time / improve the productivity
b) The furnace remains clean
 possibility for debinding and sintering
in the same equipment in a single – cycle

93. Plasma Assisted Debinding
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

94. Plasma Assisted Debinding:
Effect of the electrons on the debinding rate
(Experimental Results for Polypropylene in hydrogen electrical discharge)
Polypropylene removal (%)
100
50
0 Anode-cathode
Floating potential
Anode/shield-cathode
0 10 20 30 40 50 60
Time (min) T = 400°C

96. 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)

98. After Plasma Assisted Debinding: no organic residues
remain in the reactor

99. Al2O3 plate
anode
cathode
Parts after Plasma Assisted Debinding and Sintering (PADS)
in the same thermal cycle

100. Parts after Plasma Assisted Debinding and Sintering (PADS)
in the same thermal cycle

101. After debinding without plasma: organic residues remain in the reactor

102. After debinding without plasma: details of organic residues

103. Debinding and sintering in the same equipment
and same thermal cycle (single – cycle)
Temperature (0C)
Sintering
debinding plasma nitriding or
carbonitriding
Processing time (h)

104. Some results
- Fe+ 2Ni + 0,6C low alloy steel
- 316-L stainless steel.
Binder system: polymer and wax. Wax debinding: organic solvent.
Thermal debinding and sintering: PADS furnace.
Debinding Sintering
Alloy
parameters parameters
2NiFe0,6C 1250 ºC, 60 min,
(carbonyl Heating rate: 2,0 argon partial
powders) ºC/min. pressure
316-L Atmosphere: atomic
hydrogen 1300 ºC, 90 min,
(atomized H2 partial pressure
powders)

105. Comparison of metallurgical variables of materials processed
in PADS furnace and in a conventional route (catalytic
debinding)
Densit Carbon Hardness Ultimate Yield Elong
Conditio Proces
Alloy y content (HV 0,2 Strength Strengt ation
n s
(g/cm3) (% mass) kg) (MPa) h (MPa) (%)
0,58 –
PADS 7,65 170 575 480 4
0,62
sintered
Fe + Conv. 7,50 0,6 – 0,8 160 500 250 3
2% Ni
+ 0,6C 0,58 –
PADS 7,65 350 1210 1180 2
0,62
tempered
Conv. 7,50 0,6 – 0,8 340 950 800 3
PADS 7,70 0,0015 170 505 290 54
316-L sintered
Conv. 7,85 0,03 máx. 120 510 180 50

106. PADS process x Lupatech’s actual process
Processed alloy: 316-L stainless steel:
– Actual process: permeation controlled thermal + vacuum sintering.
– PADS process: Plasma Assisted Debinding and Sintering.
Heating rate Energy Gas
Lead time
Process during debinding consumption consumption
(h)
(ºC/min) (kW) (m3)
PADS 7 2,0 500 12
Lupatech 80 0,07 800 120

107. 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)

108. Resultados:
 Redução de custo (processo PADS): mínimo 20 %
 Redução de energia (processo PADS): : 50%
Premio Medalha de desenvolvimento
113

109. Nestor http://medalha.desenvolvimento.gov.br/arquivos/agra
Perini ciados06.htm
Cargo: Presidente da Lupatech S/A
Indicação: Sr. Paulo Belini; Sr. Jorge Gerdau Johannpeter e Sr. Raul
Anselmo Randon
Justificativa A Lupatech S/A., através de sua divisão Steelinject, é pioneira
da na América Latina na utilização da tecnologia MIM (Metal
Indicação: 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).
114

110. Processo de transferência da
tecnologia para PADS para USA
DSH Technologies, LLC, que
através da associada - Elnik
Systems vai produzir o
Lupatech (Caxias)
 equipamento e disponibilizar no
+ LabMat (UFSC) mercado mundial.
Primeiro equipamento em 3D foi
exposto na PM2008 em
Washington (8 a 12 de Junho )
115

111. 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.

112. Plasma reactors for materials processing
Possibilities:
A) Plasma reactor with an auxiliary resistive heating
The plasma is used only to promote the chemical
reactions. Plasma works with low current density
(at the exact current needed).
B) Plasma reactor without auxiliary resistive heating
Heat is generated by the plasma, i.e., only by the
bombardment of the cathode by ions and atoms of
high energy.
Problem: high sputtering from cathode – surface
contamination
Opportunity: this can be used for surface enrichment of
unalloyed iron parts

113. Modification of the
chemical composition of
parts during plasma
assisted sintering
Surface enrichment of unalloyed
iron with Chromium

114. 6 1150 °C
Concentração de Mo (%peso) 1000 °C
800 °C
5
Concentration of Mo (%weight)
4
3
2
1
0
0 5 10 15 20 25 30
Profundidade (m)
Depth(µm)
Enrichment with Molybdenum: Temperature Influence (1Torr; 700V; 1h ;
10%H2 + 90%Ar; Gas flow = 5 x 10-6 m3/s (300 sccm)

115. 8
3,5 Torr
7 1 Torr
Concentração de Mo (%peso)
6
Concentration of Mo (%weight)
5
4
3
2
1
0
0 10 20 30 40 50 60 70 80 90 100
Profundidade ( m)
Depth(µm)
Enrichment with Molybdenum: Pressure Influence ( 1150 °C ; 700V; 1h ; 10%H2 +
90%Ar; Gas flow = 5 x 10-6 m3/s (300 sccm)

116. 800°C; 500 V
500 V
250
700 V
200
Amount
Contagem
150
800°C; 700 V 100
50
0
0,0 0,2 0,4 0,6 0,8 1,0
Tamanho de partícula (m)
Particle size (µm)
Deposition of atoms/ions sputtered from the
cathode (clusters of size in the nanometer range)

117. Surface dense layer in plasma assisted sintering
(parts placed on the cathode)
 
View of the lateral side Base, which is in contact to the
which is exposed to ion support and does not receive
bombardment
bombardment
Sputtering +
Ion bombardment deposition and Dense surface layer
activated diffusion
The International Journal of Powder Metallurgy, Vol. 34, No. 8, 1998, pg.55–62.

118. Surface dense layer in plasma assisted sintering
(parts placed on the cathode)
Sintering of unalloyed iron samples produced by powder compaction
As compacted Afther sintering (on cathode)
 Ionic bombardment of the surface improves diffusion rates;
The densification is further enhanced by the
retrodeposition of atoms.

119. OUTLINE
1) Plasma technology applied to powder materials
processing
a) Plasma Assisted Debinding and Sintering (PADS) of PIM parts
(dissociation of organic macromolecules)
b) Plasma Assisted Sintering: Surface modification via plasma
(surface morphology, chemical composition / surface enrichment ,
cathodic sputtering, …).
c) Thermo-chemical surface treatments - via plasma
(cleaning, nitriding, cementation,…)

120. c) Thermo-chemical surface treatments - via plasma
(nitriding, cementation, nitro cementation)
NITRIDE LAYER
20 m 20 m
Unalloyed iron: sintering followed by plasma nitriding
Surface and Coatings Technology 141(2001) 128-134

121. Reator de nitretação por plasma Montagem parcial da carga a ser
escala piloto (4 mil peças por tratada.
carregamento)

122.  Remoção do óleo de calibração dos poros residuais e nitretação por plasma de
materiais sinterizados em único ciclo térmico (patente);
Desenho esquemático célula de limpeza e nitretação – escala industrial  4,5
milhões peças/ano
127

123.  Remoção do óleo de calibração dos poros residuais e nitretação por plasma
de materiais sinterizados em único ciclo térmico (patente);
Foto da célula em operação na Empresa GKN (fornecedor
de peças para a Embraco) 128

124. Foto da célula em
operação na
Empresa GKN
(fornecedor de
peças para a
Embraco)
129