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imerys-graphite-and-carbon.com
TIMCAL Graphite
TIMCAL Graphite
TIMREX®
TIMREX® C-THERMTM
SPECIALTY CARBONS FOR CARBON BRUSHES
EngineeringMaterials
TIMCAL CokeTIMREX®
2
Imerys Graphite & Carbon
WHAT IS OUR MISSION?To promote our economic, social and cultural advance-ment with enthusiasm, efficiency and dynamism by of-fering value, reliability and quality to ensure the lasting success of our customers.
WHAT IS OUR VISION?To be the worldwide leader and to be recognized as the reference for innovative capability in the field of carbon powder-based solutions.
Imerys Graphite & Carbon has a strong tradition and history in carbon manufacturing. Its first manufacturing operation was founded in 1908. Today, Imerys Graphite & Carbon facilities produce and market a large variety of synthetic and natural graphite powders, conductive carbon blacks and water-based dispersions of consistent high quality. Adhering to a philosophy of Total Quality Management and continuous process improve-ment, all Imerys Graphite & Carbon manufacturing plants comply with ISO 9001:2008. Imerys Graphite & Carbon is committed to produce highly specialized graphite and carbon materials for today’s and tomorrow’s customers needs.Imerys Graphite & Carbon belongs to Imerys, the world leader in mineral-based spe-cialties for industry.
WHO ARE WE?
HQ Bodio, SwitzerlandGraphitization and processing of synthetic graphite, manufacturing of water-based dispersions, processing of natural graphite and coke, and manufacturing and processing of silicon carbide
Changzhou, ChinaManufacturing of descaling agents and processing of natural graphite
Fuji, JapanManufacturing of water-based dispersions
Willebroek, BelgiumManufacturing and processing of conductive carbon black
Lac-des-Îles, CanadaMining, purification and sieving of natural graphite flakes
For the updated list of commercial offices and distributors please visit www.imerys-graphite-and-carbon.com
Terrebonne, CanadaExfoliation of natural graphite, processing of natural and synthetic graphite
With headquarters located in Switzerland, Imerys Graphite & Carbon has an inter-national presence with production facilities and commercial offices located in key markets around the globe. The Group’s industrial and commercial activities are man-aged by an experienced multinational team of more than 430 employees from many countries on three continents.
WHERE ARE WE LOCATED?
3
Our value proposition
We at Imerys Graphite & Carbon deliver tailor made solutions for Carbon brushes market with superior consistency of key products’ parameters: purity, crystallinity, particles size distribution, oversize control.
We at Imerys Graphite & Carbon address with our portfolio and with our R&D efforts the key requirements of Carbon brushes industry:
APPLICATIONREQUIREMENTS
RELATED ISSUE CARBON ADDITIVES TECHNICAL REQUIREMENTSINVOLVED
BENEFITSFROM IMERYSGRAPHITE PORTFOLIO
Electrical resistivity Different resistivity depending on application
Various crystallinity levels and Particles Size Distribution (PSD).
Large variety of solutions, in terms of crystallinity and PSD.
Long life of electric motor
Wear resistance (electrical and mechanical)
High Purity, specific crystallinity and PSD for a tailored resistivity and friction coefficient (μ).
Consistent, high purity. Large variety of solutions, in terms of crystallinity and PSD. Thermal conductivity additive C-THERMTM.
Commutation film formation.
Special additive for transfer film’s thickness control.
Good adhesion between resin and graphite.
Engineered particles’ surface, optimized PSD.
Low carbon brush cost Low resin consumption
Optimized PSD. Large variety of solutions, in terms of PSD.
Good commutation, low noise, low sparking
Transfer film behavior,Vibration damping
Various crystallinity levels and PSD (depending on application).
Large variety of solutions, in terms of crystallinity and PSD.
Inspired by F.P. Bowden, D. Tabor (1964), “The friction and lubrication of solids”, Oxford University Press, UK.
High electrical resistivitylow/no compressibility
Nocrystallinity
Highcrystallinity
Low electrical resistivityhigh compressibility
Naturalgraphite
Coke
Secondarysynthetic graphiteor scrap graphite
Primarysynthetic graphiteT
KSKC
SFG
4
Overview of Imerys Graphite & Carbon solutions
CARBON BRUSHES TYPE PROPERTIES
Graphite powders %C min. Resin bonded
Copper sintered
Electrical resistivity
Compressibility
Primary synthetic graphite T 99.9% High Low
KS 99.9% Medium high Medium
KC 99.9% Medium low Medium high
SFG 99.9% Low High
Natural graphite flakes BE 99.5% Low High
Flakes 94.0-96.0% Low High
Special additives Application benefits
Petroleum coke 99.5-99.7% Stabilization of friction coefficient
C-THERM™ 97.5-99.7% High thermal conductivity for lower wear
HRG High resistivity graphite 99.9% Very high el. resistivity, low oil absorption
ENSACO carbon black 99.9% Reduction of el. resistivity, mechanical resistance
Especially recommended Recommended
Medium-high resistivity primary synthetic graphite
High resistivityprimary synthetic graphite
0 20 40 60 80 100 120 140 160
T15
T44
T15-75
T150
T75
(µm)
0 20 40 60 80 100 120 140 160
KS6
KS15
KS25
KS5-25
KS5-75 TT
KS75
KS150
KS44
KS5-44
(µm)
5
0 200 400 600 800 1000 1200 1400 1600
PC40 OC
FC800
FC250-1500
FC250
(µm)
Calcinatedpetroleum coke
Natural flakes94 to 96%C
Natural flakes>99.5%C
Low resistivityprimary synthetic graphite
Medium-low resistivity primary synthetic graphite
0 20 40 60 80 100
KC44
KC75
KC5-44
(µm)
0 20 40 60 80 100 120 140 160
BE44
BE90
BE75
(µm)
(µm)0 50 100 150 200 250 300 350
PP25
50X80
50X100
M80
M150
PP44
M100
0 20 40 60 80 100 120 140 160
SFG6
SFG15
SFG44
SFG5-75
SFG150
SFG75
(µm)
6
Tests methods
Model Carbon brushes have been prepared in R&D lab following the standard procedure:– Mixing: graphite powder is dry mixed with phenolic resin powder (typically 80% wt. graphite – 20% wt. resin or 70% wt. graphite – 30% wt. resin)– Compaction: the mixed powders are pressed in a rectangular mould (either 20 x 30 mm2, 50x12 mm2 or 5x35 mm2) at different pressures (from 1 t/cm2 to 5 t/cm2)– Curing: the pressed samples are cured in an oven according to the following
thermal treatment: 25 -> 80 °C (120 minutes), 80 -> 135 °C (660 minutes), 135 -> 180 °C (270 minutes), 120 minutes at 180 °C, cooling
The dimensions of the model carbon brushes are measured after the thermal treat-ment with a micrometer, the weight is measured with a precision balance, and the density is calculated (mass/volume).
The transverse rupture strength is measured by three point method: the sample is placed on two supporting pins a set distance apart and a third loading pin is lowered from above at a constant rate until sample failure.
PRESSED DENSITY
SAMPLES PREPARATION
BENDING STRENGTH
L
T
Pressed Density: Mass / W x L x T
Pressure
Load
Carbon brush
W
7
The electrical resistivity is measured by the four-point method both in the in-plane (XY) and through-plane (Z) direction. The four-point method applied for these measurements greatly reduces the possibility of errors due to poor contacts.
The thermal conductivity is measured with TCT416 instrument by Netzsch.
ELECTRICAL RESISTIVITY
Current carrying electrodes
Measuring electrodes
Carbon brush
IDC
Digital Ohmmeter
Digital Ohmmeter
Current carryingelectrodes
Measuringelectrodes(gold wires)
IDC Carbonbrush
Interlayer(graphite foil)
XY (in-plane)
Z (through-plane)
THERMAL CONDUCTIVITY
T = 60C
T = 25C
T2
T1
Car
bon
brus
h
8
The measurement of elastic springback gives an indication of the the resilience of com-pacted graphite powder. A defined amount of dry powder is poured into a die. After inserting the punch and sealing the die, air is evacuated from the powder. Pressure is applied (p=0.477 t/cm2) and the powder sample thickness is measured. Thickness is measured again after pressure has been released.
SPRING-BACKMEASURINGMETHOD
Pressure meter
Punch
Meteringelement
Seal
Die
Compact
Vacuum line
Pressure
Springback
SB =H (0) - H (p)
H (0)x 100%
The oil absorption test is a special centrifugation method showing high reproducibility, developed by Imerys Graphite & Carbon. A special centrifuge tube is filled with 0.5 g ofTIMREX® graphite powder and then covered with paraffin oil. After centrifuging, the tube is weighed and the oil absorption of 100 g of powder is calculated (based upon the weight increase of the 0.5 g sample).
OIL ABSORPTION MEASURING METHOD
Acceleration
CentrifugationTube
Oil
SampleFilterSieve
9
Data: pressed density
Pres
sed
dens
ity (g
/cm
3 )
Pressure (t/cm2)
4 6 820
1.7
1.9
1.6
1.5
1.4
2.2
2.1
2.0
1.8
BE44
SFG44
KS44
T44
Pres
sed
dens
ity (g
/cm
3 )
Pressure (t/cm2)
4 620
1.6
1.8
1.5
1.4
1.3
1.9
1.7
BE150
SFG150
KS150
T150
Pres
sed
dens
ity (g
/cm
3 )
100 150500
1.7
1.9
1.6
1.5
1.4
1.3
2.1
2.0
1.8
Particles size d90 (microns)
BE
SFG
KS
KC
T
Pres
sed
dens
ity (g
/cm
3 )
Particles size d90 (microns)
100 150500
1.3
1.5
1.2
1.8
1.7
1.6
1.4
BE
SFG
KS
KC
T
Carbon brush(20% wt. resin)
Pure graphite (2.5 t/cm2
compacting pressure)
Carbon brush(30% wt. resin, 2 t/cm2
compacting pressure)
Pure graphite
Pressed density increases with increasing applied pressure. Natural graphite (BE) has higher pressed density compared to primary synthetic graphite. Pressed density of primary synthetic grades can be ranked according to crystallinity level (T<KS<KC<SFG).For synthetic graphite of type T and KS, the pressed density significantly decreases with increasing particle size.
Pressed density vs. graphite type
Pressed density vs. particles size distribution
10
Data: springback and bending strength
Carbon brush(30% wt. resin, 2 t/cm2 compacting pressure)
Bend
ing
stre
ngth
(MPa
)
100 150500
30
20
60
50
40
BE
SFG
KS
T
Particles size d90 (microns)
Springbackof pure graphite
Sprin
gbac
k (%
)
Particles size d90 (microns)
100 150500
5.0
15.0
0
30.0
25.0
20.0
10.0
BE
SFG
KS
KC
T
Springback and compact density of graphite powders are physically connected parame-ters, which give information about the compressibility of powders and dimensional stabil-ity of compacts in any pressing direction. Springback is influenced mainly by compacting pressure, particle size distribution and crystalline structure of graphite. Typically, high crystalline structure results in low springback. Compacts produced from powders having a low springback can be easily formed and pressed with greater accuracy and density.
Bending strength of carbon brushes typically decreases with increasing particles size distribution (d90). This trend is more evident for high crystallinity grades (SFG, natural graphite).
11
Data: electrical resistivity
Elec
trica
l res
istiv
ity X
Y (m
Ohm
.cm
)
0
5
15
30
25
20
10
Particles size d90 (microns)
BE
SFG
KS
KC
T
80 160120400
Elec
trica
l res
istiv
ity Z
(mOh
m.c
m)
80 1601204000
40
120
200
160
80
Particles size d90 (microns)
BE
SFG
KS
KC
T
Carbon brush(30% wt. resin, 2 t/cm2
compacting pressure)
It has to be taken into consideration that the compressibility of each graphite grade affects the electrical resistivity because of micro-cracks and residual porosity of the carbon brush.
12
Data: electrical resistivity-anisotropy
The electrical resistivity of carbon brushes is highly anisotropic, due to the orientation of the graphite particles during compression. Electrical resistivity anisotropy (through-plane / in-plane electrical resistivity) can range from a ratio of circa 6 for KS primary synthetic graphite up to circa 14 for natural graphite (BE).
Elec
trica
l res
istiv
ity X
Y (m
Ohm
.cm
)
Pressed density (g/cm3)
0
10
20
15
5
BE150
SFG150
T150
KS150
1.70 1.901.501.30
Elec
trica
l res
istiv
ity a
niso
tropy
Pressed density (g/cm3)
0
8
6
4
2
16
12
14
10
1.70 1.901.501.30
BE150
SFG150
T150
KS150
Elec
trica
l res
istiv
ity Z
(mOh
m.c
m)
Pressed density (g/cm3)
0
80
120
100
60
40
1.70 1.901.501.30
BE150
SFG150
T150
KS150
Carbon brush(20% wt. resin, 2-5 t/cm2
compacting pressure)
13
Benefits from optimized particles size distribution
We at IMERYS Graphite & Carbon have developed a long time ago optimized particle size distributions to match a few key requirements of carbon brush producers:– Lower cost of carbon brushes can be obtained thanks to resin consumption
reduced by 30 to 50%– Higher wear resistance can be obtained thanks to reduced electrical wear
(significantly less sparking) and mechanical wear– Better commutation properties– Lower brush density, with higher electrical resistivity and improved mechanical
properties– More elasticity for better noise-vibration performance
Oil a
bsor
ptio
n (g
oil
/ 100
g g
raph
ite)
0
40
20
80
120
100
60
PSD
Optimized PSD
KS25
KS5–
25
KS44
KS5–
44
KS75
KS5–
75 T
T
T75
T15–
75
SFG7
5
SFG–
75
KC44
KC5–
44
Elec
trica
l res
istiv
ity (m
Ohm
.cm
)
Pressed density (g/cm3)
1
10
1000
100
rho XY KS5–75 TT
rho XY KS75
rho Z KS75
rho Z KS5–75 TT
1.6 1.71.51.4
Bend
ing
stre
ngth
(N/m
m2 )
Pressed density (g/cm3)
25
20
35
30
KS5–75 TT
KS75
1.6 1.71.51.415
Carbon brush(20% wt. resin, 2, 3, 5 t/cm2 compacting pressure)
Oil absorptionof pure graphite
The absorption behaviour is determined by particle size distribution, bulk density, crystalline structure, BET, surface porosity, particle shape and surface tension between graphite and binder.
14
Special grades / Additives
HRG GRAPHITE
TYPICAL VALUES KS44 KS75 HRG250
Malvern d10 [μm] 5 5 5
Malvern d50 [μm] 18 23 19
Malvern d90 [μm] 46 56 52
Oil Absorption [%] 94 83 65
Scott density [g/cm3] 0.19 0.24 0.31
Carbon brush(30% wt. resin0.5–2 t/cm2
compacting pressure)
Elec
trica
l res
istiv
ity (m
Ohm
.cm
)
Pressed density (g/cm3)
0
500
400
300
200
100
rho XY HRG250
rho XY KS75
rho Z KS75
rho Z HRG250
1.4 1.51.31.2
HRG shows:– Much higher resistivity with similar pressed density compared to T / KS – Lower oil absorption by about 30% compared to KS – Higher Scott density by about 40% compared to KS – Mechanical properties similar or better than T / KS– Improved wear properties thanks to optimized shape and surface structure of
powder grains– Improved commutation but lower efficiency (more power consumption P=R*I2)
High resistivity graphite (HRG) was developed to combine high resistivity (typical of sec-ondary synthetic graphite, obtained by scrapping of electrodes) with the high mechanical performance given by primary synthetic graphite.
15
C-THERMTM
ENSACO CARBON BLACK / COKE
POWDER SOFT GRANULES
>99.7 %C C-THERMTM002 C-THERMTM001
>97.5 %C C-THERMTM012 C-THERMTM011
Elec
trica
l res
istiv
ity (m
Ohm
.cm
)
Ther
mal
con
duct
ivity
(W/m
.K)
0
2.52
1.51
3.5
4.5 140
120
100
80
60
40
20
0
4
3
In-plane electricalresistivity (4 t/cm2)In-plane thermalconductivity (2.5 t/cm2)
0.5
% KS75 / C-THERMTM
80 / 0 75 / 5 70 / 10 60 / 20 40 / 40 0 / 80
C-THERMTM can be used as minor additive to improve the thermal conductivity (better heatdissipation, resulting in lower wear of the carbon brush). It can be also used to decrease the electrical resistivity of the carbon brush. It is available both as powder and soft granules with two different purity levels.
We at IMERYS Graphite & Carbon can provide special Carbon based additives for specific needs in carbon brushes formulation:– stabilization of friction layer and friction coefficient (fine Coke powders, with oversize
control)– tailoring of electrical resistivity values (ENSACO® electrically conductive carbon black)
ENSACO® 250G is a conductive carbon black that can boost both in-plane andthrough-plane electrical conductivity of polymer-carbon composites.
Carbon brush(20% wt. resin)
Carbon brush(TIMREX® KS150 + ENSACO®
250G and 20% wt. resin;2 t/cm2 compacting pressure)
ENSACO® 250G content (wt. %)
Elec
trica
l res
istiv
ity in
-pla
ne (m
Ohm
.cm
)
Elec
trica
l res
istiv
ity th
roug
h-pl
ane
(mOh
m.c
m)
50 7.5
7
6
8
9
10
0
15
5
25
30
20
10
35 In-plane XY
Through-plane Z
16
EUROPE
Imerys Graphite & Carbon Switzerland Ltd. Group Head Office • Strada Industriale 12 • 6743 Bodio • SwitzerlandTel: +41 91 873 20 10 • Fax: +41 91 873 20 19 • graphiteandcarbon.ch@imerys.com
Imerys Graphite & Carbon Belgium SABrownfieldlaan 19 • 2830 Willebroek • BelgiumTel: +32 3 886 71 81 • Fax: +32 3 886 47 73 • graphiteandcarbon.be@imerys.com
Imerys Graphite & Carbon Germany GmbHBerliner Allee 47 • 40212 Düsseldorf • GermanyTel: +49 211 130 66 70 • Fax: +49 211 130 667 13 • graphiteandcarbon.de@imerys.com
France Representative Office c/o Imerys154-156 rue de l’Université • 75007 Paris • FranceTel: +33 1 495 565 90/91 • Fax: +33 1 495 565 95 • graphiteandcarbon.fr@imerys.com
UK Representative OfficeTel: +44 1 270 212 263 • Fax: +44 1 270 212 263 • graphiteandcarbon.uk@imerys.com
ASIA-PACIFIC
Imerys Graphite & Carbon Japan K.K. Tokyo Club Building 13F • 3-2-6 Kasumigaseki • Chiyoda-ku • Tokyo 100-0013 • JapanTel: +81 3 551 032 50 • Fax: +81 3 551 032 51 • graphiteandcarbon.jp@imerys.com
Imerys Graphite & Carbon (Changzhou) Co. Ltd. 188# Taishan Road • Hi-Tech Zone • Changzhou 213022 • ChinaTel: +86 519 851 008 01 • Fax: +86 519 851 013 22 • graphiteandcarbon.cn@imerys.com
Shanghai Branch Office c/o Imerys 1438 Hong Qiao Road • Chang Ning District 6F • Gubei International Fortune Centre II Shanghai 201103 • ChinaTel: + 86 21 2223 0136 • Fax: + 86 21 2223 0199 • graphiteandcarbon.cn@imerys.com
Singapore Representative Office c/o Imerys Asia Pacific80 Robinson Road #19-02 • 068898 SingaporeTel: +65 67 996 060 • Fax: +65 67 996 061 • graphiteandcarbon.sg@imerys.com
AMERICAS
Imerys Graphite & Carbon USA Inc. 29299 Clemens Road 1-L • Westlake (OH) 44145 • USATel: +1 440 871 75 04 • Fax: +1 440 871 60 26 • graphiteandcarbon.us@imerys.com
Imerys Graphite & Carbon Canada Inc. 990 rue Fernand-Poitras • Terrebonne (QC) J6Y 1V1 • Canada Tel: +1 450 622 91 91 • Fax: +1 450 622 86 92 • graphiteandcarbon.ca@imerys.com
Imerys Graphite & Carbon is a trademark of the Imerys Group © 2
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© 2
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arb
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ay b
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