Tribo-chemistry - ltu.se/file/Minami201110_TribologyDays.pdf · D Inorganic salts dispersed in...

Tribo-chemistryHow to investigate mechanism of additives

Ichiro MINAMILuleå Tekniska Universitet, Sverige

Iwate University, Japan

November 10, 2011

Tribology DaysSeminar on Automotive Tribology

Outline

Introduction

Tribo-chemistry and lubricant chemistry

Targets of tribo-chemistry

Role of over-based calcium sulfonates

Background – belt CVT lubricants

Dependence of Ca contents in boundary film on friction

Interaction of organic friction modifiers with rubbing surfaces

Background – DLC coatings for engine elements

Stable isotopic tracers

Strategy of surface analysis for tribo-chemistry

Lubricant chemistry

Definition

Scientific study of substances that reduce any disadvantages caused

by friction, thereby improve quality of machine operation.

Appearance of lubricant

Liquids (oils)

Semi-liquids (greases)

Solids (as additives or as coatings)

Liquid lubricants: base oil(s) + additives (5-20 mass%)

Tribo-improvers

Stabilizers or sustainers Rheo-

improvers

Tribo-chemistry

Definition

Science and technology of substances at rubbing contact. Mechano-

chemistry is closely related, however tribo-chemistry regards mostly

lubrication.

Objectives

Investigating how substances behave at rubbing contact.

Developing task-specific lubricants

Major targets: Tribo-improving additives

Friction modifiers

Anti-wear agents

Load carrying additives (Extreme pressure additives)

Belt CVT system

High friction between belt-pulley for efficient power transmission

Courtesy of Idemitsu Kosan Co., Ltd.

Low friction in bearings for better fuel economy

Challenging model

Additive formulation

Tribologicalenergy

Tribo-material

Tribo-material

Over-based calcium sulfonates

SO3

SO3

SO3

SO3

CaCO3

SO3

SO3

SO3

SO3

Inorganic salts dispersed in hydrocarbon

oils by surfactants

Mainly used as “detergents” to neutralize

acid contaminants

Exhibit certain AW/EP properties

H.Hong,A.T.Riga,J.M.Cahoon,J.N.Vinci:

Lubrication Engineering, 49(1), 19-24 (1993).

How do they reduce friction?Can we control friction?

Ca-Sul

Base oil & others

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0 200 400 600 800 1000 1200Load, N

Fric

tion

coef

ficie

nt,－

C C+I C+Z C+I+Z I Z Z+I B

Tribo-test: Rotating-cylinder & flat type

C : Ca-sul, I : imide, Z:ZnDTP

C : Ca-sul, I : imide

Ca+ O- S-

C

Fe+

C+I

I

worn surface

worn surface

worn surface

worn surface

Sample

higher INTENSITYlower

Chemical mapping: TOF-SIMS

C:Ca-sul, Z:ZnDTP

C

C+Z

Z

Fe+ Ca+ O- S- Zn+ P-

worn surface worn surfaceworn surfaceworn surfaceworn surface

worn surface

Sample

higher INTENSITYlower

Chemical mapping: TOF-SIMS

5 nm

３４７．２ｅＶＣａ

３４８．３ｅＶ

Depth

CaO

Ca(OH)2

Qualitative depth profile: XPS

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50Depth, nm

Con

cent

ratio

n, w

t%

Ca:worn surface

Ca:out of wear track

Fe:worn surfaceFe:out of wear track

Quantitative depth profile: XPS

0

5

10

15

20

25

30

35

0 10 20 30 40 50Depth, nm

Con

cent

ratio

n of

Ca,

wt%

Sample C+I (Ca-Sul+Imid)

Sample C+Z (Ca-Sul+ZnDTP)

Sample C (Ca-Snl)

Quantitative depth profile: XPS

Calcium alkylsulfonate

Calcium carbonate

(1) Adsorption

(2) Pyrolysis of the inorganic saltCaCO3 → CaO (3) Film formation

HeatPress

Process of boundary film formation

Over based Ca- Sulfonates(Precursor)

+Imide or ZnDTP (Controller)

Depth

Over based Ca- Sulfonates (Precursor)

:CaO :FexOy

Boundary film model: results of additive interactions

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1 H He

2 Li Be B C N O F Ne

3 Na Mg Al Si P S Cl Ar

4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn

La La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ac Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Group

Perio

dThe periodic table of elements

Trends of environmentally friendly engine oils

Low viscosity base oils

Wear protection

Low wear materials

AW additives

Chemical

Reduce heteroatom contents

HCO-additivesOn going projects

Rheological

Achievement by Nissan Motor

Tribology Letters, Vol. 18(2), 245-251 (2005).

0.00

0.05

0.10

0.15

steel-steel steel-DLC steel-DLC steel-DLC

5W-30GF-3 5W-30 +MoDTC

5W-30 +GMO

Material and lubricant

Fric

tion

coef

ficie

nt, -

GMO

O

O

OHOH

Mechanism?

How to detect HC-compounds?

Boundary filmCC

CC

CC

CC

CC

CH2CH3

CHCH

CH

CHC

HH

H

H

HH

H

H

HH

HH

H HH

H

H

H

H

H

HH

H

H

H

CC

CC

CC

CC

HC

C

CH3

HH

H

H

HH

HH

H

H

H

H

H

HH

H

H

H

13CD (2H)Hydrocarbon moieties can be distinguished

Samples

where C means 13C

g-GMO

OC

C

OC

OHOH

c-GMO

CO

O

OHOH

Results of GMO in PAO

CO

O

OH

OH

OC

C

OC

OH

OH

0.00

0.05

0.10

0.15

Additive-free (PAO)

GMO c-GMO g-GMO

Additive

Fric

tion

coef

ficie

nt, -

DLC flat

Steel cylinder

Similar friction reductionby the isotope derivatives

The fragmentation of GMO (positive)

m = 265 for GMO and g-GMO, m = 266 for c-GMO

m = 339 for GMO, m = 340 for c-GMO, m = 342 for g-GMO

O

O

OHOH

Mass spectrum of un-rubbed surfaces (positive)

2 0 0 2 5 0 3 0 0 3 5 00

5 0

1 0 0

1 5 0

2 0 0T

ota

l Co

unts

(0

.18

amu

bin

)Integral: 10906 11UNSAVED + Ions 173µm 1061768 cts

225202 253 321211 219 231 281

239337

207

265

2 0 0 2 5 0 3 0 0 3 5 00

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

Tot

al C

oun

ts (

0.1

8 a

mu

bin

)

Integral: 25439 12UNSAVED + Ions 173µm 1195215 cts

226 313 322215 231

279202 239219207

266

340

2 0 0 2 5 0 3 0 0 3 5 00

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

To

tal C

oun

ts (

0.1

8 am

u b

in)


253227215372239 388202 221

207 337

342265

c-GMO

g-GMO

GMOm/z 265

m/z 339

m/z 266

m/z 265m/z 342

m/z 340

2 0 0 2 5 0 3 0 0 3 5 00

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0T

ota

l C

ou

nts

(0

.18

am

u b

in)


243225 253219207 335279202 211

239

339

265

2 0 0 2 5 0 3 0 0 3 5 00

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252 336215 226207 219 279 380202 239

266

340

2 0 0 2 5 0 3 0 0 3 5 00

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252227215 279 342219 370

313202239

265 388

rubbed withc-GMO in PAO

rubbed withg-GMO in PAO

rubbed withGMO in PAO

m/z 265m/z 339

m/z 266

m/z 265m/z 342

m/z 340

2 0 0 2 5 0 3 0 0 3 5 00

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0T

ota

l C

ou

nts

(0

.18

am

u b

in)


243225 253219207 335279202 211

239

339

265

2 0 0 2 5 0 3 0 0 3 5 00

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252 336215 226207 219 279 380202 239

266

340

2 0 0 2 5 0 3 0 0 3 5 00

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252227215 279 342219 370

313202239

265 388

2 0 0 2 5 0 3 0 0 3 5 00

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0T

ota

l C

ou

nts

(0

.18

am

u b

in)


243225 253219207 335279202 211

239

339

265

2 0 0 2 5 0 3 0 0 3 5 00

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252 336215 226207 219 279 380202 239

266

340

2 0 0 2 5 0 3 0 0 3 5 00

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

To

tal

Co

un

ts (

0.1

8 a

mu

bin

)


252227215 279 342219 370

313202239

265 388







m/z 265m/z 339

m/z 266

m/z 265m/z 342

m/z 340

Mass spectrum of rubbed surfaces (positive)

GMO does exist on rubbed DLC surfaces

Profile of surface analyses frequently found in tribology articles

lattice depth

Infrared spectroscopy　(IR) 10 μmφ 1 μm Mainly organic compounds Functional groupdepends on functional

group

Electron probe micro analysis

（EPMA，SEM-EDX)1 μmφ 1 μm Elements larger than Be Elements 0.01 mass%

X-ray photoelectron spectroscopy

（XPS，ESCA)1 mmφ 5 nm Elements larger than Li

chemical state ofelements

0.1 atomic%

Auger electron spectroscopy

（AES)1 μmφ 1 nm Elements larger than Li Elements 0.1 atomic%

Secondary ion mass spectroscopy

（SIMS)1 μmφ 1 nm All elements partial structure ppb

Method

Analytical area

Target Results Sensitivity

Principle of surface analysis

Input signal

Target molecule

Output signal

Detect and analysis

Outputs

Spectrum

Qualitative and quantitative

analyses

Chemical mapping

Distribution of target chemical

species

0.0

0.2

0.4

0.6

0.8

1.0

1.2

94

96

98

100

102

104

106

108

110

112

114

Nor

mal

ized

inte

nsity

Binding energy, eV

rubbed

un-rubbed

Si (Oxide)

Si (Elemental)

Wear track (0.6mm)

Si

Size of rubbed surface (aluminum alloy)

Width = 2.2 × 10-2 [mm] : calculated by Hertz’s equation

Length = 12.7 [mm]

Area of rubbed surface > 2.8 × 10-1 [mm2] = 2.8 × 105 [μm2]

Analytica area of EPMA and AES: 7.9 × 10-1 [μm2]

Size of molecule : = 1.3 × 10-1 [nm2] = 1.3 × 10-7 [μm2]

Where should be spotlighted?

Analytical area： Example

nm2

mm2

Lubrication mode for surface analysis

Parameter (V�η/L)

Fric

tion

coef

ficie

nt

boundarylubrication hydrodynamic

lubrication

mixedlubrication

hydrodynamic filmboundary film

preferablesurface anal.

Flow chart of surface analysis Tribo-test

repeatability

morphology

analysis

consideration

Results

hypothesis

Literaturedatabase

yes

no

reasonableunreasonable

Chemical resolution and sensitivity

Chemical species of interest

Appropriate method for the chemical species

Spatial resolution and sensitivity

Analytical size (lateral and deep)

Analytical point and/or area

Sample quality

Surface roughness

Quantity of the target

Contamination

Strategy for successful surface analysis in tribo-chemistry

Review on stable isotopic tracers for tribo-chemistry

Ichiro Minami: “A Novel Tool for Mechanistic Investigation of Boundary Lubrication: Stable Isotopic Tracers” in New Tribological Ways, p425-450, Edited by Taher Ghrib, InTech Publisher (April 2011), ISBN 978-953-307-206-7.

This is an open access book. Please visit athttp://www.intechopen.com/articles/show/title/a-novel-tool-for-mechanistic-investigation-of-boundary-lubrication-stable-isotopic-tracers

Tribo-chemistry - ltu.se/file/Minami201110_TribologyDays.pdf · D Inorganic salts dispersed in...

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