development of advanced calcium-lithium soap grease with minimum uses of lithium hydroxide
TRANSCRIPT
Development of Advanced Calcium-Lithium Soap
Grease with Minimum Uses of Lithium Hydroxide
Dr. Ashok K. Goyal, N.Parameswaran, Dr. B. Ghosh & Ananda Sengupta
Balmer Lawrie & Co Ltd Applications Research Laboratory,
Kolkata
Smart Phones
Smart Watches
Smart T.V.
Laptops
Tablets
Electric Vehicles
SMART WORLD OF SMART TECHNOLOGY
Lithium Ion Batteries - Most Popular Lithium has the highest electric output per unit weight. Battery manufacturers across the world are moving to
lithium.
POWER SOURCE FOR SMART TECHNOLOGY
Ceramics and glass Industries - 35%
Rechargeable Batteries - 29%
Lubricating Greases - 8%
Air Treatment - 5%
Polymer Production - 5%
Primary Batteries - 2%
Primary Aluminum Production - 1%
Other Uses - 9%
Above data are taken from U.S. Geological Servey Minerals Yearbook, 2013
Present Uses of Lithium Hydroxide in Different Sectors
Calcium Soap Greases
Calcium Complex Greases
Simple Lithium Soap Greases
Lithium Complex Greases
Aluminium Complex Greases
Sodium Soap Greases
Non-Soap Greases
Polyurea Greases
Sulphonate Complex Greases etc.
Types of Lubricating Greases
Lesser Availability of Lithium Hydroxide Because of
• Increasing Demand lithium batteries in Smart Devices
• Increasing Demand in Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV)
• Depleting Natural Sources of Lithium
The price of Lithium Hydroxide increasing day by day
Present Scenario for Availability of Lithium Hydroxide for Grease Manufacturing
Project was taken to develop a grease without or lesser uses of lithium hydroxide exhibiting properties near to lithium soap greases.
Calcium hydroxide was chosen as a main base because calcium soap greases are the second largest produced greases.
Calcium hydroxide (Hydrated lime) is easily available every where at cheaper cost.
Knowledge about the properties of conventional calcium soap and calcium complex soap greases alongwith the lithium soap greases is very essential to overcome the drawbacks in newly developed grease.
Development of Advanced Calcium-Lithium Soap Grease
Calcium soap greases are oldest metal soap greases
Dropping points of calcium soap grease are in between 90-120 ⁰C
Water is very much essential to stabilize the structure of grease
Upper temperature limit in any application is only 50-70 ⁰C
At high temperature water evaporates leading to breaking in grease soap structure
Applicable only in less demanding applications
Fair shear stablity
Calcium Soap Greases
Calcium complex greases have the high dropping point
On storage at room temperature these greases will slowly harden when exposed to air.
The hardening begins at the grease/air interface and slowly extend further into the bulk of the grease with time.
This phenomenon is well known as “Case Hardening”
Calcium complex greases also severely harden under sustained high temperatures.
Because of case hardening tendency these greases can not become popular and acceptable for uses.
Poor Shear Stability
Calcium Complex Soap Greases
High Dropping Point (High Heat Resistance)
Excellent Shear Stability
Smooth Texture
No hardening Tendency
Easily Pumpable
Good water resistant property
Very good anti-wear performance
Can be used in Multipurpose applications
Easy Manufacturing Process
Simple Lithium Soap Greases
High Dropping Point (High Heat Resistance)
Very good Shear Stability
Smooth Texture
No significant hardening Tendency
Easily Pumpable
Good water resistant property
Very good anti-wear performance
Easy Manufacturing Process
Can be used in Multipurpose applications
Development of Advanced Calcium-Lithium Soap Grease
Manufacturing Process
Similar to the process of simple lithium soap greases or lithium complex greases
Fatty Acid / Fat Melting
Saponification
Complexation / Chelation
Cooling
Additive Mixing
Homogenization after cooling
Developed grease offers substantial savings in terms of reduced power and fuel consumption due to lesser processing temperature required for manufacturing
Development of Advanced Calcium-Lithium Soap Grease
Dropping point of the developed grease was checked as per ASTM D 566 test method
Results were compared with Calcium Soap, Calcium complex and lithium soap greases
Dropping Point of developed grease was found near to the lithium soap greases
Dropping Point
Development of Advanced Calcium-Lithium Soap Grease
S. No. Type of Grease Dropping
Point, ⁰C
1. Calcium soap grease (Hydration method) 86
2. Calcium soap grease (Anhydrous method) 123
3. Calcium complex Grease (Conventional
Method) 266
4. Advanced calcium-lithium soap grease 195
5. Simple lithium soap grease 199
Dropping Point Test Data of Different Greases with Developed Grease
Dropping Point
Evaluation of the grease soap structure stability was carried out by Two Methods
100,000 Up & Down Strokes (Vertical Shearing) ASTM D 217
Rolling Stability Test at Room Temp. (Rotational Shearing under load)
ASTM D 1831
Stability Against Mechanical Shearing
S.
No. Type of Grease
Penetration
after 60 strokes
@ 25 ⁰C
Penetration after
100000 strokes @
25 ⁰C
Penetration
change after roll
stability test @
rt, 16 hrs.
1. Calcium soap grease
(Hydration method) 287 353 (+70) +63 Units
2. Calcium soap grease
(Anhydrous method) 292 366 (+74) +66 Units
3. Calcium complex Grease
(Conventional Method) 285 376 (+91) +87 Units
4. Advanced calcium-
lithium soap grease 283 316 (+33) +36 Units
5. Simple lithium soap
grease 288 315 (+27) +32 Units
Test Data of Mechanical Shearing Stability of Developed Grease and Other Greases
Stability Against Mechanical Shearing
Case hardening tendency of the developed grease has been checked by
At Room Temperature in Open Air
Wheel Bearing Leakage Test at 105 ⁰C for 6 hours (ASTM D 1263)
Roll Stability Test at 82 ⁰C for 96 hours (modified ASTM D 1831)
Hardening Tendency
S. No. Type of Grease
Unworked
Penetration @
25 ⁰C
Penetration @
25 ⁰C after 60
days storage at
rt
Penetration
@ 25 ⁰C after
90 days
storage at rt
1. Calcium complex Grease 274 187 (-87) 171
2. Advanced calcium-lithium
soap grease 276 273 (-3) 272
3. Simple lithium soap grease 279 277 (-2) 277
Tendency of Case Hardening in Different Greases on Storage at Ambient Temperature
Hardening Tendency
S. No. Test Performed
Test Results
Advanced Ca-Li
soap Grease
Simple lithium
soap grease
1. Change in penetration after roll stability
at 82 ⁰C for 96 hrs. +43 units +54 units
2. Wheel bearing Leakage Test
i Oil leakage in grams 0.73 0.88
ii Change in penetration of grease applied
in bearing hub of the instrument -9 units -8 units
iii Condition of the grease Smooth Smooth
Tendency of Case Hardening in Different Greases on Storage at Elevated Temperature
Hardening Tendency
Anti-wear properties of the grease was testes by Four Ball Wear Scar Diameter Measurement (ASTM D 2266) RPM - 1200 Time - 3600 Sec. Temp. - 75 ⁰C Load - 40 kg.
Coefficient of Friction by SRV Instrument (ASTM D 5707) Temp. - 50 ⁰C Time - 7200 Sec. Amplitude/stroke - 1 Frequency - 50 Hz.
Anti-wear Characteristics
Calcium Soap grease Advanced Ca-Li Soap Grease Simple Lithium Soap Grease
Simple Lithium Soap Grease Advanced Ca-Li Soap Grease Lithium soap grease with AW/EP additive Advanced Ca-Li grease with AW/EP Additive
Frictional Torque with Time During Four Ball Anti-Wear Test with and without Anti-Wear Additive in different greases
Anti-wear Characteristics
S. No. Type of Grease Four Ball Wear
Scar Dia, mm
Coefficient of
Friction by SRV
1. Calcium soap grease 0.71 0.119
2. Advanced calcium-lithium soap
grease 0.57 0.113
3. Advanced calcium-lithium soap
grease with EP/AW additives 0.46 0.106
4. Simple lithium soap grease 0.55 0.111
5. Simple lithium soap grease with
EP/AW additives 0.45 0.104
Anti-Wear Characteristics Data of the Greases Received from Four Ball and SRV Test Methods
Anti-wear Characteristics
Application temperature limit of metallic soap greases are decided by their dropping/melting points.
Maximum application temperature of greases are generally 70-100 ⁰C lesser than their dropping points
Maximum temperature limit for simple lithium greases is kept around 100-120 ⁰C
Similarly Maximum temperature limit for Advanced Calcium -Lithium soap grease should be around 100-120 ⁰C
Anti-wear test at SRV instrument has been performed with ramping of temperature
Heat /Thermal Stability of the Grease Thickener
Frequency - 50 Htz
Amplitude/stroke - 1.0 mm
Temperature - Time
50 ⁰C - 30 minutes
80 ⁰C 30 minutes
100 ⁰C - 30 minutes
120 ⁰C - 30 minutes
150 ⁰C - 30 minutes
180 ⁰C - 30 minutes
Heat /Thermal Stability of the Grease Thickener
Temperature Ramping Anti-wear test at SRV
Temperature Ramping Anti-wear test at SRV
Anti-wear performance of developed calcium-lithium soap grease is very good up to 100 ⁰C and shows similar behavior as shown by simple lithium soap grease.
Heat /Thermal Stability of the Grease Thickener
Calcum Complex Grease
Advanced Calcum –Lithium Soap Grease
Lithium Soap Grease
Advanced calcium-lithium soap grease is substantially non-corrosive (with additive) under prolonged wet conditions
The grease also retains its chemical composition for extended periods of time under operating conditions.
Advanced calcium –lithium soap grease does not suffer from loss of lubricating power due to case hardening
No significant hardening is associated with an improvement in the pumpability of the developed grease
Miscellaneous Characteristics
S.
No. Characteristics
Advanced Ca-Li
Non EP Grease
Advanced Ca-Li
EP Grease
Simple Li Soap
Grease
Simple Li Soap
EP Grease Test Method
1. Appearance Smooth &
Homogenous
Smooth &
Homogenous
Smooth &
Homogenous
Smooth &
Homogenous Visual
2. Worked Penetration, after 60 strokes
(W60) 283 285 288 289 ASTM D 217
3. Worked Penetration after 100000
strokes (change in Units) 316 (+33) 319 (+34) 315 (+27) 318 (+29) ASTM D 217
4. Dropping Point, °C 195 213 199 198 ASTM D 566
5. Wear Scar Dia, mm 0.57 0.46 0.55 0.45 ASTM D 2266
6. Four Ball Weld Load, Kgs. 160 250 160 250 IP 239
7. Roll Stability test 16 Hrs @ room
temp., Change in Penetration +36 Unit +38 Units +35 Units +37 Units
ASTM D 1831
(Modified)
8. Roll Stability test 96 Hrs @ 82 ⁰C,
Change in Penetration +43 Units +47 Units +54 Units +57 Units
ASTM D 1831
(Modified)
9.
Wheal Bearing Leakage Test
ASTM D 1263 (i) Oil Leakage in gms, 0.73 0.86 0.88 0.97
(ii) Evidence of abnormal change in
consistency for structure of the
material
No abnormal
change
No abnormal
change
No abnormal
change
No abnormal
change
10. Hardening on Storage after 3 months,
change in penetration
No significant
hardening
No significant
hardening
No significant
hardening
No significant
hardening ASTM D 1403
Comparison of the Properties of Advanced Calcium-Lithium Soap Greases with Lithium Soap Greases
Advanced calcium-lithium soap grease has been developed by using easily available calcium hydroxide as a main alkaline material with minimal use of lesser abundant lithium hydroxide.
Excellent tribological properties and suitable for use in industrial applications.
Very good mechanical shear stability in both vertical and rotational motion
Very good dropping point results which are comparable with the dropping point of simple lithium soap grease.
Wear characteristics of the developed grease are closer to the simple lithium soap greases.
Conclusions
The case hardening tendency has been overcome in the developed grease
No significant hardening was also observed at elevated temperatures
Equal flexibility to the grease formulators to develop high performance products by using additives as used in lithium soap greases.
Substantial savings in terms of reduced power and fuel consumption due to lesser processing temperature required for manufacturing
Developed grease may be very useful for the grease Industry to reduce the uses of lithium hydroxide in grease making
Conclusions
Acknowledgments
The Authors are sincerely grateful to the Management of M/s. Balmer Lawrie & Co. Ltd. for giving an
opportunity to present the paper at 18th NLGI-IC Conference