A AP PP PL LI IC CA AT TI IO ON N N NO OT TE E - - S ST TA AB BI IL LI IT TY Y O OF F L LU UB BR RI IC CA AN NT TS S F FO OR R C CO OL LD D R RO OL LL LI IN NG G O OI IL L T TE EC CH HN NO OL LO OG GY Y

chivalrousslateΠετρελαϊκά και Εξόρυξη

8 Νοε 2013 (πριν από 3 χρόνια και 5 μήνες)

253 εμφανίσεις

A
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C
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C
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The NEXT STEP
®
in Dispersion Analysis www.lum-gmbh.com

Fast stability ranking and influence of emulsion preparation

1. Introduction

To meet the constant demands for a productivity increase in sheet and tinplate cold mills,
for an improved product quality and lower prodcution costs, several technical solutions
are applied. Higher rolling speeds and reductions, reduction of surface carbon and roll
wear, and consistent mill performance are ways, where lubricants play an important role.

Strip cleanliness, or amount of extraneous materials (e.g. dirt, iron particles,
carbon, etc.) on the steel surface, is a key performance requirement for cold
rolling mills. Strip cleanliness is critical for mills supplying coating lines and the
automotive industry.
First basic performance concern for cold rolling lubricants, the lubricant
usually applied as an emulsion should form an adequate film in the inlet of
the roll bite (film forma). Second, intrinsic neat oil properties should display the desired
properties (e.g., lower friction and/or reduced roll wear).

Multisample analytical centrifugation, based on STEP
®
-technology, is suitable for the
qualitative and quantitative characterization of the emulsion stability, the results are in
agreement with conventional methods, but are obtained much faster, require smaller
sample volumes and allow multisample analysis under identical conditions. Three
lubricants of different composition were analyzed.


2. Monitoring of destabilization process for lubricants



Lubricant 3, prepared with low homogenizer speed, measured 1000 sec at 11 xg, 45°C, every 10
th
profile displayed.

As typical for oil-in-water emulsions the separation of the contineous phase is the
primary process of lubricant destabilization. The boundary water-emulsion is moving
from the cell bottom (position here 114 mm) upwards, the separation process is
characterized by the creaming of oil droplets inside the contineous acqueous phase.

3. Fast stability ranking and influence of emulsion preparation

The higher the slope within the initial range of the Integral transmission curves (see next
page), the higher the clarification speed of the lubricant, the more unstable is the
lubricant. The value for the speed as characteristic analytical parameter is output by
SEPView® software (see 4.).



First

profile
Last profile
Moving boundary Water - Emulsion

A
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N
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O
O
G
G
Y
Y



The NEXT STEP
®
in Dispersion Analysis www.lum-gmbh.com



Fast evaluation of lubricant stability within 1000 sec at 11 xg, 45°C, determined with Integral
transmission mode in the range 101-111 mm. Lubricants prepared with high homogenizer speed.

The order of stability is Lubricant 1 (stable) > Lubricant 2 > Lubricant 3 (unstable).


The influence of the emulsion preparation (homogenizer speed) was evaluated by
comparing low and high homogenizer speeds. The same order of stability was found,
hence the clarification speed values are higher for Lubricant 3 (14.8%T/h) and Lubricant
2 (7.8 %T/h), when prepared with low homogenizer speed. The stable Lubricant 1 has
the same value (1 %T/h) for both homogenizer speeds.

4. Comparison with conventional emulsion stability index

Conventional stability ranking – several hours Fast stability ranking within minutes


0
1
2
3
4
5
6
7
8
9
10
0 0.2 0.4 0.6 0.8 1
Conventional ESI
Clarification speed
[% Transmission / h]
ESI = C
2
(Oil in bottom phase) / C
1
(Oil in top phase)
ESI = 1 for ideal stable emulsion
ESI < 1 for unstable lubricant (technical product).

Clarification speed by LUMiSizer/LUMiFuge within 1000
sec, 11 xg, 45°C, high homogenizer speed.
ESI values provided by customer.

The order of stability obtained by multisample analytical centrifugation, is the
same as from the conventionally determined emulsion stability index ESI.

5. Summary

The analytical photocentrifuges LUMiSizer® and LUMiFuge®, based on STEP®-
technology, determine the lubricant stability in a very short time, require only a small
amount of sample volume and allow the measurement of up to 12 samples under
identical conditions. The temperature range between 4 – 60 °C provides high flexibility
for analysis.

6. References

• Stability Analyser LUMiFuge® 116 for Rapid Evaluation of Emulsion Stability and Demulsifier Selection,
D. Lerche, T. Sobisch, S. Küchler, CME 2002, available as P114-24
• STEP-Technology see www.lum-gmbh.com/pages/technology.htm
• Dispersion Stability and Particle Characterization by Sedimentation Kinetics in a Centrifugal Field, D. Lerche,
J. Dispersion Sci. Technol. 23 (5), 699-709, 2002
• Impact of Novel Cold Rolling Oil Technologies and Materials on Strip Cleanliness, N. L. J. M. Broekhof, C. E.
Mueller, http://www.ethoseastafrica.com/Lubricity_ColdRollingOil.aspx
Lubricant 3
(
unstable
)

Lubricant 2
Lubricant 1
(
stable
)

Waiting period
Several hours
Temperature
Concentration C
1
Concentration C
2
Lubricant 3
(
unstable
)
Lubricant 2
Lubricant 1
(
stable
)