TITLE: A water-based lubricant composition for metal working operations
such as cold rolling and hot rolling of steel.
FIELD OF INVENTION:
This invention relates to a water-based lubricant composition for metal
working operations such as cold rolling and hot rolling of steel.
BACKGROUND OF THE INVENTION:
This invention relates to the use of an aqueous lubricant on metal during size
reduction, as in rolling or other compression. The aqueous lubricant is to
replace the oil based lubricants presently employed. The aqueous lubricant is
preferred because of the large amount of water present in it eliminates the
fire hazard which is present when highly heated metal and oil are brought
into contact with one another. By eliminating the fire hazard, size reduction
operation can be carried out at faster speed. Nano size clay mineral played
an excellent role in inducing proper lubricity during hot rolling for size
reduction.
US Patent 3,676,345- Aqueous lubricant.
The study reveals that when the metals are rolled or compressed they are
lubricated by an aqueous solution of an organic, polar, surface acting

composition having a negative heat of solution which is phosphate or
phosphite of an alcohol ether which is soluble in the water at a lower
temperature but insoluble in the water at the temperature to which the
aqueous solution is heated during compression of the metal. The role of the
aqueous lubricant is to eliminate the fire hazard involved in the use of the
present non-aqueous lubricants.
US Patent-7,435,707B2-Oil-in-water emulsions and a method of producing.
This study discloses that the frequently lubricating oils, greases and coatings
come into contact with the environment through leakage, excretion of old
lubricants during re application, general disposal, mechanical removal, water
wash out, thermal degradation and the like. The release of lubricants, greases
and coatings pose an environmental concern. But the development which
contain majority of water and natural products will lessen environemental
contamination or impact which would result through the use of currently
used mineral or synthetic oil-based lubricants, greases and/or coatings.
US Patent 4,225,447 discloses an emulsifiable concentrate for use in water-
in-oil fire resistant hydraulic fluide comprising a lubricant and an
alkenylsuccinic anhydride or a salt thereof.
WO/2006/134061 discloses a new technology based on the use of
tribotechnic substance (nano-powder compound with lubricating oil) useful
for maintenance of engines worn out mechanisms of any vehicular and
industrial engine.

It is known from US Patent 4,215,002 to prepare water content hydraulic
fluids by adding to water 0.5 to 4 wt% of a blend of C. sub 6-18
alkylphosphonate or an amine adduct thereof and an ethoxylate of an acid or
an alcohol containing from 3-20 ethoxy groups where in the acid or alcohol
is derived from fatty or synthetic sources.
US Patent 4,667,088 claims aqueous metal working lubricant containing
polyoxypropylene polyoxyethylene polyoxyprqfylene block copolymers and
it relates to lubricant compositions (water soluble) suitable for use in metal
working operations.
Reamer US Patent-2,981,686 discloses an aqueous metalworking lubricant
comprising a water soluble hetero-copolymer of mixture of oxyethylene and
oxypropylene groups.
US Patent 6355604 discloses a multifunctional aqueous lubricant,
characterized in that it comprises at least one water soluble salt of
dithiodiglycolic acid and at least one water soluble compound chosen from
the group consisting of phosphoric acid esters or water-soluble salts of
alkylthio acids.
US Patent 4,253,975 discloses an aqueous hydraulic fluid containing a metal
dithiophosphate and a system of solubilizers there for.

US Patent 4,289,636 claims that to provide aqueous lubricating
compositions water and a minor amount of water-soluble amide derived
from primary and secondary alkylamines and succinic, tetrahydrophthalic or
tetrahydrofuran tetracarboxilic acids. The amide is effective as a corrosion or
antirust inhibitor. Aqueous lubricant formulations containing the amide in
combination with other known special purpose additives provide a blend
having good hard water stability characterization.
WO/2003/089551 claims the environmentally compatible additives for
aqueous lubricants to reduce the friction coefficient and wear on the
surfaces.
Friction during flat rolling of metals-J.G.Lcnard, University of Waterloo,
Ontario, Canada.
During commercial flat rolling of steel and aluminum strips control of the
coefficient of friction at the roll/work piece contact is achieved by careful
choice of the lubricant. The choice also affects the productivity and surface
quality of the rolled strips. The coefficient of friction is defined as the
average ratio of the shear stress and the roll pressure. The coefficient drops
with increasing speed and depends on the factors like the lubricant viscosity,
the flow strength of the metal and its strain and strain rate hardening also
need to be considered as they affect the flattening of the asperities and the
attendant growth of the true area of contact. As the speed increases more
lubricant is dragged in to coat the surfaces and the coefficient of friction

decreases. As the pressure increase so does the viscosity, and as the viscosity
grows, frictional resistance falls.
The coefficient of friction during dry rolling of steel strips is in the range of
0.1 to 0.3. when the neat oils are used at higher speeds, it drops to 0.06 to
0.15. when cold rolling soft aluminum with various lubricant, coefficient of
friction varies from a low of 0.05 to as high as 0.4. In general, under similar
circumstances, the softer the metal, the higher the coefficient of friction. Hot
rolling soft aluminum with emulsions indicated frictional coefficients in
between 0.05 and 0.25.
Journals of Materials processing Technology 97(2000) 61-68.
In the hot rolling experiments using low carbon steel strips, the use of
lubricants or the oil-in water emulsions resulted in significant reductions of
the mill loads and in attendant improvements of the rolled surfaces but the
selection of the most appropriate mix was found to be problematic, as the
small changes of the concentration of the oil caused major changes in the
lubricating conditions at the roll/sample interface.
Tribology Letter, Vol. 25, No. 3, March 2007
The SDS (sodium dodecyl sulfate)-functionalized MWCNTs, as an additive
in water based lubricants, possess a great potential to improve tribological
performances of lubricant, such as the load carrying capacity, extreme
pressure, and the anti-wear and friction reduction properties. It can reduce

the friction and wear of steel-sliding system by chemical adsorption on steel
and filling up the valleys of the mating surfaces.
Wear 249 (2001) 50-55
The effect of increasing viscosity of water (lubricant base) by addition of
polyacrylamide is tested, the wear prevention effect is small. The sufficient
wear prevention effect is obtained having added up to 10 wt% solid lubricant
(methalamine cyanuric acid adduct) to the water. The wear rate of Ti base
coating rubbing against copper is higher than that of the case against steel.
However, the addition of MCA with 10 wt% to the water shows the
equivalent wear prevention effect to white spindle oil.
Journals of Materials processing Technology 99 (2000) 86-93
The adhesion hypothesis explains the origins of resistance to motion in terms
of adhesive bonds formed between the two contacting surfaces that are in
interatomic distance apart. The bonds must be separated if relative motion is
to occur. As the load increases so does the number of contacting asperities.
Introducing the lubricant in the contact surface brings more parameters in
the picture the viscosity, the oil film thickness and the asperity height, the
ratio of the latter two indicating the nature of the lubricating regime.
The events at the roll-work piece interface are responsible for the quality of
the resulting surface of the rolled product. In order to control surface quality,

it is the friction forces, or more specifically the coefficient of friction that is
to be controlled.
The results showed that the coefficient of friction decreased with increasing
speed and reduction.
Influence of a Nonionic surfactant on the water retention properties of
unsaturated oils -A. Karagunduz, K.D. Pennell and Michael H.Young.
When the surfactants are used to improve the effectiveness of the chemicals,
due their amphiphilic nature, surfactants tend to accumulate at gas-liquid and
solid-liquid interfaces, and thus have potential to influence their behaviour.
In the presence of surfactant, soil water contents decreased incrementally as
the surfactant concentration was increased from 0 g/L up to the critical
micelle concentration (CMC) of Triton X-100 (0.15 g/L). Over the same
surfactant concentration range, the surface tension of the water decreased
and the solid-liquid contact angle decreased from 40 degree to 10 degree.
The observed changes in contact angle with surfactant concentration were
attributed to the formation of an adsorbed surfactant monolayer on the quartz
surface; the hydrophobic surfactant moiety oriented outward for untreated
(hydrophilic) quartz and the hydrophilic surfactant moiety oriented outward
for methylated (hydrophobic) quartz. When the concentration of Triton X-
100 was further increased, it has been proposed that interactions between the
hydrophobic moieties of surfactant monomers led to the formation of an
adsorbed surfactant bilayer thereby reducing the contact angle with water.

Tribology Letters, Vol.26, No. 2, May 2007
Industrial lubricants play an important role minimizing surface asperity
contact of machine elements. This task is enhanced by addition of friction
and wear-reducing agents composed by polar molecules added to the
lubricant. As the load arid metallic contact increase, the protecting additive
film formed on surface should be more resistant and that leads to a higher
additive chemical reaction commonly through the use of sulpher-
phosphorus-based EP additives, which form Organometallic salts on the
loaded surfaces that serve as sacrificial films to protect against aggressive
wear. The addition of a very small concentration (0.01%) of the ammonium
thiomolybdate solution to distrilled water produced initially a friction
coefficient of approximately 0.47 in the first 30 min of the friction test in the
Pin-on Disk trobometer. After that the friction coefficient drops down to a
value to 0,1 and keeps fairly constant through the rest of the test. As the
concentration increases (0.025%-0.3%) the friction coefficient drops down
to 0.1 which is directly related to the film forming ability of the ammonium
thiomolybdate salt.
It can be seen from the SEM micrographs that the use of additive contributes
with a reduction of wear attributed to the protective surface layer formation,
which influences the reduction of mechanical area of contact between the
two surfaces.

Tribology Transactions, Vol. 42 (1999), 3,479-486
Water containing fluids are employed in a number of roles where they need
to exhibit effective lubricating properties, such as in hydraulics and metal
working including potential advantages like low cost, fire resistance,
biodegradability and relative ease of disposal. One of the most fruitful
investigative approaches has been to measure the film-forming properties of
O/W emulsions in rolling and sliding contacts using techniques such as X-
ray transmittance and optical interferrometry.
The study reveals that at zero or low surfactant concentrations, contact angle
is low because the polar surfaces are not fully covered by a monolayer of
surfactant and are thus hydrophilic. As the concentrations increases, a
surface monolayer forms, rendering the surfaces more hydrophobic. At high
concentrations, a bilayer forms, to produce a hydrophilic surface once more.
All of these solutions had pH 6.5, which is below the point of zero charge
for steel of 6.8 and because of this the surfactant should give physical
adsorption.
It can be seen that at low speeds, the surfactant solution forms a thin but
measurable film of about 2 to 3 nm thickness, largely independent of speed.
However above 0.5 m/s, the film thickness rises with speed in a
conventional elastohydrodynamic fashion.
Wear 28(1974) 197-206
The role if the lubricants are to keep two sliding surfaces separated. In the
case of water lubrication of black rubber at low speeds and low pressures the

lubricating ability of water is shown to be enhanced by addition of
electrolytes to the water. The mechanisms reveal that the negative ions from
the electrolytic solution collect on each sliding surface, repel each other and
prevent the close approach of two sliding surfaces.
The effect of roll roughness and lubricant viscosity on the loads on the mill
during cold rolling of still strips-Kevin Dick and J.G. Lcnard, Department of
Mechanical Engineering, University of Waterloo, Waterloo, Canada.
Effective lubrication is essential to control the tribological interactions
between the work rolls and the work piece in the cold rolling process. The
interactions include four phenomena, the requirements of which need to be
satisfied to create well-lubricated contacts. First, sufficient amounts of the
emulsion must be made available at the entry to the roll bite. The emulsion
must then be entrained, that is, the oil droplets must be captured and drawn
into the contact zone between the work and the rolled strip. After successful
entry the emulsion must be spread through the contact uniformly well so all
the surfaces are covered evenly.
The dependence of the roll force per unit width on the viscosity of the oils in
the emulsions is observed. It is observed that increasing viscosity should
lead to lower loads, at least in the boundary and in the mixed lubrication
regime. Raising the work roll roughness appears to have increased the
efficiency of the tribological conditions, evident in the decrease of the loads
on the rolling mill with increasing rolling velocities, the exception being the
combination of the highest roll roughness and highest viscosity lubricant.

Use of lubricants and emulsions during hot rolling of carbon steel, A.
Shirizly and J.G Lenard, Dcpt. of Mechanical Engineering, University of
Waterloo, Ontario, N2I. 3G1, Canada.
The appropriate lubricant or oil-in-water emulsion during hot rolling can
reduce the loads on the mill and improve the surface quality. The effects of
different lubricants, scale thickness and lubricant delivery location on the
roll forces, roll torques along with the quality of the rolled surfaces are
examined. The results indicate that choosing the proper emulsion is not easy
as even a minor change in the emulsion concentration causes a significant
change of the mill loads.
Journal of Applied Electrochemistry 23(1993) 456-462.
The potential at a metal-aqueous lubricant interface is important because it
determines a number of surface properties, any one of which may be
expected to influence friction and wear in a rubbing system. Aqueous
lubricants find potential applications as metal working and hydraulic fluids,
and often contain a fatty acid to impart some lubricity and corrosion
resistance. It has been observed that the static coefficient of friction between
iron and mild steel in such a model lubricant could be halved by changing
the potential from -400 to +300 mv vs S.H.E. This was attributed to
electrostatic interactions between the electrode and negatively charged
octanoate species.

Annals of Biomedical Engineering, Vol. 23, pp.112-115, 1995
A standard (four ball) test has been used to study the anti-wear capabilities
of ovine synivial fluid, the phospholipids extracted from it, a synthetic
synovial fluid, and the phospholipids removed from the articular surface by
a lipid solvent. Despite using speeds and loads that were "extreme" by
engineering criteria, the indices of wear were comparable to those of the best
industrial lubricants. The recent studies have shown that the phospholipids in
synovial fluid is highly surface active, implying an ability to adsorb to tissue
surfaces. When extracted, it is a superb boundary lubricant, giving
coefficients of kinetic friction as low as 0.002-0.005 under high load, i.e.,
within the physiological range.
J.Applied Metalworking Vol.3, No. 2, January 1984 173
It has long been recognized that friction and lubrication are important
aspects of metal working processes, influencing not only the mechanics of
the individual operation, but also product quality and economics of the
overall operation.
Wear, vol.222, Issue 2 Nov. 1998 p 120-128
Diamond-like carbon (DLC) films can be divided into two major categories
according to their hydrogen content. These categories have similarities in
tribological performance, but the films also behave in a different manner in
different tribological conditions. The a-C and a-C:H films had a low friction
coefficient in dry sliding conditions (0.15 to 0.22), which was further

decreased by 10-40% under boundary lubrication. The a-C:II(Ti) films
exhibited good self-lubricating properties (0.10) in dry sliding conditions
and the a-C films had the lowest friction coefficient in water-(0.03) and oil-
lubricated (0.08) conditions. The hydrogen-free hard carbon films showed
excellent wear resistance in dry, water-and oil-lubricated conditions, but
hydrogenated a-C:H films suffered from severe wear in aqueous conditions.
The performance of a-C:H films could be improved by titanium alloying.
The performance of a-C:H films could be improved by titanium alloying. In
dry sliding conditions, the tribolayer formation of DLC films influenced the
friction and wear performance, but in oil-lubricated conditions boundary
lubrication layers were formed, which governed the tribological mechanisms
in the contact.
US Patent 4,667,088 Kane Kramer
This study claims that in order to perform satisfactorily on an industrial
scale, an aqueous lubricant fluid must meet several important requirements
like acceptable load bearing and friction modifying properties, corrosion
inhibiting properties and chemical stability under conditions of operation.
Another requirement is the avoidance of deposits on the rolls and workpiece
following the rolling operation.
Such deposits results from drying of the fluid, and they are difficult to
remove. Other important requirements include avoidance of excessive foam
formation.

US Patent 6355604
The study discloses that under high loads, AW additives make it possible to
greatly reduce the wear of the components in contact; EP additives can
generate a degree of wear but they prevent the phenomena of welding and
adhesion. Whole oils have excellent lubricant properties but, when
throughputs are high, the removal of heat requires the use of emulsions. For
this reason, there is increasing use of aqueous fluids, which are either
synthetic fluids (aqueous solutions based on water soluble additives) or
semisynthetic fluids (oil-in-water microemulsions comprising a large
amount of emulsifiers). However, while aqueous fluids arc very efficient in
removing heat and have an improved resistance to bacterial proliferation,
their use is often restricted to metal working operations where the frictional
and wear conditions are not excessively severe.
US Patent 4419251
According to the present invention, an emulsifier/dispersant system is
combined with an antiwear/antirust inhibitor system, and the combined
systems, when added to an appropriate base oil, provide an improved soluble
oil concentrate capable of forming stable, translucent oil-in water emulsions
with water in which the oil is present as the continuous phase. It has been
found that, when both the system are combined with an appropriate base oil
and mixed with a sufficient quantity of water, the resulting oil-in-water
emulsions are excellent lubricants characterized by improved wear

preventing characteristics and antirust performance. When utilized as high
water-content hydraulic fluids, significant improvement in bearing fatigue
life is obtained which thus makes it possible to prolong or extend the pump
life of hudraulic pumps conventionally used in industrial applications.
Lubricant considerations in wet steel wire drawing by Katherine Helmetag.
Water based lubricants are desirable when low or no residual film is desired
and cooling requirements are very high. Very fine wires often must be drawn
in water based systems to avoid higher lubricant film thicknesses and
occlusion of the die. If pumping capacity is limited and can not be upgraded
to handle higher viscosities, water-based lubricants can be used.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a water-based lubricant composition
for metal working operations.
Another object of this invention is to propose a lubricant composition that
reduces the cost of rolling of steel.
Further object of this invention is to propose a composition that improves
the surface and texture of steel.

Still another object of this invention is to propose a lubricant composition
that reduces the oxide scales during rolling of steel.
BRIEF DESCRIPTION OF THE INVENTION:
According to this invention relates to a water-based lubricant composition
for metal working operations comprising: clay material of 1µ particle size;
deflocculating agent, additives and water to make a dispersed solution.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig. 1: shows dispersed clay nano particles after 40 days of exposure;
Fig. 2: shows three dimensional structure of clay minerals with the Si-
tetrahedra and Al-octahedra;
Fig. 3: Time vs Conductivity plot for different surfactant used with clay;
Fig. 4: Settling of Clay nano fluid with time;
Fig. 5: Time vs Electrical conductivity plot for the aqueous lubricant made
with clay nano particles;
Fig. 6: Coefficient of friction of aqueous lubricant with clay nano particles.

DETAILED DESCRIPTION OF THE PRESENT INVENTION:
The present invention relates to lubricant compositions and more particularly
to water-based lubricant compositions suitable for use in metalworking
operations such as the cold rolling and hot rolling of steel and the invention
relates to such metalworking operations.
It is an object of the invention to provide a stable polymeric material that can
be added simply, quickly and cost effectively to an aqueous medium to
produce an environmentally friendly aqueous lubricant.
It is a further object of the invention to coat metal oxide surfaces and other
charged surfaces with a lubricating composition to reduce the friction
coefficient and wear on the surfaces.
Methodology:
1. Extensive literature survey.
2. Procurement of clay nano particles and milled in house for required
size.
3. Characterization of nano particles for particle size, thermal stability,
structure etc.
4. Formulation of lubricant with nano particles.
5. Characterization of lubricant
6. Recommendation

Experimentation:
• Procured clay mineral was of In particle size which is grinded in
house in different grinding mill and finally in the Planetary ball mill to
make the nano particle. These particles along with the deflocculant
agent and additives were mixed with plant DM water to make
dispersed solution and stirred with mechanical stirrer to get the
homogeneous solution for more than an hour.
• Measured the particle size and zeta potential in Dynamic Light
Scattering is also known as Photon Correlation Spectroscopy. This
technique is one of the most popular methods used to determine the
size of particles and zeta potential of the dispersed solution.
• The pH of the solutions measured were nearly 6 and to make it
alkaline 5.0% NaOH solution added and the pH is adjusted between
10.11.
• Conductivity and Viscosity of the dispersed solution measure with
Conductivity meter and Viscometer.
• All the solutions were exposed in One litre measuring cylinder to
study the stability of the dispersed particle as shown in figure 1 and
with the other set of experimentation electrical conductivity of the
solution measured at different time interval.
• Thermal stability of the nano fluid was tested by heating the steel
samples at 900ºC in the Muffle Furnace and pour the fluid on it
followed by the EDX analysis of steel samples to see the surface
condition of the steel.

Subsequent to the experimentations few formulations were considered for
further studies.
Kaolinite is an aluminium silicate mineral whose chemical formula is
Al2SiO5 (OH)4 has been used as the solid for this new formulation. Chemical
analysis of the material is shown in Table 1.
Table 1: Chemical analysis of clay minerals:

Kaoline (Hydrated aluminium silicate) is a. natural, fine grain, well
crystallized clay mineral composed of book like or layered structure.
Each "page" of the book like structure has a repeating alumina-silica layer
configuration as shown in figure 2. Each layer consists of one tetrahedral
silica sheet and one alumina octahedral sheet tied together with shared
oxygen. This layer structure provides easy dispersibility and good lubricity
in water.

Effect of surfactant on lubricant formulation: Particle charge can be
controlled by using surface active agents which directly adsorb to the surface
of the colloid and change its characteristics. We have considered two
surfactants-
1) Sodium hexa meta phosphate (SHMP)
2) Darvan
However, the electrical conductivity of the lubricant with Darvan (Surfactant
2) is less in comparison to the sodium hexa mcta phosphate (Surfactant 1) as
shown in figure 3. In case of the lubricant, where Clay along with sodium
hexametaphosphate is used, shows a very high range of electrical
conductivity, which is desirable for long term stability of the dispersed
solution.
Prior art confirmed that the condensed phosphates are adsorbed to form
strong complexes with the positive sites on the edges of the nano particles.
This adsorption causes a change in the surface charge density, whereby the
electro kinetic potential of the clay and serpentine nano particles become
even more negative and so the electrical conductivity is very high. At the
lowest NaHMP concentration, the adsorption process is the most relevant.
So we have considered 0.1% concentration for sodium hexameta phosphate.
Additives are commonly used to improve the properties of solid-liquid
dispersions. In many cases the additives have two or more different
functions in the dispersion process, so that the words additives and
dispersants tend to be employed interchangeably, especially in industry. We
therefore use only the term "dispersants" in our text and concentrate on the
stabilization of particles. For the additive, Triton-X-100 (an octylphenol

ethoxylate) is used without any dilution or purification. It is a hydrophilic
compound and can be stored safely for long time at room temperature. It
affects the interfacial properties e.g surface tension and contact angle of the
suspension.
Surface tension of the liquid decreases with the addition of Triton-X-100
with the concentration from 0 to 0.15g/L. Above the concentration of
0.15g/L, the surface tension remains essentially constant. We have
considered 0.15% for our purpose.
The particle size distribution for all the formulations were measured by
Direct Light Scattering. The average particle size is given below:
Table 2: Experimental Results:

If the size of the particle is large (.300 nm), then on average, equal number
of molecules strike them on all sides at each instant. Hence the particles are
bombarded more or less uniformly. In this case, the motion of the particles
will be governed by both gravity and the viscosity of the liquid. But in case
of smaller particles (>300nm), according to the law of probability, the
number of particles striking on all sides may not be equal. The inequality in

the number of molecular impacts on different sides gives rise to a force
causing the suspended particles to move in zigzag paths and the motion is
governed by the viscosity of liquid(11,l2).
It is known that for the bigger particle size, gravity and viscosity both act on
the dispersed solution and hence the settling time is less than the smaller
one, where only viscosity of the solution acts. In this case we have got the
settling time more than 300 hours as shown in figure 4.
Zeta Potential: The zeta potential of suspension is measured in DLS system
as shown in Table 2. Zeta potential is the potential difference between the
dispersion medium and the stationary layer of fluid attached to the dispersed
particle. The magnitude of the measured zeta potential can be used to predict
the long-term stability of the product. If the particles in a suspension have a
large negative or positive zeta potential then they will tend to repel each
other and there is dispersion stability. However, if the particles have low
zeta potential values, i.e. close to zero, then there is nothing to prevent the
particle's aggregation. Tablc 3 indicates that higher the zeta potential value
more will be the dispersed state of nano fluids. It is seen from Table 2, that
the new formulation is having the zeta potential (52.4 mV) in the range of
good stability as mentioned in Table-3.

Table 3: Stability at different Zeta Potential

Electrical Conductivity: For the present formulations continuous increasing
electrical conductivity has been observed, which indicates the dispersed
condition of nano particles in solution for more than 300 hours. Initially the
reaction is first order and the rate is slow, that's why the amount of released
ions were less and following the chemical kinetics the reaction rates
increases with time increasing the ion concentration in the nanofiuids
followed by increase in electrical conductivity.
This is because increase of negative charge on the micelle of clay is being
adsorbed as an anion; it gives rise to complex with the flocculant cations and
substitutes the cations in the double layer of the nano particles with Na+ ions.
In this case, we are getting more than 300 hours under increasing electrical
conductivity which again shows the good stable condition of the fluid for a
long time, which is needed for application process.

Co-efficient of Friction: For characterizing the lubricant, co-efficient of
friction is measured by Pin on Disc apparatus according to ASTM-G 40. It
can be seen from Table 4 that the dynamic coefficients of friction of the new
formulation made is 0.010 µ The static coefficient of friction, in case of
aqueous lubricant, is very high, which is the maximum force that must be
over come to initiate macroscopic motion between two bodies.
Table 4: Coefficient of friction at constant load and speed

This static coefficient of friction can be neglected while calculating the
coefficient of friction as the time period covered by static friction is very less
which is dominated by the dynamic coefficient of friction.
Frictional force generated for static coefficient of friction is 16.01 with in 8
seconds and the average of frictional force for dynamic coefficient of
friction is 16.82 for rest 892 seconds of experiments. The coefficient of
friction (Static + Dynamic) is thus 0.32. Since neglecting the static
coefficient of friction the frictional force for dynamic coefficient of friction
is 0.81 and the coefficient of friction is 0.01.

This is also reported by U.J. Moller etal that when a body is at rest the
frictional resistance is greater than when it is moving. The frictional
coefficient of static friction is greater than the frictional coefficient
experienced while in motion i.e. dynamic friction. So the static friction may
not be considered for rolling surfaces.
Desmond F. Moore also reported that introduction of a fluid film between
two moving and rough surfaces provides a lubricating effect, which
substantially reduces the coefficient of friction between them. Such films are
usually sufficiently thin that viscous forces are large in comparison with
inertia forces, so that the latter may be neglected.
If we consider the static friction then also our formulation meets the standard
value for a good rolling lubricant. As discussed by Shirizly ct.al that when
the hot mill roll is cooled only by water, the coefficient of friction between
the roll and the strip is usually in a range of 0.25-0.50, whilst when a typical
hot rolling lubricant is applied the coefficient of friction decreases to the
range of 0.22-0.28.
Moreover, the aqueous lubricant is to replace the oil based lubricant
presently employed, and because of the large amount of water present, the
aqueous lubricant is preferred as it eliminates the fire hazard. By eliminating
the fire hazard, size reduction operations can be carried out at faster speeds.

The conventional oil based lubricants can be replenished with the aqueous
lubricant as regards minimizing fire hazards, rolling force and wear of the
work roll.

WE CLAIM:
1. A water-based lubricant composition for metal working operations
comprising:
clay material of lµ particle size;
deflocculating agent, additives and water to make a dispersed solution.
2. The composition as claimed in claim 1, wherein the same clay
material is kaoline(hydrated aluminium silicate).
3. The composition as claimed in claim 1, wherein the additive used is
Trilon-X-100 ie an octylphenol ethoxylate.
4. The composition as claimed in claim 1, wherein the concentration of
sodium hexametaphosphate is 0.1% and the concentration of Triton-X
is 0.15%.
5. A process for the preparation of water based lubricant composition
comprising:
grinding the clay material to connect into nano particle,
mixing the nano particles, deflocculant, additives and plant DM water
to make dispersed solution,
subjecting the dispersed solution to the step of stirring,
maintaining the pH of the solution to be alkaline.

7. The process as claimed in claim 1, wherein the pH of the said dispersed
solution is maintained between 10 & 11 by adding 5.0% of NaOH solution