Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND COMPOSITION FOR CREATION
OF CONVERSION SURFACE
Related Applications
[0001] This patent application claims priority to U.S. Provisional Patent
Application
Serial No. 60/443,995 filed on January 31, 2003, and U.S. Provisional Patent
Application Serial No. 60/480,672 filed on June 23, 2003, which are
incorporated by
reference in their entirety.
Technical Field of the Inyention
[0002] The present invention relates generally to the field of metal
conversion
surfaces, in particular, the creation of a phosphate-metal chemisorbed layer
for iron
and aluminum parts as well as to other metal substrates capable of forming a
conversion surface.
Back~TOUnd of the Inyention
[0003] The creation of an iron-phosphate conversion surface is known to create
a
I S surface that exhibits high dry lubricity, among other benefits. Creation
of the iron-
phosphate conversion surface on an iron part or piece of equipment
traditionally is
accomplished through a phosphatizing bath process. This bath also typically
includes
the element of zinc in order to optimize the process of deposition of the
phosphate
onto the surface of the item of interest. While the use of a bath process is
practical for
coating particular types of parts or pieces, i.e. large items where the
surface is
otherwise exposed to the elements, the bath process requires that the parts to
be
treated be disassembled in order to receive the coating.
[0004) U.S. Patent No. 5,540,788 issued to DeFalco teaches a process for
creating an
iron-phosphorus surface through the formation of a conversion surface on iron
substrates by delivering the phosphatizing compound in a lubricating fluid.
This
method includes the formation of a conversion surface to create the
iron/phosphate
surface onto completed machinery engines. The composition can be introduced
through the lubricating oil into a running engine. The composition disclosed
includes
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a source of phosphoric acid, an alkali metal hydroxide and a source of
reactive NH2
groups. Notably, the source of the reactive NH2 groups produces the reactive
NH2
groups as a result of the highly exothermic reaction that is described.
Testing
indicates that the same compounds that act as a source of reactive NH2 groups
in the
above reaction do not produce reactive NH2 groups under different physical
conditions since they follow a different reaction path. The reactive NH2
groups
produced in the DeFalco patent are best described as phosphamids. This
specific
chemistry results from the highly exothermic reaction described in the DeFalco
patent. It is also noted that the physical conditions of having a high pH
results in the
production of free ammoiua. When the phosphamids circulate with the
lubrication
medium in the engine, a phosphate-iron conversion surface specific to this
composition was created.
[0005] Various forms of phosphate-containing substances have been used to
create
the desired conversion surface on iron as well as non-ferrous metals, each
resulting in
a specific surface with unique characteristics. Most efforts have focused on
the
deposition of the phosphorus-containing coating on iron substrates and include
the use
of zinc. It would be advantageous to create a cost-effective composition that,
when
contacted with a metal substrate or part, would create a phosphate-metal
conversion
surface. It would be advantageous if this composition were useful for the
conversion
of iron surface. It would be advantageous if this composition were useful for
the
conversion of non-ferrous surfaces capable of forming a conversion surface. It
would
be particularly advantageous if this composition were useful for the
conversion of
aluminum surfaces, including aluminum alloys. It would be advantageous to
create a
conversion surface that is resistant to corrosion and that has a high
coefficient of
lubricity even when dry. It would be advantageous to include a method of
delivering
this composition to the parts to be converted without disassembly of the
pieces to be
coated.
[0006] In addition to ferrous components, efforts to create improved non-
ferrous
components, in particular aluminum components, are numerous. Such efforts to
create improved aluminum components, such as 2-cycle engines commonly found in
snow mobiles, lawn mowers, weed-trimmers, mopeds, outboard motors, ATVs, dirt
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bikes, chain saws and the like, have typically focused on the composition of
the
aluminum alloy as opposed to the creation of a conversion surface. For
example, a
distinct silicon-alununum alloy composition is disclosed in U.S. Patent No.
6,419,769.
Similarly, rare earth elements have been added to aluminum alloys for
strength, such
as the composition discussed in U.S. 5,284,532.
[0007] Two-cycle engines, because of the typical applications, are often used
sporadically. For example, snow mobiles are shut down during off season. This
leads to additional difficulties related to condensation and resulting
corrosion.
Corrosion inhibitors are often added to avoid this type of difficulty.
[0008] Aluminum alloy engines include a lubricating oil for lubricity of the
engine.
The lubricating oil is selected for high film strength to minimize wear. This
prevents
metal-to-metal contact and provides protection against piston scuffing. When
temperatures of operation are high, two-cycle motors lose power and torque.
The
aluminum pistons expand from heat and cause an increase in friction. Various
proprietary lubricating oils have been introduced into the market place to
improve
performance at high operating temperatures. The ASTM D-4863 two-cycle motor
lubricity test measures torque output at 350 °C (662 °F) and is
a benchmark for
performance.
[0009] The field of lubricant technology is characterized by a never-ending
search for
improved lubricants and additives. Additives, essential for satisfactory
performance of
lubricants for all manner of modern engines, serve many roles, including those
of
providing detergency, antioxidant properties, and suspension of contaminants.
In an
effort to improve lubricity, various synthetic oils and various additives have
been
investigated. Numerous combinations of synthetic esters have been measured for
increased lubricity. Further additives have also been proposed to reduce wear.
One
example is U.S. Patent 6,242,394 disclosing a two-stroke cycle lubricant. U.S.
Patent
No. 6,172,013 discloses lubricating oil compositions having enhanced friction
coefficient and wear properties through the use of additives of molybdenum and
diesters of aliphatic or aromatic dicarboxylic acids. Adducts of glyoxylic
acids and
phenols are lcnown. For example, U.S. Pat. No. 5,281,346, Adams, discloses a
two-
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cycle engine lubricant comprising. alkali or alkaline earth metal salts of
carboxylic
aromatic acids.
[0010] Various forms of phosphate-containing substances have been investigated
to
create the desired lubricant or surface, each phosphate-containing substance
resulting
S in a specific surface composition with unique characteristics. Most efforts
have
focused on the deposition of the phosphorus-containing coating on iron
substrates and
include the use of zinc. It would be advantageous to create a cost-effective
composition that would create a phosphate-metal conversion surface on a non-
ferrous
surface. It would be advantageous to create a phosphate-metal conversion
surface on
an aluminum alloy engine. It would be advantageous if tlus conversion surface
could
be created on the engine or part while in operation. It would be advantageous
to
create a conversion surface on the aluminum alloy engine that would improve.
dry
lubricity, efficiency, strength and/or emission control. It would be
advantageous to
include a method of delivering this composition to the parts to be converted
without
disassembly of the pieces to be coated. It would be advantageous to create a
composition and method that does not require zinc.
Summary of the Invention
[0011] The present invention includes compositions and methods useful for the
creation of phosphorus-containing conversion surfaces on metal components. The
composition of the invention is useful to create a thin layer on metal
surfaces.
[0012] The invention includes a phosphorus-containing solution containing
[Y]HZP04, [Y]2HP04, and water or other solvent as components of an
intermediate
solution, where Y is a cation. [Y]HZP04, [Y]ZHP04 as well as other salts
discussed
herein are also called salt components. The cationic portion of the salt
components
can be any cation, with potassium being a preferred cation. In this case, the
preferred
components would be KHaP04, K2HP0ø, and water. The intermediate solution is
mixed with a carrier fluid. The carrier fluid is any fluid that is operable to
maintain
the salts in at least a partially dispersed state within the carrier fluid.
Water or other
solvents used in the intermediate solution are then largely driven off such
that the salts
remain in at least a partially dispersed and/or partially dissolved state in
the carrier
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fluid to create the phosphorus-containing solution. The resulting phosphorus-
containing solution is operable to create a phosphate-metal layer on a metal
substrate
when the phosphorus-containing solution is placed in contact with the metal
substrate.
[0013] A group of preferred cations for the salts are the alkali metals or
Group lA
elements. While orthophosphoric acids have been described, the invention also
includes pyrophosphoric acids, which are the condensed analogs and therefore
derivatives of and equivalent to orthophosphoric acid. It is noted that,
through the
process to condense the orthophosphoric acid to pyrophosphoric acids, the P043-
become P2072- or other condensed phosphates. Therefore, [Y]H2PO4, [Y]ZHPO4 and
[NH4]ZHP04 are precursors to pyrophosphoric acids. The use of the
pyrophosphoric
form is therefore encompassed within the definition of the orthophosphate
form,
which can be expressed as [Y]H2P04, [Y]2HPO4 and [NH4]2HPO4 and in similar
form.
[0014] Advantageously, the phosphorus-containing solution is essentially free
of zinc.
While some amount of zinc can exist in the solution, for example, when it is
present
in raw materials, zinc is not added or present in a quantity beneficial for
plating.
Thus, the phosphorus-containing solution is considered essentially free of
zinc.
Beneficially, the solution is also substantially free of halogens.
[0015] Another preferred embodiment of the phosphorus-containing solution
includes
the addition of [NRq]2HPO4 to the intermediate solution of [Y]HaP04, [Y]2HP04,
and
water or other solvent. R in [NRq] can be an alkyl group, hydrogen, or
combinations
of both. Thus, this encompasses ammonium as well as amine phosphates. When the
solution is prepared using ammonium compounds or amine compounds, the nitrogen
in the solution is essentially all in the form of ammonium or amine ions.
There is at
most a negligible amount of free ammonia such that the solution is
substantially
ammonia free.
[0016] Yet another embodiment includes the addition of [X]CaH30a where CaH302-
ion is an acetate group such that the intermediate solution contains at least
[Y]H2P04,
[Y]ZHP04, [X]C2H3O2 and water or other solvent. Preferred embodiments include
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X as NH4 or K or other Group IA elements. [NR4]2HPO4 , where R hydrogen, alkyl
groups or a combination of both, can also be added to this mixture. This
intermediate
solution is combined with the carrier fluid and the water or other solvent is
largely
removed to create the phosphorus-containing solution. Preferably the solvent,
such as
alcohols, have sufficient volatility to allow for removal from the
intermediate solution
mixed with Garner fluid through the addition of heat, although this is not a
required
characteristic. When the phosphorus-containing solution is prepared using
ammonium
compounds, ammonium compounds being defined as those compounds containing
NHx groups, the nitrogen in the phosphorus-containing solution is essentially
all in
the form of ammonium ions. Amine ions are also encompassed herein. There is at
most a negligible amount of free ammonia. Furthermore, the mixture is
advantageously created without the production of excessive amounts of heat,
i.e., no
highly exothermic reaction is performed.
[0017] In a preferred embodiment, the phosphorous-containing solution has a pH
between about 6.0 and 8Ø
[0018] The phosphorus-containing solution of the invention can be used in
various
types of environments, such as aqueous or hydrophilic environments. In the
case of a
hydrophilic enviromnent, it is advantageous to include a carrier fluid and a
dispersant
to promote dispersion in the carrier fluid. The carrier fluid can be a
lubricating fluid
that is to be placed in contact with the metal parts or metal substrate or, in
a preferred
embodiment, the carrier fluid is a separate hydrophilic fluid that is highly
miscible
with lubricating fluid, such as a motor oil. One characteristic of the carrier
fluid is
that the salts of the phosphorus-containing solution axe at least partially
soluble in the
carrier fluid.
[0019] In certain circumstances, the carrier fluid is a quantity of a target
fluid, such as
the lubricating fluid. The target fluid is the fluid that is identified as the
majority fluid
that is intended to bring the phosphorus-containing solution into contact with
the
metal to be treated. The phosphorus-containing solution can be dispersed
through the
target fluid through the use of physical mixing, such as a high speed shear
mixer, or
other means. In such instances, the target fluid acts as the carrier fluid.
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[0020] The current invention includes a process for creating a conversion
surface on a
metal part or metal substrate in a system using the phosphorus-containing
solution.
The system can be as simple as a metal part operable to be brought into
contact with
the phosphorus-containing solution or it can be a complex series of parts,
such as in
an engine, where the phosphorus-containing solution is brought into contact
with at
least part of the system. Where the part is at least partially in contact with
the
phosphorus-containing solution or target fluid containing the phosphorus-
containing
solution, the phosphate-metal layer surface is created resulting in a
converted metal
substrate have the phosphate-metal layer or conversion surface on surfaces of
the
metal substrate contacted by the phosphorus-containing solution. The amount of
phosphorus-containing solution used is the amount effective to create the
conversion
surface. Preferred embodiments of the target fluid that is contacting the part
include a
lubricating fluid or a phosphating bath. The conversion surface that is
created as a
result of this process has characteristics and composition specific to the
metal
contained in the metal part and to the phosphorus-containing solution. When
the
metal part includes iron, a phosphate-iron surface is created on the surface
of the iron.
When the metal part includes aluminum, an aluminum-phosphate surface is
created.
When the metal contains nickel, a phosphate-nickel surface is created. Similar
results
are observed with chromium and molybdenum.
[0021] In addition to being useful for ferrous metal components, the present
invention
includes compositions and methods useful for the creation of phosphorus-
containing
conversion surfaces on non-ferrous components, such as aluminum two cycle
engines.
The composition of the invention is useful to create a thin layer on metal
surfaces.
[0022] One preferred embodiment includes a lubricating composition or
lubricant that
has a substantial amount of an oil having a lubricating viscosity. An amount
of the
phosphorus-containing solution is added to the oil thereby creating a
lubricating
composition operable to create a conversion surface upon a metal component
upon
being brought into contact with the metal component.
[0023] Another embodiment of the invention includes a method of forming a non-
ferrous metal-phosphate conversion surface on non-ferrous metal components by
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contacting the non-ferrous metal component in a contact region with an active
phosphorus solution to form the non-ferrous metal-phosphate conversion surface
on
the contact region. The contact region can be limited to a portion of the
surface of the
metal component or can encompass the entire metal component. The active
phosphorus solution is prepared by mixing a phosphorus-containing acid with an
allcali metal hydroxide salt and an ammonium/amine compound under conditions
designed to create a highly exothermic reaction thereby producing the active
phosphorus-solution. The ammonium/amine compound is an active compound that
contains either ammonium or amine and is operable to interact in the
exothermic
reaction. Ammonium hydroxide and ammonia paratungstate are two examples of
such compounds.
Detailed Description
[0024] While the active phosphorus solution was disclosed as being useful to
produce conversion surfaces on iron, new investigations indicate that, when
carried to
the surface of aluminum in an appropriate carrier, the active phosphorus
solution can
be used to create a conversion surface on aluminum.
[0025] While many engines are iron, 2-cycle engines tend to be made of
aluminwn.
This invention is also useful for the creation of a conversion surface on such
engines.
The phosphorus-containing solution of the invention can be introduced to the
engine
while in use through any fluid circulating to the parts.
[0026] Aluminum-phosphate conversion surfaces are created upon contacting of
the
aluminmn part or engine with the phosphorus-containing solution of the
invention or
the active phosphorus solution. With either solution, this conversion surface
can be
produced in bath processes or in situ. Unlike traditional electro-deposition
in baths,
the phosphorus-containing solution of the current invention does not utilize
zinc. The
phosphorus-containing solution can be delivered into contact to create the
aluminum
' conversion surface on the aluminum part through the use of a target fluid.
An
example of a preferred target fluid is a lubricating oil in a two-cycle
aluminum engine
as part of a motorized vehicle or other equipment. The phosphorus-containing
solution is combined with the lubricating oil to create a lubricating
composition. The
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lubricating composition including the substantial amount of oil having a
lubricating
viscosity and an amount of the phosphorus-containing primary solution operable
to
create a conversion surface upon the aluminum part or metal component. Like
the
phosphorus-containing solution, the active phosphorus solution is also useful
for
creating the conversion surface on an aluminum part by contacting the active
phosphorus solution to the aluminum engine, preferably delivered into contact
through the use of target fluid.
(0027] For the lubricating composition, examples of amounts used in testing
include
amounts between about .01% by weight to about .5% by weight of phosphorus in
the
lubricating composition. A preferred embodiment includes .3% by weight of
phosphorus. lilcreased amounts of phosphorus are effective as well. It is
notable that
a very cost-effective solution can be prepared with low weight percent of
phosphorus.
(0028] While the phosphorus-containing solution is used to create conversion
surfaces on engines for benefits derived therefrom, the process of the
invention
includes the creation of conversion surfaces using the phosphorus-containing
solution
of the invention on any metal part or metal substrate. For example, aircraft
parts are
often made of aluminum. The application of the conversion surface upon
aircraft
parts can reduce coefficients of friction. Motorboat engines, lawn mowers or
other
equipment that includes metal motors or metal parts benefit from the
conversion
surface of the invention. By creating a cost-effective manner of creating the
conversion surface, application to a wide range of equipment becomes
economically
feasible. This process is also used with the active phosphorus solution on non-
ferrous
components.
[0029] The conversion surface is formed as a result of contacting the aluminum
alloy of the part or component with an amount of the phosphorus-containing
solution
or active phosphorus solution operable to create the conversion surface. The
resulting
conversion surface with use of the phosphorus-containing solution includes
aluminum
phosphate and aluminum oxide. The addition of the phosphorus-containing
solution
to an aluminum surface results in the formation of the reaction product of
A1P04,
aluminum phosphate, and A1a03, aluminum oxide, as a conversion surface on the
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alumilzum component. Test run using infrared and X-ray testing techniques
confirm
the existence of these species. Other aluminum species also are produced
depending
upon composition of an aluminum alloy of the aluminum surface and side
reactions.
In a preferred embodiment, acetate compounds are utilized to manipulate the pH
of
the solution.
Example 1:
[0030] One example of a preferred formulation includes the phosphorus-
containing
solution with the following amounts
1.597 mots KH2PO4
0.693 mol K2HP04
0.315 mol [NH4]2HP04
and water.
[0031] W this example, the identified salts are mixed with and dissolved in an
amount
of water sufficient to at least partially dissolve the salts. The test shown
above used
55.6 moles of water. This creates the intemediate solution, which in this case
has 2.9
mole % Of KHZPO4, 1.2 mole % of KZHP04, 0.5 mol % of K2HP04 and 95.3 mol
of water. The intermediate solution is then mixed with the carrier fluid. The
water is
then driven off thermally from the mixture of the intermediate solution with
the
carrier fluid to produce the phosphorus-containing solution of the invention.
The
resulting phosphorus-containing solution of the invention is referred to as
being
substantially dry or water free due to the negligible amount of water
remaining in the
solution. Preferably, the water is driven off to a level of around 0.1 wt% of
the
phosphorus-containing solution. It is noted that more water can remain in the
solution
without changing the functionality of the phosphorus-containing solution, but
0.1 wt
% has been selected as a preferred product specification.
[0032] Phosphorus-containing solutions with K or other cation between 0.16 and
16
mole % have been evaluated. Solutions outside of this range will also be
effective,
although with varying degrees of cost effectiveness or efficiency.
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(0033] The pH of the phosphorus-containing solution can be controlled through
manipulation of the ratios of components. By manipulating the ratios of the
resulting
HZPO4- and HP042- ions, the phosphorus-containing solution can be created in
the
preferred pH range of about 6.0 to about 8Ø For example, the ratio is
approximately
15.8 for a pH of 6. The ratio is about .0158 for a pH of 8. Test results were
controlled for a pH of 7, although the entire range is considered neutral and
therefore
preferred. Through simulation, the following amounts are anticipated to reach
the
indicated pH using the ratio as the only means of manipulating the pH.
Salt Components, in Salt Components,
Mole in Wt
pH KHZP04, K2HP04, KH2PO4,wt K2HPO4,
mole mole wt
6.0 41.5 13 5706.25 2293.2
6.5 17.7 29 2433.75 5115.6
7.0 7.5 40 1031.25 7056
7.5 3 46.5 412.5 8202.6
8.0 1.5 48 206.25 8467.2
Example 2:
[0034] Preparation of the formulation includes dissolving KHZP04, K2HP04 and
I~Acetate salts in water. No ammonium salts are used in this example, so the
final
formulation will contain no ammonia.
[0035] The procedure includes adding 51 lbs of deionized water, 17.6 lbs of
KHZP04,
14.2 lbs of K2HP04 and 2.2 lbs of Kacetate in that order to two 5-gallon
plastic pails.
An additional 16.4 lbs of water was added thereafter. The salts were added to
the
water with rapid mechanical agitation and the mixture was heated after the
addition of
all the salts. The dissolution of the KHzP04 was slightly endothermic,
dropping the
temperature of the batch by 4 to 5 degrees C. While complete dissolution is
not
necessary, this experiment included heating the mixture to 40 degrees C in
order to
dissolve the remaining salts. Alternately, additional water can be added if
complete
dissolution is desired. The pH after complete dissolution was in the target
range of
7.0 - 7.1 so no adjustment of pH, such as, through the addition of KOH or
acetic
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acid, was made. The resulting P value was approximately 65,000 ppm after final
dilution such that no salts crystallize out of solution.
[0036] Examples 3 - 5: The following intermediate mixtures were formed and
tested:
Example 3:
Formula Wt., g/g-
Components, g-mole mole Wt. Used, g
KH2PO4 1.597 136.1 217.3
KZHP04 1.008 174.2 175.6
KOAc 0.289 98.1 28.4
45 % KOH 1.256 56.1 156.6
Water 36.2 18.0 652.2
Total = 40.3 1,230.0
EF 1000 P, moles/L =2.61
EF 1000 P, ppm = 65,591
Example 4
Components, g-mole Formula Wt., g/g-mole Wt. Used, g
KHZP04 1.597 136.1 217.3
KZHP04 1.008 174.2 175.6
45% KOH 1.545 56.1 192.6
Water 35.8 18.0 644.5
Total = 1,230.0
EF 1000 P, moles/L =2.61
EF 1000 P, ppm = 65,591
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Example 5
Components, g-mole Formula Wt., g/g-mole Wt. Used, g
KH2PO4 58.7 136.1 7,990.4
K2~04 37.0 174.2 6,446.8
KOAc 10.2 98.1 998.8
45 % KOH 0.0 56.1 0.0
Water 1,698.1 18.0 30,599.6
Total = 46,035.6
[0037] In these intermediate mixtures, KH2P04 is between 38 and 55 mole
percent of
the salts. KZHP04 ranged from 24 to 35 mole percent of the salts. The salts
were
diluted with water such that moles of phosphorus (P) per liter of the
intermediate
solution was approximately 2.61 moles/L. This intermediate solution was mixed
with
the carrier fluid. Phosphorus-containing solutions prepared with much lower
concentrations of phosphorus have also been found to be effective.
[0038] Example 6:
1.597 moll KH2P04
0.693 mol K2HP04
0.315 mol [NH4]2HPO4
0.289 mol [NH4]CaH302
and water.
[0039] [NH4]CZH30z can also be referred to as [NH4]Oac.
[0040] In a preferred embodiment, KHZP04, K~HP04, [NH4]ZHPO4 and water are
created into the intermediate solution that is added to refined oil carrier
fluid and
mixed with dispersants to create the phosphorus-containing solution. Exemplary
dispersants include allcenyl succinimides or similar type of dispersants,
including the
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previously-marketed product TFA 4690C. In a preferred embodiment, a dispersant
with a total base number of from 30 to 160 on an oil-free basis is used. The
phosphorus-containing solution preferably ranges from approximately 8 to 12 wt
% of
the intermediate solution while the refined oil carrier fluid ranges from ~~
to 92 wt
of the resulting mixture. The intermediate solution is added in at
approximately 10
wt. % of the refined oil carrier fluid in a preferred embodiment. The
resulting mixture
is heated to drive off a significant amount of water. The resulting mixture
exhibits
characteristics that can be described as a colloid or an emulsion. When the
intermediate mixture is mixed into a lubricating oil, an effective amount of
the
phosphorus in the phosphorus-containing solution can be very dilute and still
remain
effective. One example of a preferred embodiment is 0.3 wt% phosphorus in the
intermediate solution. Upon addition to the lubricating oil, the phosphorus
content
can be in the range of 5 - 100 ppb and still be effective. Preferred range of
phosphorus in the phosphorus-containing solution is 300-1250 ppm. Additional
preferred range of phosphorus is 300-600 ppm. Particularly preferred range of
phosphorus is 300-400 ppm. Higher amounts are also effective as shown in the
previous examples.
[0041] An example of an alternate embodiment of the phosphorus-containing
solution
includes mixing about 2.6 molar (M) orthophosphate with alkali metal and
ammonium canons, having a pH of 7 at ambient temperatures. A measured volume
of
this aqueous phosphorus-containing solution is suspended in an oil-dispersant
mixture, most of the water removed thermally, and diluted to about 0.3 wt% P.
Advantageously, the phosphorus-containing solution can be contacted to metal
parts
while the engine is running and without disassembly of the engine.
[0042] Laboratory tests with the phosphorus-containing solution of KHZPO4,
KaHPO4, [NH4]ZHPO4 and water as an additive show major improvements. Sodium
has also been evaluated for use as a cation in this formulation. Group IA
metals are
preferred cations. Other cations can include organic compounds. Factors
related to
selection of the cation include commercial expense andlor corrosion
resistance.
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[0043] Laboratory measurements have revealed the nature of the surface layer.
Application of the phosphorus-containing solution to 1018 carbon steel at
180°F was
followed by a series of analytical tests. Optical microscope examination (20X)
clearly
reveals a fairly uniform surface layer from the application of the phosphorus-
containing solution of the invention to the carbon steel. ScamZing electron
microscopy
(SEM) of the steel surface after the application of the phosphorus-containing
solution
in the oil-based mixture shows a relatively smooth layer. State-of the-art
surface
analytical instrumental measurements have shown that a thin surface conversion
layer, ranging from 15-80 Angstroms depending upon conditions and
concentrations,
is formed. This layer is of variable composition and contains Fe, O, P, N, and
K. The
layer is believed to form from the reaction of phosphate species in the
mixtures with
the oxide surface of the metal (Fe), initially of about 25 Angstroms in
thickness. The
surface compounds resulting from this chemical reaction resulting in the
conversion
layer appear to range from the simple FeP04 to more complex phosphates such as
NH4Fe2[P04]2, K3Fe3[PO4]4~ xH2O, NH4Fe3[H2PO4]6[HPO4]2~ xHZO,
KFe2[HPO4]2[PO4], and related compounds, depending upon operating conditions.
Coordination of the phosphate structure to the surface metal (Fe) ions in the
surface
layer is believed to be the origin of the stability of these surface
compounds.
[0044] The diverse oils of lubricating viscosity include natural and synthetic
lubricating oils and mixtures thereof. These lubricants include crankcase
lubricating
oils for spark-ignited and compression-ignited internal combustion engines,
including
automobile and truck engines, two-cycle engines, aviation piston engines,
marine and
railroad diesel engines, and the lilce. They can also be used in gas engines,
stationary
power engines and turbines and the like. Automatic transmission fluids,
transaxle
lubrica~lts, gear lubricants, metal-working lubricants, hydraulic fluids and
other
lubricating oil and grease compositions can also benefit from the
incorporation of the
compositions of the present invention.
[0045] A mixture of phosphoric acid, all~ali metal hydroxide and a source of
reactive
NH2 groups have been explored in U.S. Patent No. 5,540,788, which is herein
incorporated by reference. This mixture, referred to as the phosphamid
mixture, has
been disclosed for use in creation of an iron-phosphate conversion surface.
The
CA 02514795 2005-07-28
WO 2004/070081 PCT/US2004/002886
process to create the phosphamid mixture is through chemical reaction, not
through
dissolution or dissolving. The phosphamid mixture is achieved as a result of a
highly
exothermic reaction that leads to the creation of the phosphamid. The current
active phosphorus solution as used in the creation of aluminum conversion
surfaces is
an improvement of the disclosure related to phosphamid and its use.
[0046] The phosphamid mixture continues to be useful and is the subject of
further
development as disclosed herein. The exothermic reaction and the production of
free
ammonia at elevated pHs are two characteristics of phosphamid production that,
under particular circumstances, can be considered less desirable. The
phosphorus-
containing solution of the current invention avoids the production of free
ammonia
and the related issues tluough maintaining pH in a range of approximately 6 to
8, or
maintaining the pH below the level at which ammonia is formed, as well as
avoiding
the results and complexity of the creation of the highly exothermic reaction.
[0047] Tests of the active phosphorus solution indicate that the active
phosphorus
solution interacts with non-ferrous metals to create conversion surfaces. An
exemplary non-feiTOUS metal discussed above is aluminum. The active phosphorus
solution creates a phosphorus-aluminum conversion surface when brought into
contact with aluminum. Other non-ferrous metals capable of creating conversion
surfaces also interact with the active phosphorus solution.
[0048] While the invention has been shown or described in only some of its
forms, it
should be apparent to those spilled in the art that it is not so limited, but
is susceptible
to various changes without departing from the scope of the invention. For
example,
conversion surfaces on aluminum and iron parts have been specifically
discussed.
Use of the phosphoms-containing solution or active phosphorus solution on
other
metals or metal parts is also encompassed within this invention. Alloys are
also
encompassed within the discussion of metals.
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