U.S. patent number 3,652,414 [Application Number 04/789,425] was granted by the patent office on 1972-03-28 for anti-seize lubricating compound.
Invention is credited to Frank E. Bergeron, deceased.
United States Patent |
3,652,414 |
Bergeron, deceased |
March 28, 1972 |
ANTI-SEIZE LUBRICATING COMPOUND
Abstract
A lubricating and sealing compound for sealing pipe threads and
the like comprising: (1) 4 percent to 92.5 percent by weight of a
base lubricating agent and, preferably, of a base grease produced
using a soap from the group of aluminum, barium, calcium complex,
lithium and sodium soaps; (2) 2 to 20 by weight of a fish oil-based
lead soap; (3) 0.5 to 10 percent by weight of a sulfur modified
sperm oil such as sulfurized or sulfonated sperm oil; and (4) 5 to
90 percent by weight of solids. The solids comprise either copper
alone or, preferably, copper in combination with; (5) 5 to 30
percent by weight of this compound of powdered lead; and (6) 5 to
30 percent weight of amorphous graphite.
Inventors: |
Bergeron, deceased; Frank E.
(La Canada, CA) |
Family
ID: |
25147608 |
Appl.
No.: |
04/789,425 |
Filed: |
January 6, 1969 |
Current U.S.
Class: |
508/119;
508/123 |
Current CPC
Class: |
C10M
5/00 (20130101); C10M 7/00 (20130101); C10M
2201/042 (20130101); C10M 2207/282 (20130101); C10M
2201/041 (20130101); C10M 2207/125 (20130101); C10N
2050/10 (20130101); C10N 2010/08 (20130101); C10M
2201/103 (20130101); C10M 2219/024 (20130101); C10M
2201/064 (20130101); C10M 2203/108 (20130101); C10M
2207/34 (20130101); C10M 2207/129 (20130101); C10N
2010/04 (20130101); C10N 2010/06 (20130101); C10M
2219/044 (20130101); C10N 2010/02 (20130101) |
Current International
Class: |
C10m 005/22 () |
Field of
Search: |
;252/19,35,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wyman; Daniel E.
Assistant Examiner: Vaughn; I.
Claims
It is claimed:
1. An anti-sieze lubricating compound comprising an oil thickened
to a grease consistency with a metallic stearate soap selected from
the group consisting of aluminum stearate soap, barium stearate
soap, calcium complex stearate soap, lithium stearate soap, and
sodium stearate soap; and containing synergistic anti-sieze
proportions of:
a. a fish oil lead soap,
b. sulfurized sperm oil,
c. finely divided copper,
d. powdered lead, and
e. amorphous graphite.
2. The lubricating compound of claim 1 wherein the fish oil in the
fish oil lead soap is selected from the group consisting of tuna
oil, herring oil, menhaden oil, anchovy oil, mackeral oil and
sardine oil.
3. The lubricating compound of claim 2 wherein the oil which is
thickened to a grease consistency is mineral oil.
4. The lubricating compound of claim 3 containing from about 1
percent to about 15 percent by weight of the fish oil lead
soap.
5. The lubricating compound of claim 4 containing from about 0.5
percent to about 7.5 percent by weight of the sulfurized sperm
oil.
6. The lubricating compound of claim 5 containing at least 5
percent by weight of copper and between about 5 percent and about
30 percent by weight of each of the powdered lead and the amorphous
graphite.
7. An anti-sieze lubricating compound comprising an oil thickened
to a grease consistency with an aluminum stearate soap and
containing synergistic anti-sieze proportions of:
a. a fish oil lead soap,
b. sulfurized sperm oil,
c. finely divided copper,
d. powdered lead, and
e. amorphous graphite.
8. The lubricating compound of claim 7 wherein the fish oil in the
fish oil lead soap is selected from the group consisting of tuna
oil, herring oil, menhaden oil, anchovy oil, mackeral oil, and
sardine oil.
9. The lubricating compound of claim 8 wherein the oil which is
thickened to a grease consistency is mineral oil.
10. The lubricating compound of claim 9 containing from about 1
percent to about 15 percent by weight of the fish oil lead
soap.
11. The lubricating compound of claim 10 containing from about 0.5
percent to about 7.5 percent by weight of the sulfurized sperm
oil.
12. The lubricating compound of claim 11 containing at least 5
percent by weight of copper and between about 5 percent and about
30 percent by weight of each of the powdered lead and the amorphous
graphite.
Description
BACKGROUND OF THE INVENTION
This invention relates to anti-seize lubricants and, more
particularly, to lubricating and sealing compounds for pipe
threads, bolting and the like.
In applications such as in oil well drilling, piping must be
capable of being threadedly coupled and uncoupled even though
subjected to high temperatures, for example, 450.degree. F. and
above, and to high pressures, for example up to 6,000 p.s.i. and
higher. Additionally, threaded pipe joints must be capable of
preventing leakage of fluids through the helical thread passages of
pipe joints even though the fluids may be under relatively high
pressure and even though the pipe joints may be subjected to
constant vibration. Bare metal contact between threaded-together
pipes, under the foregoing conditions, results in the pipes
"freezing" and/or welding together. Additionally, thread tolerances
are such that substantial leakage can occur where only
metal-to-metal contact exists between threaded-together pipes.
To overcome the foregoing problems, various lubricants and/or
sealing compounds have been developed. Such compounds, when painted
onto interlocking threads, produce a marked improvement over
metal-to-metal contact in preventing both welding of the metal
parts and leakage of fluids through the threaded joint. One such
lubricating and sealing compound is described in U.S. Pat. No.
2,543,741, issued Feb. 27, 1951, to H. C. Zweifel. The Zweifel U.S.
Pat. No. 2,543,741 describes an improved sealing and lubricating
compound for pipe threads and the like containing a combination of
copper, powdered lead and amorphous graphite in a petroleum vehicle
comprising mineral oil and metallic soaps such as aluminum,
lithium, sodium and calcium soaps and clay base thickeners. The
improved characteristics of this compound rest primarily on the
superior lubricating characteristics of the flaked copper and upon
the superior sealing characteristics of the combination of
amorphous graphite and powdered lead in combination with the
copper. A further desirable characteristic of the Zweifel compound
is that it is capable of laying down a thin film of copper at
locations on the threaded metal surfaces where the surface has been
worn and roughened due to extreme pressure.
The Zweifel composition prolongs the useful life of the threaded
joints in which it is employed because it tends to heal the scars
and roughened areas resulting from excessive wear and makeup
torques just below that pressure required to cause the joint to
"freeze or seize" during makeup or breakout. However, roughened
surfaces and relatively high pressures are required to lay down the
aforementioned copper film. Thus, the copper film primarily acts as
a healing agent rather than a score prevention agent. Although the
Zweifel U.S. Pat. No. 2,543,741 compound represents an improvement
in its ability to withstand breakdown as measured by the standard
Timken test method, as compared to the base grease from which it
was prepared, today's deep drilling techniques, as employed in oil
field drilling, demand an even greater ability to withstand
breakdown.
As previously noted, the ability of a lubricant to withstand
extreme pressures without breaking down is a highly desirable
characteristic of such compounds. However, it has been generally
overlooked that, as the load bearing capabilities of the
lubricating agent increase, the area of the scar produced on a test
block subjected to the aforementioned Timken test increases
markedly. Although a larger scar area would generally indicate a
longer life for the metal because of a lower pressure per unit area
of scar, the larger scar ares itself has an offsetting detrimental
effect on the useful life of the metal part. That is, the
detrimental increase in scar area more than offsets the beneficial
increase in the load bearing capacity provided by the lubricant.
Therefore, it is of paramount importance to reduce the scar area.
Presently available lubricating compounds, while notably increasing
the load bearing capacity of threaded joints, do so at the expense
of the useful life of the threaded parts due to the aforementioned
increase in scar area.
SUMMARY OF THE INVENTION
The compound of this invention is an anti-seize compound comprising
a base lubricating agent in amount between about 4 percent and
about 92.5 percent by weight, a fish oil-based lead soap in amount
between about 2 percent and about 20 percent by weight, a sulfur
modified sperm oil in amount between about 0.5 percent and about 10
percent by weight, solids in amount between about 5 percent and
about 90 percent by weight, the solids comprising copper alone or,
preferably, powdered lead in amount between about 5 percent and
about 30 percent by weight of the compound, and amorphous graphite
in amount between about 5 percent and about 30 percent by
weight.
More specifically, the base lubricating grease is presently
preferably formulated from the combination of a mineral oil and a
soap selected from the group of aluminum soap, calcium complex
soap, barium soap, lithium soap, and sodium soap. The fish
oil-based lead soap is formulated from the combination of lead and
a fish oil such as tuna oil, herring oil, sardine oil and menhaden
oil, in a suitable petroleum base oil. The sulfur modified sperm
oil may be sulfonated sperm oil, but is preferably sulfurized sperm
oil.
The compound of this invention exhibits the aforedescribed
desirable characteristics of the lubricating compound described in
the Zweifel U.S. Pat. No. 2,543,741. That is, the compound of this
invention has excellent lubricating and sealing characteristics due
to the presence in this compound of the copper, graphite and
powdered lead solids. Furthermore, the compound of this invention
exhibits a substantially increased load bearing capacity and wear
reducing ability as compared with the compound described in the
Zweifel U.S. Pat. No. 2,543,741.
The addition of the various aforedescribed components to the base
grease to produce the compound of this invention produces a
lubricating compound which has a substantially higher resistance to
load than does the base grease alone. Unexpectedly, and contrary to
the performance of other similar lubricating compounds, the
compound of this invention produces wear scar areas on test blocks
(when subjected to the Timken test) which are smaller than the wear
scars produced by the base grease alone at lower loading. Thus, the
useful life of metal surfaces protected by the compound of this
invention is improved both by the increased load carrying ability
of this compound and by its ability to decrease the size of scar
marks produced in the metal surface.
In contrast to the Zweifel U.S. Pat. No. 2,543,741 compound, the
compound of this invention acts as a scar prevention agent as
contrasted with a scar healing agent in that the copper contained
in the compound is laid down on a metal surface protected by this
compound in thin film form at relatively low pressures and even on
smooth surfaces. That is, even before the surface has been
roughened, as required for copper deposition from the Zweifel U.S.
Pat. No. 2,543,741 compound, the copper is laid down as a thin film
to begin protecting the metal surface from additional loading. The
early deposition of copper by the compound of this invention
extends the useful life of the metal part which it is intended to
protect because the wear resistance of the copper takes effect
before the wear resistance of the lead soap and sulfur modified
sperm oil, which decreases with increasing loading, is lost,
thereby providing an overlapping of the wear resistance
characteristics of the lead soap and copper and thus increasing the
wear resistance characteristics of the total compound.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In general, the lubricating compound of the invention is an extreme
pressure, anti-seize compound which comprises, in combination,
specific amounts of a base lubricating agent, a fish oil-based lead
soap, a sulfur modified sperm oil, and solids comprising either
copper alone or, preferably, the combination of powdered lead,
copper, and amorphous graphite. This compound has a grease
consistency and is formulated using amounts of the above-identified
components so that the solids are dispersed therein.
Preferably, the base lubricating agent is a grease derived from the
combination of a mineral oil and a soap selected from the group of
aluminum, barium, lithium, calcium complex, and sodium soaps. The
fish oil-based lead soap is a soap derived from the combination of
lead and a fish oil in a suitable petroleum oil base and the sulfur
modified sperm oil may be sulfurized or sulfonated sperm oil.
This compound exhibits improved load bearing and wear reducing
characteristics. As to the latter characteristic, not only are
scars produced on the underlying, protected surfaces reduced in
area, but copper is deposited on the underlying surface at
substantially lower loads than heretofore achieved. The reasons for
these improved results and, particularly, for the early, i.e., low
load, deposition of copper are not fully understood. However, it is
presently believed that the early deposition of copper is due to an
interaction between the fish oil-based lead soap and sulfurized or
sulfonated sperm oil to form a compound which forms a film on the
underlying surface to which the copper adheres.
All concentrations given herein are percent by weight and are
percent by weight of the total compound of this invention unless
otherwise indicated.
Turning now to the particular components of the compound of this
invention, the base lubricating agent will first be described. The
base lubricating agent may be a viscous oil alone, for example, a
bright stock or it may be a semi-solid grease comprising an oil and
a gelling agent or soap. The oil in the grease may be any suitable
oil such as a polymerized hydrocarbon, e.g., polybutyne or
polyisobutene, a synthetic oil, e.g., dioctyladipate or,
preferably, a mineral oil. Combinations of these oils may also be
used. The preferred mineral oil is preferably a neutral type
hydrocarbon oil having a Saybolt Universal viscosity at 100.degree.
F. in the range between about 100 and about 500 seconds (S.U.S.).
Useful mineral oils well-known in the grease-making art include,
for example: pale oil, red oil, process oil, neutral oil, floor
oil, brown neutral oil, neutral distillate, treated neutral oil,
and blends of these mineral oils from any petroleum source. These
oils may contain bright stocks or other hydrocarbon materials
capable of modifying the physical characteristics of the neutral
oils.
Preferably, the gelling agent is a metallic soap. However, it may
also be an inorganic thickening agent such as lampblack or
processed clay. The metallic soap may not be normal calcium soap or
lead soap, but it may be aluminum, calcium complex, lithium,
barium, or sodium soap. A particularly useful metallic soap is
aluminum stearate soap. As used herein, the term "soap" is intended
to include compounds formed from the combination of metal elements
or inorganic elements with animal or vegetable fats, fatty acids or
fatty acid derivatives as well as certain petroleum derivatives
such as oxidized petroleum.
The presently preferred combination of a mineral oil and a soap are
employed in a ratio of mineral oil to soap between about 10:1 and
about 19:1 by weight.
The petroleum of the base grease in the total composition is at
least about 4 percent, and is sufficient to make 100 percent by
weight of the final compound. The upper limit will be 92.5 percent
or 82.5 percent depending upon whether the solids are copper alone
or copper, amorphous graphite and powdered lead, respectively.
Below this lower concentration, the composition is too viscous at
applicable temperatures to be properly applied when used for the
purposes intended. If less than this amount is used in the
composition and low viscosity dilluents are used to compensate for
the absence of the vehicle, i.e., the base grease, the composition
may, upon standing, no longer be homogeneous. Above this upper
concentration, one or more of the components will be present in a
ratio to the other components that will result in the compound
being partially or completely ineffective in its intended
applications.
The fish oil-based lead soap, which is an extreme pressure agent,
comprises: (a) a petroleum or mineral oil base derived from the
combination of a bright stock having a viscosity between about 110
S.U.S. (Saybolt Universal Seconds) and about 250 S.U.S. at
210.degree. F. and a neutral oil having a viscosity between about
100 S.U.S and about 500 S.U.S. at 100.degree. F.; (b) a fish oil
including herring oil, menhaden oil, sardine oil, mackerel oil,
anchovy oil and, preferably, tuna oil; and (c) lead preferably
derived from litharge (PbO).
An example of an effective fish oil-based lead soap has the
following composition:
Mid Continent Bright Stock (150 S.U.S. at 210.degree. F.) 37.0 lb.
Tuna oil 107.5 lb. 30-P oil (310 S.U.S. at 100.degree. F.) 147.0
lb. Litharge 86.0 lb.
The weight fractions of the components present in the fish
oil-based lead soap are selected so that the tuna oil is miscible
with the other oils and so that the resulting lead soap has a
semi-solid or semi-plastic consistency. The amount of fish oil
varies within a relatively limited range. For example, in the
above-identified, tuna oil-based lead soap, the tuna oil may vary
in amount between about 110 lb. and about 105 lb. Above about 110
lb. the resulting soap is so hard as to be practically unworkable
and has to be heated before attempting to mix it with the base
lubricating agent. Below about 105 lb., the resulting soap is too
thin and tends to break down the structure of the base grease.
The fish oil-based lead soap is made by first mixing the litharge
and the bright stock together to form a paste. Heating of this
paste is commenced and the tuna oil is added with stirring. Heating
is continued until the temperature of the mix rises above about
300.degree. F. and, preferably, to a temperature between about 300
F. and about 320.degree. F. When this elevated mix temperature has
been reached, the low viscosity neutral oil is slowly added to thin
the mix. The temperature of the mix is maintained above about
300.degree. F. during the entire addition of the neutral oil. If
the mix temperature falls below about 300.degree. F., the reaction
time is extended to the extent that the time becomes impractical
and the desired reaction may not be completed. Heating of the mix
is continued until substantially all of the litharge has
reacted.
The fish oil-based lead soap is present in the compound of this
invention in an amount between about 2 percent and about 20
percent. Below about 2 percent, the ability of the lead soap to
perform the functions herein described is lost because of a
dilution phenomenon characteristic of such compounds in a
lubricating grease structure as opposed to their effectiveness in a
non-thickened lubricating oil. This minimum ratio is established to
assure the extreme pressure properties resulting in the synergistic
phenomonon involving the essential presence of sulfurized or
sulfonated sperm oil to accomplish the phenomenon of copper
deposition and lower range, extreme pressure properties described
herein. Above about 20 percent, the effectiveness of the lead soap
diminishes at a rate to make economically unfeasible the use of an
increased ratio of the lead soap to the other components of the
composition.
The sulfur modified sperm oil may be either sulfonated or
sulfurized sperm oil, but is preferably the latter which is a sperm
oil having a sulfur content of about 8 to 12 percent by weight. The
sperm oil is present in amounts between, about 0.5 percent to about
10 percent by weight. Below about 0.5 percent, the sperm oil is too
diluted by the base grease to have any appreciable effect on the
weld-prevention and wear-reduction properties of the compound of
this invention. Above about 10 percent, the effectiveness of the
sperm oil diminishes too rapidly to make the use of amounts of
sperm oil above 10 percent economically feasible.
The copper or the combination of copper, powdered lead and
amorphous graphite comprise what is hereafter designated as the
"solids" constituents of the hereindescribed compound. The copper
is fully described in the Zweifel U.S. Pat. No. 2,543,741 and that
description is incorporated herein by reference. The term copper as
used herein and in the claims denotes both elemental copper and
copper alloy which, in turn, is used herein to designate an alloy
having copper as the major constituent. The copper is present in
the form of fine flakes or scales and preferably is in the form of
particles ranging in size from about 1 micron to at least about
one-half times larger, in their largest dimension, than the maximum
combined tolerances of both the mating male and female threads.
Generally, the copper particle or flake should not exceed, in its
greatest dimension, about 76 microns. Ordinarily, the thickness of
the copper particles or flakes will fall within the range of about
3.9 .times. 10.sup..sup.-5 to about 19.5 .times. 10.sup..sup.-5
inches and will generally be of substantially uniform
thickness.
The combination of powdered lead and amorphous graphite acts as a
damming or sealing agent. This combination effectively seals pipe
threads at temperatures ranging from -87.degree. F. up to
450.degree. F. and above, and at pressures up to 6,000 p.s.i. and
higher. The consistency of the amorphous graphite and powdered lead
is such that they can be easily removed by normal cleaning
procedures from the threads.
The total combined solids content, that is, the total of the
copper, powdered lead and amorphous graphite, is at least about 15
percent by weight of the total composition, with each of these
components present in amounts of at least 5 percent, and may range
as high as about 90 percent of the total composition. If copper
alone is employed, the lower limit is about 5 percent by weight.
Below the lower limit of about 15 percent for the combined solids
or about 5 percent for copper alone, the dilluent effect of the
base grease and/or other components prevents the presence of
sufficient flake copper at points of contact between mating
surfaces, for example, threaded members, to adequately prevent
excessive wear and/or seizure, welding or galling as the case may
be. A lower concentration can result in leakage of threaded joints
as described in the Zweifel U.S. Pat. No. 2,543,741. Above the
upper limit of about 90 percent of total solids, application of
this compound becomes impractical because of its thickness.
The amorphous graphite and powdered lead are present in a ratio of
lead to graphite varying within the range of 1:3 to 3:1.
Satisfactory results have been produced employing equal amounts of
copper, graphite and lead, for example, about 10 percent by weight
of the total compound, to give a total solids content of about 30
percent. The maximum amount of each of the lead and graphite is
preferably about 30 percent.
The anti-seize, lubricating compound of this invention may be made
by combining the components in various ways. For example, it has
been found convenient to add the base grease to a conventional
grease kettle and, thereafter, to add each of the other components
to the base grease with stirring. Generally, no heating is required
to completely mix the various components.
To illustrate the unexpected advantages resulting from use of the
compound of this invention, various greases having the composition
as shown in Table I were made up.
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TABLE I
grease Designation Composition
__________________________________________________________________________
Base grease 92.5 % mineral oil (310 SUS at 100.degree. F.) + 7.25 %
aluminum stearate soap. Grease A 70% Base grease + 10% copper + 10%
lead + 10% graphite. Grease B 85% Base grease + 10% tuna oil-based
lead soap (21.5% lead) + 5% sulfurized sperm oil. Grease C 55% Base
grease + 10% copper + 10% lead + 10% graphite + 10% tuna oil-based
lead soap (21.5% lead) + 5% sulfurized sperm oil. Grease D 90% Base
grease + 10% commercial extreme pressure additive (Parapoid 10C)
__________________________________________________________________________
grease A represents a lubricating compound made according to the
Zweifel U.S. Pat. No. 2,543,741 and Grease B represents an improved
lubricating compound made according to the method described in a
U.S. patent application of the instant inventor, assigned to the
instant assignee and filed herewith (hereafter "said copending
application"). Grease C represents a compound of this invention and
Grease D represents a presently available extreme pressure
lubricant containing extreme pressure agents other than those
employed in the present invention.
Each of the compositions of Table I was subjected to a test
designed to show the breakdown load of each grease, i.e., the load
at which each grease was no longer able to protect the underlying
metal surface. The test equipment was a standard Timken lubricant
tester for testing extreme pressure lubricants in which a metal
ring or test cup is made to revolve and rub against a test block or
coupon which is held stationary. A reservoir of special design was
provided which continuously flowed lubricant onto the outer surface
of the rotating ring so that lubricant was carried into lubricating
position between the outer surface of the rotating ring and the
contacting surface of the test block or coupon (the underlying
surface). The ring was caused to rotate at about 800 r.p.m. and,
simultaneously therewith, a load was applied downwardly to the
lever arm carrying the test block in a manner to increase the
pressure of the test block against the rotating cup or ring. The
upward loading of the test block was increased with each test,
which ran for about 10 minutes, until the load at which the
lubricant passes and fails was determined.
At the end of each 10 minute test, the scar produced on the test
block by the revolving ring was examined. A test block scar with
straight line sides and no metal pickup indicated that the
lubricant was properly protecting the metal surface of the block,
whereas a test block scar with metal pickup causing the boundary
lines of the scar pattern to be irregular indicated that the
lubricant was not capable of protecting the metal surface of the
test block at that test load. The loads at which the lubricant
protected the metal surfaces (although not necessarily completely)
were designated as "pass" loads and the loads at which the
lubricant broke down and was completely unable to protect the
underlying metal surface were designated as "fail" loads. In
addition to a determination of the pass and fail loads, the area of
the scar produced on the test block at the pass load, was
determined. The results of the foregoing tests are set out in Table
2 below.
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TABLE 2
scar Grease Lever Load Area Pass Load Scar Area Designation Pass
Fail in..sup.2 % Change % Change
__________________________________________________________________________
Base grease 15 20 0.0235 Base Base Grease A 35 40 0.0260 +133 +11
Grease B 45 50 0.0355 +200 +51 Grease C 45 50 0.0225 +200 -4.2
Grease D 25 30 0.0150 +67 -36
__________________________________________________________________________
as can be seen from Table 2, each of the compounds showed a load
increase over the base grease (15 lb. pass). The grease employing
the presently available commercial extreme pressure additive
(Grease D) produced the lowest load increase (25 lb. pass) whereas
the two compounds (Grease B of said copending application and
Grease C of this invention) containing the combination of fish
oil-based lead soap and sulfurized sperm oil produced the largest
increase in pass load (45 lb. pass). The base grease plus solids
(Grease A) produced a moderate increase in lever load (35 lb.
pass). From the foregoing, it is apparent that the compound of this
invention has a substantially greater load resistance than does
either the compound with a presently available commercial additive
(Grease D) or a compound containing only the base grease and the
same amount of copper, lead and graphite (Grease A). The latter
comparison indicates that the substantial increase in load
resistance derives from the combined fish oil-based lead soap and
sulfurized sperm oil and that this increase is apparently not
affected by the presence of the solids.
Other advantageous characteristics of the compound of this
invention were also noted in connection with examination of the
wear scars produced by the foregoing test. First, it was observed
that copper was deposited from the composition of this invention on
the smooth unscored surface of the wear scar produced at 30 lbs.
loading, i.e., at 15 lb. less than the pass load. Although the
deposition of a protective layer of copper was described in the
Zweifel U.S. Pat. No. 2,543,741 such deposition of copper was
always previously associated with scoring or roughening of the wear
surface. That is, deposition of copper was heretofore possible only
on surfaces which had been scored or roughened by the load applied
to them. This was borne out by the foregoing tests summarized in
Table 2. At both 20 lb. and 25 lb. lever loads with Grease A, no
scoring or roughening of the underlying metal surface was observed
and no copper deposition was observed. However, copper deposition
was observed with this Grease (A) at 35 lb. load together with a
scored underlying metal surface.
Thus, the function of copper in the Zeifel U.S. Pat. No. 2,543,741
composition was as a sealant in that the surface was required to be
roughened before the copper would deposit to protect the surface
from further injury. In contrast, the deposition of copper from the
composition of this invention does not require that the surface be
initially roughened or scored. Therefore, such deposition of copper
begins to protect the metal surface from scoring at pressure less
than those at which scoring occurs.
The early, i.e., at relatively low loads, deposition of copper
means that the advantages of the protective layer of copper on the
metal surface is obtained at lower load conditions so that the
protection effected by the copper is obtained before the protection
from the lead soap component of the grease is lost. This
overlapping of protection derived from the lead soap and the copper
film results in continuous protection over a wider range of loads
thereby resulting in substantially longer protection of the metal
surface from scoring.
Comparison of the scar areas indicates that a synergistic result is
produced by the components of the compound of this invention, i.e.,
apparently by the combination of the fish oil-based lead soap,
sulfurized sperm oil and solids (copper, graphite, lead). In which
combination these components act to produce the synergistic effect
is not presently known. However, the synergistic effect itself is
readily observable from the test data of FIG. 2.
Grease A (containing the solids, but no lead soap or sperm oil)
exhibits a wear scar area increase over the base grease of 11
percent at its higher pass load of 35 lb. Thus, a substantial
increase (+133 percent) in pass load over the base grease is
accompanied by a small increase (+11 percent) in scar area over the
base grease. Grease B (containing no solids, but containing both
fish oil-based lead soap and sulfurized sperm oil) exhibits a 200
percent increase in pass load over the base grease, but is
accompanied by a 51 percent increase in scar area over the base
grease.
From this data, it would be expected that a grease containing the
solids and fish oil-based lead soap and sulfurized sperm oil would
exhibit a wear scar area increase and that this increase would
probably be between the increases for Grease A and Grease B.
However, this expected result does not occur as shown by the data
obtained from the tests on Grease C. Instead, the load increase is
equal to the higher load increase (+200 percent) of Grease B and
this is accompanied by a decrease (-4 percent) in scar area over
the base grease. Thus, at loads triple those to which the base
grease can be safely subjected, Grease C actually permits less wear
than does the base grease at its lower pass load. By comparison,
although Grease A and B are capable of withstanding higher loads
than the base grease, this capability is accompanied by a wear scar
increase.
Grease D (employing a commercial extreme pressure additive) also
exhibited a decrease in wear scar area as compared to the base
grease. However, this scar area decrease was associated with only a
67 percent increase in load resistance. At 35 lb. load (fail), this
grease permitted substantial scoring of the underlying surface and
at 45 lb. load (fail) it permitted total scoring of the underlying
surface. Because of its lower load capability, it could not be
successfully used in the extreme pressure applications in which
Grease C of this invention could be successfully employed.
Should scoring of the wear surface take place when using the
composition of this invention, copper will be deposited in the
scored area to thereby effect a healing of the scored area. Thus,
in addition to the increased protection derived from the early
deposition of copper from the herein-described composition on
smooth wear surfaces, the healing advantages of the Zweifel U.S.
Pat. No. 2,543,741 composition are retained.
When a lubricant is subjected to a load at or near its failure
load, it is common for a weld ridge resulting from metal build-up
to be produced at points along the edge of the wear area. In each
such instance, a distressed area is produced in the wear scar
adjacent to the weld ridge. This distress area serves to further
weaken the metal, thereby further decreasing its useful life. This
phenonomen was observed in connection with the tests run on the
Zweifel U.S. Pat. No. 2,543,741 composition at 35 lbs. load. By
comparison, although weld ridges were produced in the test blocks
at 40 lb. and 45 lb. load when using the hereindescribed
composition, no evidence of distress in the wear scar area adjacent
the weld ridge was observed. Therefore, the useful life of the
metal is extended due to the elimination of the stress area
adjacent to a weld ridge when using the sealing and lubricating
composition of this invention.
From these tests, it will be apparent that the compound of this
invention produces the advantages provided by the Zweifel U.S. Pat.
No. 2,543,741 composition and, furthermore, that it produces the
additional advantages of early copper deposition on smooth surfaces
and decreased wear scar area even at high pass loads.
* * * * *