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Патент USA US2136655

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2.136.655
. Patented Nov. 115‘, (1938. .
UNITED‘ "STATES: PATENT 0mm;
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2,130,655'
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F Julian G. Ryaf??ii?ik assign“
Shell Development Company, San‘ Francisco,
Oali?, a corporation of Delaware '
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. No Drawing. j Original applicationnctober 18,
1937. Serial No. 169,645.. Divided and this ap
plication March 26,1938; ‘Serial‘NoL 198,271 .
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_ 3- Claims. (01. raj-+151)
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compositions have been devised toireduce. this.
This invention is chie?yS concerned with hear-.
ing compositionsusedin internal combustion eni
. ‘gines.
It. has been recognized. that bearings ‘
should-comprise at least. two constituent parts,_
corrosionin the- belief that it wasentirely' due tov
the lubricant used.‘ Howeven-I'hav‘e discovered
that one of-the main causes of becomingcorror' '
namely, a soft part to, conform to the crankshaft > sive can be traced to the composition of 'theibear-"’ 5
'_ and readjust itself to irregularities in operation , ing alloys-and it'is the object‘ of- thisinvention ‘to
and-a hard part to support the load and have . provide substantially
_ anti-frictionalqualities in order not to seize onto .. internal combustion e
the shaft.
10
These properties have in the past been _
found in tin base bearing alloys'icomm'only known
as “babbitt”.
-'
, ‘V
' .
,.
»
l
_
>
on-corrosive bearings for
‘nes. "
' '
:
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-,
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_
' I have-found. that the corrosion is in- part :due
to galvanic action betwee the constituents of the
bearing material submerg d in‘mineral or,hydro-'
carbon oil. ‘This galvanic ‘action __ takes .place
‘through the intermediary .of ‘the lubricating oil.
The electrical conductivity of the 'oil is veryslight
‘
This application is a division of my application
' : Serial No. 169,645 ?led October 18, 1937'.
In recent years owing to the greater speeds re
is 'quired of‘aut‘omotive engines,‘ the higher oilltemev
under normal circumstances, but upon ‘oxidation 15
peraturesproduced have caused a‘ softening of
of the lubricant andfthe- accumulation of, small
the babbitt and in some cases, ‘actual melting . amounts of water in the crankcase of the‘ motor
due to the eutectic melting'pointbe'ing around the conductivityv is materially increased. ' 450° F. and_
2120
F.
.
the softening point being around
e
p
t
.
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According to my investigation, I have found
that in some cases the 'cadmiumasilver bearings 20,
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Endeavor ‘has therefore béen'made to develop
after being ‘run in anautomobile motor for sev- '
bearing ‘ metals, which would have anti-friction
eral hours showed pitting of the’ bearings. vSub
properties-and have a high enough melting point ‘sequent analysis {of the oil failed to show any
that the softeningftemperature would‘be raised cadmium particles in the oil, thus eliminating
above that of the tin‘ base bearings andeat the abrasion of the metal or insufficient oiliness of‘ 25
same time be economical.
I
_
_
, .
' Two'of the bearing materials which have been‘v '
the oil-as the cause of corrosion. This led to the.
conclusion that at‘ least part of ‘the corrosion wasx
produced to meet this requirement :are cadmium?v
was to
further-supported
electrochemical by
action.
the fact
‘This
that
conclusion
only the .
silver and cadmium-silver-‘copper compositions.‘ due
30 Cadmium is the main constituent/bf these compo
' cadmium went into solution and silverwas not.
sitions. Cadmium has a 'melting' point of about _' found dissolved in oil in conformity with its lower
650° F. and a Brinell hardness of over-20. (Fur
, position in; theelectromotive series.
thermore cadmium has good bonding properties
as evidenced by its
Further ex'-_
p'e'riments were then conducted to establish the’
successful use. with zinc in: electrode potentials between. cadmium and silver
_
~
electrpdes placed’v in _a used vmotor lubricating oil 35
high strength solders. '
Silver, when added to the cadmium in relatively '.bath. Measured at‘ an oil temperature of ‘210°
small quantities, improves the casting qualities ' F. a potential'of .630 voltwas established. In ‘I
of cadmium by making it less susceptible to oxi
order-to investigate the eifect of electrolyte fur
dation at casting temperaturesfand by increasing
40 the ?uidity.
ther,_ small buttons of polished cadmium with .
Silver, further,_ has a marked in- > pure silver inserts were exposed to oils under a 40
variety of test conditions. The polished surface
?uence upon the physical characteristics of cad
mium by improving grain structure.
_ wasjexamined under ‘a microscope before and y. .
A- typical cadmium silver bearing. alloy‘ will after the tests.v The results of these tests showed ‘
‘have the following composition: cadmium 97.75% . that cadmium corrodes easily and that galvanic
45 and silver 2.25% ,the
'byt‘e'cadmium.“
v
silver beingheldin solution
r
action accelerates'the corrosion. The silver‘ in-.
e
serts were not attacked.
A series of tests with .
The a'tldition of small amounts of copper to the
composition has the property of'raising the Brin
numerous alloyshave, established that there exists
nell hardness appreciably.‘ A typical cadmium- v
siege of. an alloy and the electric potential between
50 silver-copper composition is as follows: cadmium
a direct relationship between the rate of corro- .
the electrodes made of the alloyed metals, when 50
98.75%, silver 0.75%’ and copper 0.50%.
these electrodesv are placed in a lubricating oil
These bearings have, in general,» been quite suc-_ " . electrolyte.
cessful. However, in manycases',‘ corrosion of
I have found that by alloying a‘ small quantity
the hearing has taken place,‘ Many theories have‘ "oil v"a‘potential depressing substance with the '
55
been advanced to explainthis, and various oil
bearing material corrosion may‘ be prevented or 55
2,136,855
2
lowing test was made: ‘Small pieces of the same
at least substantially reduced. Of various sub‘
stances tested in alloys with the cadmium-silver
and cadmium-silver-copper bearings I have found
material as was used for the anodes in the above
test were machined into the form of cylindrical
weighing 8 grams each, carefully polished
that antimony is particularly e?‘ective for the‘ slugs
and washed with solvent. Each specimen was
purpose desired.
placed in a test tube containing a meas
Below are tabulated the results obtained using then
ured amount of a used lubricating oil. The test
an oil electrolyte at 340° F.
tubes and contents were each kept at a tempera
ture of 340° F., air was continually bubbled
through the oil to simulate actual operating con 10
ditions. At the end of a period of sixteen hours
the slugs were removed and after careful wash
ing and. drying, were weighed. The results are
Equilibrium
Composition
of cathode
potential
Composition of anode
Cadmium
millivolts
_
Cadmium-+0. 2% antimony by wt.-.
shown below:
. Cadmium-+2. 0% antimony by wt...
15
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_ Cadmium+5. 0% antimony by wt...
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Number of
Alloy
specimens
Average
loss
From the above it will be seen that cadmium
alone gave an equilibrium potential of 545 milli
volts. Corrosion of the cadmium was apparent
after about 15 minutes in the test cell. During
this time the surface‘ of the cadmium electrode
Mgs.
changed considerably. At ?rst it had avbright
1. Commercial cadmium-silver cop is
9
24
2. (1)+0.l% antimony _______ __
5
l3
3. v(Di-‘0.2% antimony _______ _.
5
7
From the above it appears conclusively that
polished ?nish but later showed a coarse grain
structure. The‘addition of antimony to cad
25 mium reduced the potential and corrosion with
both by equilibrium potential tests and actual
corrosion tests of the bearing metal that anti
the result that the cadmium-antimony electrodes w mony has the effect of reducing the corrosion of
after an hour, had a very ?ne grained ?nish and bearing when added in small quantities. An
timony hardens the alloy and for this purpose
copper has been in the past added to cadmium
silver bearings. It is therefore possible to re 30
place the copper with antimony which will serve
showed only slight corrosion._ Microscopic ex
amination showed that'the crystal structure of
30 the metal was changed by the presence of the
antimony.
This isv probably also a factor'in
reducing corrosion._
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' both to harden the alloy and reduce corrosion.
_ While I have shown only tests using speci?c
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. Further tests were made, using a silver cath
amounts of antimony, the conclusion must be
ode and an anode of standard cadmium-silver‘
‘copper bearing metal and anodes ‘of the same ‘ drawn that amounts between the examples will
with small amounts of antimony added.
be bene?cial for the purpose intended and that
I do not intend to limit myself to the exact pro
The
results of these tests are tabulated below using
' the same oil at 340° F.
portions given.
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I claim as my invention:
cglg?lgégn
Composition of anode
1. A hearing metal consisting of silver 0.5% 40
to 1%, copper 0.25% to 0.75%, antimony 0.1%
potential
miliivolts
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to 1% and the remainder cadmium.
2. A bearing metal consisting of silver 0.5%
Commercial cadminm-sllver-coppen
525
Commercial cadmium-silver-oopper
+0.1% antimony by weight. '
Commercial cadmium-silver-copper
-to 1%, copper 0.25% to 0.75%, antimony 0.1%
465
+02% antimony by weight-
to 0.2% and the remainder cadmium. ‘
.
To obtain further information regarding the
addition of‘ antimony to bearing alloys the fol
3. A hearing metal consisting of silver 0.5%
to 1%, copper 0.25% to 0.75%, antimony 0.1%
and the remainder cadmium.
JULIAN G. RYAN.
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