U.S. patent application number 09/993806 was filed with the patent office on 2002-03-14 for overlay material for plain bearing.
Invention is credited to Gruenthaler, Karl-Heinz, Huhn, Hans-Ulrich, Lucchetti, Werner, Niegel, Fritz.
Application Number | 20020031684 09/993806 |
Document ID | / |
Family ID | 7834761 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020031684 |
Kind Code |
A1 |
Niegel, Fritz ; et
al. |
March 14, 2002 |
Overlay material for plain bearing
Abstract
A lead-free multilayer material for plain bearings and a process
for the production of corresponding bearing shells for improved
emergency running and mechanical load-carrying capacity
characteristics. The multilayer bearing material comprises a
lead-free copper alloy having a copper content ranging from 50 to
95 wt. %, and an overlay formed of a lead-free tin and copper
having a tin content ranging from 70 to 97 wt. % and a copper
content ranging from 3 to 20 wt. %.
Inventors: |
Niegel, Fritz;
(Oestrich-Winkel, DE) ; Gruenthaler, Karl-Heinz;
(Usingen, DE) ; Lucchetti, Werner; (Walluf,
DE) ; Huhn, Hans-Ulrich; (Schlangenbad-Wambach,
DE) |
Correspondence
Address: |
Robert L. Stearns
Reising, Ethington, Barnes, Kisselle
Learman & McCulloch, P.C.
5291 Colony Drive North
Saginaw
MI
48603
US
|
Family ID: |
7834761 |
Appl. No.: |
09/993806 |
Filed: |
November 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09993806 |
Nov 6, 2001 |
|
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|
09108785 |
Jul 2, 1998 |
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Current U.S.
Class: |
428/675 ;
428/677 |
Current CPC
Class: |
Y10T 29/49705 20150115;
Y10T 428/1291 20150115; Y10T 29/49707 20150115; Y10T 428/12924
20150115; C25D 5/12 20130101; F16C 2204/12 20130101; F16C 33/124
20130101; Y10T 29/49709 20150115; Y10T 428/12722 20150115; Y10S
384/912 20130101; F16C 33/121 20130101; F16C 33/125 20130101; C25D
7/10 20130101; C25D 15/02 20130101; F16C 2204/10 20130101; F16C
2204/34 20130101; C25D 3/60 20130101; F16C 2300/02 20130101 |
Class at
Publication: |
428/675 ;
428/677 |
International
Class: |
B32B 015/02; B32B
015/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 1997 |
DE |
P 197 28 777.8 |
Claims
What is claimed is:
1. A composite multilayer material for plain bearing comprising: a
metallic backing layer; a bearing metal layer; a diffusion barrier
layer, and an electroplated overlay, said bearing characterized by
said bearing metal layer being selected from a group of alloys
consisting essentially of: Cu--Al, Cu--Zn, Cu--Zn--Si, Cu--Zn--Al
and Cu--Al--Fe; and said bearing metal layer being formed of a lead
free copper alloy having a copper content in the range of about 50
to 95 wt. % and said overlay being formed of a lead-free Sn--Cu
alloy having copper in the range of about 3 to 20 wt. % and tin in
the range of about 70 to 97 wt. %.
2. The material of claim 1 wherein said overlay includes at least
one component selected from the group of materials consisting
essentially of: bismuth, silver and nickel in a proportion
.ltoreq.20 wt. %.
3. The material of claim 1 wherein said overlay includes a
dispersion of hard particles selected from a group of particles
consisting essentially of: Al.sub.2O.sub.3, Si.sub.3N.sub.4,
diamond, TiO.sub.2, and SiC.
4. The material of claim 1 wherein said diffusion barrier layer
comprises nickel.
5. The material of claim 1 wherein said diffusion barrier layer
comprises a nickel layer having a thickness of about 1 to 3 .mu.m
and a nickel-tin layer having a thickness of about 2 to 10
.mu.m.
6. The material of claim 1 wherein said diffusion barrier layer
comprises a cobalt layer having a thickness of about 1 to 3
.mu.m.
7. A multilayer plain bearing comprising: a metallic backing layer,
a bearing metal layer, a diffusion barrier layer, and an
electroplated overlay, said bearing characterized by said bearing
metal layer selected from a group of alloys consisting essentially
of: Cu--Al, Cu--Zn, Cu--Zn--Si, Cu--Zn--Al, and Cu--Al--Fe; said
bearing metal layer being formed of a lead-free copper alloy having
a copper content in the range of about 50 to 95 wt. % and said
overlay being formed of a lead-free Sn--Cu alloy having copper in
the range of about 3 to 20 wt. % and tin in the range of about 70
to 97 wt. %.
8. The bearing of claim 7 wherein said overlay includes at least
one component selected from the group of materials consisting
essentially of: bismuth, silver and nickel in a proportion
.ltoreq.20 wt. %.
9. The bearing of claim 7 wherein said overlay includes a
dispersion of hard particles selected from a group of particles
consisting essentially of: Al.sub.2O.sub.3, Si.sub.3N.sub.4,
diamond, TiO.sub.2, and SiC.
10. The bearing of claim 7 wherein said diffusion barrier layer
comprises nickel.
11. The bearing of claim 7 wherein said diffusion barrier layer
comprises a nickel layer having a thickness of about 1 to 3 .mu.m
and a nickel-tin layer having a thickness of about 2 to 10
.mu.m.
12. The bearing of claim 7 wherein said diffusion barrier layer
comprises a cobalt layer having a thickness of about 1 to 3 .mu.m.
Description
[0001] This application is a continuation of application Ser. No.
09/108,785, filed Jul. 2, 1999, the priority of which is
claimed.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a composite multilayer material for
plain bearings, comprising a ternary layer, a bearing metal layer,
a diffusion barrier layer and an overlay applied by electroplating.
The invention also relates to a process for the production of
bearing shells.
[0004] 2. Description of Related Art
[0005] Composite multilayer materials with a structure comprising
steel backing/lead-bronze/lead-tin-copper overlay have proven very
reliable and to have a high mechanical load carrying capacity. Such
composite multilayer materials are described in Glyco
Ingenieurberichte January 1991, for example.
[0006] A typical representative of these groups of materials has
the following structure:
[0007] steel
[0008] CuPb22Sn bearing metal nickel barrier
[0009] PbSn10Cu2 overlay.
[0010] The electrodeposited overlay in particular is a
multifunctional material, which, inter alia, takes on the following
tasks:
[0011] embedability with respect to foreign particles
[0012] running-in or conformability of sliding counterparts
[0013] corrosion protection for the lead-bronze
[0014] emergency running properties in the case of an oil
shortage.
[0015] The bearing metal likewise contains certain emergency
running reserves in case the overlay is completely worn away.
[0016] These bearing designs, which have proven effective for
decades, today still contain quantities of lead in the bearing
metal and the overlay. This is unsatisfactory from the point of
view of the environmental impact of heavy metals.
[0017] The only lead-free plain bearings currently produced are
aluminum-based. Two-component bearings comprising an aluminum alloy
on steel are preferably used. Alloy elements in the aluminum are
preferably tin, silicon, nickel and copper. Disadvantages of these
groups of materials are their low fatigue strength, low notch
sensitivity, low heat resistance, insufficient embedability and
relatively poor heat conductivity.
[0018] Electrodeposition has hitherto mainly been carried out using
baths containing fluoroborate. Copper deposition could be carried
out only up to a rate of 2 vol. % in these baths, while in cyanide
baths deposition rates for the copper of up to 20 vol. % could be
achieved. However, it has become clear that the coating is
extremely brittle and in this respect is not very durable.
[0019] DE-OS 27 22 144 discloses the use, as a soft metal bearing
alloy for multilayer plain bearings, of an alloy comprising more
than 6 to 10 wt. % copper and 10 to 20 wt. % tin, the rest being
lead. This alloy may, inter alia, be applied by electrodeposition,
wherein a nickel intermediate layer is provided as a diffusion
barrier. However, this known alloy, which is produced using
conventional electrolyte baths, exhibits coarse tin
distribution.
[0020] The coating of electronic components is described in
"galvanisches Abscheiden von Zinn-Blei aus Fluoroborat und
fluorboratfreien Elektrolyten" ("Electrodeposition of tin-lead from
fluoroborate and fluoroborate-free electrolytes") by H. van der
Heijden in "Metalloberflche" ("Metal surface") 39 (1985) 9, pages
317-320. It has been shown that tin and lead may be easily
dissolved in various organic sulphonic acids with the general
formula RSO.sub.3H, wherein R represents an alkyl group. The
sulphonic acids are described as completely stable during
electrolysis. The use of such fluoroborate-free baths for
electroplating of sliding elements is mentioned, as are suitable
additives necessary for the production of sliding elements.
[0021] Aqueous, acidic solutions are known from DE 39 02 042 A1 for
the electrolytic deposition of tin and/or lead-tin alloys. These
binary electroplating baths are used as corrosion protection, e.g.
for printed circuit boards and batteries, wherein a relatively soft
layer is deposited which is not wear-resistant and thus cannot be
used for sliding elements. In addition to metal salts, inhibitors
and free alkanesulphonic acids, these known electroplating baths
comprise brighteners, which make it impossible to use these baths
for example as ternary baths. It has been shown that, when copper
salts are added for example, only a maximum of 1% copper may be
deposited, because the bath composition is essentially suited to
tin.
[0022] JP 02/93096A (Pat. Abstract of Japan, C-732, Vol. 14/No.
294) describes a process for producing sliding elements, in which
the overlay of Pb--Sn--Cu is applied to the prefabricated
semi-finished product by electroplating. To this end, a
fluoroborate-free electrolyte is used which does not contain
brighteners but does contain free alkylsulphonic acid and non-ionic
wetting agents. With these known electroplating baths, however,
again only coarse tin deposition is achieved, wherein the layer
structure is generally irregular. The high demands made of plain
bearing are not met wholly satisfactorily.
[0023] DE 195 45 427 likewise describes fluoroborate-free
electroplating baths for the production of overlays of
lead-tin-copper, said baths containing a grain-refining agent
comprising carboxylic acid and a fatty acid glycol ester. In this
way, finely crystalline deposition of the tin is achieved with
completely homogenous distribution thereof, copper deposition of
from 2 to 16 wt. % being obtained.
[0024] The prior German Application DE 196 22 166 describes ternary
layers with hard particles, wherein fluoroborate-free
electroplating baths with added alkylsulphonic acid are used for
the overlay, to obtain a completely homogenous distribution of the
hard particles in the matrix material. In addition to
lead-containing overlays, these alkylsulphonic acid baths may also
be used for the application of lead-free layers of SnCuNi, Sn, SnCu
and CuSn. However, it has been shown that, although copper contents
of up to 16% may be obtained with these lead-free layers, these
layers do not exhibit satisfactory properties as far as mechanical
load carrying capacity and fatigue strength are concerned.
SUMMARY OF THE INVENTION
[0025] The object of the invention is therefore that of providing a
lead-free composite multilayer material which exhibits at least the
positive characteristics with respect to reliability, emergency
running properties and mechanical load carrying capacity which are
exhibited by conventional lead ternary bearing materials. It is
also the object of the invention to provide a process for producing
bearing shells.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The object is achieved, with regard to the composite
multilayer material, in that the bearing metal layer consists of a
lead-free copper alloy with a copper content of from 50 to 95 wt. %
and in that the overlay consists of a lead-free alloy comprising
tin and copper, the copper content amounting to from 3 to 20 wt. %
and the tin content to from 70 to 97 wt. %.
[0027] Lead-free copper alloys are already known from bush
production (c.f. "Lagerwerkstoffe aufKupferbasis" ("Copper-based
bearing materials") Deutsches Kupferinstitut e.V. 1961) and have
proven effective. However, bushes are exposed to lower mechanical
loads and lower rotational speeds than bearing shells. For this
reason, consideration has not hitherto been given to the use of
these materials for bearing shells. However, it has emerged that
such copper materials are suitable for bearing shells if an overlay
is additionally applied.
[0028] Since it was also necessary to omit lead from the overlay,
there was not complete freedom of choice with regard to the overlay
material to be used in conjunction with the lead-free bearing
material. It has emerged that tin-copper alloys exhibit the best
results in relation to corrosion resistance, load carrying capacity
and embeddability when the copper content is between 5 and 20%.
[0029] The bearing metal layer preferably consists of a
copper-aluminum, copper-tin, copper-zinc, copper-zinc-silicon,
copper-zinc-aluminum or copper-aluminum-iron alloy. Examples are
CuAl8, CuSn8, CuZn33, CuZn31Si, CuZn40Al2 or CuAl10Fe.
[0030] The overlay may contain bismuth and/or silver and/or nickel
each in a proportion of no more than 20 wt. %.
[0031] The overlay may additionally comprise hard particles,
wherein Al.sub.2O.sub.3, Si.sub.3N.sub.4, diamond, TiO.sub.2 or SiC
are possible materials. These hard particles may be included in the
overlay on their own or in combination.
[0032] The diffusion barrier layer may consist of a nickel layer
from 1 to 3 .mu.m thick and a nickel-tin layer from 2 to 10 .mu.m
thick deposited thereon. In another variant the diffusion barrier
layer consists of cobalt, which may likewise have a thickness of
from 1-3 .mu.m.
[0033] The process for producing bearing shells provides that
firstly the bearing metal of lead-free copper material is cast onto
steel strip, wherein it may be necessary to provide wetting agent
layers of nickel, tin or copper on the steel strip depending on the
wettability of the bearing metal melt with respect to the steel
strip. Such layers are produced in electroless manner, by
electroplating or by the molten state method and are preferably
from 1 to 20 .mu.m thick.
[0034] Adjustment of the fine-grained structure of the bearing
metal is effected by a combination of metal working and heat
treatment processes.
[0035] After this thermomechanical treatment of the composite
material, bearing shells are pressed therefrom. The bearing shells
are provided with a diffusion barrier layer of nickel,
nickel/nickel-tin or cobalt and a tin-based lead-free overlay by
electroless chemical or electrochemical processes.
[0036] A ternary, fluoroborate-free electroplating bath is used
from which brighteners are omitted but to which there are added
non-ionic wetting agents and free alkylsulphonic acid, a fatty acid
polyglycol ester and a grain-refining agent comprising a carboxylic
acid also being used.
[0037] Hard material particles are dispersed in the bath especially
to increase wear-resistance. The addition of suitable wetting
agents to the bath makes it possible to codeposit the particles
with the overlay.
[0038] The percentages by volume of the dispersate amount to up to
20%, the particle size amounting on average to .ltoreq.1 .mu.m.
[0039] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is,
therefore, to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
* * * * *