U.S. patent application number 13/257396 was filed with the patent office on 2012-04-12 for method for coating a sliding element and sliding element, in particular a piston ring.
Invention is credited to Marcus Kennedy.
Application Number | 20120088093 13/257396 |
Document ID | / |
Family ID | 41652074 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120088093 |
Kind Code |
A1 |
Kennedy; Marcus |
April 12, 2012 |
METHOD FOR COATING A SLIDING ELEMENT AND SLIDING ELEMENT, IN
PARTICULAR A PISTON RING
Abstract
The invention relates to a method wherein nanoparticle are first
produced and then infused in the coating during the coating process
by means of a PVD and/or CVD method. A sliding element comprises a
coating formed by means of a PVD and/or CVD method comprising
separately produced nanoparticles.
Inventors: |
Kennedy; Marcus;
(Dusseldorf, DE) |
Family ID: |
41652074 |
Appl. No.: |
13/257396 |
Filed: |
December 10, 2009 |
PCT Filed: |
December 10, 2009 |
PCT NO: |
PCT/EP2009/066824 |
371 Date: |
December 5, 2011 |
Current U.S.
Class: |
428/323 ;
106/286.1; 106/286.4; 106/286.5; 427/202; 428/334; 977/773 |
Current CPC
Class: |
C23C 16/303 20130101;
F16J 9/26 20130101; C23C 30/00 20130101; Y10T 428/25 20150115; Y10T
428/263 20150115; C23C 16/34 20130101; C23C 16/308 20130101 |
Class at
Publication: |
428/323 ;
428/334; 106/286.1; 106/286.4; 106/286.5; 427/202; 977/773 |
International
Class: |
B32B 5/16 20060101
B32B005/16; B05D 1/36 20060101 B05D001/36; C23C 16/44 20060101
C23C016/44; B32B 9/00 20060101 B32B009/00; C09D 1/00 20060101
C09D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2009 |
DE |
102009013855.2 |
Claims
1. A method for coating, comprising at least one layer and formed
on at least one outer surface, a sliding element, wherein
nanoparticles are initially produced, and then infused into the
coating during the coating process, which is implemented by means
of a PVD and/or a CVD method, the coating being formed containing a
metal oxynitride.
2. The method according to claim 1, wherein the coating is formed
containing a metal nitride.
3. The method according to claim 1 wherein the coating is formed
containing CrON.
4. The method according to claim 1, wherein the nanoparticles
comprise up to 20 volume % of the coating.
5. The method according to claim 1, wherein the coating is formed
such that the nanoparticles are 1 to 100 nm in size.
6. The method according to claim 1, wherein the coating is formed
such that the nanoparticles are chosen from the group of oxides,
carbides and/or silicides, and one or more of the compounds
comprise Me.sub.xO.sub.y, Me.sub.xC.sub.y and Me.sub.xSi.sub.y with
Me: Cr, Ti, Ta, Si, In, Sn, Al, W, V, Mo and/or x=1 to 3 and/or Y=1
to 3.
7. The method according to claim 1, wherein the coating is formed
with a total thickness of up to about 100 .mu.m.
8. The method according to claim 1, wherein the coating is formed
over cast iron or steel as the base material of the sliding
element.
9. A sliding element with a coating comprising at least one layer,
formed by means of a PVD and/or a CVD method, on at least one outer
surface, which has separately produced nanoparticles, wherein the
coating contains a metal oxynitride.
10. The sliding element according to claim 9, wherein the coating
contains a metal nitride.
11. The sliding element according to claim 9, wherein the coating
contains CrON.
12. The sliding element according to claim 9, wherein the
nanoparticles comprise of up to 20 volume % of the coating.
13. The sliding element according to claim 9, wherein the
nanoparticles are 1 to 100 nm in size.
14. The sliding element according to claim 9, wherein the
nanoparticles are chosen from the group of oxides, carbides and/or
silicides, and one or more of the compounds comprise
Me.sub.xO.sub.y, Me.sub.xC.sub.y and Me.sub.xSi.sub.y with Me: Cr,
Ti, Ta, Si, In, Sn, Al, W, V, Mo and/or x=1 to 3 and/or Y=1 to
3.
15. The sliding element according to claim 9, wherein the whole
thickness of the coating is up to about 100 .mu.m.
16. The sliding element according to claim 9, wherein the base
material of the sliding element comprises cast iron or steel.
17. The method of claim 1, wherein the sliding element is a piston
ring.
18. The method of claim 2, wherein the metal nitride is selected
from at least one of CrN, AlN or TiN.
19. The method of claim 5, wherein the nanoparticles are 5 to 75 nm
in size.
20. The method of claim 5, wherein the nanoparticles are 5 to 50 nm
in size.
21. The method of claim 7, wherein the total thickness is 5 to 50
.mu.m.
22. The sliding element of claim 9, comprising a piston ring.
23. The sliding element of claim 10, wherein the metal nitride
comprises at least one of CrN, AlN or TiN.
24. The sliding element of claim 13, wherein the nanoparticles are
5 to 75 nm in size.
25. The sliding element of claim 13, wherein the nanoparticles are
5 to 50 nm in size.
26. The sliding element of claim 15, wherein the total thickness is
5 to 50 .mu.m.
Description
TECHNICAL DOMAIN
[0001] The invention relates to a method for coating a sliding
element and a sliding element, in particular a piston ring. It is a
requirement for sliding elements, such as piston rings, that they
only ever bring about small friction losses. For example, with
piston rings acting as sliding elements in internal combustion
engines, an increase in friction has a direct effect upon fuel
consumption. Furthermore, oil consumption is affected by the
condition of the piston rings. In particular, with regard to this,
the so-called burn mark strength and outbreak strength, which must
be particularly high in order to permanently realise the required
friction values, are to be observed.
PRIOR ART
[0002] As previously used items piston rings are known which are
coated by means of PVD methods on a hard material base, in
particular chromium nitride. Furthermore, the electrochemical
deposition of chromium layers associated with the incorporation of
A1203 or diamond particles, the size of which comes within the
micrometre range, is known.
[0003] A DLC (diamond-like carbon) coating system, that can include
tungsten carbide depositions in nanocrystalline form, which are
produced during the separation process and are up to 10 nm in size,
is revealed by WO 2007/079834 A1.
[0004] Finally, DE 199 58 473 A1 relates to a method for producing
composite layers with a plasma beam source, wherein nanocrystalline
particles can be embedded, and that can be combined with known,
separately controllable CVD or PVD methods.
DESCRIPTION OF THE INVENTION
[0005] The object forming the basis of the invention is to make
available a method for coating a sliding element and a
corresponding sliding element with which the required friction and
wear and tear properties can be realised over the required life
span.
[0006] This object is achieved by means of the method described in
claim 1.
[0007] Therefore, the invention proposes a method for coating,
comprising at least one layer and formed on at least one outer
surface, a sliding element, in particular a piston ring, wherein
nanoparticles are initially produced, and then infused into the
coating during the coating process. In other words, the
nanoparticles are not produced in situ, i.e. during the coating
process, but they are produced separately, to a certain extent ex
situ, and incorporated into the coating during the coating process.
The mechanism which can be used in this way and which leads to
improved mechanical properties, such as fatigue strength, burn mark
strength, outbreak strength, breaking strength and elongation at
rupture, functions as follows according to the current state of
knowledge. It is also noted that the invention is not restricted to
this. The incorporation of the described particles gives rise to
local crystal lattice deformations which lead to the
aforementioned, improved mechanical properties. Furthermore, an
improvement of the wear and tear characteristics due to the
exceptionally high grain limit density and increased elasticity and
less friction are achieved.
[0008] The advantages of the infused nanoparticles can also be made
use of in the dispersion or precipitation hardening to be
implemented. That is to say, the displacements produced when
stressed or already existing cannot be worked or "cut" through by
the particles or the depositions, but bulge out to a certain extent
between the particles. In this way, displacement rings are formed
which must be bypassed by the displacements. With this bypassing,
higher energy is required than when the latter are "cut through" by
the particles or depositions. The loading capacity is thus
increased. Furthermore, the invention advantageously further makes
use of the effect that the yield stress for the migration of the
displacements increases as the particle spacing decreases and the
particle size decreases. The material strength increases due to
this. This effect can be obtained particularly well with
nanoparticles. Furthermore, it has been shown within the scope of
the invention that upon the basis of their high defect density on
the surface, the latter can be infused and incorporated practically
independently of the material to be reinforced during the coating
process. In this way, the desired depositions, which can be
incoherent, partially coherent or coherent, and have the effects
described above with regard to the mechanical properties, can
advantageously be formed. The production of the nanoparticles ex
situ advantageously further guarantees that the chemical and
crystallographic structure of the nanoparticles can be controlled.
Furthermore, by means of this control, when producing the
nanoparticles it can be guaranteed that the latter can be infused
into the layer hereby growing during the coating process in the
desired manner.
[0009] The coating as such is advantageously implemented by means
of tried and tested PVD (physical vapour deposition) and/or CVD
(chemical vapour deposition) coating processes.
[0010] Advantageous further developments of the method according to
the invention are described in the further claims.
[0011] For the base material or the matrix of the coating a
material that contains nitrides, in particular metal (oxy)nitrides,
and in particular Cr(O)N, AlN or TiN, has proven to be particularly
advantageous.
[0012] In initial trials it transpired that a volume portion of the
nanoparticles of 20% or less leads to good properties.
[0013] Furthermore, one was able to have good experiences with
nanoparticles which have a particle size (diameter) of 1 to 100 nm,
preferably 5 to 75 and in particular 5 to 50 nm.
[0014] For the nanoparticles compounds from the group of oxides,
carbides and/or silicides with the composition Me.sub.xO.sub.y,
Me.sub.xC.sub.y or Me.sub.xSi.sub.y are preferred. The metal here
can be chromium, titanium, tantalum, silicon, indium, tin,
aluminium, tungsten, vanadium or molybdenum, and/or x can be 1 to 3
and/or y can be 1 to 3.
[0015] With regard to the layer thickness, particularly good
properties have been determined with a coating thickness of max.
100 .mu.m, and preferably in the range of 5 to 50 .mu.m.
[0016] Even though the coating according to the invention can be
used in many different ways, due to the proven properties it is
currently preferred if the base material, i.e. the coating material
of the sliding element to be coated according to the invention, is
cast iron or steel.
[0017] The aforementioned object is achieved, furthermore, by the
sliding element described in claim 9, wherein this is particularly
a piston ring. The preferred embodiments of the sliding element
according to the invention correspond to those of the method
according to the invention for producing the latter. This applies
in the same way to the advantages that occur, which lie in
particular in a permanent sliding element permanently having the
required friction values and wear and tear properties.
[0018] For the preferred case of a piston ring, it is mentioned
that as sliding surfaces, one or more faces, i.e. the upper and/or
the lower side and/or the contact surface, i.e. the outer cylinder
surface of the piston ring, can be coated. The contact surface can
be coated more thickly with the coating according to the invention
with incorporated, separately produced nanoparticles than at least
one of the faces. The cross-over between the contact surface and at
least one face can be rounded on the coating, in the same way as
this cross-over on the base material of the piston ring can be
rounded. The coating of both faces can be of the same thickness. In
particular applications also only the contact surface can be
coated.
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