U.S. patent application number 14/762517 was filed with the patent office on 2015-12-17 for controlled thermal coating.
The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Karsten BARAUTZKI, Mario FELKEL, Sascha Martin KYECK, Johannes RICHTER, Rolf WILKENHONER.
Application Number | 20150361541 14/762517 |
Document ID | / |
Family ID | 47681677 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150361541 |
Kind Code |
A1 |
WILKENHONER; Rolf ; et
al. |
December 17, 2015 |
CONTROLLED THERMAL COATING
Abstract
The combined measurement of particle speed, particle
temperature, particle intensity, burner current and the control
thereof within a tolerance range allow the coating structure,
coating thickness and the coating weight to be maintained despite
wear-associated fluctuations in the coating process.
Inventors: |
WILKENHONER; Rolf;
(Kleinmachnow, DE) ; BARAUTZKI; Karsten;
(Schonwalde, DE) ; FELKEL; Mario; (Berlin, DE)
; KYECK; Sascha Martin; (Berlin, DE) ; RICHTER;
Johannes; (Berlin, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munchen |
|
DE |
|
|
Family ID: |
47681677 |
Appl. No.: |
14/762517 |
Filed: |
January 20, 2014 |
PCT Filed: |
January 20, 2014 |
PCT NO: |
PCT/EP2014/051038 |
371 Date: |
July 22, 2015 |
Current U.S.
Class: |
427/8 |
Current CPC
Class: |
C23C 4/134 20160101;
C23C 4/129 20160101 |
International
Class: |
C23C 4/12 20060101
C23C004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2013 |
EP |
13152230.2 |
Claims
1. A method for thermal coating by means of a material flow (42) by
means of a nozzle (30), in particular by means of a powder flow, in
which a material (M.sub.xy) of the material flow (42) is heated,
partially melted and/or melted, in particular by means of a plasma
or a flame, in which at least one of the target variables (Z.sub.1,
Z.sub.2, Z.sub.3, . . . ) material flow velocity (v.sub.P) of the
material flow (42) and/or brightness distributions (H(x,y);
.intg.H(x y)dxdy) or temperature distribution (T(x,y);
.intg.T(x,y)dxdy) of the material flow (42) and/or voltage
(U.sub.B) between an electrode (36) and the nozzle (30) and/or the
power (P) of the nozzle (30) are measured or determined and
controlled.
2. The method as claimed in claim 1, in which a brightness
distribution (H(x,y);) .intg.H(x,y)dxdy) of the material flow (42)
or the voltage (U.sub.B) between the nozzle (30) and the electrode
(36) or the power (P) at the nozzle (30) are controlled as at least
one target variable (Z.sub.1, Z.sub.2, Z.sub.3, . . . ).
3. The method as claimed in claim 1, in which, as target variables
(Z.sub.1, Zd.sub.2), either the material flow velocity (v.sub.P)
and the voltage (U.sub.B) between the nozzle (30) and the electrode
(36) or the material flow velocity (v.sub.P) and the power (P) at
the nozzle (30) are controlled.
4. The method as claimed in claim 1, in which, as target variables
(Z.sub.1, Z.sub.2), a brightness distribution (H(x,y); .intg.H(x
y)dxdy) of the material flow (42) and the material flow velocity
(v.sub.P) are controlled.
5. The method as claimed in claim 1, in which, as target variables
(Z.sub.1, Z.sub.2), a temperature distribution (T(x,y);
.intg.'T(x,y)dxdy) of the material flow (42) and the material flow
velocity (v.sub.P) are controlled.
6. The method as claimed in claim 1, in which, as target variables
(Z.sub.1, Z.sub.2, Z.sub.3), either a temperature distribution
(T(x,y); .intg.T(x,y)dxdy) of the material flow (42), the material
flow velocity (v.sub.P) and the voltage (U.sub.B) between the
nozzle (30) and the electrode (36) or a temperature distribution
(T(x,y); .intg.T(x,y)dxdy) of the material flow (42), the material
flow velocity (v.sub.P) and the power of the nozzle (30) are
controlled.
7. The method as claimed in claim 1, in which, as target variables
(Z.sub.1, Z.sub.2, Z.sub.3), either the brightness distribution
(H(x,y); .intg.H(x,y)dxdy) of the material flow (42), the material
flow velocity (v.sub.P) and the voltage (U.sub.B) between the
nozzle (30) and the electrode (36) or the brightness distribution
(H(x,y); .intg.H(x,y)dxdy) of the material flow (42), the material
flow velocity (v.sub.P) and the power (P) at the nozzle (30) are
controlled.
8. The method as claimed in one or more of claim 1, 2, 3, 4, 5, 6
or 7, in which the current intensity (I.sub.B) between the nozzle
(30) and the electrode (36) and/or the gas flow rates ({dot over
(m)}.sub.H2, {dot over (m)}.sub.Ar) of the nozzle (30) are varied
as control variables (R1, R2, R3), in order to keep the target
variables (Z1, Z2, Z3) such as the brightness distribution (H(x,y);
.intg.H(x,y)dxdy) of the material flow (42) or the temperature
distribution (T(x,y); .intg.T(x,y)dxdy, of the material flow (42)
or the voltage (U.sub.B) at the nozzle (30) or the power (P) at the
nozzle (30) and/or the material flow velocity (v.sub.P) in a
specific tolerance range or constant.
9. The method as claimed in one or more of claims 1 to 8, in which
the current intensity (I.sub.B) is increased or lowered as a
control variable (R1, R2, R3).
10. The method as claimed in one or more of claims 1 to 9, in which
the gas flow rate ({dot over (m)}.sub.Ar, {dot over (m)}.sub.H2) of
the primary gases (argon, helium) and/or of the secondary gases
(hydrogen, . . . ) of the nozzle (30) are increased or lowered as
at least one control variable (R1, R2, R3).
11. The method as claimed in one or more of claims 1 to 10, in
which the material flow rate ({dot over (m)}.sub.m) is not varied
during the coating.
12. The method as claimed in one or more of claims 1 to 11, in
which the temperature distribution (T(x,y)) of the material flow
(42) is used as the temperature.
13. The method as claimed in one or more of claims 1 to 11, in
which an integral value (.intg.T(x,y)dxdy) of the material flow
(42) is used as the temperature of the material flow (42).
14. The method as claimed in one or more of claims 1 to 11, in
which an integral value (.intg.H(x,y)dxdy) of the material flow
(42) is used as the brightness value.
15. The method as claimed in one or more of claims 1 to 11, in
which the brightness distribution (.intg.H(x,y)dxdy) of the
material flow (42) is used as the brightness value.
16. The method as claimed in one or more of claim 1 to 11, 14 or
15, in which the light intensity or radiation power of the material
flow (42) is used as the brightness value (H).
17. The method as claimed in one or more of claims 1 to 16, in
which an HVOF method is used.
18. The method as claimed in one or more of claims 1 to 16, in
which a plasma spraying method is used.
19. The method as claimed in one or more of claims 1 to 18, in
which, before the coating, proceeding from one and/or more initial
values of the control variables (R1, R2, R3) at which the desired
target variables (Z1, Z2, Z3) are achieved and/or maintained, sets
of parameters for various constellations, such as higher, lower and
constant, of the control variables (R1, R2, R3) are set, and the
variations in the target variables (Z1, Z2, Z3) are determined,
these then being used later for control.
Description
[0001] The invention relates to a thermal coating process. Thermal
spraying processes are used for producing metallic and ceramic
layers, in which a material melts completely or at least
partially.
[0002] The material is injected into a nozzle, for example of a
plasma torch, or externally. The nozzle, at least, becomes worn
owing to very high plasma temperatures and the inflow of powder
material. This leads to wear-related fluctuations in the coating
process, which are caused primarily by a drop in voltage at the
torch.
[0003] To date, these fluctuations have been compensated for by
readjusting the powder mass flow, in order to keep the desired
layer weight of the blade or vane in the tolerance range.
[0004] This is not optimal, however, since merely the drop in power
at the torch which is induced by the drop in voltage is compensated
for by an increase in the powder mass flow.
[0005] It is an object of the invention, therefore, to solve the
aforementioned problem.
[0006] The object is achieved by a method as claimed in claim
1.
[0007] The dependent claims list further advantageous measures
which can be combined with one another, as desired, in order to
obtain further advantages.
[0008] In the drawings:
[0009] FIGS. 1-3 show parameter profiles from the prior art,
[0010] FIGS. 4-9 show parameter profiles according to the
invention,
[0011] FIG. 10 shows a nozzle,
[0012] FIGS. 11, 12 show a temperature distribution,
[0013] FIG. 13 shows a turbine blade or vane.
[0014] The description and the figures represent only exemplary
embodiments of the invention.
[0015] Coatings are applied by thermal coating processes such as
SPPS, HVOF, APS, LPPS, VPS, . . . . In these processes, a plasma or
a flame is generated in a nozzle, a material flowing in through the
nozzle or at the end of the nozzle.
[0016] The wear on the nozzle or on the coating apparatus causes
the material flow properties and therefore also the degree of
melting of the material, in particular of the powder, to
change.
[0017] FIG. 1 shows an exemplary profile of the voltage U.sub.B
between the nozzle 30 and an electrode 36 (FIG. 10) according to
the prior art.
[0018] The voltage U.sub.B between the nozzle 30 and the electrode
drops over time t and then merges into saturation. In the case of
other types of nozzle, a continuous drop in the voltage U.sub.B
over time t or other profiles are also possible.
[0019] The profile of the average temperatures T and of the average
material flow velocity v.sub.P (not shown) over time is
analogous.
[0020] As an effect of this, the layer weight m.sub.c decreases
over time (FIG. 2) and/or the porosity p (FIG. 3) increases.
[0021] The properties of the flame or of the plasma and/or of the
molten material, which emerge from the nozzle 30 during the thermal
coating, in particular during the plasma coating or HVOF coating,
are therefore determined according to the invention.
[0022] In this respect, what are determined are target values Z1,
Z2, Z3, such as in particular of the voltage U.sub.B between the
nozzle and the electrode 36 or the power P at the nozzle 30,
material flow velocity v.sub.P, the temperature T.sub.P of the
material flow 42 and/or a brightness distribution H(x,y) or
temperature distribution T(x,y), where H=light intensity or
radiation power of the particles Mxy in the material flow 42. This
is effected by measuring instruments, which determine quantitative
data by way of pyrometry or CCD cameras.
[0023] If deviations are thus identified during the measurement, it
can be concluded that wear has occurred, and parameters R1, R2, R3
for varying the target variables Z1, Z2, Z3 are accordingly set,
such that the desired target values of Z1, Z2, Z3 are achieved
again.
[0024] The target values (Z1, Z2, Z3) are controlled through the
adaptation of the control variables (R1, R2, R3), here the current
intensity I.sub.B of the nozzle 30, and the flow rates of the
primary and/or secondary gases in H.sub.2, in A.sub.r at the nozzle
30, by virtue of which the target parameters Z1, Z2, Z3 can be set
in a targeted manner.
[0025] Primary gases are argon (Ar) and/or helium (He) and
secondary gas is, for example, hydrogen (H.sub.2), these flowing
through the nozzle 30.
[0026] Use may be made of one, two or three control variables,
proceeding from an optimum desired state for Z1, Z2, Z3 for the
three control variables R1, R2, R3 used here.
[0027] Proceeding from the control variables R1, R2, R3, with which
the target variables Z1, Z2, Z3 are observed, parameter sets K1,
K2, . . . , with which the control variables R1, R2, R3 are
simultaneously or partially increased (>1.0) or reduced
(<1.0) or remain constant (1.0), are determined beforehand.
[0028] Here, 1.0 represents a nominated value for R1, R2, R3, . . .
, that is the set value divided by the initial state of R1, R2,
[0029] The values 1.1; 0.9 correspondingly represent a
corresponding increase or reduction of R1, R2, . . .
TABLE-US-00001 R1 R2 R3 K1 1.1 1.1 1.1 K2 1.1 1.0 1.0 K3 1.1 1.0
1.1 K4 1.1 1.0 0.9 K5 0.9 0.9 0.9 K6 0.9 1.1 1.0 K7 . . . . . . . .
.
[0030] On account of these increases and/or variations in the
control variables R1, R2, R3, the varied values of the, preferably
three, target variables Z.sub.1, Z.sub.2, Z.sub.3 used here are
then determined:
TABLE-US-00002 R1 R2 R3 Z1 Z2 Z3 K1 1.1 1.1 1.1 1.2 0.8 0.8 K2 1.1
1.0 1.0 1.2 1.2 1.2 K3 1.1 1.0 1.1 1.2 1.2 1.2 K4 1.1 1.0 0.9 1.2
1.2 1.2 K5 . . . . . . . . . . . . . . . . . .
[0031] The values 1.1; 0.9; 1.0 correspondingly represent a
corresponding increase, reduction or no variation in the
standardized values of Z1, Z2, . . .
[0032] The variations in the target variables Z1, Z2, Z3, here the
particle temperature T.sub.P, voltage U.sub.B, power P and particle
velocity, depend on the respective nozzle 30.
[0033] It is similarly possible to record a data table only with
higher (.uparw.) and lower (.dwnarw.) values for R1, R2, . . . ,
i.e. no constant values (-) for the control variables.
TABLE-US-00003 R1 R2 R3 Z1 Z2 Z3 K1 1.1 1.1 1.1 1.2 0.8 0.8 K8 1.1
1.1 0.8 1.2 1.2 1.3 K9 1.1 0.9 1.1 1.2 1.1 1.1 K10 0.9 1.1 0.9 1.2
1.2 1.2 K11 .cndot. .cndot. .cndot. .cndot. .cndot. .cndot.
[0034] It is similarly possible to formulate the higher (1.0) or
lower (0.9) values of R1, R2, R3 with different magnitudes and to
determine the effect on the target variables Z1, Z2, Z3:
[0035] K1: R2 has greater variations on a percentage basis than R1,
R3; K2: R1 has greater variations on a percentage basis than R2,
R3; K4: R3 smaller than R1, R2.
TABLE-US-00004 R1 R2 R3 Z1 Z2 Z3 K12 1.1 1.2 1.1 1.1 0.9 0.9 K13
1.2 1.1 1.1 1.1 1.4 1.2 K14 1.1 1.1 1.1 1.1 1.1 1.1 K15 1.1 1.0 0.8
1.1 1.1 1.1
[0036] These parameter sets K1, . . . determined in advance are
then used for control if a deviation occurs for Z1, Z2, Z3.
[0037] If the value deviates from Z1, Z2, . . . , it is determined
which combination K1, K2, . . . of Z1, Z2, Z3 comes closest to the
deviation, if appropriate a best-fit adaptation is carried out, and
the control values R1, R2, R3 of this combination K1, K2, . . .
thus found are then used for the further operation of the nozzle 30
and electrode 36, in order to compensate for the deviations.
[0038] As a result of this control, the layer structure, the layer
thickness and the layer weight m.sub.c (FIG. 6) of the blade or
vane and also the porosity p (FIG. 7) remain constant over time
t.
[0039] As a result of the current intensity I.sub.B being
controlled (FIG. 4), the power P is kept relatively constant (FIG.
5). This is then also identifiable from the constant values of the
particle temperatures and the particle velocities V.sub.P (not
shown).
[0040] FIG. 10 shows a nozzle 30, in which argon (Ar) or helium
(He) are introduced as primary gas and/or hydrogen (H.sub.2) is
introduced as secondary gas at one nozzle end 31, and at the other
end 33 material (Mx,y) is added.
[0041] By virtue of the application of the voltage U.sub.B between
the electrode 36 and the nozzle 30, a high-energy arc generates a
plasma, which forms the plasma flame.
[0042] Similarly, it is possible for the gas flow rates {dot over
(m)}.sub.G of argon {dot over (m)}.sub.Ar (FIG. 8) and also those
of hydrogen {dot over (m)}.sub.H2 (FIG. 9) at the nozzle 30 to be
controlled, in order to achieve the desired results, in particular
for the voltage U.sub.B.
[0043] FIG. 11 shows a distribution 36 of the temperature T(x,y) or
of the brightness H(x,y) in the outflow direction z of the material
flow 42.
[0044] Here, there is a hottest, inner core 39' and regions 39'',
39''' which are located further outward and are less hot. The
presence of a plurality of regions 39', 39'', 39''' is only
schematic here in respect of a continuous drop or variation in the
temperature or brightness.
[0045] FIG. 12 is a lateral view of the material flow 42 and the
brightness distribution H(x,y) thereof or the temperature
distribution T(x,y) thereof.
[0046] In this lateral view, the brightness values in the x
direction are added up for a y position.
[0047] The brightness H(x,y) is determined by all particles
M.sub.xy along the x direction for a position y and the temperature
T of the particles M.sub.xy, since not only do the outer particles
radiate in the region 39''', but also the inner particles radiate
outward in the region 39' and are sensed.
[0048] The temperature T(x,y) is instead determined only by the
outer particles in the region 39'''.
[0049] It is also possible for an integral value R of an area
.intg.H(x,y)dxdy to be determined over the plan view shown in FIG.
11 or FIG. 12, and an individual integral brightness value R is
formed.
[0050] This value R can be used for control.
[0051] If deviations are identified in this integral value R,
control occurs.
[0052] It is similarly possible for an integral temperature value
R=.intg.'T(x,y)dxdy to be determined over the cross section shown
in FIG. 12 or FIG. 11 for the control.
[0053] This integral, singular value R then also represents a
control variable Z.
[0054] Similarly, it is possible for a visual comparison to be made
at various times between two images of FIGS. 11 and 12 for the
temperature distribution T(x,y) or brightness distribution H(x,y),
and for deviations to be determined.
[0055] If deviations are identified, control likewise occurs.
[0056] The material flow rate {dot over (m)}.sub.M of the material
flow is in this case preferably not varied during the control.
[0057] FIG. 13 shows a perspective view of a rotor blade 120 or
guide vane 130 of a turbomachine, which extends along a
longitudinal axis 121.
[0058] The turbomachine may be a gas turbine of an aircraft or of a
power plant for generating electricity, a steam turbine or a
compressor.
[0059] The blade or vane 120, 130 has, in succession along the
longitudinal axis 121, a securing region 400, an adjoining blade or
vane platform 403 and a main blade or vane part 406 and a blade or
vane tip 415.
[0060] As a guide vane 130, the vane 130 may have a further
platform (not shown) at its vane tip 415.
[0061] A blade or vane root 183, which is used to secure the rotor
blades 120, 130 to a shaft or a disk (not shown), is formed in the
securing region 400.
[0062] The blade or vane root 183 is designed, for example, in
hammerhead form. Other configurations, such as a fir-tree or
dovetail root, are possible.
[0063] The blade or vane 120, 130 has a leading edge 409 and a
trailing edge 412 for a medium which flows past the main blade or
vane part 406.
[0064] In the case of conventional blades or vanes 120, 130, by way
of example solid metallic materials, in particular superalloys, are
used in all regions 400, 403, 406 of the blade or vane 120,
130.
[0065] Superalloys of this type are known, for example, from EP 1
204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO
00/44949.
[0066] The blade or vane 120, 130 may in this case be produced by a
casting process, by means of directional solidification, by a
forging process, by a milling process or combinations thereof.
[0067] Workpieces with a single-crystal structure or structures are
used as components for machines which, in operation, are exposed to
high mechanical, thermal and/or chemical stresses. Single-crystal
workpieces of this type are produced, for example, by directional
solidification from the melt. This involves casting processes in
which the liquid metallic alloy solidifies to form the
single-crystal structure, i.e. the single-crystal workpiece, or
solidifies directionally. In this case, dendritic crystals are
oriented along the direction of heat flow and form either a
columnar crystalline grain structure (i.e. grains which run over
the entire length of the workpiece and are referred to here, in
accordance with the language customarily used, as directionally
solidified) or a single-crystal structure, i.e. the entire
workpiece consists of one single crystal. In these processes, a
transition to globular (polycrystalline) solidification needs to be
avoided, since non-directional growth inevitably forms transverse
and longitudinal grain boundaries, which negate the favorable
properties of the directionally solidified or single-crystal
component.
[0068] Where the text refers in general terms to directionally
solidified microstructures, this is to be understood as meaning
both single crystals, which do not have any grain boundaries or at
most have small-angle grain boundaries, and columnar crystal
structures, which do have grain boundaries running in the
longitudinal direction but do not have any transverse grain
boundaries. This second form of crystalline structures is also
described as directionally solidified microstructures
(directionally solidified structures).
[0069] Processes of this type are known from U.S. Pat. No.
6,024,792 and EP 0 892 090 A1.
[0070] The blades or vanes 120, 130 may likewise have coatings
protecting against corrosion or oxidation, e.g. (MCrAlX; M is at
least one element selected from the group consisting of iron (Fe),
cobalt (Co), nickel (Ni), X is an active element and stands for
yttrium (Y) and/or silicon and/or at least one rare earth element,
or hafnium (Hf)). Alloys of this type are known from EP 0 486 489
B1, EP 0 786 017 B1, EP 0 412 397 B1 or EP 1 306 454 A1.
[0071] The density is preferably 95% of the theoretical density. A
protective aluminum oxide layer (TGO=thermally grown oxide layer)
is formed on the MCrAlX layer (as an intermediate layer or as the
outermost layer).
[0072] The layer preferably has a composition
Co-30Ni-28Cr-8Al-0.6Y-0.7Si or Co-28Ni-24Cr-10Al-0.6Y. In addition
to these cobalt-based protective coatings, it is also preferable to
use nickel-based protective layers, such as Ni-10Cr-12Al-0.6Y-3Re
or Ni-12Co-21Cr-11Al-0.4Y-2Re or Ni-25Co-17Cr-10Al-0.4Y-1.5Re.
[0073] It is also possible for a thermal barrier coating, which is
preferably the outermost layer and consists for example of
ZrO.sub.2, Y.sub.2O.sub.3--ZrO.sub.2, i.e. unstabilized, partially
stabilized or fully stabilized by yttrium oxide and/or calcium
oxide and/or magnesium oxide, to be present on the MCrAlX.
[0074] The thermal barrier coating covers the entire MCrAlX layer.
Columnar grains are produced in the thermal barrier coating by
suitable coating processes, such as for example electron beam
physical vapor deposition (EB-PVD).
[0075] Other coating processes are possible, e.g. atmospheric
plasma spraying (APS), LPPS, VPS or CVD. The thermal barrier
coating may include grains that are porous or have micro-cracks or
macro-cracks, in order to improve the resistance to thermal shocks.
The thermal barrier coating is therefore preferably more porous
than the MCrAlX layer.
[0076] Refurbishment means that, after they have been used,
protective layers may have to be removed from components 120, 130
(e.g. by sand-blasting). Then, the corrosion and/or oxidation
layers and products are removed. If appropriate, cracks in the
component 120, 130 are also repaired. This is followed by recoating
of the component 120, 130, after which the component 120, 130 can
be reused.
[0077] The blade 120, 130 may be hollow or solid in form. If the
blade 120, 130 is to be cooled, it is hollow and may also have
film-cooling holes 418 (indicated by dashed lines).
* * * * *