CA2039944C - High speed flame spraying process having particle velocity of at least 300 m/s - Google Patents
High speed flame spraying process having particle velocity of at least 300 m/s Download PDFInfo
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- CA2039944C CA2039944C CA002039944A CA2039944A CA2039944C CA 2039944 C CA2039944 C CA 2039944C CA 002039944 A CA002039944 A CA 002039944A CA 2039944 A CA2039944 A CA 2039944A CA 2039944 C CA2039944 C CA 2039944C
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- blades
- coating
- protective coating
- compressor
- undergo
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/002—Cleaning of turbomachines
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
- C23C4/06—Metallic material
- C23C4/067—Metallic material containing free particles of non-metal elements, e.g. carbon, silicon, boron, phosphorus or arsenic
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
- F01D5/288—Protective coatings for blades
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Plasma & Fusion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Coating Apparatus (AREA)
Abstract
In a process for coating the blades of a rotating, thermal machine, said blades undergo a first cleaning process in the operating state of the machine, i.e. "on line", the appropriate agent fox this, which depends on whether the blades are uncoated or coated, being mixed in with the air stream to the compressor.
After switching off the machine and opening the same, the blades undergo in the stationary state, that is to say in the bladed state of the corresponding rotor or stator, a preparation process for the subsequent treatment stage. According to requirements, this preparation process may, for example, consist in the blades being immersed in a vibrating erosive bath. The actual coating of the blades takes place by means of a high-speed flame spraying process, in which the protective coating is sprayed onto the surface of the base material at a particle velocity of at least 300 m/s. Thereafter, the blades also undergo an after-treatment which, according to requirements, serves to reduce the surface roughness and/or is provided to apply a top coating.
After switching off the machine and opening the same, the blades undergo in the stationary state, that is to say in the bladed state of the corresponding rotor or stator, a preparation process for the subsequent treatment stage. According to requirements, this preparation process may, for example, consist in the blades being immersed in a vibrating erosive bath. The actual coating of the blades takes place by means of a high-speed flame spraying process, in which the protective coating is sprayed onto the surface of the base material at a particle velocity of at least 300 m/s. Thereafter, the blades also undergo an after-treatment which, according to requirements, serves to reduce the surface roughness and/or is provided to apply a top coating.
Description
HIGH SPEED FLAME SPRAYING PROCESS HAVING
PARTICLE VELOCITY OF AT LEAST 300 m/s BACKGROUND OF THE INVENTION
s Field of the Invention The present invention relates to a process for coating blades of a rotating thermal machine.
Discussion of Background For example in the open gas turbine process, the ~o air taken in by the compressor also contains water vapor and solid and gaseous impurities. These have an adverse effect due to erosion, soiling and corrosion. Some of the deposits on the blades have a considerable concentration of corrosively acting constituents such as NaCl and KC1. The salts cause not only high-temperature corrosion on the turbine blading but also increased pitting corrosion in the compressor region and a complex chemical reduction in the strength of the blade material. In the case of high atmospheric humidity, there occurs in the region of the zo compressor intake a concentration of water vapor, which explains the greater degree to which corrosion attacks the front rows of blades. In order to overcome this problem to a certain extent, blades of rotating thermal machines are often provided with protective coatings. These are used zs both in the case of steam and gas turbine blades and in the case of compressor blades. Thus, the main objective is to increase the resistance to corrosion and oxidizing attacks as well as to erosion and abrasion (wear). If, in spite of surface treatment, the blades do exhibit damage of a degree 3o which could endanger operational reliability, the next step is to proceed to remove the blades: either they are replaced by new ones or reconditioned and refitted. This removal and fitting entails relatively high costs and time spent. Furthermore, the true condition of the blading is 35 only evident after a relatively long time, i.e. after precleaning, and therefore the decision as to whether ~cn reconditioning of the blades is ~feas'~~'~b~l~ '~ or not, or already necessary, can only be taken much later. The disadvantages of this method are the great time losses, the high operating costs of the installation, higher costs for inspections and the uncertainty over the question of the reconditionability of the blades.
Therefore, the tendency has been instead to look for ways and means of remedying this situation. In this context, a process has become known by which the entire bladed rotor is lifted out of the stator in order to be reconditioned in a separate installation. The bladed rotors to be coated must be degreased in a suitable way, any organic coatings which may have been applied at an earlier time must be completely removed.
Subsequently, the areas to be coated are roughened by dry sand blasting with aluminum oxide and the metallic surface activated. The zones not to be coated must be masked with suitable materials. Thereafter, the undercoats are applied, each having to be fired. This results in a laborious procedure: a sintering process or firing process takes about 55 hours and, on average, has to be carried out four times. This sintering or firing process during coating comprises a heat treatment at about 350° Celsius over a holding time of about 10-12 hours. In addition, in order to carry out the individual process steps, quite large installations of specific geometric design have to be provided, consider for instance that during the sintering process the entire bladed part of the rotor has to be surrounded by a furnace cover.
SUI~'~IARY OF THE INVENTION
Accordingly, one object of this invention is to provide a process of the type mentioned at the beginning with a more efficient method in terms of the times required and costs expended for the reconditioning of the blades. Another object of the invention is to maximize the service life of the coating by suitable processes and protective coatings.
- 3 - 'J' ~ .'' '' ~ ~a ,~ a o~ ".a4f;,~(~
The essential advantages of the invention are to be seen in that the bladed rotor does not have to be lifted out of its mounting in the stator for the first process of reconditioning: the cleaning or removal of protective coating can be carried out before the actual shutting-down of the machine, i.e. of the compressor, that is to say during a final phase of operation ("on line"). As a result, an even exposure of the blades to be treated is attained, the consequently achieved efficiency of this cleaning process, which ensures extensive removal of any protective coating there may be, permitting an immediate decision on the reconditionability of the blades. This decision can be made already after shutting down the machine and ,..
removing the upper part of the stator. If, after appropriate analysis of the condition of the blades, it is decided to recondition them, it is sufficient to lift the bladed rotor out of the mount and place it on blocks, where the further process steps of reconditioning can be carried out without the aid of a sophisticated structure. This leads to low operating costs (overhauling costs), which means that there is nothing to prevent this type of treatment being carried out periodically. Consequently, the operational reliability of the installation is increased.
A further significant advantage of the invention is to be seen in that, by using a high-speed flame spraying process, the blades, pretreated in the fitted state, receive an appropriate protective coating, preferably Si and A1 based, just where and when needed, it being possible for this coating process to be carried out without lengthy heat treatment and without the aid of special additional equipment, This simplifies the entire technical coating procedure, while the costs are lower by about half than in the case of the known, processes. In addition, the service life of this type of coating is much higher than in the case of the coatings currently used for this so-called complete coating. Since the pretreatment of the blades or the after-treatment after spraying on the protective coating is of great significance for the service life of the coating, direct corrective measures can be undertaken s specifically, as found to be required. What is obtained after a very short time with low reconditioning costs by means of a process which is very environmentally friendly is blading of top quality which guarantees the operational reliability of the installation over a prolonged period.
~o According to a broad aspect of the present invention there is provided a process for coating blades of a rotating thermal machine having a compressor. The blades undergo a first cleaning process, in the operating state of the thermal machine, by means of an agent mixed with the air 15 Stream to the compressor for a predetermined time through a centrally placed three-jet nozzle which acts in an intake channel of the compressor. The blades undergo a preparation process for the subsequent treatment stage wherein the blades are treated in an erosive bath after opening the 2o machine in a stationary state. The blades are coated in the stationary state with an aluminium-based protective coating by means of a high-speed flame spraying process which sprays protective coating particles onto the surface of a base material at at least a velocity of 300 m/s. The porosity of 2s the protective coating is below 0.5% and the composition of the coating is one of the following: a) 6 to 15o by weight Si, the remainder being aluminium; b) pure aluminium, c) 80% by weight A1, 5 to 15o by weight Si and the remainder being Cu, Mn, Mg, Ni.
3o Advantageous and expedient further developments of the way in which the object is achieved according to the invention are identified in the further claims.
- 4a -BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference s to the following detailed description when considered in connection with the accompanying drawings, wherein all elements not required for direct understanding of the invention have been omitted and the direction of flow of the various media is indicated by arrows and wherein:
Fig. 1 shows a turbo group with units for a pretreatment stage;
Fig. 2 shows a view of Fig. 1 in the plane II-II;
Fig. 3 shows a cleaning stage or removal of protective coating in a vibrating, erosive bath;
15 Fig. 4 shows a view of the rotor according to Fig.
3 along the plane IV-IV;
Fig. 5 shows a final cleaning process with jet nozzles; and Fig. 6 shows a coating of the blades by a high-2o speed flame spraying process.
- ~y '3 ~1 ~; .~ 4 i~ ~ ap .! .,' ~ :~l i.~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in Figure 1 a conventional gas turbo group 11 is shown, essentially comprising a compressor part lla, a combustion chamber llb and a turbine part llc. In the pretreatment of the blades, a distinction must be drawn between whether, in the original state, they were uncoated or coated.
Irrespective of this precondition, a first cleaning of the blades takes place before shutting down the machine, i.e. the compressor. In the case of coated blades, this cleaning is based preferably on erosion °
abrasion by soft-blasting granules. Of course, the cleaning of uncoated blades can be performed simply by means of an aqueous solvent, for example trichloroethylene. The cleaning agent (soft-blast granules, aqueous solution etc.) is injected into the air stream to the compressor for a certain time through a centrally placed three-jet nozzle 1 (also see Fig. 2 in this respect), which acts in the intake channel of the compressor. The even and intensive exposure 12 of the compressor blades produces an efficient cleaning process in the case of uncoated blades or an extensive removal of the old protective coating in the case of coated blades. The cleaning process is repeated several times, as required. Since the soft-blasting granules burn at temperatures of about 300 degrees Celsius, there are no problems in this respect with regard to disposal. If an aqueous solution is used, consideration likewise has to be given to these aspects. The control arrangement for the multi-jet nozzle 1 consists of a ball cock 2, which is connected downstream, in the direction of flow of the cleaning agent, of a mixing chamber 3 and serves for controlling the rate of flow.
The pressure in this mixing chamber 3 is displayed by a pressure gauge 7. Provided upstream of the mixing chamber 3 is a tank 4, in which for example granules '' t~ ~i ~'1 i: ~ p 0 ' L :i ~.~ ~S ~~ l.~
are stored, a screen 5 and an inlet valve 6 ensuring that the mixing chamber 3 is supplied with homogeneous material. The required pressure in the tank 4 is provided by means of an air feed line 10, a pressure reducing valve 8 and a main valve 9 in the air line being further auxiliary means of the control arrangement. By corresponding provisions, the turbine blading can be similarly treated.
If necessary, the blades undergo further cleaning or removal of protective coating. As Figs. 3 and 4 show, this takes place by means of a vibrating, erosive bath 14. For this purpose, the bladed rotor lla and llc is taken from the stator and placed on blocks _ 13a and 13b in such a way that a certain part of the blading is immersed in the bath 14. The individual erosive components of the bath 14 are made to vibrate by a vibration generator 15, causing removal of the residual soiling or residual protective coating on the blades. In principle, all types of blades of a rotor of a gas turbo group can be treated in this way.
A final cleaning is carried out according to Fig. 5 with an industrial glass blasting agent 18. This final cleaning is based on erosion removal by said agent, which may consist of glass. A certain part of the blading is covered by a special capsule 16; with simultaneous suction extraction 19 of the injected agent, the cleaning is accomplished by means of one or more jet nozzles 17.
Further process steps can he n,-w;r;Pr; a~
required:
- Grinding away of the still existing pitting at the most corroded points.
- A crack testing of the blades.
- A dimensional check of the blades, if they have undergone a grinding process.
- Roughening of the surface by sand blasting.
- ~ a ~jv~~~~~yy:.~.tl~.
- Before actual coating, it is recommendable to preheat the blades to about 80 degrees Celsius, for example by means of radiator.
Fig. 6 shows a possible way in which the high s speed flame spraying process can proceed. For this purpose, a shrouding 16 is provided, which is accessible from the side and encloses a number of ,.
prepared blades. By means of a spray nozzle 20, the protective coating is applied to the blades, it being .
readily possible to perform the guidance of the jet nozzle 20 manually. A suction extraction 19 ensures that excess agent can be removed immediately from the vicinity of the blades.
An aftertreatment of the sprayed blades generally comprises the following process steps:
- To reduce the surface roughness, light rubbing over with an emery cloth and/or blasting, for example with glass beads.
- To protect the undercoating and further reduce the surface roughness, a top lacquer coating can be applied with a paint-spray gun. This is on condition that this lacquer does not require a high sustained firing temperature (no furnace construction). A two-component lacquer may be used for this, at least for the first rows of the compressor, where still relatively low tempera-tures prevail in operation.
A plastic-based polyurethane reaction lacquer may be an example of such a top coating.
Regarding the quality of the protective coating, it should be said that conventional compressor coatings very often exhibit low erosion resistance.
Since such galvanic protective coatings axe only effective if they are present in the metal-coating-electrolyte system, a locally eroded coating is reduced in its protective effect.
- 8 - s: v er ~':' ''~. !i The aluminum-based protective coating employed here is an active corrosion-protected coating, the composition of which is preferably as follows:
1. One protective coating consists of 6 to 15~ by weight Si, the remainder aluminum;
PARTICLE VELOCITY OF AT LEAST 300 m/s BACKGROUND OF THE INVENTION
s Field of the Invention The present invention relates to a process for coating blades of a rotating thermal machine.
Discussion of Background For example in the open gas turbine process, the ~o air taken in by the compressor also contains water vapor and solid and gaseous impurities. These have an adverse effect due to erosion, soiling and corrosion. Some of the deposits on the blades have a considerable concentration of corrosively acting constituents such as NaCl and KC1. The salts cause not only high-temperature corrosion on the turbine blading but also increased pitting corrosion in the compressor region and a complex chemical reduction in the strength of the blade material. In the case of high atmospheric humidity, there occurs in the region of the zo compressor intake a concentration of water vapor, which explains the greater degree to which corrosion attacks the front rows of blades. In order to overcome this problem to a certain extent, blades of rotating thermal machines are often provided with protective coatings. These are used zs both in the case of steam and gas turbine blades and in the case of compressor blades. Thus, the main objective is to increase the resistance to corrosion and oxidizing attacks as well as to erosion and abrasion (wear). If, in spite of surface treatment, the blades do exhibit damage of a degree 3o which could endanger operational reliability, the next step is to proceed to remove the blades: either they are replaced by new ones or reconditioned and refitted. This removal and fitting entails relatively high costs and time spent. Furthermore, the true condition of the blading is 35 only evident after a relatively long time, i.e. after precleaning, and therefore the decision as to whether ~cn reconditioning of the blades is ~feas'~~'~b~l~ '~ or not, or already necessary, can only be taken much later. The disadvantages of this method are the great time losses, the high operating costs of the installation, higher costs for inspections and the uncertainty over the question of the reconditionability of the blades.
Therefore, the tendency has been instead to look for ways and means of remedying this situation. In this context, a process has become known by which the entire bladed rotor is lifted out of the stator in order to be reconditioned in a separate installation. The bladed rotors to be coated must be degreased in a suitable way, any organic coatings which may have been applied at an earlier time must be completely removed.
Subsequently, the areas to be coated are roughened by dry sand blasting with aluminum oxide and the metallic surface activated. The zones not to be coated must be masked with suitable materials. Thereafter, the undercoats are applied, each having to be fired. This results in a laborious procedure: a sintering process or firing process takes about 55 hours and, on average, has to be carried out four times. This sintering or firing process during coating comprises a heat treatment at about 350° Celsius over a holding time of about 10-12 hours. In addition, in order to carry out the individual process steps, quite large installations of specific geometric design have to be provided, consider for instance that during the sintering process the entire bladed part of the rotor has to be surrounded by a furnace cover.
SUI~'~IARY OF THE INVENTION
Accordingly, one object of this invention is to provide a process of the type mentioned at the beginning with a more efficient method in terms of the times required and costs expended for the reconditioning of the blades. Another object of the invention is to maximize the service life of the coating by suitable processes and protective coatings.
- 3 - 'J' ~ .'' '' ~ ~a ,~ a o~ ".a4f;,~(~
The essential advantages of the invention are to be seen in that the bladed rotor does not have to be lifted out of its mounting in the stator for the first process of reconditioning: the cleaning or removal of protective coating can be carried out before the actual shutting-down of the machine, i.e. of the compressor, that is to say during a final phase of operation ("on line"). As a result, an even exposure of the blades to be treated is attained, the consequently achieved efficiency of this cleaning process, which ensures extensive removal of any protective coating there may be, permitting an immediate decision on the reconditionability of the blades. This decision can be made already after shutting down the machine and ,..
removing the upper part of the stator. If, after appropriate analysis of the condition of the blades, it is decided to recondition them, it is sufficient to lift the bladed rotor out of the mount and place it on blocks, where the further process steps of reconditioning can be carried out without the aid of a sophisticated structure. This leads to low operating costs (overhauling costs), which means that there is nothing to prevent this type of treatment being carried out periodically. Consequently, the operational reliability of the installation is increased.
A further significant advantage of the invention is to be seen in that, by using a high-speed flame spraying process, the blades, pretreated in the fitted state, receive an appropriate protective coating, preferably Si and A1 based, just where and when needed, it being possible for this coating process to be carried out without lengthy heat treatment and without the aid of special additional equipment, This simplifies the entire technical coating procedure, while the costs are lower by about half than in the case of the known, processes. In addition, the service life of this type of coating is much higher than in the case of the coatings currently used for this so-called complete coating. Since the pretreatment of the blades or the after-treatment after spraying on the protective coating is of great significance for the service life of the coating, direct corrective measures can be undertaken s specifically, as found to be required. What is obtained after a very short time with low reconditioning costs by means of a process which is very environmentally friendly is blading of top quality which guarantees the operational reliability of the installation over a prolonged period.
~o According to a broad aspect of the present invention there is provided a process for coating blades of a rotating thermal machine having a compressor. The blades undergo a first cleaning process, in the operating state of the thermal machine, by means of an agent mixed with the air 15 Stream to the compressor for a predetermined time through a centrally placed three-jet nozzle which acts in an intake channel of the compressor. The blades undergo a preparation process for the subsequent treatment stage wherein the blades are treated in an erosive bath after opening the 2o machine in a stationary state. The blades are coated in the stationary state with an aluminium-based protective coating by means of a high-speed flame spraying process which sprays protective coating particles onto the surface of a base material at at least a velocity of 300 m/s. The porosity of 2s the protective coating is below 0.5% and the composition of the coating is one of the following: a) 6 to 15o by weight Si, the remainder being aluminium; b) pure aluminium, c) 80% by weight A1, 5 to 15o by weight Si and the remainder being Cu, Mn, Mg, Ni.
3o Advantageous and expedient further developments of the way in which the object is achieved according to the invention are identified in the further claims.
- 4a -BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference s to the following detailed description when considered in connection with the accompanying drawings, wherein all elements not required for direct understanding of the invention have been omitted and the direction of flow of the various media is indicated by arrows and wherein:
Fig. 1 shows a turbo group with units for a pretreatment stage;
Fig. 2 shows a view of Fig. 1 in the plane II-II;
Fig. 3 shows a cleaning stage or removal of protective coating in a vibrating, erosive bath;
15 Fig. 4 shows a view of the rotor according to Fig.
3 along the plane IV-IV;
Fig. 5 shows a final cleaning process with jet nozzles; and Fig. 6 shows a coating of the blades by a high-2o speed flame spraying process.
- ~y '3 ~1 ~; .~ 4 i~ ~ ap .! .,' ~ :~l i.~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in Figure 1 a conventional gas turbo group 11 is shown, essentially comprising a compressor part lla, a combustion chamber llb and a turbine part llc. In the pretreatment of the blades, a distinction must be drawn between whether, in the original state, they were uncoated or coated.
Irrespective of this precondition, a first cleaning of the blades takes place before shutting down the machine, i.e. the compressor. In the case of coated blades, this cleaning is based preferably on erosion °
abrasion by soft-blasting granules. Of course, the cleaning of uncoated blades can be performed simply by means of an aqueous solvent, for example trichloroethylene. The cleaning agent (soft-blast granules, aqueous solution etc.) is injected into the air stream to the compressor for a certain time through a centrally placed three-jet nozzle 1 (also see Fig. 2 in this respect), which acts in the intake channel of the compressor. The even and intensive exposure 12 of the compressor blades produces an efficient cleaning process in the case of uncoated blades or an extensive removal of the old protective coating in the case of coated blades. The cleaning process is repeated several times, as required. Since the soft-blasting granules burn at temperatures of about 300 degrees Celsius, there are no problems in this respect with regard to disposal. If an aqueous solution is used, consideration likewise has to be given to these aspects. The control arrangement for the multi-jet nozzle 1 consists of a ball cock 2, which is connected downstream, in the direction of flow of the cleaning agent, of a mixing chamber 3 and serves for controlling the rate of flow.
The pressure in this mixing chamber 3 is displayed by a pressure gauge 7. Provided upstream of the mixing chamber 3 is a tank 4, in which for example granules '' t~ ~i ~'1 i: ~ p 0 ' L :i ~.~ ~S ~~ l.~
are stored, a screen 5 and an inlet valve 6 ensuring that the mixing chamber 3 is supplied with homogeneous material. The required pressure in the tank 4 is provided by means of an air feed line 10, a pressure reducing valve 8 and a main valve 9 in the air line being further auxiliary means of the control arrangement. By corresponding provisions, the turbine blading can be similarly treated.
If necessary, the blades undergo further cleaning or removal of protective coating. As Figs. 3 and 4 show, this takes place by means of a vibrating, erosive bath 14. For this purpose, the bladed rotor lla and llc is taken from the stator and placed on blocks _ 13a and 13b in such a way that a certain part of the blading is immersed in the bath 14. The individual erosive components of the bath 14 are made to vibrate by a vibration generator 15, causing removal of the residual soiling or residual protective coating on the blades. In principle, all types of blades of a rotor of a gas turbo group can be treated in this way.
A final cleaning is carried out according to Fig. 5 with an industrial glass blasting agent 18. This final cleaning is based on erosion removal by said agent, which may consist of glass. A certain part of the blading is covered by a special capsule 16; with simultaneous suction extraction 19 of the injected agent, the cleaning is accomplished by means of one or more jet nozzles 17.
Further process steps can he n,-w;r;Pr; a~
required:
- Grinding away of the still existing pitting at the most corroded points.
- A crack testing of the blades.
- A dimensional check of the blades, if they have undergone a grinding process.
- Roughening of the surface by sand blasting.
- ~ a ~jv~~~~~yy:.~.tl~.
- Before actual coating, it is recommendable to preheat the blades to about 80 degrees Celsius, for example by means of radiator.
Fig. 6 shows a possible way in which the high s speed flame spraying process can proceed. For this purpose, a shrouding 16 is provided, which is accessible from the side and encloses a number of ,.
prepared blades. By means of a spray nozzle 20, the protective coating is applied to the blades, it being .
readily possible to perform the guidance of the jet nozzle 20 manually. A suction extraction 19 ensures that excess agent can be removed immediately from the vicinity of the blades.
An aftertreatment of the sprayed blades generally comprises the following process steps:
- To reduce the surface roughness, light rubbing over with an emery cloth and/or blasting, for example with glass beads.
- To protect the undercoating and further reduce the surface roughness, a top lacquer coating can be applied with a paint-spray gun. This is on condition that this lacquer does not require a high sustained firing temperature (no furnace construction). A two-component lacquer may be used for this, at least for the first rows of the compressor, where still relatively low tempera-tures prevail in operation.
A plastic-based polyurethane reaction lacquer may be an example of such a top coating.
Regarding the quality of the protective coating, it should be said that conventional compressor coatings very often exhibit low erosion resistance.
Since such galvanic protective coatings axe only effective if they are present in the metal-coating-electrolyte system, a locally eroded coating is reduced in its protective effect.
- 8 - s: v er ~':' ''~. !i The aluminum-based protective coating employed here is an active corrosion-protected coating, the composition of which is preferably as follows:
1. One protective coating consists of 6 to 15~ by weight Si, the remainder aluminum;
2. Another protective coating consists of pure aluminum;
3. Another protective coating consists of 80$ by weight A1, 5 to 15~ by weight Si, the remainder Cu, Mn, Mg, Ni.
The chemical structure of the abovementioned protective coatings and the application process likewise described above (high-speed flame spraying process) provide a less erosion-sensitive "sacrificial anode" coating, which actively protects the base material against corrosion. The application process, which is a high-energy coating process, provides erasion-resistant protective coatings which have good adhesion and the desired electrical connection to the base material without further protective coating-specific aftertreatment. The proposed protective coatings may be additionally provided with a top coating. This dirt-repelling top coating may, for example, be black. Such a dirt-repelling top coating makes it easier to detect icing on the blades by means of ice detectors. The high-speed flame spraying process, which opexates at a particle velocity of at least 300 m/s, represents an optimum bonding of the coating to the base material of the blades. Even in the case of a relatively thick protective coating, it is ensured that the coating does not peal off. The explanation for this is that, upon impact of the powder particles, the high kinetic energy produces residual compressive stresses in the coating respectively sprayed befare. The maximised resistance against corrosion is attributable to the fact that the coatings used here have a very high hardness. The process proposed here has the effect that the oxide content of the coating is lower than in the case of protective coatings sprayed in air. That means that the coating is more pure, for which reason it oxidizes less quickly, ,.
any oxidation their may be occurring only on the surface. Due to the fact that the protective coatings .
axe very dense, there porosity is below 0.5~. There is virtually no chance of them being destroyed by corrosion: in the salt spray test specified in DIN 50021, a commercially available ceramic aluminum coating was compared with a protective coating according to the above composition and with the above process. The results have fully confirmed the above statement. In a fatigue process, an analogous comparison was carried out: it was found that the loading until the first fatigue crack in the blade was 20$ higher in the case of blades coated according to the above composition and the above process than in the case of the comparison blades. This means that the immunity of the blading to fatigue failure could be increased.
On the basis of the stated advantages and the results after several thousand operating hours in a compressor of a coastal installation, an improvement in the service life of the active protective coating of 50~ resulted.
Obviously, numerous 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 herein.
The chemical structure of the abovementioned protective coatings and the application process likewise described above (high-speed flame spraying process) provide a less erosion-sensitive "sacrificial anode" coating, which actively protects the base material against corrosion. The application process, which is a high-energy coating process, provides erasion-resistant protective coatings which have good adhesion and the desired electrical connection to the base material without further protective coating-specific aftertreatment. The proposed protective coatings may be additionally provided with a top coating. This dirt-repelling top coating may, for example, be black. Such a dirt-repelling top coating makes it easier to detect icing on the blades by means of ice detectors. The high-speed flame spraying process, which opexates at a particle velocity of at least 300 m/s, represents an optimum bonding of the coating to the base material of the blades. Even in the case of a relatively thick protective coating, it is ensured that the coating does not peal off. The explanation for this is that, upon impact of the powder particles, the high kinetic energy produces residual compressive stresses in the coating respectively sprayed befare. The maximised resistance against corrosion is attributable to the fact that the coatings used here have a very high hardness. The process proposed here has the effect that the oxide content of the coating is lower than in the case of protective coatings sprayed in air. That means that the coating is more pure, for which reason it oxidizes less quickly, ,.
any oxidation their may be occurring only on the surface. Due to the fact that the protective coatings .
axe very dense, there porosity is below 0.5~. There is virtually no chance of them being destroyed by corrosion: in the salt spray test specified in DIN 50021, a commercially available ceramic aluminum coating was compared with a protective coating according to the above composition and with the above process. The results have fully confirmed the above statement. In a fatigue process, an analogous comparison was carried out: it was found that the loading until the first fatigue crack in the blade was 20$ higher in the case of blades coated according to the above composition and the above process than in the case of the comparison blades. This means that the immunity of the blading to fatigue failure could be increased.
On the basis of the stated advantages and the results after several thousand operating hours in a compressor of a coastal installation, an improvement in the service life of the active protective coating of 50~ resulted.
Obviously, numerous 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 herein.
Claims (5)
1. A process for coating blades of a rotating thermal machine having a compressor, said blades undergoing a first cleaning process, in the operating state of the thermal machine, by means of an agent mixed in with the air stream to the compressor for a predetermined time through a centrally placed three-jet nozzle which acts in an intake channel of said compressor; and said blades undergoing a preparation process for the subsequent treatment stage wherein said blades are treated in an erosive bath after opening said machine in a stationary state, said blades being coated in said stationary state with an aluminium-based protective coating by means of a high-speed flame spraying process which sprays protective coating particles onto the surface of a base material at at least a velocity of 300 m/s, wherein the porosity of the protective coating is below 0.5% and the composition of the coating is one of the following:
a) 6 to 15% by weight Si, the remainder being aluminium b) aluminium, c) 80% by weight Al, 5 to 15% by weight Si, the remainder being Cu, Mn, Mg, Ni.
a) 6 to 15% by weight Si, the remainder being aluminium b) aluminium, c) 80% by weight Al, 5 to 15% by weight Si, the remainder being Cu, Mn, Mg, Ni.
2. The process as claimed in claim 1, wherein said blades when in said stationary state, after the application of said protective coating, undergo an after-treatment to reduce the surface roughness and to apply a top coating.
3. The process as claimed in claim 1, wherein said blades when in said stationary state, after the application of said protective coating, undergo an after-treatment to reduce the surface roughness or to apply a top coating.
4. The process as claimed in claim 1, wherein said agent mixed in with the air stream for cleaning the blades consists of soft-blasting granules.
5. The process as claimed in claim 2 or 3, wherein said top coating consists of a plastic-based polyurethane reaction lacquer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH1237/90-0 | 1990-04-11 | ||
| CH123790 | 1990-04-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2039944A1 CA2039944A1 (en) | 1991-10-12 |
| CA2039944C true CA2039944C (en) | 2001-01-02 |
Family
ID=4205685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002039944A Expired - Fee Related CA2039944C (en) | 1990-04-11 | 1991-04-08 | High speed flame spraying process having particle velocity of at least 300 m/s |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0451512B1 (en) |
| JP (1) | JP3027214B2 (en) |
| CA (1) | CA2039944C (en) |
| DE (1) | DE59100238D1 (en) |
| DK (1) | DK0451512T3 (en) |
| ES (1) | ES2044634T3 (en) |
| PL (1) | PL165873B1 (en) |
| RU (1) | RU2062303C1 (en) |
| UA (1) | UA27027A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008116757A3 (en) * | 2007-03-27 | 2009-01-15 | Alstom Technology Ltd | Turbomachine blade with erosion and corrosion protective coating and method of manufacturing the same |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08193568A (en) * | 1995-01-13 | 1996-07-30 | Hitachi Ltd | Runner of hydraulic machinery and manufacture of runner |
| AT403059B (en) * | 1995-10-04 | 1997-11-25 | Engel Gmbh Maschbau | METHOD FOR PRODUCING A COATING ON THE SURFACE OF PLASTICIZING SCREWS FOR INJECTION MOLDING MACHINES |
| AT402943B (en) * | 1995-10-04 | 1997-09-25 | Engel Gmbh Maschbau | METHOD FOR PRODUCING WEAR AND CORROSION PROTECTED SURFACES ON PLASTICIZING SCREWS FOR INJECTION MOLDING MACHINES |
| DE102004001575A1 (en) | 2004-01-10 | 2005-08-04 | Mtu Aero Engines Gmbh | Method for producing hollow blades and a rotor with hollow blades |
| US8113787B2 (en) | 2007-06-20 | 2012-02-14 | Alstom Technology Ltd. | Turbomachine blade with erosion and corrosion protective coating and method of manufacturing |
| EP2752559A1 (en) * | 2013-01-08 | 2014-07-09 | Siemens Aktiengesellschaft | Method of cleaning of a gas turbine rotor within a housing |
| CN110420769B (en) * | 2019-08-02 | 2020-06-09 | 柳州联顺戴克雷汽车部件有限公司 | Prevent spraying equipment of grain with allotment function |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2709569A (en) * | 1948-08-28 | 1955-05-31 | Thompson Prod Inc | Impeller member and method of making same |
| US3010843A (en) * | 1958-04-28 | 1961-11-28 | Gen Motors Corp | Abradable protective coating for compressor casings |
| FR2564350B1 (en) * | 1984-05-17 | 1987-11-20 | Snecma | DIFFUSION REPAIR PROCESS |
-
1991
- 1991-03-11 EP EP91103660A patent/EP0451512B1/en not_active Expired - Lifetime
- 1991-03-11 ES ES91103660T patent/ES2044634T3/en not_active Expired - Lifetime
- 1991-03-11 DK DK91103660.6T patent/DK0451512T3/en not_active Application Discontinuation
- 1991-03-11 DE DE9191103660T patent/DE59100238D1/en not_active Expired - Fee Related
- 1991-04-08 JP JP3074902A patent/JP3027214B2/en not_active Expired - Lifetime
- 1991-04-08 CA CA002039944A patent/CA2039944C/en not_active Expired - Fee Related
- 1991-04-09 PL PL91289795A patent/PL165873B1/en unknown
- 1991-04-10 RU SU914895114A patent/RU2062303C1/en active
- 1991-04-10 UA UA4895114A patent/UA27027A1/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008116757A3 (en) * | 2007-03-27 | 2009-01-15 | Alstom Technology Ltd | Turbomachine blade with erosion and corrosion protective coating and method of manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| PL289795A1 (en) | 1991-12-02 |
| EP0451512A1 (en) | 1991-10-16 |
| ES2044634T3 (en) | 1994-01-01 |
| JP3027214B2 (en) | 2000-03-27 |
| DK0451512T3 (en) | 1993-12-27 |
| EP0451512B1 (en) | 1993-08-04 |
| PL165873B1 (en) | 1995-02-28 |
| UA27027A1 (en) | 2000-02-28 |
| DE59100238D1 (en) | 1993-09-09 |
| JPH04225865A (en) | 1992-08-14 |
| CA2039944A1 (en) | 1991-10-12 |
| RU2062303C1 (en) | 1996-06-20 |
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| EEER | Examination request | ||
| MKLA | Lapsed |