Method for microstructure control of ceramic thermal spray coating

The first method for controlling the microstructure of ceramic thermal sprayed coatings Technical collar The present invention relates to thermal sprayed coatings, and in particular, to control the formation of cracks in ceramic coatings.

BACKGROUND OF THE INVENTION Modern gas turbine engines, especially those used on airplanes, work at high speeds and high temperatures to enhance performance and improve efficiency. The turbines of modern lazy gas turbine engines are generally of axial flow design and include many axial flows. Segments Each axial flow segment includes a set of blades radially mounted on the outer periphery of a disk fixed to the shaft. Many air duct segments surrounding each segment limit the leakage of gas flowing around the tip of the blade. These air duct segments Positioned on the inner surface of the stationary shell or shell. The installation of the air duct section improves the thermal efficiency because more work can be obtained from the gas flowing through each section, contrary to the leakage from the tip of the blade.

Although the air duct sections limit the leakage of gas around the blade tip, they cannot completely eliminate this slag leakage. It has been found that even a very small amount of gas flowing around the blade tip can deleteriously affect the efficiency of the turbine. Therefore, the design of the gas turbine engine Those who use larger lengths to design effective sealing structures. These structures usually include a coated air duct section combined with the coating of the blade tip, which makes the blade tip wear-resistant. In operation, the blade tip is cut into the wind Sealing is provided in the coating of the road section. This prevents damage to the blades and minimizes the possible tip barriers and air leakage.

Unfortunately, the current coating of the duct section, which is usually ceramic, suffers from additional material loss caused by abrasion or peeling. Generally speaking, abrasion is caused by various factors such as wear and rust that cause the coating material to wear away. In the engine Abrasion during operation is usually caused by particle impact. Spalling or spalling is usually caused by delamination cracks on the ceramic-metal interface due to thermal stress and aggressive thermal environment. Spalling is basically a fragmentary coating loss including many small adhesion volumes of coating materials.

Most of the coating loss caused by abrasion and peeling is caused by the presence of microcracks in the split ceramic coating. Microcracks formed parallel to the surface of the substrate, or horizontal cracks, can cause coating when subjected to the above-mentioned operating conditions or environment. Layer peeling. In contrast, the vertical orientation of microcracks increases the strain tolerance of the coating, which prolongs the service life of the coating. The mechanism of microcrack formation in a split ceramic coating is thermally induced stress. During the deposition period

200610108698.4 The first thermal gradient is induced into the coating. These gradients are controlled so as to allow the coating to be applied to the surface without open cracks, and then as each thin layer builds up and subsequently cools, the surface shrinks to produce the stress levels required to propagate the cracks to the surface. Reheat the surface and close the crack before applying the next thin coating. The relative travel direction of the crack propagation through the thickness of each coating or parallel to the substrate depends on the thickness of each coating applied before the crack propagation is induced.

The loss of ceramic coating increases the clearance at the tip of the blade and is therefore harmful to the efficiency of the turbine. It is also harmful to the blade itself. For example, the blade may be damaged due to an increase in temperature because the engine must be operated at an increased temperature to compensate Loss of thrust. This performance loss can be prevented by improving the quality of the split ceramic coating.

Now, U.S. Patent No. 6,102,656 (the '656 patent) discloses such a method of applying a split ceramic coating in an effort to improve the ceramic coating. Applying a ceramic coating on a substrate is an automatic process, for example, The substrate is placed in a jig, which rotates around an axis or moves along the linear direction of the conveyor belt.

As described in the 656 patent, in such an automatic process, the substrate 10 can move in the direction swept by the arrow 12 (see Figure 1). The plasma torch device 14 is aligned with the substrate as indicated by the arrow 26 10 Move in the opposite direction and shoot the plasma flame tongue 16. The plasma flame tongue 16 is defined by a pair of solid lines pointing to the surface 18 of the substrate 10. The plasma torch device 14 includes a ceramic (or powder) material feeder (not shown) ), it sprays a certain amount of ceramic material 20 into the plasma flame tongue 16 in the direction indicated by the arrow 28. The ceramic material 20 is entrained in the plasma flame tongue 16 and brought to the surface 18. As shown in the figure, the plasma The flame tongue 16 includes a wider spray pattern than the ceramic material 20 to form a deposition zone 22 in the heating zone 24 on the surface 18.

The 656 patent relies on very high power levels and gas flow rates and is used with the slow relative movement of the plasma torch against the component (substrate 10) to produce the air cooling necessary to heat the surface by the plasma and obtain vertical micro-cracks. These The condition represents a compromise between device capability, efficiency, and the microstructural characteristics of the ceramic coating.

The current method cannot always apply proper and effective control to the thermal gradient and thermal cycle that occurs during the spraying process. The balance between the generation of vertical cracks and the generation of horizontal cracks is very difficult to control and occurs very randomly. As shown in FIG. 1, the heating zone 24 generated by the plasma torch is larger than the deposition zone 22, and the heating zone further extends on the substrate in the direction where the deposition place has just been produced, rather than in the direction where the deposition place will be produced. Stretching, that is, the heating zone 24 in FIG. 1 further stretches to the left of the deposition zone 22 instead of

200610108698. 4 The right side of the sedimentary zone 22 stretches. Due to this relationship between surface heating and deposition position, only a moderate driving force can make cracks propagate through the thickness of the coating. As a result, shrinkage in more than one direction and thermal cycling are remotely level in the plane of the coating Ground cracks and cracks generated vertically through the coating. Horizontal cracks in parallel substrates do not improve the strain tolerance and durability of the coating; these cracks actually cause the coating to peel off.

Therefore, there is still a need to improve the method of controlling crack formation in layered ceramic coatings, so as to improve the repeatability of the method and the consistency of coating performance, as well as to facilitate independent control of crack formation and porosity.

SUMMARY OF THE INVENTION According to the present invention, a method for generating a split ceramic spray coating on a substrate generally includes (1) providing one or more heat sources located near the substrate; (2) optionally bonding a certain amount of The coating material is injected into the heat flow of one or more heat sources and deposited on the deposition area of the substrate surface to form an optional bonding coating; (3) Optionally, a certain amount of the first ceramic material is injected into one or The heat flow of a plurality of heat sources is deposited on the deposition area of the surface so as to form an optional first ceramic material layer on the optional bonding coating; (4) the first ceramic material layer is located in front of the deposition area on the surface of the first ceramic material layer. The preheated thermal gradient section applies a heat flow to expand the optional first ceramic material; (5) injecting one or more certain amounts of additional ceramic materials into the heat flow and depositing on the preheated expanded ceramic material Select the first ceramic material layer to generate one or more additional layers of ceramic material; (6) Cool one or more additional layers of ceramic material to promote the propagation of vertical cracks; (7) For one or more additional layers of ceramic material The preheated thermal gradient section of the surface of the additional layer of ceramic material applies heat flow to expand the additional ceramic material. If necessary, steps 5 to 7 can be repeated one or more times. According to the present invention, a device for splitting the ceramic coating is applied It generally includes a mechanism for supporting and moving one or several substrates; one or more heat sources arranged near one or more substrates, wherein at least one heat source is positioned to apply heat to the preheated thermal gradient section on the surface of the substrate Flow; a material deposition device arranged near one or more heat sources, wherein the material deposition device is positioned so as to deposit material on the deposition zone located behind the thermal gradient section on the surface; and monitoring the surface temperature of one or more substrates mechanism.

Various details of one or more embodiments of the present invention are given in the drawings and the following description. From the description and drawings, as well as from the claims, other features, objects, and advantages of the present invention will become very Clear · Description of the drawings

200610108698. 4 Figure 1 is a diagram of an existing system for applying a split ceramic spray coating; Figure 2 is a diagram showing how to apply a split spray coating to obtain a vertical crack microstructure in the coating; Figure 3 is a diagram of the present invention for applying a ceramic spray coating Figure 4 is a diagram of another embodiment of the ceramic spray coating system of the present invention; Figure 5 is a diagram of another embodiment of the ceramic spray coating system of the present invention; and 6 is a diagram of another embodiment of the ceramic spray coating system of the present invention.

The same reference numerals and symbols in the various drawings denote the same elements.

DETAILED DESCRIPTION In order to improve the quality of the ceramic coating, the method described here proposes to increase the number of vertical micro-cracks in the microstructure of the coating. Vertical micro-cracks provide strain tolerance, which extends the service life of the coating. "Equilibrium", "equilibrium" and their related expressions are expressed in order to promote vertical cracks in the coating between the surface of the substrate and the continuous coating to be deposited on it to reach the required temperature and thermal gradient. Described here During each process, a repeated cycle of heat flow occurs in the coating for a short time, dynamically heating the coating surface and creating a thermal gradient due to the heat capacity and thermal conductivity of the material. Allow the thermal gradient to dissipate after a period of time, for example, as small as a fraction In one second, it causes the deposited coating to shrink and cause vertical cracks to extend to the surface of the coating in a zigzag pattern. In the hoop process of the method described here, the cycle of heat flow is repeated again and again as the continuous coating is deposited .

Now referring to Fig. 2, by applying the material properties of the thermal expansion, heat capacity, and thermal conductivity of the coating and substrate, a thermal gradient can be established to control the characteristics of crack formation. Unlike the prior art method shown in Fig. 1, in During deposition, the instantaneous heating of the coating just before and/or during the passage of one or more jet nozzles or other heat sources on the substrate each time causes these gradients. The thermal gradient causes the coating surface to expand relative to the substrate, which closes The cracks simultaneously proceed with the deposition of ceramic material. After each layer of coating is deposited, the gradient is allowed to dissipate, the surface shrinks and enters the stretch that causes the crack to propagate to the surface. Repeat the cycle of surface heating, coating, cooling, and crack propagation until the desired coating thickness is reached. The benefits of this type of control include improved reproducibility of the appearance of the structure and the resulting characteristics, and independent control of crack formation and porosity.

As shown in FIG. 2, the coating system described herein generally includes an adhesive coating 30 deposited on the surface 32 of the substrate 34, and one or more continuous layers deposited on the adhesive coating 30

200610108698.4 The first applied ceramic coating 36, 38. Prior to deposition, the substrate 34 can be cleaned using any conventional method or combination thereof to remove contaminants, as understood by those of ordinary skill in the art to which the present invention pertains. For example, alumina abrasive blasting can be used to clean the substrate 34. When the substrate 34 moves in the direction indicated by the arrow 40, the heat source 42 can be disposed at least this part of the surface 32 being coated by the thermal spray deposition device 44. Part of the surface 32 is heated. The heat source 42 increases the temperature of the surface 32 before the coating is deposited on it, or the temperature of the surface 32 and the deposited coatings such as 30, 36, 38, in order to ensure proper thermal cycling and cause vertical cracks Expand in the coating.

For the purpose of illustration, not limitation, the Tujie system of Fig. 2 may include several different areas used to illustrate the thermal gradient and crack propagation described here. Before heating, there may initially be a low thermal gradient zone 50, where vertical cracks Has expanded to the surface of the deposition layer. When the substrate 34 moves, the heat source 42 increases the surface temperature of the low thermal gradient zone 50 to form a surface heating zone 52. In the surface heating zone 52, the increased temperature induces a thermal gradient to expand the surface and close the existing The substrate 34 continues to move and the surface heating zone 52 becomes exposed under the thermal spray deposition device 44. The device 44 is in the coating deposition zone 54, above the existing layers 30, 36 and/or surface 32, Deposit another continuous layer of paint 38. The new paint 38 covers the expanded surface originally called the surface heating zone 52.

When the substrate 34 continues to move in the direction of the arrow 40 and leaves the heat source 42 and the deposition device 44, the continuously applied coatings 30, 36, 38 begin to cool to form a surface cooling zone 56. When the newly deposited coating 38 and the existing coating When the temperature between the layers 30, 36 is balanced, the vertical cracks begin to expand to the surface exposed to the atmosphere to release the tensile stress. The substrate 34 continues to move while the layer 38 continues to cool to form a low thermal gradient zone 58, where the vertical cracks pass through the layer 30 , 36 and/or 38 extend to the surface exposed to the atmosphere. Optionally, an adhesive coating 30 of MCrAlY material or other suitable material may be applied to the substrate 34. MCrAlY refers to the known metal coating system, where Μ stands for dart, iron, iron or their mixture; Cr stands for rim; AI stands for aluminum; and Y stands for collar. MCrAlY materials are generally known as surface coatings because they It is coated with a predetermined composition and does not significantly interact with the substrate during the coating process. For some non-limiting examples of MCrAlY materials, please refer to U.S. Patent No. 3,528,861, which describes FeCrAlY as in U.S. Patent No. 3,542,530 Coating. In addition, US Patent No. 3,649,225 describes a composite coating in which a layer of Luo is coated on the substrate before the MCrAlY coating is deposited. US Patent No. 3,676,085 describes CoCrAlY surface coating and description of U.S. Patent No. 3,754,903

200610108698.4 First NiCoCrAlY surface coating with particularly high ductility. U.S. Patent No. 4,078,922 describes a structural alloy estimated as a matrix, which uses the presence of a combination of Bell and Ming to obtain improved oxidation resistance. In U.S. Patent No. 32,121, a preferred MCrAlY bonding coating composition is described, which is Assigned to the assignee and extracted here as a reference, if the weight percentage range is 5-40 Cr. 8-35 AL 0.1-2.0 Y. 0.1-7 Si. 0.1-2.0 Hf, from including Ni, Co Choose a balance among this group of materials and their mixtures. Please also see US Patent No. 4,585,481, which is also assigned to the assignee and is inserted here as a reference.

This MCrAlY bonding coating 30 can be applied by any method capable of producing a dense and uniform bonding coating of the desired composition. Such techniques may include, but are not limited to, cathodic sputtering, electron beam physical vapor deposition, high-speed plasma spraying technology (HVOF, HVAF), combustion methods, money spraying technology, laser beam coating, electron beam coating, etc. In the high-speed plasma spraying technology, the spray nozzle can be operated in a vacuum chamber with a pressure less than about 60 hg (60 mmHg) or in another suitable atmosphere, such as air. If a vacuum chamber is used, the substrate can be heated to About 1500T (816Γ) or about 1900T (10389) temperature. If an air atmosphere is used, the substrate temperature can be kept at less than about 600 Τ (3169).

The particle size for the bonding coating 30 can be any suitable size, and in each embodiment can be between about 15 microns (0.015mni) and about 60 microns (0.060min) with an average particle size of about 25 microns (0.025mm). ) · The adhesive coating can be applied 30 to any suitable thickness, in each embodiment it can be about 5 mils (0·127mm) to about 10 mils (0.254mm) thick. In some embodiments, The thickness can be about 6 mils (0.152 mm) to about 7 mils (0.178 mm) thick. Layered ceramic coatings 36, 38 can be applied on the bonding layer 30 or directly on the substrate 34. The ceramic coating may include one or more ceramic layers 36, 38, each of which is applied to any suitable thickness. Some embodiments may have a total thickness of about 20 mils (0.508mm) to about 150 mils (3.81mm). Other embodiments may have a total thickness of about 50 mils (1.270mm). As described here at one time or Various ceramic coatings can be produced in multiple continuous spraying processes.

Referring now to FIG. 3, a system of the present invention will be described. As understood by those of ordinary skill in the art to which the present invention pertains, the substrate 100 can be moved in the direction indicated by the arrow 112 in an automatic process. The spraying nozzle and the tube device 114 can keep fighting and heating the substrate 100, or the spraying nozzle The device 114 can move in a direction opposite to the substrate 100, as shown by the arrow 126. The spray nozzle device 114 emits a heated gas flame that can contain ionized substances

200610108698.4 No.

116. It is expected that the type of heat source used will determine whether the heat source moves or the movement of the heat source relative to the substrate 100 remains stationary. However, when coating ceramic materials, it is preferable to locate the heat source to preheat the deposition area 132 on the surface 118 of the substrate 100 The front thermal gradient zone. Representative nozzles can include, but are not limited to, air plasma spray guns, such as 3MB® commercially available from Sulzer Metco, Inc. of Westbury, New York.

Once the optional adhesive coating 122 has been applied, a ceramic (or powder) material feeder (not shown) injects a certain amount of ceramic material 120 into the plasma flame tongue 116 in the direction indicated by arrow 128. Inject ceramic material The direction of 120 is preferably the same as the direction of movement of the substrate 100 and opposite to any movement of the plasma torch device 114. The ceramic material 120 is entrained in the plasma flame Π6 and brought to the surface 118.

It is better to inject the ceramic material 120 with sufficient force to be entrained and carried by the rear or leftmost half of the plasma flame tongue 116. By controlling the direction and speed of the injected ceramic material 120, this method can also effectively control The deposition position of the ceramic material 120 on the surface 118, for example, the position of the ceramic material deposition area 132. The plasma torch 116 generates a heating zone 130 when the shrinking surface 118 surrounds the ceramic material deposition zone 132 and effectively preheats the surface 118 before the initial deposition or re-deposition of the ceramic material 120.

Generally speaking, as with thermal cycling, the deposited ceramic material begins to cool and shrink in several directions. When another layer of ceramic material is deposited, the heat input from the ceramic material sheet causes cracks in the plane of the coating. The layer undergoes changes in shrinkage and thermal gradients, and the generated microcracks may not be vertical, that is, the microcracks may be parallel to the surface 118 of the substrate 100.

Preheating the surface 118 or the deposited layer, that is, the bonding coating 122, can increase and balance the temperature around the ceramic material deposition area 132 and reduce the difference between the ceramic material being deposited on the surface 118 and/or the deposited layer and the area 132 The temperature difference exists between the thermal gradients. The shrinkage of the deposited ceramic material will become less severe than the original ceramic layer, resulting in less stress between the coatings and less tendency to generate cracks on the parallel substrate. In addition, if The preheating occurs fast enough to induce sufficient thermal gradients between the coating surface 118 and the substrate 100 to cause in-plane stresses that will cause cracks to propagate vertically to the substrate as those gradients dissipate. The resulting deposited ceramic material layer will be more like the vertical micro-crack structure required to generate.

In order to ensure preheating and control the thermal gradient, the monitoring device 134 can be used to measure the temperature of the surface 118 during the entire deposition process. Suitable monitoring devices include, but are not limited to, infrared cameras, optical pyrometers, thermocouples, including at least one Various combinations of the above devices, and similar instruments. The monitoring device 134 can provide data on the substrate and coating temperature to

200610108698.4 No. Operator, PLC, open loop control combined with passive process control, or computer that controls the automatic deposition process, etc.

Referring now to FIGS. 4 and 5, two different embodiments of the system shown in FIG. 3 are described. Referring now in particular to FIG. 4, the substrate 200 can move in the direction indicated by the arrow 212. The plasma torch device 214 can remain stationary Or it can move in the direction opposite to the movement of the substrate 200 indicated by the arrow 226 and emit a plasma flame tongue 216. Once the optional bonding coating has been applied, the ceramic (or powder) material feeder (not shown) will A certain amount of ceramic material 220 is injected into the plasma flame tongue 216 in the direction indicated by the arrow 228. The direction of the injected ceramic material 220 is preferably the same as the direction of movement of the substrate 200 and any direction of movement of the plasma torch device 214. On the contrary, the ceramic material 220 is centered in the plasma flame tongue 216 and brought to the surface 218.

One or more heat sources 236 may be used to preheat the surface area 230 living in front of the ceramic material deposition area 232. The heat source 236 may have sufficient rated power to emit a heat beam 238 to the substrate surface 218, that is, the heating area 230, so as to improve and balance the substrate. 200 and the temperature of the coating around the ceramic material deposition area 232, thereby preventing and/or reducing thermal gradients and shrinking. The heat source 236 can be oriented at a sufficient distance and angle to ensure that the ceramic material 220 is deposited or re-deposited before the first deposition. The temperature of the substrate 200 and the coating. The heat source 236 may include any radiant or convective heat source known to those of ordinary skill in the art to which the present invention pertains. Representative heat sources may include, but are not limited to, plasma or combustion thermal spraying Tubes, such as the old 3MB® or Diamond Jet torch from the Sulzer-Metco Company of Westbury, New York; combustion heaters or nozzles; radiation resistance heat sources, such as incandescent lamps, conventional or halogen lamps; laser heat sources, including at least one A variety of heat source combinations of the above heat sources, and similar devices.

As previously envisaged, the monitoring device 234 can be used to measure the temperature of the surface 218 during the deposition process. Suitable monitoring devices include, but are not limited to, infrared cameras, optical pyrometers, thermocouples, including at least one of the above devices Various combinations, and similar instruments. The monitoring device 234 can provide data about the substrate and surface temperature to the operator, PLC, open loop control combined with passive process control, or a computer that controls the automatic deposition process as described above, etc. .

Now referring specifically to FIG. 5, the substrate 300 can move in the direction indicated by the arrow 312. The plasma torch device 314 can remain stationary or can move in the direction opposite to the movement of the substrate 300 indicated by the arrow 326 and emit plasma. Body flame tongue 316.-Once the optional bonding coating has been applied, the ceramic (or powder) material feeder (not shown) will have a certain amount

The ceramic material 320 of 200610108698.4 is injected into the plasma flame tongue 316 along the direction indicated by the arrow 328. The direction of injection of the ceramic material 320 is preferably the same as the direction of motion of the substrate 300 but opposite to any direction of motion of the plasma torch device 314. The ceramic material 320 is entrained in the plasma flame tongue 316 and brought to the surface 318.

As mentioned above, one or more heat sources 336 may be used to preheat the substrate surface area 330 in front of the ceramic material deposition area 332. In this alternative embodiment, the heat source may include a laser. The laser heat source 336 emits sufficient rated power Or intensity laser beam 338 to heat the area 330 of the substrate or coating surface 318 in order to increase the temperature of the coating around the ceramic material deposition area 332 to prevent and/or reduce thermal gradients and promote the surface to expand sufficiently relative to the substrate to substantially close Existing cracks in the coating through the thickness. The laser heat source 336 can be directed at a sufficient distance and angle to ensure that the temperature of the coating is sufficiently increased before the initial deposition or re-deposition of the ceramic material 320. Representative laser heat sources may include but Not limited to laser heat sources known in the prior art used in welding and cutting applications.

As previously envisaged, the monitoring device 334 may be used to measure the temperature of the surface 318 during the deposition process. Suitable monitoring devices include, but are not limited to, infrared cameras, optical pyrometers, thermocouples, each including at least one of the above-mentioned devices. A combination, and similar instruments. The monitoring device 334 can provide data on the surface temperature of the substrate directly to the operator controlling the automatic deposition process or provide such data to the above-mentioned automatic system, and so on.

Referring now to FIG. 6, it is explained that there is an alternative embodiment of the system shown in FIG. 3. The substrate 400 can move in the direction indicated by the arrow 412. The first plasma torch device 414 can remain stationary or can be moved along The arrow 426 points to the movement in the opposite direction to the movement of the substrate 400 and emits the plasma flame tongue 416. One or more heat sources may be used, preferably a second plasma spray tube device 436 is used to preheat the ceramic material deposition zone 432 The previous existing coating surface area is the heating zone 430. The second plasma torch device 436 emits the second plasma torch 438 onto the surface 418, which is the heating zone 430, so as to improve the coating around the ceramic material deposition zone 432 The second plasma torch device 436 can be connected in series with the first plasma torch device 414 (as shown in the figure), or alternatively, it can be operated by , PLC, open loop control combined with passive process control, or independent power supply and control of the computer that controls the automatic deposition process. Nozzle devices 414 and 436 heat the surface of the existing coating to expand the coating material and close the surface through Thickness of cracks. The nozzle device 436 can mainly heat the surface of the existing coating in order to expand the coating material and close the cracks passing through the thickness to the surface. Once it has been coated

200610108698.4 The optional bonding coating, ceramic (powder) material feeder (not shown) injects a certain amount of ceramic material 420 into the plasma flame tongue 416 in the direction indicated by arrow 428. Ceramic material 420 is entrained In the plasma flame tongue 416 and brought to the surface 418.

By controlling the gas flow of the first and second two plasma nozzle devices 414 and 436, the plasma flame tongues 416 and 438 can be independently extended to obtain a high heat transfer rate to the surface 418. In order to achieve this goal, The second plasma torch device 436 can be oriented at a sufficient distance and angle to ensure the temperature of the heating coating, and cause a sufficiently high temperature gradient and expansion before the ceramic material 420 is deposited. The second plasma torch device 436 can be placed At a position closer to the surface 418 of the substrate 400 than the first plasma torch device 414, so that the second plasma torch 438 can preheat the surface 418 and any existing coatings. The first plasma torch device 414 and the first plasma torch device 414 The two plasma torch device 436 can include any plasma torch known to those of ordinary skill in the art to which the present invention pertains. A representative plasma torch can include, but is not limited to, an air plasma spray gun, such as New York State , 3MB® commercially available from Sulzer Meico, Inc. of Westbury.

As previously envisaged, the monitoring device 434 can be used to measure the temperature of the surface 418 during the deposition process. Suitable monitoring devices include, but are not limited to, infrared cameras, optical pyrometers, thermocouples, including at least one of the above devices. Various combinations, and similar instruments. As mentioned above, the monitoring device 434 can provide data about the surface temperature of the coating to the operator, PLC, open loop control combined with passive process control, or control automatic deposition as described above Process computer, etc.

Control the processing parameters of the method envisaged here to produce vertical splits (approximately perpendicular to the bonding coating surface), and these parameters are specific to variables such as gun type and fixture geometry. Generally speaking, known The precise spraying distance from the gun to the workpiece is matched with the relatively high power deposition to produce the required vertical split between about 4 to about 20 microcracks per inch. It will be understood by those of ordinary skill in the art to which the present invention pertains. Different spray guns, substrates and/or fixtures can change these parameters. Therefore, the parameters presented here can be used as a guide for selecting other suitable parameters under different operating conditions. In various embodiments, during the spray deposition of ceramic materials, including A cylindrical jig with a diameter of about 38 inches can be rotated at a speed between about 5 revolutions per minute (rpm) and about 100 revolutions per minute, and the preferred speed is about 25 rpm. The plasma spray gun can be positioned in the hollow cylindrical jig The angle of the gun to the workpiece during the coating of each workpiece can be between about 60 degrees to about 120 degrees, and in some embodiments can be about 90 degrees. The gun during the production of the ceramic layer

200610108698.4 The distance to the workpiece can vary from about 2 inches (0.05m) to about 5 inches (0.13m), and in some embodiments can be about 3.25 inches (0.083m). In order to obtain a satisfactory vertical split this A precise gun distance may be required. The lateral movement rate of the guns axial direction across the rotating fixture and substrate during deposition can be between about 0.05 inches/fixture per revolution (0.0013m/revolution) and about 1 inch/per revolution (0.03m/revolution). And can be about 0.02 inches per revolution (0.005 m per revolution) in some embodiments.

The ceramic material feed rate may be between about 15 g/min to about 300 g/min, and in some embodiments may be about 90 g/min. A carrier gas, such as ammonia, can be used to maintain The powder is under pressure and facilitates the feeding of the powder. Its flow rate can be between about 5 scfh (standard cubic inches per hour) (0.14 scmh (standard cubic meters per hour)) and about 20 scfh (0.57scmh), and in some embodiments can be about llscfh (0.31scmh). Here The defined standard conditions are room temperature (20Γ) and about one atmosphere (101 kPa). The main gas flow rate in the gun, such as ammonia, can be between about 60 scfli (1.70scmh) and about 175 scfh (4.96scmh). In some embodiments, it can be about 100scfh (2.83scmh). Similarly, the secondary gas flow rate in the gun, such as hydrogen, can be between about 5scfh (0.14scmh) and about 30scfh (0.85scmh), and in some embodiments It can be about 18scfh (0.51scmh). The voltage of the gun can be between about 60 volts and 80 volts, and in some embodiments it can be about 75 volts. Similarly, the guns current can be about 500 amperes and about Between 900 amps, and in a certain Some examples are about 700 amps. Based on the process parameters described here, it will be understood by those of ordinary skill in the art to which the present invention pertains that each parameter depends on the following variables, including but not limited to, powder type, powder size, and Especially the type of gun used, the relative speed and movement, and the method of preheating the surface used.

The system and method of the present invention are conducive to independent control of coating deposition and crack generation. The system and method described here control the thermal gradient leading to crack generation by measuring and controlling various variables that directly affect crack generation. An auxiliary heat source can be used to allow Independently control the variables of spraying and crack generation. By changing the chemical composition, porosity and crack structure, it is possible to independently control both the crack structure and the porosity of the coating, so as to obtain the required thermal conductivity, abrasion resistance, grindability, and Density, and other characteristics related to crack structure and coating.

It should be understood that the present invention is not limited to the various descriptions illustrated and described here, they should be considered only to illustrate the best mode for implementing the present invention, and at the same time they allow modification of the form, size, arrangement of parts and operating details. More precisely That is, the present invention should include all such modifications within the scope defined by the claims and the purpose of the invention.

200610108698.4