CN111279008A

CN111279008A - Internal combustion engine component with dynamic thermal barrier coating and methods of making and using such coating

Info

Publication number: CN111279008A
Application number: CN201880070232.0A
Authority: CN
Inventors: 沃伦·博伊德·莱恩托恩
Original assignee: Tenneco GmbH
Current assignee: Tenneco GmbH
Priority date: 2017-10-27
Filing date: 2018-10-26
Publication date: 2020-06-12
Also published as: WO2019084370A1

Abstract

A component for an engine is provided, the component comprising: a thermal barrier coating applied to a body portion formed of a metal, such as steel, or other ferrous or ferrous based material. According to one embodiment, a bonding layer of metal is applied to the body portion, followed by a mixed layer of metal and ceramic with a graded structure, and then optionally a top layer of metal. The thermal barrier coating may also comprise a ceramic layer between the hybrid layer and the top layer or as the outermost layer. The ceramic comprises at least one of ceria, ceria-stabilized zirconia, yttria-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia, and zirconia stabilized by another oxide. The thermal barrier coating may be applied by thermal spraying. The thermal barrier coating preferably has a thickness of less than 200 microns and a surface roughness Ra of no more than 3 microns.

Description

Internal combustion engine component with dynamic thermal barrier coating and methods of making and using such coating

Cross Reference to Related Applications

The application requires us provisional patent application No. 62/578,105, filed on 2017, month 10, month 27; and us utility patent application No. 15/848,763, filed 2017, 12, 20; and priority of U.S. utility patent application No. 15/936,285, filed on 26.3.2018, the entire contents of which are incorporated herein by reference.

Background

1. Field of the invention

The present application relates generally to engine combustion components for internal combustion engines, and methods of making the same.

2. Correlation technique

Modern heavy duty diesel engines are moving towards increased efficiency in accordance with emission and fuel economy regulations. To achieve higher efficiency, the engine must run hotter at higher peak pressures. With these increased demands, heat loss through the combustion chamber can be problematic. For example, about 4% to 6% of the available fuel energy is typically lost as heat enters the cooling system through the piston. One way to increase engine efficiency is to extract energy from the hot combustion gases through turbo compounding. For example, approximately 4% to 5% of the fuel energy may be extracted from the hot exhaust gas by turbo compounding.

Another way to improve engine efficiency is to insulate the crown of the piston to reduce heat loss that would otherwise be lost to the cooling system. Ceramic thermal barrier coatings are one method of insulating pistons. It is known to apply a metal layer to the body portion of the piston and then a ceramic layer. However, ceramics are inherently porous and combustion gases can pass through the ceramic layer and oxidize the metal layer, causing failure at the ceramic/metal layer interface and ultimately leading to ceramic layer spallation and failure. The thermal expansion coefficients of the ceramic and metal layers also do not match, further exacerbating the potential delamination and spalling of the ceramic layer over time.

Another example is a thermal spray coating formed from yttria stabilized zirconia. This material, when used alone, is unstable due to thermal effects and chemical attack from diesel engines. It has also been found that thick ceramic coatings, such as those greater than 500 microns, e.g., 1mm, are susceptible to cracking and breaking.

Despite the 40 years of piston thermal coating development experience recorded in the literature, there has been no successful and cost-effective known product to date. It has also been found that typical aerospace coatings for jet turbines are not suitable for engine pistons due to the raw material and deposition costs associated with the high degree of periodicity of the thermal stresses applied.

Another piston protection method for aluminum pistons is to convert the surface of the aluminum crown to aluminum oxide by plasma oxidation and then seal the pores of the conversion layer with polysilazane. The transition zone is very thin (50-70 microns), is considered a highly insulating and dissipative material that can heat and cool rapidly, and thus will cycle with the heat of combustion. This relatively thin conversion method for aluminum pistons is not applicable to steel or other iron-based pistons.

Disclosure of Invention

One aspect of the present application provides a component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gas produced by the internal combustion engine. The engine component includes a body portion formed of a metal, and an improved thermal barrier coating coated on the body portion. According to one embodiment, the thermal barrier coating includes a bonding layer formed of a metal disposed on the body portion, a mixed layer disposed on the bonding layer, and a top layer disposed on the mixed layer; the mixed layer is formed of a mixture of a ceramic and a metal, and the top layer is formed of a metal and fills pores of the ceramic of the mixed layer.

According to another embodiment, the thermal barrier coating comprises a bonding layer formed of a metal disposed on the body portion and a mixed layer disposed on the bonding layer. The hybrid layer includes a mixture of a ceramic and a metal, and the thermal barrier coating has a thickness no greater than 700 microns.

According to yet another embodiment, the thermal barrier coating comprises a bonding layer formed of a metal disposed on the body portion and a mixed layer disposed on the bonding layer. The mixed layer includes a mixture of a ceramic and a metal. In this embodiment, a ceramic layer entirely made of a ceramic material is disposed on the mixed layer. The ceramic layer has an outermost exposed surface of the thermal barrier coating having a surface roughness Ra of no greater than 3 microns, and the thermal barrier coating has a total thickness of no greater than 200 microns.

Another aspect of the invention provides a method of manufacturing a component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gas produced by the internal combustion engine. The method includes applying a thermal barrier coating to a body portion formed of metal. According to one embodiment, the step of applying the thermal barrier coating comprises: applying a bonding layer formed of a metal to the body portion; applying a mixed layer formed of a mixture of a ceramic and a metal to the bonding layer; and applying a top layer formed of a metal to the mixed layer, the top layer filling pores of the ceramic of the mixed layer. In this embodiment, the mixed layer provides an outermost surface with a surface roughness Ra of not more than 3 micrometers.

According to another embodiment, the step of applying the thermal barrier coating comprises: a bonding layer formed of a metal is applied to the main body portion, and a mixed layer formed of a mixture of a ceramic and a metal is applied to the bonding layer. The total thickness of the thermal barrier coating is no greater than 700 microns.

According to yet another embodiment, the step of applying the thermal barrier coating comprises: applying a bonding layer formed of a metal to the body portion; applying a mixed layer formed of a mixture of a ceramic and a metal to the bonding layer; and applying a ceramic layer entirely formed of a ceramic material to the mixed layer. The ceramic layer presents an outermost exposed surface of the thermal barrier coating and has a surface roughness Ra of not more than 3 microns. The total thickness of the thermal barrier coating is no greater than 200 microns.

Drawings

These and other advantages of the invention will be better understood when the following detailed description is considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a side cross-sectional view of a combustion chamber of a diesel engine in which components exposed to the combustion chamber are each coated with a thermal barrier coating in accordance with an exemplary embodiment;

FIG. 2 is an enlarged view of a cylinder liner exposed to the combustion chamber of FIG. 1, wherein the thermal barrier coating is applied to a portion of the cylinder liner;

FIG. 3 is an enlarged view of a valve face exposed to the combustion chamber of FIG. 1, wherein the thermal barrier coating is applied to the valve face;

FIG. 4 illustrates the thermal barrier coating applied to a seal ring of an engine according to an example embodiment;

FIG. 5 illustrates the thermal barrier coating applied to an exhaust port in a crown of an engine, according to an example embodiment;

FIG. 6 illustrates the thermal barrier coating applied to a flame retardant panel of an engine, in accordance with an example embodiment;

FIG. 7 illustrates the thermal barrier coating applied on the side of a piston ring according to an example embodiment;

FIGS. 8-11 are cross-sectional views illustrating the thermal barrier coating applied on a steel body portion according to an example embodiment;

FIG. 12 is a flow diagram illustrating various embodiments of the thermal barrier coating; and

FIG. 13 illustrates test results performed to determine performance of the thermal barrier coating according to an example embodiment.

Detailed description of exemplary embodiments

One aspect of the present application provides an engine component, such as a heavy duty diesel engine or gasoline engine, for use in an internal combustion engine 20 having a thermal barrier coating 22 applied over the engine component. The thermal barrier coating 22 reduces heat loss, thereby improving engine efficiency. Thermal barrier coating 22 is also more cost effective and stable and less susceptible to chemical attack than other coatings used to thermally insulate engine components.

Various components of the internal combustion engine may be coated with a thermal barrier coating 22. As shown in FIG. 1, the thermal barrier coating 22 may be applied to one or more components exposed to the combustion chamber 24, including the cylinder liner 28, the cylinder crown 30, the fuel injector 32, the valve seat 34, and the valve face 36. Typically, the thermal barrier coating 22 is applied only to portions of the component 20 exposed to the combustion chamber 24. For example, the entire surface of the component 20 exposed to the combustion chamber 24 may be coated. Alternatively, only a portion of the surface of the component exposed to the combustion chamber 24 is coated. The thermal barrier coating 22 may also be applied to select locations of surfaces exposed to the combustion chamber 24 depending on the conditions of the combustion chamber 24 and the location of the surfaces relative to other components.

In the exemplary embodiment of fig. 1, when the piston 26 is at top dead center, the thermal barrier coating 22 is applied to only a portion of the inner diameter surface 38 of the cylinder liner 28, the inner diameter surface 38 being opposite the top surface 44 of the piston 26, and the thermal barrier coating 22 is not located at any other location along the inner diameter surface 38 nor at any contact surface of the cylinder liner 28. However, according to another embodiment, the thermal barrier coating 22 is applied to other surfaces of the cylinder liner 28. Fig. 2 is an enlarged view of a portion of the cylinder liner 28 including the thermal barrier coating 22. In this embodiment, the inner diametric surface 38 includes a groove 40 machined therein. A groove 40 extends from a top edge of the inner diameter surface 38 along a portion of the length of the cylinder liner 28, and the thermal barrier coating 22 is disposed in the groove 40. Also in this example, the length of the grooves 40 and the thermal barrier coating 22 is 5mm to 10mm wide. In other words, the thermal barrier coating 22 extends 5mm to 10mm along the length of the cylinder liner 28. In the exemplary embodiment of FIG. 1, a thermal barrier coating 22 is also applied to the valve face 36. Fig. 3 is an enlarged view of valve face 36 including thermal barrier coating 22. However, the thermal barrier coating 22 may be applied to another portion or surface of the valve guide or valve, such as the shaft or the rear.

As shown in FIG. 4, the thermal barrier coating 22 may also be applied to the sealing ring 54 on the cylinder opening of the crown gasket; as shown in fig. 5, an exhaust port 56 of the engine crown; as shown in fig. 6, a fire deck 62 of the cylinder crown; as shown in fig. 7, there are selective areas on the side or running surface of the piston ring 64. The thermal barrier coating 22 has tribological properties when applied to the running surface of the piston ring 64.

The thermal barrier coating 22 may also be applied to other components of the internal combustion engine 20 or components associated with the internal combustion engine 20, such as valve trains, after-combustion chambers, exhaust manifolds, and other components of the turbocharger. The thermal barrier coating 22 is typically applied to the hot gases or exhaust gases of the diesel engine that are directly exposed to the combustion chamber 24, and thus at the high temperatures and pressures at which the engine 20 is operating. The body portion 42 of the component is formed of a metallic material, preferably a material such as iron, such as steel or another iron-based material. The steel used to form the body portion 26 may be, for example, an AISI4140 grade or microalloy 38MnSiVS 5. The steel used to form the body portion 26 preferably does not include phosphate, and if any phosphate is present on the surface of the body portion 26, the phosphate is removed prior to application of the thermal barrier coating 22.

The thermal barrier coating 22 is applied to one or more components of the internal combustion engine 20 or exposed to the exhaust gas produced by the internal combustion engine 20 to maintain heat in the combustion chamber 24 or exhaust gas and thereby improve thermal efficiency. Thermal barrier coating 22 is typically disposed in a specific location according to a pattern measured by a thermal map to alter the hot and cold regions of the component. The thermal barrier coating 22 is designed for exposure to the harsh conditions of the combustion chamber 24. For example, the thermal barrier coating 22 may be applied to components of the diesel engine 20 that are subjected to large and oscillating thermal cycles. Such components may experience extreme cold start temperatures and may reach 700 ℃ when in contact with combustion gases. There are also about 15 to 20 or more temperature cycles per second from each combustion event. Furthermore, the pressure swing per combustion cycle is as high as 250 to 300 bar. The thermal barrier coating 22 is typically applied in a position aligned with and/or adjacent to the position of the fuel injector, the fuel plume or the pattern from the thermal map measurement in order to alter the hot and cold regions along the body portion.

The thermal barrier coating 22 is designed for exposure to the harsh conditions of the combustion chamber. For example, the thermal barrier coating 22 may be applied to the component 20 for use in diesel engines that are subjected to large and oscillating thermal cycles. This type of component 20 can be subjected to extreme cold start temperatures and can reach 760 ℃ when in contact with combustion gases. There are also about 15 to 20 or more temperature cycles per second from each combustion event. Furthermore, the pressure swing per combustion cycle is as high as 250 to 300 bar.

According to an exemplary embodiment shown in FIG. 8, the thermal barrier coating 22 includes a hybrid layer 50, a top layer 51, a bond layer 52, and a ceramic layer 60. The initial bond layer 52 is applied directly to the metal surface of the component 20, followed by the mixed layer 50, then the ceramic layer 60, and then the top layer 51. Fig. 9 shows another embodiment including a bonding layer 52, a mixed layer 50, and a ceramic layer 60. Fig. 10 shows another exemplary embodiment including a bonding layer 52, a mixed layer 50, and a ceramic layer 60. Fig. 11 shows another embodiment, which includes a bonding layer 52 and a mixed layer 50 in a coated state. FIG. 12 is a flow chart illustrating various possible embodiments of the thermal barrier coating 22.

The bonding layer 52 is formed of metal, and good adhesion to the metal body portion 26 is achieved. The bond layer 52 also has a thin, strong bonding surface to coat the remainder of the thermal barrier coating 22 thereon. The bonding layer 52 may be the same or similar or different material as that used to form the body portion 26, such as a ferrous material, such as steel or other iron or iron-based material. The material of the bonding layer 52 is compatible with the iron or other material used to form the body portion 26. The material of the bonding layer 52 may also be formed of chromium, nickel and/or cobalt. The bonding layer 52 may also be formed of a chromium alloy, a nickel alloy, and/or a cobalt alloy. The bond layer 52 may also be a high performance superalloy such as a nickel-based superalloy or a cobalt-based superalloy. For example, the metallic bonding layer 52 may include or be selected from: cobalt nickel chromium aluminum yttrium (CoNiCrAlY), nickel chromium aluminum yttrium (NiCrAlY), nickel chromium (NiCr), nickel aluminum (NiAl), nickel chromium aluminum (NiCrAl), nickel aluminum manganese (NiAlMo), and nickel titanium (NiTi). According to a preferred embodiment, the metallic bond coat 52 is formed of NiCrAlY or NiCrAl.

The thermal barrier coating 22 typically includes a metallic bond coat layer 52 in an amount of 5 to 33 volume percent (vol%), more preferably 10 to 33 vol%, and most preferably 20 to 33 vol%, based on the total volume of the thermal barrier coating 22. The metallic binding layer 52 is provided in the form of particles having a particle size of-140 mesh (< 105 μm), preferably-170 mesh (< 90 μm), more preferably-200 mesh (<74 μm), most preferably-400 mesh (<37 μm). The thickness limit of the metallic bonding layer 52 is determined by the grain size of the material forming the metallic bonding layer 52. To reduce the risk of delamination of the thermal barrier coating 22, a low thickness is often preferred. The bonding layer 52 may have a thickness of between 20 and 100 microns, and preferably between 20 and 50 microns.

Prior to applying the bonding layer 52, the metal surface of the body portion 26 is suitably cleaned, such as by grit blasting, and then the bonding layer 52 is deposited onto the exposed surface of the body portion 26 by plasma spraying, high velocity oxy-fuel (HVOF), and/or electric arc. Note that the surface to be coated with the barrier coating 22 is preferably bare steel and is free of, for example, a phosphate coating.

Applied to the bonding layer 52 is a composite or hybrid layer 50 of ceramic and metallic materials. The metallic material in the mixed layer 50 may be the same as, similar to, or different from the candidate material specified above for the bonding layer 52. In other words, the composition of the metallic material selected for the bond coat 52 may be the same, similar, or different than the composition of the metallic material used in the hybrid layer 50 of the thermal barrier coating 22.

The ceramic material of the mixed layer 50 is typically at least one oxide, such as ceria, ceria-stabilized zirconia, yttria-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia, zirconia stabilized by another oxide, and/or mixtures thereof. The thermal conductivity of ceramic materials is low, for example less than 1W/m.K. When ceria is used in the ceramic material, the thermal barrier coating 22 is more stable at the high temperatures, pressures and other harsh conditions of a diesel engine. The composition of the ceramic material including ceria also makes the thermal barrier coating 22 less susceptible to chemical attack than other ceramic coatings, which may be unstable when used alone in a diesel engine by thermal effects and chemical combustion. Ceria and ceria stabilized zirconia are more stable under such thermal and chemical conditions. The coefficient of thermal expansion of ceria is similar to that of the steel that may be used to form the body portion 26. The coefficient of thermal expansion of ceria at room temperature is in the range 10E-6 to 11E-6, while the coefficient of thermal expansion of steel at room temperature is in the range 11E-6 to 14E-6. Similar coefficients of thermal expansion help to avoid thermal mismatch that creates stress cracks.

In one embodiment, the ceramic material is present in an amount of 70 volume percent (vol%) to 95 vol%, based on the total volume of the thermal barrier coating 22. In one embodiment, the ceramic material used to form the thermal barrier coating 22 has a ceria content of 90 to 100 weight percent (wt%), based on the total weight of the ceramic material. In another exemplary embodiment, the ceramic material comprises 90 to 100 weight percent ceria-stabilized zirconia, based on the total weight of the ceramic material. The ceria stabilized zirconia preferably comprises 20 to 25 weight percent ceria based on the total weight of the ceria stabilized zirconia. In another exemplary embodiment, the ceramic material comprises 90 to 100 weight percent yttria or yttria-stabilized zirconia based on the total weight of the ceramic material. In yet another exemplary embodiment, the ceramic material includes a total amount of 90 to 100 weight percent ceria-stabilized zirconia and yttria-stabilized zirconia, based on the total weight of the ceramic material. In another exemplary embodiment, the ceramic material comprises 90 to 100 weight percent magnesia-stabilized zirconia, calcia-stabilized zirconia, and/or zirconia stabilized with another oxide, based on the total weight of the ceramic material. In other words, any of the oxides may be used alone or in combination in an amount of 90 to 100 weight percent, based on the total weight of the ceramic material. If the ceramic material does not consist entirely of ceria, ceria-stabilized zirconia, yttria-stabilized zirconia, magnesia-stabilized zirconia, calcia-stabilized zirconia, and/or of another oxide-stabilized zirconia, the remainder of the ceramic material is typically composed of other oxides and compounds, such as alumina, titania, chromia, silica, manganese or cobalt compounds, silicon nitride, and/or functional materials (e.g., pigments or catalysts). For example, according to one embodiment, a catalyst is added to the thermal barrier coating 22 to modify combustion. Color compounds may also be added to the thermal barrier coating 22. According to an example embodiment, the thermal barrier coating 22 is tan, but may be other colors, such as blue or red.

The material selection and proportions of the hybrid layer 50 may be controlled to achieve good bonding with the body portion 26 and to adjust the desired thermal characteristics of the thermal barrier coating 22. The metallic material mixed with the ceramic material also serves to protect the ceramic material (which is naturally porous) from the thermal and corrosive attack from the hot combustion gases which would otherwise penetrate and compromise the integrity of the mixed layer 50 causing it to delaminate from the main body portion 26. According to a preferred embodiment, the mixed layer 50 is a mixture of NiCrAlY or NiCrAl metal and ceria stabilized zirconia (20 weight percent ceria, 80 weight percent zirconia) in a 50:50 weight ratio. The insulating action of the thermal barrier coating 22 protects the body portion 26, but too high a concentration may cause the body portion 26 to retain heat on the surface rather than cycling with the thermal transients of the combustion chamber, which may be exposed to the combustion chamber. By increasing the metal content, the pores of the ceramic material are filled and protected from erosion, and the thermal barrier coating 22 becomes more thermodynamic and its temperature at the combustion chamber surface can swing or cycle more closely with the combustion chamber temperature, which is directly exposed to the combustion chamber environment. The thickness/thinness of the hybrid layer 50 may also play a role in the thermal performance of the thermal barrier coating 22, with thicker coatings being more insulative and thinner coatings being more dynamic in their thermal performance. According to an exemplary embodiment, the thickness of the hybrid layer 50 is 200 microns or less, or 100 microns or less, and preferably 20 to 50 microns.

According to one embodiment, the ratio of ceramic to metal material in the mixed layer 50 is 50:50 by weight. More or less ceramic in the mixture will increase and decrease, respectively, the thermal insulation and retention properties of the thermal barrier coating 22. Those skilled in the art will appreciate that the proportions and thicknesses can be adjusted to tune the hybrid layer 50 to achieve the desired thermal performance. For example, in the present case, it is desirable that the thermal barrier coating 22 adequately protect the metallic body portion 26 from thermal and oxidative damage due to exposure to the environment of the combustion chamber of an internal combustion engine, particularly a diesel engine. On the other hand, the thermal barrier coating 22 in the present case is also tailored to be sufficiently dynamic in its thermal properties to enable the thermal barrier coating 22 to cycle in synchronization with the transient temperature fluctuations of the combustion cycle. Furthermore, these competing characteristics will be realized in the thermal barrier coating 22, which should be strong enough to withstand corrosive attack by the hot combustion gases, which is satisfied in large part by mixing the metal and ceramic 50 in a mixed layer. The pores of the ceramic are infiltrated by the metal and hot corrosive gases cannot penetrate to the extent that they would be achieved in the absence of the metal, which would otherwise result in damage to the ceramic. This does not require that the pores of the ceramic be 100% filled, but rather that enough metal be required to prevent hot gases from passing through the surface into the ceramic of the hybrid layer 50. If the mixed layer 50 of the 50:50 mixed ceramic/metal layer 50 is cut, one would expect to see that 20% or more of the pores of the ceramic material contain metallic material and that there are few open pores extending from that surface to the bottom of the thermal barrier coating. An increase in the metal/ceramic ratio will increase the proportion of metal seen in the cross-section, thereby increasing the porosity.

According to an alternative embodiment, a mixed layer 50 of ceramic and metal may be used as the gradient structure, whereby the concentration of metal is higher compared to the ceramic near the metallic bond layer 52, and the ceramic concentration increases as one extends outward until the outer surface is reached, at which the mixed layer 50 may be substantially entirely ceramic. For example, a gradient structure may be formed by a gradual or steady transition from 100% metal to 100% ceramic material. Alternatively, on the outer surface of the mixed layer 50, both the metal and the ceramic material may be present. The transition function of the gradient structure can be linear, exponential, parabolic, gaussian, binomial, or follow another equation that relates the component average to position. The gradient structure of the hybrid layer 50 helps to relieve stress due to thermal mismatch and reduces the tendency for a continuous weak oxide boundary layer to form at the interface of the ceramic and metallic materials. The gradient structure may be more compatible for transition from steel or another metal to ceramic in certain applications and may result in a more robust thermal barrier coating 22 if desired for a given application. For a hybrid layer 50 with a gradient structure, a similar dynamic temperature profile as described above can be expected.

The outermost surface of the mixed layer 50 having a gradient structure may be polished to expose the ceramic and metal, and finish-machined after coating to obtain a desired roughness. For example, the surface roughness of the mixed layer 50 having a gradient structure after spray coating may be a surface roughness of Ra10-15 micrometers, but may be polished to a surface roughness of less than Ra 15 micrometers, for example, 3 micrometers or less, more preferably 1 micrometer or less.

As described above, the uppermost and/or uppermost surface of the mixed layer 50 is generally formed entirely of ceramic, but may include both metal and ceramic. Also, an additional ceramic layer 60 formed entirely of a ceramic material may be located on top of the hybrid layer 50, as shown in fig. 1, 3, 9 and 10. The ceramic layer 60 may be the outermost layer, thus presenting the outermost exposed surface of the thermal barrier coating 22, or may be located below the metallic top layer 51. The optional ceramic layer 60 may have a thickness of 20 to 80 microns. The ceramic material used to form ceramic layer 60 may be the same as or different from the ceramic of mixed layer 50.

According to one embodiment, the thermal barrier coating 22 includes a bonding layer 52, a hybrid layer 50, a ceramic layer 60 disposed on the hybrid layer 50, and a top layer 51 formed of a metal disposed on the ceramic layer 60. The top layer 51 is finished to a surface roughness Ra of not more than 3 micrometers, or not more than 1 micrometer, or less. As shown in fig. 8, the top layer 51 may be ground until some of the ceramic layer 60 is exposed or protrudes through the top layer 51. Alternatively, the top layer 51 may be smoothed to provide a continuous outermost surface such that no ceramic layer 60 is exposed through the top layer 51.

According to another exemplary embodiment, as shown in FIGS. 9 and 10, the thermal barrier coating 22 includes a bond coat layer 52, a hybrid layer 50, and a ceramic layer 60 formed entirely of a ceramic material disposed on the hybrid layer 50, wherein the ceramic layer 60 is an outermost exposed layer of the thermal barrier coating 22. In this case, the ceramic layer 60 is processed to a thickness of not more than 200 micrometers, preferably not more than 100 micrometers, and most preferably 20 to 80 micrometers. The ceramic layer 60 is also treated or buffed to a surface roughness Ra of not more than 5 microns, not more than 3 microns or less. In fig. 9, the ceramic layer 60 is polished to various degrees along the surface so that the thickness of the ceramic layer 60 is greater in some portions than in other portions, or the removal of the ceramic layer 60 may be completed in some regions. The surface roughness and thickness of the ceramic layer 60 may be adjusted according to how much the ceramic layer 60 is finished or processed. In fig. 10, the ceramic layer 60 is trimmed to a more uniform thickness.

According to another exemplary embodiment, the thermal barrier coating 22 includes a bond coat 52, a hybrid layer 50, such that the hybrid layer 50 is the outermost layer of the thermal barrier coating 22, as shown in FIG. 11. The hybrid layer 50 is shown in a painted state prior to treatment or finishing treatment. However, the hybrid layer 50 may be subjected to a smoothing treatment or treatment to achieve a desired thickness and surface roughness. Also, the metal top layer 51 may be coated directly on the mixed layer 50.

When the thermal barrier coating 22 includes a top layer 51, it is typically the outermost layer. The top layer 51 is formed of metal and is coated on the mixed ceramic/metal layer 50 and/or ceramic layer 60 to fill the pores and seal the surface of the ceramic. The top layer 51 is then typically polished to obtain the desired roughness. The top layer 51 is typically formed from 100 mass percent metal based on the total weight of the top layer 51. The top layer 51 may be the same or similar to the bonding layer 52 or may be a different material. For example, the material used to form the top layer 51 may be a ferrous material, such as steel or another ferrous based material. The material of the top layer 51 may also be chromium, nickel and/or cobalt. The top layer 51 may also comprise a chromium alloy, a nickel alloy and/or a cobalt alloy. The top layer 51 may also be a high performance superalloy such as a nickel-based superalloy or a cobalt-based superalloy. For example, the metal top layer 51 may include a material selected from: at least one of or consisting of an alloy of the group consisting of CoNiCrAlY, NiCrAlY, NiCr, NiAl, NiCrAl, NiAlMo and NiTi. According to a preferred embodiment, the metallic top layer 51 is formed of NiCrAlY or NiCrAl, chromium and/or chromium alloys. The top layer 51 is typically deposited on the hybrid layer 50 by plasma, HVOF and/or arc spraying. The top layer 51 may serve as a protective layer for the ceramic material.

As mentioned above, the top layer 51 is optionally polished to an extent such that some tips of the underlying ceramic material are exposed through the metal top layer 51. Depending on the amount of grinding and the initial thickness of the top layer 51, there may be a region of the top layer 51 in which the tips of the underlying ceramic material pass or the ceramic tips may pass uniformly throughout the top layer 51. The top layer 51 may be polished to a surface roughness Ra of 3 microns or less, or even 1 micron or less. A surface roughness Ra of 3 microns or less provides a very smooth and highly polished surface that can benefit the flow and guidance of the fuel plume during the combustion cycle and further prevent carbon deposition. The thickness of the top layer 51 is typically in the range of 10 to 100 microns depending on how much material is removed during the finishing process and whether it is desired to have the tips of the ceramic material exposed and visible. According to one embodiment, the hybrid layer 50 or the ceramic layer 60 is not exposed below the top layer 51, so that the top layer 51 provides a smooth continuous exposed surface. According to another embodiment, some of the hybrid layers 50 or some of the ceramic layers 60 are exposed through the top layer 51.

The resulting outermost final surface may consist of the top layer 51 or some underlying ceramic material may be exposed by a grinding operation such that a mixture of ceramic and metal is present on the outermost final surface. In the latter case of this embodiment, the final surface will have most of the metallic material, and the ceramic tips or spots will be scattered and appear in the top layer 51, which is otherwise continuous, especially where the final surface is worn more than in other areas. Visually, one would see a substantially metallic final surface with a uniform or heavy distribution of ceramic spots in some areas. This can give the surface a mottled appearance with ceramic specks in the discontinuous metallic top layer 51.

It should be understood that the individual layers applied are not completely smooth and are typical characteristics that would be expected by one skilled in the art when applying a coating by plasma spraying. Roughness can affect combustion by trapping fuel in cavities on the surface of the thermal barrier coating 22. It is generally desirable to avoid the coated surface being rougher than the examples described herein. Immediately after plasma spraying, the thermal barrier coating 22 preferably has a surface roughness Ra of less than 15 μm and a surface roughness Rz of no more than 110 μm. However, the thermal barrier coating 22 may be a finishing treatment. The same is true if an HVOF or arc process is used for deposition. Due to the overlap of adjacent deposits, the material is applied and structured in splats to produce a delamination effect, but is neither smooth nor necessarily uniform when applied. There is usually a series of peaks and valleys (seen microscopically) and mixing of the materials, as subsequently applied materials may reside in the valleys of previously applied materials, while the peaks of the previous materials may appear. Projection is performed through a layer of subsequently applied material. When a subsequent grinding operation is performed to smooth the surface, the mixing effect is enhanced, with some of the upper layer material being stripped away and some of the lower layer material (especially peaks) appearing on the ground surface.

The total thickness of the thermal barrier coating 22 may be in the range of 50 to 350 microns or 50 to 700 microns, but is preferably 200 microns or less, or 150 microns or less or even less than 100 microns. For example, the thickness of the entire coating layer (bonding layer 52, hybrid layer 50, and top layer 51) is 250 micrometers or less, where the bonding layer 52 has a thickness of 20 to 50 micrometers, the hybrid layer 50 has a thickness of 20 to 50 micrometers, and the top layer 51 has a thickness of 50 to 100 micrometers. The thickness of the ceramic layer may be 20 to 100 micrometers if a ceramic layer is present between the mixed layer 50 and the top layer 51. As described above, according to one embodiment, the thermal barrier coating 22 includes only the bond coat 52 and the intermixed layer 50, with a total thickness of 700 microns or less.

Typically, 5% to 25% of the overall thickness of the thermal barrier coating 22 is formed by the bond coat 52, and about 30% to 90% of the thermal barrier coating 22 may be composed of the hybrid layer 50. When a ceramic layer is present, about 5 to 50% of the thickness may be comprised of the ceramic layer.

As described above, the thermal barrier coating 22 of the exemplary embodiment includes a smooth surface with pores filled with the top layer 51, and thus is capable of providing fuel swirl characteristics similar to an uncoated surface. Since the pores are filled, it is undesirable for the thermal barrier coating 22 to absorb fuel or lubricant.

The horizontal spray pattern of the top layer 51 is not expected to absorb hot combustion gases due to the closed spray network created by the plasma spray. The thin ceramic-based hybrid layer 50 insulates the body portion 26 but follows the transient temperature of combustion, and the top layer 51 prevents thermal oxidation due to metal chemistry. The metal body portion 26 is thus protected from thermal and oxidative damage while yielding efficiency benefits.

When the thermal barrier coating 22 includes the bond layer 52 and the intermixed layer 50, but does not include the metallic top layer 51, the overall thickness of the thermal barrier coating 22 of this embodiment is up to 700 microns, preferably no greater than 400 microns, such as 50-400 microns, more preferably no greater than 200 microns, or no greater than 150 microns. Such a two-layer structure is typically plasma sprayed onto the surface of the body portion 26. Complex geometries of the body portion 26, such as surfaces having undulating features, may be coated.

According to one embodiment, the bond coat 52 of the thermal barrier coating 22 is applied to the body portion 26 after the surface is grit blasted. Preferably, no phosphate coating or other material is applied to the surface of the body portion 26 prior to application of the bonding layer 52. Preferably, the bonding layer 52 is applied by plasma spraying to an average thickness of 50 to 100 microns, and may also be applied using one of the other methods discussed herein. The material of the bonding layer 52 of this embodiment may be the same as those described above with respect to the first exemplary embodiment. Typically, the bond layer 52 is formed from chromium, nickel, cobalt or alloys thereof or nickel-based superalloys or cobalt-based superalloys. Preferably, the bond coat 52 is formed of NiCrAlY or NiCrAl.

The hybrid layer 50 may be applied directly to the bonding layer 52, typically by plasma spraying. There are no sharp interfaces in the thermal barrier coating 22 and therefore thermal stress concentrations are avoided. The hybrid layer 50 of this embodiment may include the same ceramic and metallic materials as discussed above with respect to the first exemplary embodiment. For example, the metal may be the same material used to form the bond layer 52, such as chromium, nickel, cobalt, alloys thereof, nickel-based superalloys, or cobalt-based superalloys. The ceramic may be at least one oxide, such as ceria, ceria-stabilized zirconia, yttria-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia, zirconia stabilized by another oxide, and/or mixtures thereof. The composition of the hybrid layer 50 can be varied to tune the thermal performance. The mixed layer 50 may vary from 10 to 90 mass percent based on the total weight of the mixed layer 50, with the remainder being formed of a metallic material, such as one of the metallic materials used to form the bonding layer 52 described above. In this embodiment, the mixed layer 50 may be used as the gradient structure described above. Typically, the uppermost portion of the mixed layer 50 is formed entirely of a ceramic material. Alternatively, as described above, a ceramic layer may be applied to the hybrid layer 50.

Hybrid layer 50 may have a thickness of 50 to 350 microns such that the total thickness is less than 700 microns, for example between 100 and 450 microns, with a preferred total thickness of about 200 microns or less. In this embodiment, no other metallic or ceramic coating is applied on top of the hybrid layer 50, such that the thermal barrier coating 22 is a two-layer structure. The spray roughness Ra of the mixed layer 50 is about 10 to 15 micrometers, but if necessary, the outermost surface of the mixed layer 50 may be ground as described above to smooth the surface to have Ra of 3 micrometers or less.

A preferred example composition of the mixed layer 50 is a mixture of NiCrAlY or NiCrAl and ceria stabilized zirconia (20 mass percent ceria, 80 mass percent zirconia) in a volume ratio of 50: 50. The bond coat 52 is also preferably a NiCrAlY or NiCrAl superalloy. Also, the preferred overall thickness of the thermal barrier coating 20 is about 200 microns, the bond coat 52 has a thickness of 50 to 100 microns, and the remaining length is the hybrid layer 50.

The thermal barrier coating 22 has many advantages, including good thermal protection of the metallic body portion 26. The thermal barrier coating 22 has a low thermal conductivity to reduce heat flow through the thermal barrier coating 22. Typically, thermal barrier coatings 22 having a thickness of less than 1mm have a thermal conductivity of less than 1.00W/mK, preferably less than 0.5W/mK, and most preferably no greater than 0.23W/mK. The specific heat capacity of the thermal barrier coating 22 depends on the particular composition used, but is typically in the range of 480J/kg.K to 610J/kg.K at temperatures between 40 and 700 ℃. The thermal barrier coating 22 is achieved by the porosity of the ceramic material 50. Due to the composition and low thermal conductivity of the thermal barrier coating 22, the thickness of the thermal barrier coating 22 may be reduced relative to a comparative coating, which reduces the risk of crack formation or spallation of the insulating coating 22. While achieving the same level of thermal insulation as the greater thickness of the comparative coating. Note that the advantageously low thermal conductivity of the thermal barrier coating 22 is not desired. Thermal conductivity is particularly low when the ceramic material 50 of the thermal barrier coating 22 comprises ceria stabilized zirconia.

Various evaluations and tests have been conducted to evaluate the characteristics and performance of the thermal barrier coating 22. For example, thermal imaging is used as a fast (<1s) way to estimate the cooling rate of the thermal barrier coating 22 on a metal body. Thermal barrier coating 22 has also been demonstrated to have a very strong ability to cycle with combustion cycle temperature. One way to evaluate the dynamic cycling capability of the thermal barrier coating 22 is to measure the rate at which the coated surface of the body portion 26 cools (thermally decays) when exposed to a heating/cooling cycle.

According to an example embodiment, testing of the thermal barrier coating 22 was performed on a metal specimen formed of AISI4140, whose bond layer 52 was formed of NiCrAlY, the hybrid layer 50 was formed of 50:50 weight percent hybrid NiCrAlY and ceria stabilized zirconia, and a ceramic material 51 formed of 100 weight percent ceria stabilized zirconia as the final exposed layer. For comparison purposes, a comparative coating on an aluminum substrate was tested. A total coating thickness of between 70 and 390 microns was tested. In addition, tests were conducted on AISI4140 samples having two thermal barrier coatings 22, the two thermal barrier coatings 22 comprising a NiCrAlY bond coat layer 52, the hybrid layer 50 being a hybrid layer 50 formed of 50:50 by weight NiCrAlY and a ceria-stabilized zirconia layer, such that the total coating thickness did not exceed 200 microns.

One method is to expose the coated surface of the sample to a heat source, remove the heat source and monitor the temperature drop of the surface as a function of time. The heat source may be a flash lamp and a Forward Looking Infrared (FLIR) camera may be used for thermal imaging to measure the change in temperature value as a function of time after a bulb cycle. In this case, the indicator light blinks and then records a frame at 60Hz when cool.

The test involves evaluating the average thermal decay time of the thermal barrier coating 22 on a metal specimen, the results of which are shown in fig. 13. The evaluation of the thermal decay included determining the rate at which the coating surface dropped to half its starting temperature. The same lamp flash cycle and sample were used to heat the coating surface to about 100 ℃ and the lamp was turned off. Using thermal imaging, the temperature of the average coating surface on a line from the outer diameter of the sample to the central axis of the sample was measured. Fig. 13 compares the time it takes for the thermal barrier coating deformation to drop in half and transfer thermal energy to the coating surface after lamp flicker.

The above temperature cycling curves for the coating samples show that the average thermal decay time of the main portion 26 of the coating can be adjusted to approximate the average decay time of combustion gases observed during the combustion cycle of an internal combustion engine. . The thermal barrier coating 22 thus protects the metallic body portion 26 from corrosion and thermal damage while providing a very hot dynamic surface that can oscillate with rapid temperature increases and decreases of combustion.

Another advantage when the thermal barrier coating 22 includes a gradient structure is that the bond strength of the thermal barrier coating 22 is increased due to the composition of the gradient structure 50 and the metal used to form the body portion 26. Thermal barrier coating 22 having a thickness of 0.38mm typically has a bond strength of at least 2000psi when tested according to ASTM C633.

The thermal barrier coating 22 having the blended layer 50 may be compared to a comparative coating having a two-layer structure, which is generally less successful than the thermal barrier coating 22 having the blended layer 50. The comparative coating comprised a metallic bonding layer applied to a metallic substrate followed by a ceramic layer with discrete interfaces through the coating. In this case, the combustion gases may pass through the porous ceramic layer and may begin to oxidize the bonding layer at the ceramic/bonding layer interface. Oxidation results in the formation of a weak boundary layer, which impairs the performance of the coating.

It has been found that the heat flow of a metal sample coated with a thermal barrier coating 22 is reduced by at least 50% relative to the same sample without the thermal barrier coating 22. By reducing the heat flow through the metal body portion 26, more heat may be retained in the exhaust gas produced by the engine, thereby improving the efficiency and performance of the engine.

The thermal barrier coating 22 of the present application has been found to adhere well to the body portion 26. However, for additional mechanical anchoring, the surface of the body portion 26 to which the thermal barrier coating 22 is applied is typically free of any edges or features having a radius of less than 0.1 millimeters. In other words, it is preferred that the surface of the thermal barrier coating 22 of the body portion 26 be free of any sharp edges or corners.

According to an example embodiment, the body portion 26 may include a broken edge or chamfer machined along an outer surface of the body portion 26. The chamfer allows the thermal barrier coating 22 to creep over the edge of the surface and lock radially onto the body. Optionally, at least one pocket, depression, or rounded edge may be machined along a surface and/or edge of the body portion 26. These features help avoid stress concentrations in the thermal spray coating 22 and avoid sharp corners or edges that may cause failure of the coating. The machined pockets or depressions also mechanically lock the mechanical thermal barrier coating 22 in place, again reducing the likelihood of delamination failure.

Typically, the thermal barrier coating 22 is applied to only a portion of the component exposed to the combustion chamber. For example, the entire surface of the component exposed to the combustion chamber may be coated. Alternatively, only a portion of the surface of the component exposed to the combustion chamber is coated. The thermal barrier coating 22 may also be applied to select the location of the surface exposed to the combustion chamber depending on the conditions of the combustion chamber and the location of the surface relative to other components. In the exemplary embodiment, the thermal barrier coating 22 is applied only to a portion of the inner diameter surface of the cylinder liner 28 opposite the top 44 of the piston 26 when the piston 26 is at top dead center. Not located at any other location along the inner diameter surface nor on any contact surface of the cylinder liner 28.

Another aspect of the invention provides a method of making a coated component for an internal combustion engine, such as a diesel engine. The body portion 26, which is typically formed of steel or another iron-based or iron-based material, may be manufactured according to a variety of different methods, such as forging or casting. The method may also include welding portions of the component together. As noted above, the body portion 26 may include a variety of different designs. Prior to applying the thermal barrier coating 22 to the body portion 26, any phosphate or other material located on the surface to which the thermal barrier coating 22 is applied must be removed.

The method next includes applying the thermal barrier coating 22 to the body portion 26. The thermal barrier coating 22 may be applied to the entire surface of the body portion 26, or to only a portion of the surface. The ceramic material 50 and the metallic bonding material 52 are provided in the form of particles or powder. The particles may be hollow spheres, spray dried and sintered, sol-gel, fused and/or crushed. In an exemplary embodiment, the method includes coating the metallic bonding material 52 and the ceramic material 50 by thermal or kinetic methods. According to one embodiment, a thermal spray technique, such as plasma spraying, flame spraying, or electric arc spraying, is used to form the thermal barrier coating 22. High velocity oxy-fuel HVOF (High velocity oxy-fuel) spraying is the first example of a kinetic method to produce denser coatings. Other methods of applying the thermal barrier coating 22 to the body portion 26 may also be used. For example, the thermal barrier coating 22 may be applied by a vacuum process such as physical vapor deposition or chemical vapor deposition. According to one embodiment, HVOF is used to apply a dense layer of metallic bond material 52 to the body portion 26, and a thermal spray technique (e.g., plasma spray) is used to apply the mixed layer 50. Also, the mixed layer 50 may be applied by changing the feeding rate of the dual powder feeder while the plasma spray coating is applied.

The exemplary method begins with spraying the metal for forming the bonding layer 52 in an amount of 100 weight percent and the ceramic for forming the hybrid layer 50 in an amount of 0 weight percent, based on the total weight of the sprayed material. Once the bonding layer 52 is formed, the method includes spraying a mixture of ceramic and metal to form the hybrid layer 50. To form the gradient structure, more and more ceramic material can be added to the composition throughout the spray coating process, while reducing the amount of metallic binder material. Thus, the composition of the thermal barrier coating 22 gradually changes from 100% metallic bond material 52 at the body portion 26 to 100% ceramic material 50 on the outermost surface (which may or may not be the exposed surface). Multiple powder feeders are typically used to apply the thermal barrier coating 22 and their feed rates are adjusted to achieve the desired texture. When the hybrid layer 50 includes a gradient structure, the gradient structure is achieved during the thermal spraying. To form the thermal barrier coating 22 of the first exemplary embodiment, the method includes applying a top layer 51 over the hybrid layer 50, typically by plasma, HVOF and/or arc spraying.

The thermal barrier coating 22 may be applied to the entire body portion 26 or a portion thereof. The uncoated regions of the body portion 26 may be masked during the step of applying the thermal barrier coating 22. The mask may be reusable and a removal material is applied adjacent to the coated region. The mask may also be used to introduce a pattern 22 in the thermal barrier coating. In addition, after application of the thermal barrier coating 22, the coating edges are blended and sharp corners or edges are reduced to avoid high stress areas.

As shown in FIG. 8, the thermal barrier coating 22 has a thickness t extending from the body portion 26 to the exposed surface 58. According to an exemplary embodiment, the thermal barrier coating 22 is applied to a total thickness t of no greater than 1.0mm, preferably no greater than 200 microns. The thickness t may be uniform over the entire surface of the body portion 26, but typically the thickness t varies over the surface. The thickness t of the thermal barrier coating 22 may be lower in certain regions along the body portion 26, such as in the region where shadows from the plasma gun are located. In other regions, such as regions in line with and/or adjacent to the fuel injector, the thickness t of the thermal barrier coating 22 increases. For example, the method may comprise the steps of: the body portion 26 is fixed in line against rotation by using a scanning gun to align the body portion 26 in a particular position relative to the fuel plume and using a row of scanning guns and varying the velocity of the spray or other methods. Thermal barrier coating 22 is applied over different regions of body portion 26 to adjust the thickness t of thermal barrier coating 22.

In addition, more than one layer of thermal barrier coating 22 having the same or different composition may be applied to the body portion 26. Further, coatings having other compositions may be applied to the body portion 26 in addition to the thermal barrier coating 22.

Prior to applying the thermal barrier coating 22, the surface of the body portion 26 is washed in a solvent to remove contaminants. Next, the method generally includes removing any edges or features having a radius of less than 0.1 millimeters. The method may also include forming a broken edge or chamfer 56 in the body portion 26, or another feature that facilitates mechanical locking of the thermal barrier coating 22 to the body portion 26 and reduces stress risers. These features may be formed by machining, such as by turning, milling, or any other suitable means. The method may also include sandblasting the surface of the body portion 26 prior to applying the thermal barrier coating 22 to improve adhesion of the thermal barrier coating 22.

After the thermal barrier coating 22 is applied to the body portion 26, the coated component may be ground to remove roughness and obtain a smooth surface. The method may also include forming a mark on the surface of the thermal barrier coating 22 for identifying the coated component when the component is used in the market. The step of forming the mark typically includes remelting the thermal barrier coating 22 with a laser. According to other embodiments, additional layers of graphite, thermally conductive paint, or polymer are applied over the thermal barrier coating 22. If a polymer coating is used, the polymer will burn off during use of the component in an engine. The method may include additional assembly steps such as washing and drying, addition of rust inhibitors, and packaging. Any post-processing of the coated component must be compatible with the thermal barrier coating 22.

The resulting integral thermal barrier coating 22 provides a thermal barrier for the iron component when exposed to the combustion gases and the cycling of the internal combustion engine, and is able to cycle better with the temperature of the intake air and combustion gases than a thicker ceramic coating. The metallic top layer 51 seals the remainder of the coating 22 against the corrosive fuel environment, which sometimes penetrates and damages the thermal barrier coating. The coating technique (e.g., plasma spraying) of the top layer 51 is believed to be particularly effective in shielding the top layer 51 and the hybrid layer 50 from the hot corrosive environment. The coated metal top layer 51 has a dense network of horizontally dispersed metal material that resists the absorption of fuel because they do not have the vertical boundaries of the metal top layer 51, such as would be more readily absorbed and eroded by combustion gases and fuel if present by the electrode site coating of the top layer 51. The smoothness of the ground top layer 51 presents a surface comparable to the uncoated part and allows the performance of the part in the fuel plume management to the level of the uncoated part and much better than the ceramic coated part alone.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings, and may be practiced otherwise than as specifically described within the scope of the appended claims. In particular, all features of all claims and all embodiments can be combined with each other as long as they are not mutually contradictory.

Claims

1. Component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gases produced by said engine, comprising:

a body portion formed of metal;

a thermal barrier coating coated on the body portion;

the thermal barrier coating includes a bonding layer formed of a metal disposed on the body portion, a mixed layer disposed on the bonding layer, and a top layer disposed on the mixed layer;

the mixed layer is formed of a mixture of ceramic and metal; and

the top layer is formed of a metal and fills pores of the ceramic of the mixed layer.

2. The component of claim 1, wherein the top layer has a surface roughness Ra of no greater than 3 microns.

3. The component of claim 1, wherein the thermal barrier coating has a thickness of no greater than 700 microns.

4. The component of claim 1, wherein the bonding layer has a thickness of 20-50 microns, the hybrid layer has a thickness of 20-50 microns, and the top layer has a thickness of 50-100 microns.

5. The component of claim 1, wherein the hybrid layer has a gradient structure comprising an increasing concentration of the ceramic material from the bonding layer to the top layer.

6. The component of claim 1, wherein the bond coat is formed of NiCrAlY, the metal of the hybrid layer is NiCrAlY, the ceramic of the hybrid layer is ceria-stabilized zirconia, and the top layer is NiCrAlY.

7. The component of claim 1, wherein the component is a cylinder liner, a cylinder head, a fuel injector, a valve seat, a valve face, a sealing ring, an exhaust port, a fire shield, or a piston ring.

8. The component of claim 1, wherein the bond layer is formed from at least one of chromium, nickel, cobalt, chromium alloys, nickel alloys, cobalt alloys, nickel-based superalloys, and cobalt-based superalloys;

the ceramic of the mixed layer is formed of at least one of ceria, ceria-stabilized zirconia, yttria-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia, and zirconia stabilized by another oxide;

the metal of the mixed layer is formed by at least one of chromium, nickel, cobalt, chromium alloy, nickel alloy, cobalt alloy, nickel-based superalloy and cobalt-based superalloy; and

the top layer includes at least one of chromium, nickel, cobalt, a chromium alloy, a nickel alloy, a cobalt alloy, a nickel-based superalloy, and a cobalt-based superalloy.

9. A component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gases produced by an internal combustion engine, comprising:

a body portion formed of metal;

a thermal barrier coating coated on the body portion;

the thermal barrier coating includes a bonding layer formed of a metal disposed on the body portion and a mixed layer disposed on the bonding layer;

the mixed layer comprises a mixture of ceramic and metal; and

the thermal barrier coating has a thickness of no greater than 700 microns.

10. The component of claim 9, wherein the hybrid layer has a surface roughness Ra of 3 microns or less and the thermal barrier coating has a thickness of no greater than 200 microns.

11. The component of claim 9, wherein the bond coat is formed of NiCrAlY, the metal of the hybrid layer is NiCrAlY, and the ceramic of the hybrid layer is ceria-stabilized zirconia.

12. The component of claim 9, wherein the metal of the bond coat and/or the metal of the hybrid layer is formed of NiCrAl.

13. The component of claim 9, wherein the bonding layer has a thickness of 50 to 100 micrometers and the hybrid layer has a thickness of 50 to 350 micrometers.

14. The component of claim 9, comprising: a ceramic layer formed entirely of a ceramic material disposed on the mixed layer.

15. The component of claim 14, comprising: a top layer formed of a metal disposed on the ceramic layer, and having a surface roughness Ra of no greater than 3 microns.

16. The component of claim 15, wherein the surface roughness of the top layer is no greater than 1 micron.

17. The component of claim 15, wherein some of the ceramic layer is exposed through the top layer.

18. The component of claim 15, wherein none of the ceramic layers are exposed through the top layer.

19. The component of claim 14, wherein the ceramic layer is an outermost exposed layer of the thermal barrier coating.

20. The component of claim 19, wherein the ceramic layer has a thickness of no greater than 100 microns.

21. The component of claim 20, wherein the surface roughness Ra of the ceramic layer is not greater than 5 microns.

22. The component of claim 21, wherein the surface roughness Ra of the ceramic layer is not greater than 3 microns.

23. A method of manufacturing a component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gases produced by an internal combustion engine, comprising the steps of:

applying a thermal barrier coating to a body portion formed of metal;

the step of applying the thermal barrier coating comprises: applying a metallic bonding layer to the body portion; applying a mixed layer formed of a mixture of a ceramic and a metal to the bonding layer; and applying a top layer of metal to the mixed layer, the top layer filling pores of the ceramic of the mixed layer, and the mixed layer providing an outermost surface having a surface roughness Ra of no more than 3 microns.

24. The method of claim 23, wherein applying the thermal barrier coating to the body portion comprises: plasma spraying, flame spraying, high velocity oxy-fuel ((HVOF)), and/or arc spraying.

25. The method of claim 23, comprising: grinding the mixed layer until the surface roughness Ra of the outermost surface of the mixed layer is not more than 3 micrometers.

26. The method of claim 23, wherein the step of applying the hybrid layer comprises: increasing the concentration of the ceramic relative to the metal from the bonding layer to an outermost surface of the mixed layer.

27. A method of manufacturing a component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gases produced by an internal combustion engine, comprising the steps of:

applying a thermal barrier coating to a body portion formed of metal;

the step of applying the thermal barrier coating comprises: applying a bonding layer formed of a metal to the main body portion, and applying a mixed layer formed of a mixture of a ceramic and a metal to the bonding layer; and

the step of applying the thermal barrier coating onto the body portion comprises: applying the thermal barrier coating to a total thickness of no greater than 700 microns.

28. The method of claim 27, wherein applying the thermal barrier coating to the body portion comprises: plasma spraying, flame spraying, high velocity oxy-fuel ((HVOF)), and/or arc spraying.

29. The method of claim 27, wherein the step of applying the hybrid layer comprises: increasing the concentration of the ceramic relative to the metal from the bonding layer to the outermost surface.

30. The method of claim 27, wherein applying the thermal barrier coating comprises: and coating a ceramic layer completely formed by a ceramic material on the mixed layer.

31. The method of claim 30, comprising: coating a top layer formed of a metal on the ceramic layer, and finishing the top layer to a surface roughness Ra of not more than 3 μm.

32. The method of claim 31, comprising: smoothing the surface roughness of the top layer to no greater than 1 micron.

33. The method of claim 31, wherein some of the ceramic layer is exposed through the top layer.

34. The method of claim 31, wherein none of the ceramic layers are exposed through the top layer.

35. The method of claim 30, wherein the ceramic layer is an outermost exposed layer of the thermal barrier coating.

36. The method of claim 35, wherein the ceramic layer has a thickness of no greater than 100 microns.

37. The method of claim 36, wherein the ceramic layer has a surface roughness Ra of no greater than 5 microns.

38. The component of claim 37, wherein the surface roughness Ra of the ceramic layer is not greater than 3 microns.

39. A component for exposure to a combustion chamber of an internal combustion engine and/or to exhaust gas produced by the internal combustion engine, comprising:

a body portion formed of metal;

a thermal barrier coating coated on the body portion;

the mixed layer comprises a mixture of ceramic and metal;

a ceramic layer entirely formed of a ceramic material is provided on the mixed layer;

the ceramic layer presents an outermost exposed surface of the thermal barrier coating and has a surface roughness Ra of not more than 3 microns; and

the total thickness of the thermal barrier coating is no greater than 200 microns.

40. A method of manufacturing a component comprising the steps of:

applying a thermal barrier coating to a body portion formed of metal;

the step of applying the thermal barrier coating comprises: applying a bonding layer formed of a metal to the main body portion, applying a mixed layer formed of a mixture of a ceramic and a metal to the bonding layer, and applying a ceramic layer entirely formed of a ceramic material to the mixed layer;

the ceramic layer has an outermost exposed surface of the thermal barrier coating and has a surface roughness Ra of no greater than 3 microns, and the thermal barrier coating has a total thickness of no greater than 200 microns.