The product with the insulating layer exposed to hot gas, and the method of its manufacture

 

The invention relates to structural elements for channels of hot gases, in particular turbine blades, arozamena screens, etc. containing a metal base of oversplash based on Nickel, cobalt or iron. Which increases the adhesion layer also acts as formers of aluminum oxide/chromium oxide. The insulating layer consists of trioxide or pseudotriakidae with the structure of pyrochlore or perovskite, which photostability between room temperature and melting temperature. In addition, the invention relates to a method of manufacturing such structural elements atmospheric plasma spraying or electron beam PVD. The technical result of the invention is to create products with the insulating layer that is resistant to hot gas. 3 S. and 19 C.p. f-crystals, 5 Il.

The object of the invention is a product with a ceramic coating, in particular structural element for use in a channel of hot gases, in particular in industrial gas turbines. The invention relates also to a method of manufacturing products with the insulating layer.

This product contains a base metal alloy NTA gas turbine, in particular, as the blades of a gas turbine or jarosewich screens. Structural elements exposed to the stream of hot corrosive gases of combustion. Therefore, they must be able to withstand high thermal loads. In addition, you want these structural elements were resistant to oxidation and corrosion. First of all to the movable structural elements, such as blades of a gas turbine, however, and to a stationary structural elements should be further mechanical requirements. The power and efficiency of a gas turbine, in which find application loaded hot gas components increase with increasing operating temperature. To achieve high efficiency and high power especially loaded high temperature components of gas turbines cover a ceramic material. It acts as a heat insulating layer between the hot gas stream and the metal substrate.

From the aggressive flow of hot gas metal base protects surfaces. In this modern design elements have, in most cases, multiple coatings, respectively performing specific tasks. Thus, there is a multilayer is toano attempts were made to achieve a higher power of the gas turbine due to the improvement in coverage.

The first suggestion for improvement is to optimize the adhesion of the coating. In U.S. patent 4321310 proposed to apply the adhesive coating of MCrAlY so that it had a small surface roughness. It then formed a layer of aluminum oxide. Due to this, there should be a significant increase in the adhesion of the insulating layer.

In U.S. patent 4880614 proposed to cause adhesion between the layer of MCrAlY and metal base of high-purity aluminium layer. This aluminum is used for education on the adhesion layer is a dense layer of Al2About3. By this measure should be increased service life of structural elements with the floor.

In U.S. patent 5238752 exposed adhesive layer of the aluminides of Nickel or platinum aluminides. This adhesive layer is formed a layer of aluminum oxide. His cause heat insulating layer.

In U.S. patent 5262245 indicated that the layer of aluminum oxide as oxidised layer is formed from the base material. The base contains for this purpose is an alloy based on Nickel, with alloying components with high oxidoreductase ability.

In U.S. patent N 4676994 disclosed coating the base layer, forming an oxide luminiaries floor consists of a dense deteriorations ceramic material. It can be oxide, nitride, carbide, boredom, silicide or other refractory ceramic material. This ceramic coating applied heat insulating layer.

In most of the above U.S. patents mentioned that the insulating layer has a columnar microstructure. Thus the columns of the columnar crystallite microstructure perpendicular to the surface of the base. As the ceramic material provides stabilized zirconium oxide. As the regulator considers calcium oxide, magnesium oxide, cerium oxide and preferably yttrium oxide. The stabilizer is required to prevent phase transformation of the crystal structure from cubic to tetragonal and, finally, in monoclinic. Stabilized mainly tetragonal phase by approximately 90%.

In U.S. patent 4321311 provided voluminous defect sections in the shelter heat insulating layer for relieving stresses in the shelter heat insulating layer when the temperature changes due to the fact that the substrate and the insulating layer have different coefficients of thermal expansion. The insulating layer has a columnar structure, and between the individual columns of the coating from stabilizirawe stress when temperature changes are disclosed in U.S. patent 5236787. Here between the substrate and the insulating layer caused an intermediate layer composed of metal. While the metal portion of this intermediate layer should increase towards the base and decrease in the direction of the heat insulating layer. On the contrary, the ceramic portion should be low near the base and high near the heat insulating layer. As the heat insulating layer is proposed stabilized by yttrium oxide, zirconium oxide containing cerium oxide. Insulating layers precipitated on the basis of a plasma spraying method or a PVD method. The proportion of stabilizer yttrium oxide is 8-20% vol.

In U.S. patent 4764341 describes the binding of a thin metal coating with ceramics. For metal coating applied Nickel, cobalt, copper, and alloys of these metals. For bonding the metal layer to a ceramic substrate at last put an intermediate oxide such as aluminum oxide, cerium oxide, titanium oxide or zirconium oxide, which is at a sufficiently high temperature forms by oxidation trioxide with the inclusion of the element of the metallic coating.

The objective of the invention is the creation of products with the insulating layer under the influence.

The invention derives from the fact that the old materials of the heat insulating layer contains predominantly pseudococcidae ceramics. Under it should be understood such ceramic materials, General structural formula which can lead to both AB2or a2In3. The most preferred turned out to be material based on zirconium oxide. However, the zirconium oxide starting from 900oWith shows aging phenomenon. They are caused by sintering of the heat insulating layer of zirconium oxide. Due to this increasingly reduced as the pore volume of the defective areas in the shelter heat insulating layer. Voltage caused by the different coefficients of thermal expansion of the material of the heat insulating layer and the base material can be removed, thus, all the worse. This sintering process is enhanced by the contamination of materials. Further strengthening it acquires as a result of interaction of the heat insulating layer with components of the hot gas, the Foundation materials and the material of the adhesion layer. Primarily used as a stabilizer yttrium oxide requires aging. As long service life of the gas turbine at full load is desirable, for example, 10,000 chaonia is limited to 1250oC. because Of this nxumalo permissible surface temperature the capacity and efficiency of the gas turbine set and limited.

According to the invention, the product contains a heat insulating layer ceramics with trioxide or pseudotriakidae.

Mainly the oxide has a structure of pyrochlore or perovskite. The material of the heat insulating layer has no phase transformation from room temperature to the melting temperature. Additive stabilizer in this case is not required. The melting temperature depends on the chemical compounds. She is mostly over 2150oC.

Mainly between the substrate and the insulating layer is a connecting layer connecting with the oxide. This layer can be obtained, for example, by depositing oxide. Preferably the binding layer is formed, however, as a result of oxidation which increases the adhesion layer located between the insulating layer and the substrate. Oxidation increases the adhesion layer can occur already before application of the heat insulating layer or by the use of the product in oxygen-containing atmosphere. Which increases the adhesion layer contains thus preferably oxidoreductase metal the metal base. For this alloy base contains the corresponding metallic element. Linking oxide is mainly chromium oxide and/or aluminum oxide.

The product consists predominantly structural element of a heat engine, such as a blade of a gas turbine, the component zaroshshego screen of the combustion chamber of a gas turbine or structural element of the internal combustion engine. Structural elements of a gas turbine, such as turbine blades or Gerasimenya screens contain thus preferably the base consisting of oversplash based on Nickel, chromium or iron. On this basis is, in particular, improves the adhesion of the layer of MCrAlY. He also serves as a layer to protect from oxidation, as in air or in almost any other oxygen-containing environment (at the latest, therefore, when using structural element) of the aluminum and/or chromium is converted to oxide. This improves the adhesion layer is a heat-insulating layer. It consists of a trioxide or pseudotriakidae. The latter is mainly the structure of pyrochlore or perovskite. Under trioxide thus refers to a substance that contains atoms of more than three is hypoxia chemical elements, however, these atoms are only three different groups of elements, the atoms of individual elements in respectively one of the three different groups of elements are in crystallographic relation to the same.

These ceramic substances show desired for the heat insulating layer low conductivity. thermal conductivity, in particular at elevated temperatures, comparable to the conductivity of zirconium oxide. In addition, the ceramic insulating substance layer have a coefficient of thermal expansion comparable to the coefficient of thermal expansion of the base material. The coefficient of thermal expansion is about 910-6/K. Containing trioxide ceramic insulating substance layer mainly between room temperature and melting temperature are photostability. Thus, there is no need for the regulator requiring the property of aging. In addition, provided that they are by increasing the adhesion layer of the MCrAlY stably linked to a base. Further, it should be emphasized that the rate of evaporation of ceramic materials insulating layer is very small. For example, the speed saparivara on the method of applying insulating layers, solved due to the fact that the coating trioxide, in particular ceramics with the structure of the pyrochlore and perovskite, carry out atmospheric plasma spraying method or a PVD method, for example by way EB-PVD (Electron Beam Physical Vapor Deposition). Both methods using a suitable choice of parameters it is possible to obtain a layer of the desired porosity. Can also be obtained columnar microstructure. This does not require the employee to cover the source already had the same chemical and crystallographic properties as the material of the finished coating. First of all I hafnate tantalum can be used in the method of coating as the source material powder mixture consisting of two dioxides. The mass ratio of the two powders correspond to the stoichiometric composition obtained then by way of the cover insulating layer on the structural element. For example, a heat insulating layer of garnata tantalum can be obtained through use in the EB-PVD process as starting material a mixture of hafnium oxide and lanthanum oxide. When this molar ratio of hafnium oxide to lanthanum oxide is 1,29.

Below ceramic substances trioxide or pseudotriakidae for taloja run. The drawings depict: Fig.1: a top view of the plane structure of pyrochlore; Fig.2: fragment of the unit cell structure of pyrochlore; Fig.3: standard cell of the perovskite structure; Fig. 4: standard cell of the perovskite structure, and it is displaced relative to the unit cell of Fig.1 1/2, 1/2, 1/2; Fig.5: cross section of a fragment of the turbine blades.

The insulating layer of ceramic substances trioxide with the structure of the pyrochlore crystal structure contains 88 atoms per unit cell. General structural formula of such trioxide States And2In2About7. The "a" and "b" refers to metal ions. "O" stands for oxygen.

The pyrochlore structure is described below (Fig.1). Relatively smaller cations are coordinated with oxygen atoms form an octahedron. These octahedra form a three-dimensional lattice, in which neighboring octahedra share one oxygen atom. Relatively large cations And are in a hexagonal ring formed by the oxygen atoms of the coordination octahedra cations Century Perpendicular to the surface of the ring above or below the corresponding cation is one atom of oxygen. The length of its relationship with this little shorter than the bond length amides. Another description of the structure of pyrochlore (Fig.2) shows that the structure is composed of two types of coordination polyhedra of cations. While a relatively smaller cation coordinates In six equidistant oxygen atoms in the trigonal form of antiprism. More cation And is coordinated by six equidistant oxygen atoms and two additional oxygen atoms with a slightly shorter bond length. These eight oxygen atoms form a rotated cube around the cation A.

Difficulties in the description of the structure occur, in particular, because at different bond lengths between cations and oxygen atoms, depending on what chemical elements are specifically for cations a and b, the coordination polyhedra are distorted. Therefore, it seems that ray diffractometer measurement of powder do not allow to draw conclusions about the mutual coordination of the various atoms. In this respect required to characterize the structure of pyrochlore fairly be characterized by values of 2from ray diffractometer measurements of powder. The following table gives the values of 2characteristic of the pyrochlore intensities and meet - 420
89.0 - 511/311
Due to contamination of the investigated powder may be slight deviations from the values 2in the area of the first decimal place. When ray diffractometer measurement of powder can cause systematic errors. They can, in principle, affect the measured values of 2in two ways. First, the measured values 2may move generally in the direction of larger or smaller values 2. However, the gap between two adjacent valuesremains the same. Secondly, it may happen that intensity, in General, will appear on the scale 2with a larger or smaller gap. Then, however, the ratio of the gaps between adjacent values 2the measured sample is equal to the ratio of the respective gaps between adjacent values 2in the specified table.

The cations a and b In the General chemical structural formula represent mainly rare earth metals and aluminum (in General: cations And3+) and hafnium, zirconium, and cerium (generally: cations In4+).

For teplota: garret lanthanum (La2Hf2O7), lead zirconate lanthanum (La2Zr2O7), garret aluminum (Al2Hf2About7), garret cerium (Ce2Hf2O7), lead zirconate cerium (Ce2Zr2O7), cerate aluminum (Al2Ce2O7and cerate lanthanum (La2Ce2O7). In suitable coating materials with pyrochlore structure also contains pseudotriakidae. They may have, for example, the structural formula of La2(HfZr)O7or (CeLa)Hf2O7. In addition, taking into account the connection with non-integer indices, such as La2(Hf1,5Zr0,5)O7.It is also possible that the ions a and b had multiple items simultaneously.

These compounds are distinguished by the fact that compared to replacing them with items they have a range of solubility of several mol.%. This prevents the formation of precipitates almost over - or deteriorations composition. They differ also in that they are photostability in a wider temperature range. This means that the structure of pyrochlore is stored in responsible for the operation of channels for hot gas temperature range. So, La2Hf2About7and La2Zr2O7change your crystallic the stabilizer. Consequently excluded the effect of the stabilizer, which increases the aging of the material. Permissible operating temperatures can therefore be increased to higher values.

The coating materials with the perovskite structure have the General chemical structural formula ABO3. Compounds with perovskite structure differ from the compounds with the structure of ilmenite, also having General chemical structural formula ABO3the fact that ions And relatively less in comparison with ions Century Structure in perovskite crystallographic relation described quite accurate. It is substantially less than the pyrochlore structure. The perovskite structure contains four atoms in the unit cell. In Fig.3 shows the unit cell of the perovskite structure. In Fig.4 depicts a unit cell of the perovskite structure, which is shifted relative to the unit cell in Fig. 2 1/2, 1/2, 1/2. Smaller cations As indicated by the solid circles, large cations In - hatched circles, and the anions of oxygen - hollow circles. As can be seen from Fig.3 and 4, represents a cubic perovskite structure. In her large ions To occupy the corners of an elementary cube, smaller ions And its price is the place were either cubic closest spherical packing, in which 1/4 of the octahedral vacancies are occupied by ions A. Ions In coordinated respectively 12 ions in the form of a cubic octahedron, and ions Of respectively adjoin four ion and two-ion A.

As a material for the insulating layers are applied preferably the following compounds: lead zirconate ytterbium (YbZr3), garret ytterbium (YbHfO3), lead zirconate calcium (ZrO3and garret calcium (CaHfO3). Especially preferred are the lead zirconate ytterbium and garret ytterbium.

Also, the materials of the insulating layer with a perovskite structure is not required that all the cations of group a and b belonged to the same element. So, here are the possible connections pseudotriakidae, for example structural formula Yb(Zr0,5Hf0,5)O3etc.

As the coating materials with pyrochlore structure, materials with a perovskite structure does not show a phase transformation from room temperature to high temperature values, though not to the melting point. For this reason, they are likewise preferred as the coating materials with pyrochlore structure.

In Fig. 5 shows a fragment of a blade of a gas turbine or item jarosewich and, based on Nickel, cobalt or iron caused to increase the adhesion layer 2. Improves the adhesion of the layer 2 consists of an alloy metal-chromium-aluminum-yttrium (MCrAlY). Which increases the adhesion layer 2 serves to provide adhesion between the insulating layer 4 and the substrate 1. Contained in increasing the adhesion layer of aluminum and/or chromium is used as formers, respectively, of aluminum oxide or chromium oxide. It forms a bonding layer 3, in particular dense passive layer, respectively, of aluminum oxide and chromium oxide as an oxygen barrier protects the substrate 1 from oxidation. Heat insulating layer 4 is applied on the base 1 preferably atmospheric plasma spraying method or a PVD method, for example by way of EB-PVD. In the case of the use of atmospheric plasma spraying as a method of applying the parameters of the method can be chosen so that shelter heat insulating layer 4 was set to the desired porosity. By using method EB-PVD can be obtained columnar structure of the heat insulating layer 4. Thus the columns of the crystallites perpendicular to the surface of the base 1. Heat insulating layer 4 is, for example, from hafnate lanthanum. Heat insulating layer 4 has a relatively loose microstruct the while in a relatively loose structure. This loose structure has a certain propensity for erosion in the stream of hot gas. As protection from erosion surface of the heat insulating layer 4 can be melted in a dense and compact protective layer 5, as shown here. The protective layer 5 can be obtained, for example, by laser melting.

It is also possible the application of the heat insulating layer 4 directly on the base 1. In this case, the alloy base 1 is already made so that it is suitable for linking education oxide such as chromium oxide and/or aluminum oxide. This linking oxide forms then bonding layer 3.


Claims

1. The product is exposed to hot gas containing the metal base (1), associated with ceramic heat insulating layer (4) containing trioxide or pseudotriakidae, characterized in that the trioxide or pseudotriakidae have a crystalline structure of pyrochlore structural formula And2In2About7.

2. The product under item 1, which trioxide or pseudotriakidae is garret metal, lead zirconate metal, or cerate metal, or a mixture.

3. The product under item 2, which trioxide is cerned trioxide or pseudotriakidae contains garret lanthanum.

5. Product according to any one of paragraphs.1-4, in which between the base (1) and the insulating layer (4) formed connecting layer (3) containing linking trioxide or pseudotriakidae.

6. Product according to any one of paragraphs.1-5, in which between the base (1) and the insulating layer (4) is formed which increases the adhesion layer (2) forming a connecting trioxide or pseudotriakidae.

7. Product according to any one of paragraphs.1-6, which connects trioxide or pseudotriakidae is an oxide of aluminium and/or chromium oxide.

8. Product according to any one of paragraphs.1-7, which trioxide or pseudotriakidae has no phase transformation between room temperature and maximum permissible operating temperature in excess of 1250C.

9. Product according to any one of paragraphs.1-8, which trioxide or pseudotriakidae has a melting point above 2150C.

10. Product according to any one of paragraphs.1-9, in which a heat insulating layer (4) has pores or other volumetric defect sections.

11. Product according to any one of paragraphs.1-10, in which a heat insulating layer (4) has a columnar microstructure, and the axial direction of the crystallites perpendicular to the surface of the base (1).

12. Product according to any one of paragraphs.1-11 represent the gas turbine.

13. The product is exposed to hot gas containing the metal base (1), associated with ceramic heat insulating layer (4) containing trioxide or pseudotriakidae, characterized in that the trioxide or pseudotriakidae have a crystalline structure of the perovskite structural formula ABO3and And denotes the ytterbium, and means hafnium or zirconium, or a means calcium, and hafnium.

14. The product under item 13, which is between the base (1) and the insulating layer (4) formed connecting layer (3) containing linking trioxide or pseudotriakidae.

15. Product according to any one of paragraphs.13 and 14, containing between the base (1) and the insulating layer (4) which increases the adhesion layer (2) forming a connecting trioxide or pseudotriakidae.

16. Product according to any one of paragraphs.13-15, which connects trioxide or pseudotriakidae is an oxide of aluminium and/or chromium oxide.

17. Product according to any one of paragraphs.13-16, which trioxide or pseudotriakidae has no phase transformation between room temperature and maximum permissible operating temperature in excess of 1250C.

18. Product according to any one of paragraphs.13-17, which trioxide has a temperature of the Oh (4) has pores or other volumetric defect sections.

20. Product according to any one of paragraphs.13-19, in which a heat insulating layer (4) has a columnar microstructure, and the axial direction of the crystallites perpendicular to the surface (I).

21. Product according to any one of paragraphs.13-20, representing a loaded hot gases structural element of the internal combustion engine, in particular a gas turbine.

22. A method of manufacturing exposed to hot gas product, comprising a metal base and a ceramic heat insulating layer of the trioxide or pseudotriakidae having the crystal structure of pyrochlore structural formula And2In2About7and ceramic heat insulating layer is applied on the basis of (1) plasma spraying method or a PVD method, in particular by the method of electron-beam PVD.

 

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EFFECT: the invention ensures production of the optically transparent coatings with the low electroconductivity at the high strength and stability of its properties.

13 cl, 6 dwg, 5 ex

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