JP2993723B2 - Manufacturing method of ceramic coated heat resistant member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sprayed ceramic film used for a part or a part to be exposed to a high temperature such as a moving blade or a stationary blade of a gas turbine or a combustor of a rocket engine. The present invention relates to a method for producing a heat-resistant composite member having the same.

[Conventional technology]

In the fields of gas turbines, aerospace, nuclear fusion reactors, and the like, the development of ultra heat-resistant materials having excellent heat resistance, shielding properties, environmental resistance, and the like has been cited as an important technical issue.

Conventionally, as one method of manufacturing such a super heat-resistant material, a method of coating ceramics on the surface of a metal or an alloy by a plasma spraying method is known. As a typical example, a ZrO ₂ layer is formed on the surface of a heat-resistant superalloy base material based on Ni, Co, Fe, etc. via an intermediate layer for the purpose of improving corrosion resistance, oxidation resistance, adhesion, and thermal stress relaxation. A method of spraying ceramics such as Y ₂ O ₃ has been proposed.
As described in JP-A-156938, there is known a functionally graded material (FGM) for reducing thermal stress by providing an intermediate layer between the base material and the ceramic in which the component ratio of the both changes continuously.

[Problems to be solved by the invention]

In the above prior art, the ceramic layer on the surface formed by thermal spraying has a porous structure in which sprayed flat particles 2 form a laminated structure on a substrate 1 as shown in FIG. Film. For this reason, the strength of the ceramic layer is reduced in accordance with the content of the voids 3 as compared with the combustion ceramics and the like, and the thermal stress caused by a temperature gradient under use conditions and a thermal expansion difference between the base material and the intermediate layer. Cracks and peeling are likely to occur.

Also, even when the thermal stress is relaxed by the intermediate layer or the FGM described above, the ceramic layer is compressed at a high temperature by receiving partial heating or cooling the base material, creating a temperature difference between the front and back surfaces. When the stress acts, the voids in the ceramic layer are filled and relaxation occurs, thereby inducing a tensile stress at the time of cooling to cause cracks. Furthermore, when a high-temperature atmospheric gas invades through the voids and cracks, the metal components of the base material and the intermediate layer may be corroded and oxidized to cause peeling and detachment of the film.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a heat-resistant ceramic coated member having high thermal shock resistance, corrosion resistance, oxidation resistance and adhesion to a substrate.

[Means for solving the problem]

In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, densification has been achieved by filling ceramics and metal using a sol-gel impregnation method, an electroplating method, etc. The present inventors have discovered that it is possible to improve the strength and adhesion of a ceramic sprayed film and to impart corrosion and oxidation resistance, and have completed the present invention.

That is, in the heat-resistant coated member provided with the ceramic sprayed coating having the laminated structure of the molten particles on the surface of the heat-resistant member, a part or all of the voids between the particles or in the particles are filled with the ceramic or the metal. The gist of the present invention is a method for producing a ceramic-coated heat-resistant member.

(Operation)

 The configuration and operation of the present invention will be described.

As the substrate of the heat-resistant composite material in the present invention, for example,
Cu, Ni alloy, Co-based alloy or the like is used. The material of the ceramic thermal sprayed layer, for example, ZrO ₂ -MgO, ZrO ₂ -Ca
O, ZrO ₂ -Y ₂ O _{3 and the} like are suitable.

As a method of filling the voids, ceramics are filled with tetraethyl orthosilicate (TEOS) or aluminum phosphate solution (MAP) by vacuum impregnation into the voids of the sprayed coating, and then fired.
sol filling iO ₂ and Al ₂ O ₃ in the gap - using gel method.

In addition, as a method for filling a metal, in an electrolyte containing metal ions to be filled, a water-impervious insulating material such as silicon rubber is provided around the material so that the electrolyte contacts the base material only through the gaps of the sprayed layer. An electroplating method is used in which electroplating is performed in a state of being covered with an object, and the space is filled.

In the heat-resistant ceramic sprayed coating produced according to the present invention, since the voids in the ceramic layer are filled with other substances, the strength and Young's modulus of the ceramic layer are improved, and the thermal shock resistance can be improved accordingly. In addition, by selecting a metal, alloy, or ceramic with excellent corrosion resistance and oxidation resistance as the filling material, the high-temperature combustion gas permeates and diffuses through the voids in the ceramic layer to corrode the metal components of the base material and the intermediate layer. Alternatively, oxidation can be prevented, and excellent corrosion resistance and oxidation resistance can be exhibited. Furthermore, if the same metal as the base material is selected as the filling material in the electroplating method, the filling material will fill the voids integrally with the base material, acting as a so-called anchor, and the adhesion of the coating layer will be reduced. improves.

〔Example〕

The present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1 As shown in FIG. 2, a Ni-based alloy substrate 1 having a thickness of 3.5 mm
A ceramic layer 5 made of a ZrO ₂ -6 wt% Y ₂ O ₃ film is formed thereon as a bonding layer via a CoNiCrAlY alloy layer 4 having a thickness of 100 μm by plasma spraying with a thickness of 300 μm, and then T
It is immersed in an EOS (Tetra Eitxl Ortho Silicate: Si (OC ₂ H ₅ ) ₄ ) solution to impregnate the voids in the ceramic layer with the TEOS solution. Thereafter, it heated to 400 ° C. in air in an electric furnace to convert the TEOS to SiO ₂ 6 by hydrolysis reaction. Complete void because volume shrinkage happens during the firing in order to fill in SiO ₂ 6, further repeating the impregnation → sintering in vacuum. Each time the firing is completed, the change in the weight of the sample is measured, and the filling is completed when the increase in the weight hardly occurs. In this manner, SiO ₂ 6 voids in the ceramic layer
To obtain a sprayed heat-resistant ceramic film.

Next, the thermal shock resistance of the ceramic sprayed coating in which the voids obtained by the above method were filled with SiO ₂ and the ceramic sprayed coating not filled with SiO ₂ were evaluated for comparison.

At this time, the test piece was 9 × 9 mm and the center of the sample surface was 10 kw while the back surface of the test piece was water-cooled via a copper holder.
The irradiation was partially heated by a xenon arc lamp, and the irradiation was stopped and quenched approximately 5 seconds after the temperature at the center of the surface reached almost constant. Thereafter, the sample surface and cross section were observed, and the occurrence of cracks and the presence or absence of peeling near the interface were examined. As a result, cracks and peeling were observed in the center of the surface of the ceramic sprayed coating that had not been filled with SiO _{2 when the} surface center temperature exceeded about 700 ° C. No cracking or peeling was observed until this point, and it was confirmed that the thermal shock resistance could be significantly improved.

Example 2 As shown in FIG. 4, ZrO ₂ -6 wt.
After forming a ceramic layer 5 made of a% Y ₂ O ₃ film by plasma spraying to a thickness of 300 μm, a conducting wire 8 is attached to the back surface of the copper base 1 by soldering or the like as shown in FIG. A portion other than the surface is covered with an impermeable insulator 7 such as silicon rubber. This is immersed in an aqueous solution containing copper ions, for example, a copper sulfate electrolyte 10, and the electrolyte is sufficiently penetrated into the gaps in the ceramic layer 5 by vacuum impregnation or the like. 11 is applied to perform electrolytic plating to precipitate copper 12 in the void. At this time, if the voltage is controlled so that the current density is 0.5 mA / cm ² or less, a good filling result can be obtained. In this way, as shown in FIG.
To obtain a sprayed heat-resistant ceramic film.

Next, thermal shock resistance was evaluated in the same manner as in Example 1 for the ceramic sprayed film in which the voids obtained by the above method were filled with copper and the ceramic sprayed film not filled with copper for comparison. Was.

As a result, cracks and peeling of the coating were observed at the center of the surface of the ceramic sprayed coating that had not been filled with copper when the surface temperature exceeded about 700 ° C. No cracking or peeling was observed up to about 800 ° C in the thermal spray coating, confirming that the thermal shock resistance and adhesion were significantly improved.

Example 3 As shown in FIG. 5, a ceramic layer 5 composed of a ZrO ₂ -6 wt% Y ₂ O ₃ film was formed on a Ni-based alloy substrate 1 having a thickness of 3.5 mm to a thickness of 3 mm.
After being formed by the 00 μm plasma spraying method, as shown in FIG. 3, a conductive wire 8 is attached to the back surface of the Ni-based alloy base material 1 by soldering or the like, and a portion other than the surface of the ceramic layer 5 is impermeable to silicon rubber or the like. Covered with an insulator 7. This is Ni
After immersing in an electrolytic solution containing ions, for example, a nickel sulfate electrolytic solution 10 and sufficiently penetrating the electrolytic solution into the voids in the ceramics layer by vacuum impregnation or the like, a DC voltage 11 is applied between the Ni electrode 9 and the electrolytic solution. Plating is performed to precipitate Ni13 in the voids. The energization was terminated when the gap having a thickness of about 100 μm was filled in the base material, the sample was taken out, the insulator 7 and the conductor 8 were removed, and then ultrasonic cleaning was performed in distilled water to remain in the ceramics layer. Remove the remaining electrolyte and dry.
Next, it is immersed in a TEOS solution in a vacuum, and the TEOS solution is sufficiently penetrated into the voids in the ceramic layer. Thereafter, heated to 400 ° C. in air in an electric furnace and converted into SiO ₂ 6 as shown in FIG. 5 the TEOS hydrolysis reactions. During firing, volume contraction occurs, so that the voids are completely filled with SiO ₂ , so that impregnation and firing in vacuum are repeated. Each time the firing is completed, the change in weight of the sample is measured. In this way, the gap in the ceramic layer in the range of about 100 μm on the substrate side is Ni, and the gap on the surface side is about 200 μm.
A ceramic sprayed coating in which voids in the range of μm were filled with SiO ₂ was obtained.

Next, the voids obtained by the above methods Ni and SiO ₂
Example 1 shows a ceramic sprayed coating filled with, a ceramic sprayed coating without any filling treatment for comparison, a ceramic sprayed coating with all voids filled with Ni, and a ceramic sprayed coating with all voids filled with SiO _2. The same thermal shock resistance test as described above was performed. As a result, as shown in Table 1, it was confirmed that the thermal spray resistance and the adhesion to the substrate were significantly improved in the ceramic sprayed coating in which the substrate side of the ceramic layer was filled with Ni and the surface side was filled with SiO _2. Was.

In addition, a heat cycle test in which heating to 1000 ° C in air and cooling to room temperature were repeated in an electric furnace, and the thermal fatigue resistance and oxidation resistance were evaluated. No cracking or peeling was observed in the ceramic sprayed coating filled with Ni on the material side and SiO ₂ on the surface side, and no oxidation of the substrate occurred, confirming that the thermal fatigue resistance and oxidation resistance were improved. Was.

Example 4 As shown in FIG. 6, the base material side
CoNiCrAlY alloy layer, the surface side of which is ZrO ₂ -6wt% Y ₂ O ₃ , with an intermediate layer 14 between which the composition ratio of both changes continuously
After the ZrO ₂ -6 wt% Y ₂ O ₃ ceramic layer 5 is formed, it is immersed in a TEOS solution in a vacuum and TEOS is inserted into the voids in the ceramic layer.
Impregnate the solution. Then, in an electric furnace at 400 ℃ in air
Heated to, to convert the TEOS to SiO ₂ 6 by hydrolysis reaction. Since the volume shrinks during firing, the voids are completely
To fill in the O ₂ 6, further repeating the impregnation → sintering in vacuum. Each time the firing is completed, the weight change of the sample is measured,
The filling is completed when no increase in weight is observed. In this way, all the voids in the ceramic layer
A heat-resistant ceramic-coated member having an intermediate layer filled with SiO ₂ and having a continuously changing composition between the ceramic layer and the substrate was obtained.

Next, a heat-resistant ceramic-coated member having an intermediate layer in which the voids in the ceramic layer obtained by the above method are filled with SiO ₂ and whose composition continuously changes between the ceramic layer and the base material, The thermal shock resistance was evaluated in the same manner as in Example 1 for a heat-resistant ceramic-coated member having an intermediate layer in which the composition continuously changed between the ceramic layer in which the voids were not filled with SiO ₂ and the substrate. As a result, the surface center temperature in samples that do not fill the void with SiO ₂
When the temperature exceeded 800 ° C, cracks occurred in the center of the ceramic layer.However, it was confirmed that cracks did not occur in the ceramic layer until the surface center temperature reached 1000 ° C in the sample in which all voids were filled with SiO ₂ , and the thermal shock resistance could be improved. did it.

Example 5 As shown in FIG. 3, ZrO ₂ -6 wt.
% Y ₂ O ₃ ceramic layer 5 is formed to a thickness of 300 μm by a plasma spraying method, and then conducting wire 8 is attached to the back surface of copper base 1 by soldering or the like.
Is covered with an impermeable insulator 7 such as silicon rubber. This is immersed in an electrolytic solution containing copper ions, for example, a copper sulfate electrolytic solution 10, and the electrolytic solution is sufficiently penetrated into the voids in the ceramic layer 5 by vacuum impregnation or the like.
And a DC voltage 11 is applied between the electrodes to perform electrolytic plating.
As shown in the figure, copper 12 is precipitated in the void. At this time, the voltage was controlled so that the current density changed with respect to the plating time as shown in FIG. As the current density increases, the deposition rate increases, but the circulation of the electrolyte in the fine pores is poor, so the supply of copper ions cannot be made in time. Progresses rapidly in the relatively large pores in which the pores are sufficiently filled, and the filling rate of the voids in the entire space in the layer decreases. In this way, the voids in the ceramic layer as shown in FIG. 8 are filled with copper, and the filling rate of copper changes in the thickness direction (the filling rate is large on the base material side, and small on the surface side). A ceramic sprayed coating was obtained.

Next, the ceramic sprayed coating in which the voids obtained by the above method are filled with copper, and the copper filling rate changes in the thickness direction, and the ceramic sprayed coating not subjected to the filling treatment with copper for comparison were performed. The thermal shock resistance was evaluated in the same manner as in Example 1.

As a result, it was confirmed that the thermal spray resistance and the adhesion to the substrate were significantly improved in the ceramic sprayed coating in which the voids were filled with copper and the filling rate of copper changed in the thickness direction.

Embodiment 6 The entire surface of a portion of a gas turbine rotor blade A made of a Ni-based alloy exposed to combustion gas as shown in FIG. 9 (hatched portion in FIG. 9).
Then, in the same manner as in Example 1, a ceramic sprayed coating in which the voids according to the present invention were filled with SiO ₂ was formed. Further, in the same manner as in Example 3, a ceramic sprayed coating in which voids according to the present invention were filled with Ni and SiO ₂ was formed. The thickness of the ceramic layer is 300 μm, and the CoNiCrAlY alloy layer of the bonding layer is
100 μm.

Next, for these gas turbine blades A and for comparison, gas turbine blades on which a ceramic sprayed coating not subjected to filling treatment was formed, an air heating test using an electric furnace at 1050 ° C. and an electric furnace at 1050 ° C. A thermal cycle test in which heating in the middle atmosphere and air cooling outside the furnace were repeated was performed. In the heat cycle test, the heating time was 30 minutes, and the cooling temperature was 200 ° C. for 20 minutes. As a result, the air gap according to the present invention
The blades formed with the ceramic coating filled with SiO ₂ and the blades formed with the ceramic coating filled with Ni and SiO ₂ in the voids were sound after the test for about 1000 hours. On the other hand, in the blade with the ceramic film that was not filled, the film peeled off in about 300 hours.
As a result of the thermal cycle test, a gap according to the invention SiO ₂
The wings with the ceramic film filled with
In the blade with the ceramic film filled with Ni and SiO ₂ , the ceramic film was sound after 1000 repetitions. On the other hand, in the blade with the ceramic film that was not filled, the ceramic layer peeled off after about 100 repetitions. As described above, the turbine blade having the ceramic film in which the gap is filled according to the present invention is less susceptible to damage such as peeling of the ceramic film as compared with the conventional turbine blade. Since the reduction of the material temperature can be stably maintained, the reliability and the life of the turbine blade can be improved. The ceramic coating according to the present invention can be applied not only to the turbine blades described in the present embodiment but also to devices and members exposed to a high heat load, such as a turbine combustor, a combustor of a rocket engine and a nozzle.

〔The invention's effect〕

As described above, according to the present invention, since the thermal shock resistance, corrosion resistance and oxidation resistance of the ceramic sprayed film with respect to the base material and the adhesion with the base material can be improved, there is no cracking or peeling even at high temperatures. A heat-resistant ceramic heat-resistant covering member can be provided. Further, the heat-resistant ceramic-coated member according to the present invention is promising as a material for a moving and stationary blade or a combustor of a high-temperature gas turbine, which is expected to be developed in the future, or a combustor of a high-performance rocket engine. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a ceramic-coated heat-resistant member obtained by thermal spraying, FIG. 2 is a schematic cross-sectional view of a ceramic-coated heat-resistant member in which all voids are filled with SiO ₂ , and FIG. illustration of the filling process, Figure 4 is cross-sectional schematic view of a ceramic-coated heat-resistant member a portion of the voids were filled with Cu, FIG. 5 is a ceramic coating filled with the base material side of the gap Ni, the surface of SiO ₂ Cross-sectional schematic view of heat-resistant member, sixth
The figure is a schematic cross-sectional view of a ceramic-coated heat-resistant member having an intermediate layer having a continuously changing composition in which all voids are filled with SiO ₂ , FIG. 7 is a graph showing a change in plating time and current density, and FIG. FIG. 9 is a cross-sectional view showing a state where a specific space is filled, and FIG. 9 is a perspective view of a turbine blade embodying the present invention. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Sprayed particles 3 ... Void 4 ... Binding layer 5 ... Ceramic layer 6 ... Si filled in the void
O ₂ , 12… Cu filled in voids, 13… N filled in voids
i, 14 ... An intermediate layer whose composition changes continuously.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Mehata 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 4/04

Claims (8)

(57) [Claims] 1. A method for manufacturing a ceramic-coated heat-resistant member having a laminated ceramic sprayed coating of molten particles on a surface of a heat-resistant substrate, wherein an electrolytic solution containing metal ions is formed after the sprayed coating is formed on the surface of the substrate. A method for producing a ceramic-coated heat-resistant member, characterized in that voids in the film are filled with a metal by energization in the inside. 2. The method according to claim 1, wherein the filler is made of a metal such as Cu, Ni, Co, or an alloy thereof. 3. The method of manufacturing a ceramic-coated heat-resistant member according to claim 1, wherein the filling rate of the filling material in the voids is changed in the thickness direction of the film by changing the current density of the current. 4. The method for producing a ceramic-coated heat-resistant member according to claim 1, wherein the substrate is a heat-resistant alloy containing Fe, Co or Ni as a main component, or Cu or a Cu alloy. 5. A method for manufacturing a ceramic-coated heat-resistant member having a laminated ceramic sprayed film made of molten particles on a surface of a heat-resistant substrate, wherein the metal salt solution is applied to the film after forming the thermal sprayed film on the surface of the substrate. Impregnated inside,
A method for producing a ceramic-coated heat-resistant member, characterized in that firing is performed thereafter, and the impregnation and firing are repeated to fill voids in the coating with ceramic formed from the metal salt. 6. The method for producing a ceramic-coated heat-resistant member according to claim 5, wherein the filling material is made of ceramics of SiO ₂ , Al ₂ O ₃ , ZrO ₂ or a mixture thereof. 7. A method for producing a ceramic-coated heat-resistant member having a laminated ceramic sprayed film made of molten particles on a surface of a heat-resistant base material, wherein the sprayed film is formed on the surface of the base material, and then an electrolytic solution containing metal ions is formed. Filling the gaps in the film with a metal by passing current therein, then impregnating the film with a metal salt solution, and then performing firing, repeating the impregnation and firing to fill the voids in the film with the metal salt. A method for producing a ceramic-coated heat-resistant member, characterized by filling the formed ceramic. 8. The method according to claim 7, wherein the ceramic filler is a metal oxide, a metal nitride, a boride, a metal carbide, a silicide, or a mixture thereof.