Disclosure of Invention
The invention provides a preparation method of a high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of a titanium alloy composite material, aiming at solving the technical problems that the thermal expansion mismatch between a coating and a substrate and Thermal Growth Oxide (TGO) is easily formed at an interface of a YSZ/MCrAlY (M is Ni and Co) thermal barrier coating in the prior art, so that the bonding stability of the thermal barrier coating and the substrate is poor, TBC is easily shed, and the thermal shock service life is low.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides a preparation method of a high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of a titanium alloy composite material, which comprises the following steps: and spraying rare earth silicate powder on the titanium alloy matrix to prepare the high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of the titanium alloy composite material.
In the above technical solution, it is preferable that: the rare earth silicate powder has a chemical formula of YxYb2-xSiO5Wherein x is 0-0.6.
In the above technical solution, it is further preferable that: x is 0, 0.2, 0.4 or 0.6.
In the above technical solution, it is preferable that: one specific embodiment of the preparation method is as follows: the method comprises the following steps:
the method comprises the following steps: preparing rare earth silicate powder;
step two: mixing the rare earth silicate powder obtained in the step one with deionized water, ammonium citrate and Arabic gum to obtain rare earth silicate slurry; performing ball milling, sieving and granulation on the rare earth silicate slurry to obtain rare earth silicate spraying powder;
step three: pretreating the titanium alloy matrix to obtain a pretreated titanium alloy matrix;
step four: preparation of coatings using APS technology
And (4) putting the rare earth silicate spraying powder obtained in the step two into a plasma spraying powder feeder, and spraying a rare earth silicate ceramic layer on the pretreated titanium alloy matrix obtained in the step three to obtain the high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of the titanium alloy composite material.
In the above technical solution, it is preferable that: when the rare earth silicate powder has a chemical formula of YxYb2-xSiO5The specific steps of the first step are as follows:
yb is mixed according to the molar ratio of the chemical formula2O3Powder, Y2O3Powder and SiO2Mixing the powders, adding water and zirconia balls into the mixed powder, and placing on a ball millBall milling is carried out for 6-12 h, the obtained slurry is dried, centrifugally ball milled and sieved, the obtained product reacts for 10-12 h at 1400-1500 ℃, and Y is obtainedxYb2-xSiO5And (3) powder.
In the above technical solution, it is preferable that: the ball milling time in the second step is 72 hours; said Y isxYb2-xSiO5The mass ratio of the powder to the deionized water to the ammonium citrate to the arabic gum is 100: (100-150): (0.4-0.8): (1-2).
In the above technical solution, it is further preferable that: said Y isxYb2-xSiO5The mass ratio of the powder to the deionized water to the ammonium citrate to the arabic gum is 100:150:0.8: 2.
in the above technical solution, it is preferable that: the pretreatment process in the third step comprises the following steps: carrying out sand blasting treatment on the surface of the titanium alloy matrix by using corundum sand, then cleaning the titanium alloy matrix in an ultrasonic cleaner by using ethanol, and drying to obtain the pretreated titanium alloy matrix.
In the above technical solution, it is preferable that: in the fourth step, the spraying current is 500-700A, the spraying power is 30-40 kW, the plasma gas is argon gas and hydrogen gas, the argon gas flow is 30-40 SLPM, the hydrogen gas flow is 10-20 SLPM, and the spraying distance is 90-110 mm.
In the above technical solution, it is preferable that: spraying Y in the four stepsxYb2-xSiO5The thickness of the ceramic layer is 100 to 300 μm.
The invention has the beneficial effects that:
the invention provides a preparation method of a high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of a titanium alloy composite material, which adopts novel rare earth silicate (such as Y)xYb2-xSiO5) As thermal barrier coating material, rare earth silicate (such as Y) is used as raw materialxYb2-xSiO5X is 0-0.6), has high oxidation resistance and low oxygen permeability, and has a thermal expansion coefficient between NiCoCrAlY and titanium alloy. Thus converting rare earth silicates (e.g. Y)xYb2- xSiO5) As the titanium alloy surface thermal barrier coating, the problem of poor bonding stability of the TBC and the titanium alloy substrate interface caused by the mismatching of the thermal expansion of the coating and the substrate is effectively solved, so that the bonding strength of the titanium alloy surface TBC and the high-temperature thermal shock service life are remarkably improved.
The invention firstly adopts a solid-phase reaction method to synthesize YxYb2-xSiO5Spray granulation of the synthetic powder followed by preparation of Y by APS techniquexYb2-xSiO5And (4) coating. The rare earth silicate material is synthesized by a solid phase method, and is used as a novel anti-oxidation and anti-ablation thermal protection coating on the surface of the titanium alloy to remarkably improve the bonding strength of a TBC (titanium alloy) on the surface of the titanium alloy, and simultaneously, the 800 ℃ high-temperature water quenching thermal shock service life of the rare earth silicate material is improved by about 35% compared with that of a traditional YSZ/NiCoCrAlY thermal barrier coating and is improved by about 38% compared with that of a single YSZ thermal barrier coating, and experimental results show that the novel rare earth silicate material has important application value for the surface thermal protection of the titanium alloy (Ti6Al4V/TC 4.
The ceramic layer thermal barrier coating prepared by the invention has good high-temperature thermal stability, low thermal conductivity and good oxidation resistance, and is suitable for being used as a high-temperature thermal protection thermal barrier coating of a titanium alloy hot end component.
Detailed Description
The invention provides a preparation method of a high-temperature oxidation-resistant rare earth silicate Thermal Barrier Coating (TBC) on the surface of a titanium alloy (Ti6Al4V/TC4) composite material, which comprises the following steps: and spraying rare earth silicate powder on the titanium alloy matrix to prepare the high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of the titanium alloy composite material.
The chemical formula of the rare earth silicate powder is YxYb2-xSiO5(x is 0 to 0.6) as an example, the preparation process of the preparation method is explained in detail.
The invention provides a preparation method of a high-temperature oxidation-resistant rare earth silicate Thermal Barrier Coating (TBC) on the surface of a titanium alloy (Ti6Al4V/TC4) composite material, which comprises the following steps:
the method comprises the following steps: preparation of YxYb2-xSiO5A powder, wherein x is 0-0.6;
step two: y obtained in the step onexYb2-xSiO5Mixing the powder with deionized water, ammonium citrate, and acacia to obtain YxYb2-xSiO5Slurry of YxYb2-xSiO5Ball-milling, sieving and granulating the slurry to obtain YxYb2-xSiO5Spraying powder;
step three: pretreating the titanium alloy matrix to obtain a pretreated titanium alloy matrix;
step four: preparing coating by APS technology, and mixing Y obtained in the second stepxYb2-xSiO5Putting the spraying powder into a plasma spraying powder feeder, and spraying Y on the pretreated titanium alloy matrix obtained in the step threexYb2-xSiO5And (5) a ceramic layer is formed to obtain the high-temperature oxidation-resistant rare earth silicate thermal barrier coating on the surface of the titanium alloy composite material.
According to the invention, Y is first preparedxYb2-xSiO5Powder of preparation YxYb2-xSiO5The preferable specific steps of the powder are as follows:
yb of2O3Powder, Y2O3Powder and SiO2Mixing the powder according to a molar ratio, adding water and zirconia balls into the mixed powder, carrying out ball milling on the mixed powder for 6-12 h in a ball mill, drying, carrying out centrifugal ball milling and sieving on the obtained slurry, and reacting the obtained product for 10-12 h at 1400-1500 ℃ to obtain Y0.4Yb1.6SiO5Powder; most preferably Yb2O3Powder, Y2O3Powder and SiO2The molar ratio of the powders was 4:1: 5.
According to the invention, Y is obtainedxYb2-xSiO5Mixing the powder with deionized water, ammonium citrate, and acacia to obtain YxYb2-xSiO5Slurry of YxYb2-xSiO5Ball milling is carried out on the slurry, the ball milling time is preferably 72 hours, the slurry passes through a 120 mu m sieve, the sieved slurry is sent into a spray dryer at 100-125 ℃ for spray granulation, so as to obtain spherical powder with good fluidity, the spray dried powder is sieved through a vibrating sieve, and the spray granulated powder with the particle size of 32-100 mu m is selected as APS spraying powder. Preferably said Y is0.4Yb1.6SiO5The mass ratio of the powder to the deionized water to the ammonium citrate to the arabic gum is 100: (100-150): (0.4-0.8): (1-2), most preferably 100:150:0.8: 2.
According to the invention, the titanium alloy substrate is pretreated before sprayingSo that the sprayed coating effect can reach the best, the working requirement under the high-temperature oxidation atmosphere is met, and the pretreatment process specifically comprises the following steps: the surface of the titanium alloy substrate is made of corundum sand (Al) with the granularity of 36 meshes2O3) Carrying out sand blasting treatment, wherein the sand blasting time is preferably 2-5 seconds, so that the surface of the matrix is roughened, and the effect of improving the bonding strength of the coating is achieved; and after sand blasting treatment, cleaning the titanium alloy matrix in an ultrasonic cleaner by using ethanol, removing oil stains and residual fine particle impurities on the surface, naturally drying, and then putting into a drying oven for drying for later use.
According to the invention, Y obtained as described above is used to prepare a coating using APS technologyxYb2-xSiO5Respectively putting the sprayed powder into a plasma spraying powder feeder, and firstly spraying Y on the pretreated titanium alloy matrixxYb2-xSiO5The thickness of the ceramic layer is preferably 100-300 mu m, more preferably 260-286 mu m, and the high-temperature oxidation-resistant thermal barrier coating on the surface of the titanium alloy composite material is obtained.
According to the invention, in the spraying process, the spraying current is 500-700A, the spraying power is 30-40 kW, and the plasma gas is argon (Ar)2) And hydrogen (H)2) Wherein the flow rate of argon gas is 30-40 SLPM, the flow rate of hydrogen gas is 10-20 SLPM, and the spraying distance is 90-110 mm.
According to the invention, the rare earth silicate YxYb2-xSiO5The thermal expansion coefficient of the titanium alloy substrate is about 6.99 ppm/DEG C, has good matching property with the titanium alloy substrate, and has high oxidation resistance and low oxygen permeability. Thus designing a novel YxYb2-xSiO5The oxidation-resistant thermal barrier coating with the ceramic layer structure effectively solves the problem that the coating and the matrix fall off due to thermal expansion mismatch and poor bonding strength, obviously prolongs the thermal shock service life of the thermal barrier coating, and ensures that the coating is not easy to fall off. Meanwhile, the components and the proportion of the coating material can be freely adjusted, the damage degree of the spraying process to the substrate material is lower, and the method is very suitable for the preparation of the high-melting-point ceramic coating and the industrial mass production.
In order to more clearly illustrate the present invention, the following examples are given to further illustrate the present invention, but the present invention is not limited to the following examples.
Example 1
Ytterbium oxide (Yb) is taken according to a molar ratio of 4:1:52O3) Powder, yttrium oxide (Y)2O3) Powder and Silica (SiO)2) Mixing the powder, adding deionized water and zirconia balls into the mixed powder, performing roll ball milling for 12h, taking out the balls after ball milling, drying slurry in a drying oven at 100 ℃, performing rapid centrifugal ball milling on the powder obtained after drying for 10min, and sieving by a 120-micron sieve. The obtained uniformly mixed Yb2O3、Y2O3And SiO2The raw material powder is subjected to solid phase reaction for 12 hours at the high temperature of 1400 ℃ to synthesize high-purity Y0.4Yb1.6SiO5And (3) powder.
Mixing the prepared Y according to the mass ratio0.4Yb1.6SiO5Powder: deionized water: ammonium citrate: mixing Arabic gum at a ratio of 100:150:0.8:2, ball milling for 72h, and sieving with a 120 μm sieve; and (3) carrying out spray granulation on the screened slurry at the temperature of 100 ℃, screening the spray granulation powder by using a vibration sample separation screen, and selecting the spray granulation powder with the particle size of 32-100 mu m as plasma spraying powder.
Carrying out surface sand blasting treatment on the titanium alloy matrix, placing the treated titanium alloy matrix in an ultrasonic cleaner, ultrasonically cleaning the titanium alloy matrix with ethanol, taking out the titanium alloy matrix after cleaning, naturally drying the titanium alloy matrix after air drying, placing the titanium alloy matrix in a 60 ℃ drying oven, and drying the titanium alloy matrix for later use.
The prepared Y is0.4Yb1.6SiO5The powder is fed into high-temperature plasma flame flow generated by a plasma spray gun, and a layer of Y with the thickness of 280 mu m is sprayed on the surface of a substrate0.4Yb1.6SiO5Coating, and naturally cooling to room temperature.
In the spraying process, the spraying current is 550A, the spraying power is 30kW, and the plasma gas used for spraying is argon (Ar)2) And hydrogen (H)2) Wherein the gas flow of argon is 30SLPM, the gas flow of hydrogen is 10SLPM, and the spraying distance is 90 mm.
FIG. 1 shows a ceramic powder Y for a thermal barrier coating prepared in example 1 of the present invention0.4Yb1.6SiO5XRD pattern of the ceramic powder phase and scanning electron microscope photograph of the thermal barrier coating prepared on the surface of the titanium alloy, from which the composition of the ceramic powder phase is Y0.4Yb1.6SiO5And the product is pure; the prepared thermal barrier coating is uniformly distributed, is tightly combined with the matrix, and has a compact ceramic layer structure.
Example 2
Respectively putting the purchased YSZ powder and NiCoCrAlY powder into a plasma spraying powder feeder, firstly, selecting NiCoCrAlY powder, feeding the NiCoCrAlY powder into high-temperature plasma flame flow generated by a plasma spray gun, spraying a NiCoCrAlY coating with the thickness of 100 mu m on the surface of a matrix, and then naturally cooling to room temperature. And then, selecting YSZ powder to be sent into high-temperature plasma flame flow generated by a plasma spray gun, spraying a layer of YSZ coating with the thickness of 280 mu m on the surface of the substrate, and naturally cooling to room temperature.
In the spraying process, the spraying current is 550A, the spraying power is 30kW, and the plasma gas used for spraying is argon (Ar)2) And hydrogen (H)2) Wherein the gas flow of argon is 30SLPM, the gas flow of hydrogen is 10SLPM, and the spraying distance is 90 mm.
The preparation method of the single YSZ thermal barrier coating sample is the same as that of the YSZ thermal barrier coating in example 2.
FIG. 2 is a scanning electron micrograph of a thermal barrier coating on the surface of a titanium alloy prepared in example 2 of the present invention (a) a YSZ/NiCoCrAlY thermal barrier coating; (b) the YSZ thermal barrier coating can be found from the figure that the prepared thermal barrier coating is uniformly distributed, is tightly combined with a substrate and has a compact ceramic layer structure.
Example 3
Ytterbium oxide (Yb) is taken according to the molar ratio of 7:3:102O3) Powder, yttrium oxide (Y)2O3) Powder and Silica (SiO)2) Mixing the powder, adding deionized water and zirconia balls into the mixed powder, performing roll ball milling for 12h, taking out the balls after ball milling, drying slurry in a drying oven at 100 ℃, performing rapid centrifugal ball milling on the powder obtained after drying for 10min, and sieving by a 120-micron sieve. The obtained uniformly mixed Yb2O3、Y2O3And SiO2The raw material powder is in 14High-temperature solid-phase reaction at 00 ℃ for 12h to synthesize high-purity Y0.6Yb1.4SiO5And (3) powder.
Mixing the prepared Y according to the mass ratio0.6Yb1.4SiO5Powder: deionized water: ammonium citrate: mixing Arabic gum at a ratio of 100:150:0.8:2, ball milling for 72h, and sieving with a 120 μm sieve; and (3) carrying out spray granulation on the screened slurry at the temperature of 100 ℃, screening the spray granulation powder by using a vibration sample separation screen, and selecting the spray granulation powder with the particle size of 32-100 mu m as plasma spraying powder.
Carrying out surface sand blasting treatment on the titanium alloy matrix, placing the treated titanium alloy matrix in an ultrasonic cleaner, ultrasonically cleaning the titanium alloy matrix with ethanol, taking out the titanium alloy matrix after cleaning, naturally drying the titanium alloy matrix after air drying, placing the titanium alloy matrix in a 60 ℃ drying oven, and drying the titanium alloy matrix for later use.
The prepared Y is0.6Yb1.4SiO5The powder is fed into high-temperature plasma flame flow generated by a plasma spray gun, and a layer of Y with the thickness of 280 mu m is sprayed on the surface of a substrate0.6Yb1.4SiO5Coating, and naturally cooling to room temperature.
In the spraying process, the spraying current is 550A, the spraying power is 30kW, and the plasma gas used for spraying is argon (Ar)2) And hydrogen (H)2) Wherein the gas flow of argon is 30SLPM, the gas flow of hydrogen is 10SLPM, and the spraying distance is 90 mm.
Two other kinds of thermal barrier ceramic powder (Yb)2SiO5/Y0.2Yb1.8SiO5Powder) preparation method and Y in example 30.6Yb1.4SiO5The powders were prepared in the same manner except that the molar ratio of the reactants added was varied according to the product composition. The preparation method of the titanium alloy surface thermal barrier coating is the same as that of the example 3.
FIG. 3 is a thermal barrier coating ceramic powder (Yb) prepared in example 3 of the present invention2SiO5/Y0.2Yb1.8SiO5/Y0.6Yb1.4SiO5) XRD pattern of the titanium alloy and scanning electron microscope photograph of the thermal barrier coating prepared on the surface of the titanium alloy, and the pure synthesized thermal barrier ceramic powder product can be found from the imageCleaning; the prepared thermal barrier coating is uniformly distributed, is tightly combined with the matrix, and has a compact ceramic layer structure.
The YSZ/NiCoCrAlY, YSZ and Y are respectively prepared on the surface of the titanium alloy by using the embodiment methodxYb2- xSiO5(x is 0/0.2/0.4/0.6) oxidation-resistant thermal barrier coating (samples are correspondingly named as a-f), the prepared titanium alloy surface thermal barrier coating is heated at 800 ℃ for 5min and then subjected to water quenching thermal shock test, the experimental result is shown in table 1, and the sample photo and the section electron microscope photo after thermal shock are shown in fig. 4 and 5.
Table 1 shows the results of the thermal shock life of different thermal barrier coatings on the surface of the titanium alloy composite material after water quenching at 800 ℃ for thermal shock
a:YSZ+NiCoCrAlY
|
b:YSZ
|
c:Yb2SiO5 |
d:Y0.2Yb1.8SiO5 |
e:Y0.4Yb1.6SiO5 |
f:Y0.6Yb1.4SiO5 |
210 times
|
205 times (x)
|
253 times (a)
|
269 times
|
283 times (twice)
|
259 times |
The thermal shock test results prove that: as can be found from fig. 5, the rare earth silicate material as a novel high temperature resistant and oxidation resistant thermal barrier coating material on the surface of the titanium alloy has better high temperature resistance and oxidation ion permeability resistance than a conventional YSZ/NiCoCrAlY thermal barrier coating, reduces the generation of an oxide layer on the surface of the titanium alloy, and has excellent high temperature oxidation resistance and protection performance on the surface of the titanium alloy, and the 800 ℃ water quenching thermal shock life results show that the thermal barrier coatings of the rare earth silicate material have a longer thermal shock life than the conventional thermal barrier coating, although the conventional thermal barrier coating does not fall off, it can be found through the sectional electron microscope photographs of experimental samples that a large number of cracks are generated on the surface of the coating to cause failure of the coating, as shown in fig. 5 and table 1; compared with the traditional YSZ/NiCoCrAlY and single YSZ thermal barrier coatings, the thermal barrier coating using the rare earth silicic acid as the titanium alloy surface has better high temperature resistance, oxidation ion permeability resistance and thermal shock resistance life, the thermal shock life of the optimal silicate material thermal barrier coating is improved by about 35% compared with the traditional YSZ/NiCoCrAlY thermal barrier coating, and is improved by about 38% compared with the single YSZ thermal barrier coating, and the method using the rare earth silicate as the titanium alloy surface thermal protection is an effective method.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.