Zirconium oxide composite powder as well as preparation method and application thereof

Abstract

The invention discloses zirconium oxide composite powder as well as a preparation method and application thereof, and belongs to the field of zirconium oxide materials for oil and gas wells. The invention provides zirconium oxide composite powder which comprises a zirconium oxide solid solution containing yttrium oxide and cerium oxide and aluminum silicate fibers. The zirconium oxide composite powder material is applied to oil and gas wells, solves the problem that the existing zirconium oxide composite powder material for oil and gas wells cannot simultaneously ensure the mechanical property and corrosion resistance, and has the characteristics of good mechanical property and corrosion resistance.

Description

Technical Field

[0001] The invention belongs to the field of zirconium oxide materials used in oil and gas wells, and in particular relates to a zirconium oxide composite powder, a preparation method and application thereof. Background Art

[0002] As global oil and gas resource exploration gradually extends to deep wells and complex geological environments, downhole tools and equipment have increasingly stringent performance requirements for key materials. Zirconia is widely used in key components such as drill bit coatings, valve seals, and sensor protective layers in the oil and gas field due to its excellent high-temperature stability, high hardness, and wear resistance. It can significantly improve the life and reliability of equipment under extreme working conditions.

[0003] However, existing zirconia ceramics still face the following technical bottlenecks in the actual application of oil and gas wells: the traditional zirconia powder preparation relies on solid-phase reaction method or high-temperature sintering (>1500℃), which leads to grain coarsening and insufficient density, and high energy consumption restricts the industrialization cost; the sol-gel method can reduce the synthesis temperature, but its process is complicated and the powder is easy to agglomerate, making it difficult to achieve high purity and uniform doping (such as Y 2 O 3 、CeO 2 stabilizers, which affect the phase change toughening effect of the material; in addition, H 2 S, CO 2 , high mineralization Cl - Solutions and other strong corrosive media, while conventional zirconia ceramics are prone to low-temperature degradation under long-term hot and humid conditions, resulting in the transformation of the tetragonal phase to the monoclinic phase, inducing microcracks and resulting in insufficient corrosion resistance. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is that the existing zirconium oxide composite powder material used in oil and gas wells cannot simultaneously ensure the mechanical properties and corrosion resistance of the material. A zirconium oxide composite powder with good mechanical properties and corrosion resistance, a preparation method thereof and an application thereof are proposed.

[0005] In order to solve the technical problem, the technical solution adopted by the present invention is:

[0006] In one aspect, the present invention provides a zirconium oxide composite powder, comprising: a zirconium oxide solid solution containing yttrium oxide and cerium oxide, and aluminum silicate fibers.

[0007] Preferably, in terms of mass percentage, it comprises: 85-94% of zirconium oxide solid solution containing yttrium oxide and cerium oxide, 3-5.2% of magnesium oxide, 1.5-4.5% of aluminum silicate fiber, and 0.5-0.8% of niobium oxide.

[0008] Preferably, the zirconium oxide solid solution containing yttrium oxide and cerium oxide includes 80-85% zirconium oxide, 2.5-6% yttrium oxide and 2-3% cerium oxide.

[0009] Preferably, the fiber diameter of the aluminum silicate fiber is selected from 1-3 μm, and the aspect ratio is selected from 20:1-50:1.

[0010] Preferably, the purity of zirconium oxide is ≥99.9%, and the average particle size is 30-100nm; the purity of yttrium oxide is ≥99.9%, and the average particle size is 100-200nm; the purity of cerium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of magnesium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of niobium oxide is ≥99.5%, and the average particle size is 100-300nm; the crystal of zirconium oxide is monoclinic phase, and the specific surface area is 50-100m 2 / g; Ce in cerium oxide 3+ / Ce 4+ The molar ratio is 1.5-2.5:1.

[0011] Preferably, in the zirconium oxide composite powder, tetragonal zirconium oxide accounts for 79-91%, and cubic zirconium oxide accounts for 9-21%.

[0012] On the other hand, the present invention provides a method for preparing zirconium oxide composite powder of any of the above technical solutions, including a powder mixing step, the powder mixing step comprising: firstly ball-milling zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide, and niobium oxide, and then adding aluminum silicate fiber and mixing evenly to obtain a mixture.

[0013] Preferably, it includes a raw material pretreatment step, a powder mixing step, a calcination step, a slurry preparation and dispersion step, and a granulation step; the raw material pretreatment step includes: acid washing the aluminum silicate fiber to remove surface impurities, washing with water to neutrality and then drying; the calcination step includes: calcining the mixture at 800-1200°C for 5-8h to obtain a calcined powder; the slurry preparation and dispersion step includes: dispersing the calcined powder to a particle size D50 less than 0.5μm and D90 less than 0.8μm, and then adding a dispersant and a binder and stirring to obtain a slurry; the granulation step includes: spray drying the slurry to remove moisture therein and obtain granulated powder, and the particle size of the granulated powder is 30-70μm.

[0014] Preferably, in the slurry preparation and dispersion steps, the amount of dispersant is 0.5-1.5%, and the amount of binder is 2-3.6%, measured by mass percentage; the dispersant is selected from ammonium polyacrylate; and the binder is selected from one of polyvinyl alcohol, glycerol, and polyethylene glycol.

[0015] The present invention also proposes an application of the zirconium oxide composite powder of any of the above technical solutions in oil and gas wells.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] On the one hand, the present invention proposes a zirconium oxide composite powder, optimizes the components, optimizes the grain boundary design and the crystal phase stability strengthening mechanism by regulating oxygen vacancies, and simultaneously improves the mechanical properties and corrosion resistance of the material. Specifically, Y 2 O 3 、CeO 2 , Nb 2 O 5 Jointly regulate the oxygen vacancy concentration and stabilize the equilibrium between the tetragonal and cubic phases. 2 O 3 Dominant phase stability, CeO 2 Enhance the generation of oxygen vacancies and reduce the phase transition temperature, Nb 2 O 5 Charge compensation is used to balance the vacancy increase effect, inhibit excessive oxygen vacancies, and maintain the tetragonal phase-dominated structure. An imbalance in the proportions will lead to deterioration of toughness or corrosion resistance. At the same time, an appropriate amount of aluminum silicate fibers induces orderly distribution of oxygen vacancies through the interfacial stress field, thereby improving the fracture toughness, bending strength and corrosion resistance of the material.

[0018] On the other hand, the present invention proposes the application of the above-mentioned zirconium oxide composite powder in oil and gas wells. The material still maintains high strength and high toughness mechanical properties, strong corrosion resistance to hydrogen sulfide corrosion and chloride corrosion, and high wear resistance under the high temperature, high pressure and highly corrosive oil and gas well environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the oxygen vacancy spectrum of the zirconium oxide composite powder provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The technical scheme in the specific embodiment of the present invention is described in detail and completely below. Obviously, the described embodiment is only a part of the specific implementation of the overall technical scheme of the present invention, rather than all implementations. Based on the overall concept of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0021] In one aspect, the present invention provides a zirconium oxide composite powder, comprising: a zirconium oxide solid solution containing yttrium oxide and cerium oxide, and aluminum silicate fibers. The zirconium oxide composite powder optimizes the components, optimizes the grain boundary design and the crystal phase stabilization strengthening mechanism by regulating oxygen vacancies, and simultaneously improves the mechanical properties and corrosion resistance of the material. Specifically, Y 2 O 3 、CeO 2 , Nb 2 O 5 Jointly regulate the oxygen vacancy concentration and stabilize the equilibrium between the tetragonal and cubic phases.2 O 3 Dominant phase stability, CeO 2 Enhance the generation of oxygen vacancies and reduce the phase transition temperature, Nb 2 O 5 Charge compensation is used to balance the vacancy increase effect, inhibit excessive oxygen vacancies, and maintain the tetragonal phase-dominated structure. An imbalance in the proportions will lead to deterioration of toughness or corrosion resistance. At the same time, an appropriate amount of aluminum silicate fibers induces orderly distribution of oxygen vacancies through the interfacial stress field, thereby improving the fracture toughness, bending strength and corrosion resistance of the material.

[0022] In a preferred embodiment, the composition includes, by mass percentage, 85-94% zirconium oxide solid solution containing yttrium oxide and cerium oxide, 3-5.2% magnesium oxide, 1.5-4.5% aluminum silicate fiber, and 0.5-0.8% niobium oxide. The technical solution limits the amount of zirconium oxide solid solution containing yttrium oxide and cerium oxide, magnesium oxide, aluminum silicate fiber, and niobium oxide, because the content of the above-mentioned multiple components must meet the limited requirements to achieve synergistic optimization of performance. Among them, Y 2 O 3 、CeO 2 , Nb 2 O 5 Jointly regulate the oxygen vacancy concentration and stabilize the equilibrium between the tetragonal and cubic phases. 2 O 3 Dominant phase stability, CeO 2 Enhance the generation of oxygen vacancies and reduce the phase transition temperature, Nb 2 O 5 Charge compensation is used to balance the vacancy increase effect, suppress excess oxygen vacancies, and maintain the tetragonal phase-dominated structure. Imbalance in proportion will lead to deterioration of toughness or corrosion resistance. MgO refines the grains and suppresses the aggregation of oxygen vacancies at grain boundaries. An appropriate amount of aluminum silicate fibers induces orderly distribution of oxygen vacancies through the interfacial stress field, improving fracture toughness, bending strength and corrosion resistance. When the aluminum silicate fiber content is less than 2.5%, the reinforcement is insufficient. When it is higher than 4.5%, the interface defects increase, resulting in a significant decrease in fracture toughness. At the same time, excessive fibers increase the surface roughness and increase the friction coefficient. The synergistic effect between the above components ensures the controllability of oxygen vacancies, high density and mechanical-corrosion resistance balance. Exceeding the range will destroy the stability of the phase structure or introduce defects.

[0023] It can be understood that in the above-mentioned zirconium oxide composite powder, the amount of the zirconium oxide solid solution containing yttrium oxide and cerium oxide can also be 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93% and any point value within the range thereof, the amount of magnesium oxide can also be 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5.0% and any point value within the range thereof, the amount of aluminum silicate fiber can also be 2.0%, 2.5%, 3.0%, 3.5% and any point value within the range thereof, and the amount of niobium oxide can also be 0.6%, 0.7% and any point value within the range thereof.

[0024] The present invention has found that the oxygen vacancy concentration can be controlled within a certain range by compounding yttrium oxide, magnesium oxide, cerium oxide, niobium oxide and zirconium oxide, and the addition of aluminum silicate components to form a Zr-Si / Al-Zr transition layer can enhance the bonding and block the penetration of corrosive media, and refine the ZrO 2 grains, increasing the density of grain boundaries to inhibit oxygen vacancy migration and intergranular corrosion. 3+ Mg 2+ The oxygen vacancy gradient is formed at the interface by aggregation, and the oxygen vacancy distribution is dynamically regulated. Through the coordinated optimization of interface passivation protection and long-term stability of the matrix, the specific structure of the fiber is utilized to simultaneously improve the mechanical properties and corrosion resistance of the material.

[0025] After being formed and sintered, the zirconium oxide composite powder obtained by the present invention has the characteristics of high strength, good toughness and excellent corrosion resistance. The fracture toughness is 9.8MPa . m 1 / 2 The bending strength is 1150MPa, and the corrosion rate in the simulated oil and gas well environment is less than 0.05%. While ensuring the mechanical properties, the corrosion resistance is significantly improved compared with traditional zirconia materials.

[0026] Zirconia (ZrO 2 ) has a high melting point, high hardness and good chemical stability, and is often used as an anti-corrosion material in harsh environments such as oil and gas wells. Oxygen vacancies are point defects in zirconia. Excessive oxygen vacancies will form continuous diffusion channels, making H 2 S, CO 2 , Cl -Corrosive substances such as oxygen vacancies can more easily penetrate into the interior of the material, causing intergranular corrosion or stress corrosion cracking, and high oxygen vacancy concentrations lead to more defects in the surface oxide layer, reducing the compactness and self-repairing ability of the passivation film, making the material susceptible to corrosion by acidic or salt solutions, and increasing the corrosion rate. However, if there are too few oxygen vacancies, a stable lattice cannot be formed, resulting in structural instability and deterioration of mechanical properties, making it difficult for zirconium oxide to stabilize in a high-temperature phase. Phase changes are prone to occur during cooling, accompanied by volume expansion, causing cracking or peeling of the coating, exposing the fresh surface and accelerating corrosion. Therefore, it is necessary to find a balance point that maintains sufficient oxygen vacancies to maintain phase stability, but not too much to cause increased corrosion. In some of the embodiments, by introducing specific dopants, the oxygen vacancy concentration is regulated to a reasonable range, taking into account both structural stability and corrosion resistance.

[0027] Yttrium oxide and cerium oxide, as stabilizers, form solid solutions with zirconium oxide, which can reduce the lattice distortion energy. The generated oxygen vacancies release the lattice stress and inhibit the tetragonal phase (t-ZrO 2 ) to monoclinic phase (m-ZrO 2 ) transformation. Low-valent cations (such as Y 3+ Mg 2 + ) doped into ZrO 2 In order to balance the charge, oxygen vacancies are generated. However, if the oxygen vacancies are too high, the lattice symmetry will increase, forming cubic zirconia, which is not good for toughness. 2 O 5 Charge compensation to balance Y 2 O 3 The vacancy increasing effect of / MgO suppresses the excess oxygen vacancies and maintains the tetragonal phase-dominated structure.

[0028] In addition, the surface of aluminum silicate fiber is rich in Al-O and Si-O bonds. During the sintering process, it forms a transition layer (such as Zr-Si-O or Al-Zr-O glass phase) through interface reaction with the zirconia matrix, which enhances the interface bonding force, thereby inhibiting the peeling of the fiber and the matrix, reducing interface defects, and blocking the penetration path of the corrosive medium along the interface. The fiber acts as a heterogeneous nucleation point, refines the zirconia grains, increases the grain boundary density, shortens the oxygen vacancy migration path, reduces the enrichment of oxygen vacancies at the grain boundary, and reduces the active sites of intergranular corrosion. 3+ Mg 2+ Low-valent cations tend to accumulate at the fiber-matrix interface, forming a local oxygen vacancy concentration gradient (higher oxygen vacancy density at the interface and lower inside the matrix). The high oxygen vacancies at the interface promote the rapid formation of a passive film, which blocks corrosive media (such as H 2 S, CO 2 , Cl - The low vacancy density inside the matrix maintains the overall structural stability.

[0029] In summary, the amount and type of dopants are controlled, the concentration of oxygen vacancies is regulated by charge compensation and lattice distortion, the proportion of crystal structure in zirconia is balanced, and the characteristics of tetragonal zirconia with few grain boundary defects can effectively block the penetration of corrosive media and phase transformation toughening. The cubic phase is controlled within a certain range to avoid brittle fracture under the action of corrosion-stress coupling, thereby optimizing the mechanical properties and corrosion resistance of the material.

[0030] In a preferred embodiment, the zirconium oxide solid solution containing yttrium oxide and cerium oxide includes 80-85% zirconium oxide, 2.5-6% yttrium oxide, and 2-3% cerium oxide. The technical solution specifically defines the proportions of zirconium oxide, yttrium oxide, and cerium oxide in the zirconium oxide solid solution containing yttrium oxide and cerium oxide. If the content of the oxide dopant (yttrium oxide, cerium oxide) is not within the above range, it will lead to too low oxygen vacancies, imbalanced phase structure, and high material brittleness. If the amount of yttrium oxide added is too much, it will cause the cubic phase ratio to far exceed the normal range, and the performance will be deteriorated overall.

[0031] It can be understood that in the above-mentioned zirconium oxide solid solution containing yttrium oxide and cerium oxide, the proportion of zirconium oxide can also be 81%, 82%, 83%, 84% and any point value within the range, the proportion of yttrium oxide can also be 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5% and any point value within the range, and the proportion of cerium oxide can also be 2.2%, 2.4%, 2.6%, 2.8% and any point value within the range.

[0032] In a preferred embodiment, the fiber diameter of the aluminum silicate fiber is selected from 1-3 μm, and the aspect ratio is selected from 20:1-50:1. It is understandable that the fiber diameter of the aluminum silicate fiber can also be 1.5 μm, 2.0 μm, 2.5 μm and any point value within the range, and the aspect ratio can also be 30:1, 40:1 and any point value ratio within the range. In the above-mentioned zirconium oxide composite powder, if the diameter of the aluminum silicate fiber is too fine, the strength is insufficient and it is easy to agglomerate, and if it is too thick, the interface bonding is poor. The above-mentioned 1-3 μm can balance the strength, interface and process. If the aspect ratio is too short, the crack propagation resistance decreases and the enhancement is ineffective. If it is too long, it is difficult to disperse and arrange in a directional manner. The random distribution leads to anisotropy and increased strength volatility. 20:1-50:1 ensures stress transfer and process controllability.

[0033] In a preferred embodiment, the purity of zirconium oxide is ≥99.9%, and the average particle size is 30-100nm; the purity of yttrium oxide is ≥99.9%, and the average particle size is 100-200nm; the purity of cerium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of magnesium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of niobium oxide is ≥99.5%, and the average particle size is 100-300nm; the crystal of zirconium oxide is monoclinic phase, and the specific surface area is 50-100m2 / g; Ce in cerium oxide 3+ / Ce 4+ The molar ratio is 1.5-2.5:1.

[0034] It can be understood that the average particle size of zirconium oxide can also be 40nm, 50nm, 60nm, 70nm, 80nm, 90nm and any point value within the range, the average particle size of yttrium oxide can also be 120nm, 140nm, 160nm, 180nm and any point value within the range, the average particle size of cerium oxide can also be 200nm, 300nm, 400nm and any point value within the range, the average particle size of magnesium oxide can also be 200nm, 300nm, 400nm and any point value within the range, and the average particle size of niobium oxide can also be 150nm, 200nm, 250nm and any point value within the range.

[0035] In a preferred embodiment, the tetragonal zirconia accounts for 79-91% of the zirconia composite powder, and the cubic zirconia accounts for 9-21%. It is understandable that the tetragonal zirconia in the zirconia composite powder can also be 80%, 82%, 84%, 86%, 88% and any value within the range, and the cubic zirconia can also be 10%, 12%, 14%, 16%, 18%, 20% and any value within the range. In addition, the oxygen vacancy absolute spin number of the above zirconia composite powder is (1.8-7.3)e+11spins / mm 3 .

[0036] On the other hand, the present invention provides a method for preparing a zirconium oxide composite powder of any of the above technical solutions, including a powder mixing step, wherein the powder mixing step includes: firstly ball-milling zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide, and niobium oxide, and then adding aluminum silicate fibers and mixing them evenly to obtain a mixture. The technical solution specifically defines the step-by-step powder mixing step, because the step-by-step ball milling process used in powder mixing can avoid the destruction of the aluminum silicate fiber structure and the generation of agglomeration defects, so that the oxide particles are evenly dispersed and refined to form a uniform matrix, ensuring that Y 3+ Mg 2+ The uniform distribution of doping can stabilize the concentration gradient of oxygen vacancies, which is beneficial to inhibit the migration of vacancies to the grain boundary and reduce intergranular corrosion when the fiber is added later. 2 , Y 2 O 3 、CeO 2 , Nb 2 O 5 When mixed with aluminum silicate fibers, the fibers will hinder the diffusion of oxides, resulting in uneven dispersion and loss of interface control, leading to a significant decrease in the overall performance of the material.

[0037] In a preferred embodiment, the method comprises a raw material pretreatment step, a powder mixing step, a calcination step, a slurry preparation and dispersion step, and a granulation step; the raw material pretreatment step comprises: acid washing the aluminum silicate fiber to remove surface impurities, washing with water to neutrality and then drying; the calcination step comprises: calcining the mixture at 800-1200°C for 5-8h to obtain a calcined powder; the slurry preparation and dispersion step comprises: dispersing the calcined powder to a particle size D50 less than 0.5μm and D90 less than 0.8μm, and then adding a dispersant and a binder and stirring to obtain a slurry; the granulation step comprises: spray drying the slurry to remove moisture therein and obtain granulated powder, the particle size of the granulated powder is 30-70μm.

[0038] In a preferred embodiment, in the slurry preparation and dispersion steps, the amount of dispersant used is 0.5-1.5%, and the amount of binder used is 2-3.6%, calculated by mass percentage; the dispersant is selected from ammonium polyacrylate; the binder is selected from one of polyvinyl alcohol, glycerol, and polyethylene glycol.

[0039] The present invention also proposes an application of a zirconium oxide composite powder of any of the above technical solutions in oil and gas wells. The oil and gas well environment is characterized by high temperature, high pressure, and high corrosion, and the following core requirements are put forward for material properties, including mechanical properties (high strength and high toughness), strong corrosion resistance (resistance to hydrogen sulfide corrosion and chloride corrosion), and high wear resistance. By effectively evaluating the fracture toughness, bending strength, friction coefficient and corrosion rate of the above zirconium oxide composite powder provided by the present invention, and the corrosion rate is carried out in a sulfur-containing and chlorine-containing solution to simulate the oil and gas well environment, the mechanical properties and corrosion resistance of the above zirconium oxide composite powder when used in oil and gas wells are effectively guaranteed.

[0040] In order to more clearly and in detail introduce the zirconium oxide composite powder, the preparation method and application thereof provided by the embodiments of the present invention, a description will be given below in conjunction with specific embodiments.

[0041] Example 1

[0042] A zirconium oxide composite powder for oil and gas wells is prepared, and the raw material ratio is as follows, calculated by mass percentage:

[0043] Zirconium oxide 82%, yttrium oxide 2.5%, cerium oxide 2.3%, magnesium oxide 5.2%, aluminum silicate fiber 4%, niobium oxide 0.5%, dispersant 1%, binder 2.5%. Among them, aluminum silicate fiber needs to be treated by acid washing.

[0044] The preparation process comprises the following steps:

[0045] (1) Raw material pretreatment: Alumina silicate fiber was treated with 3% HNO 3 Acid wash at 80℃ for 2h to remove surface impurities, wash with water until neutral and then dry.

[0046] (2) Powder mixing: firstly, zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide and niobium oxide are ball-milled and mixed in a certain proportion for 5 hours, and then the pretreated aluminum silicate fiber is added and mixed for 2 hours and then spray-dried.

[0047] (3) Powder calcination: The powder dried in step (2) was calcined at 1050°C for 6 hours.

[0048] (4) Slurry preparation and dispersion: The calcined powder is dispersed to a particle size D50 of less than 0.3 μm and D90 of less than 0.5 μm, and a certain proportion of dispersant and binder are added and stirred to obtain a slurry.

[0049] (5) Granulation: The slurry obtained in step (4) is spray-dried in a spray granulation tower to remove moisture and obtain granulated powder, the particle size of which is about 50 μm.

[0050] The average particle size of the selected zirconium oxide is about 65nm, and the specific surface area is (87±5)m 2 / g; the average particle size of the selected cerium oxide is about 250nm, Ce 3+ / Ce 4+ The molar ratio is 1.73:1; the diameter of the selected aluminum silicate fiber is about 1.5 μm, and the aspect ratio is 20:1-30:1; the selected dispersant is ammonium polyacrylate; and the selected binder is polyvinyl alcohol.

[0051] Example 2

[0052] A zirconium oxide composite powder for oil and gas wells, the raw material ratio is as follows, calculated by mass percentage:

[0053] Zirconium oxide 80%, yttrium oxide 4.4%, cerium oxide 2.8%, magnesium oxide 4.6%, aluminum silicate fiber 3.3%, niobium oxide 0.7%, dispersant 1.5%, binder 2.7%. Among them, aluminum silicate fiber needs to be treated by acid washing.

[0054] The preparation process comprises the following steps:

[0055] (1) Raw material pretreatment: same as in Example 1

[0056] (2) Powder mixing: firstly, zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide and niobium oxide are ball-milled and mixed for 3 hours according to a certain proportion, and then the pretreated aluminum silicate fiber is added and mixed for 3 hours and then spray-dried.

[0057] (3) Calcination: The powder dried in step (2) was calcined at 1100° C. for 5 h.

[0058] (4) Slurry preparation and dispersion: The calcined powder is dispersed to a particle size D50 of less than 0.45 μm and D90 of less than 0.7 μm, and a certain proportion of dispersant and binder are added and stirred to obtain a slurry.

[0059] (5) Granulation: Same as Example 1

[0060] The average particle size of the selected zirconium oxide is about 100nm, and the specific surface area is (65±3)m 2 / g; the average particle size of the selected cerium oxide is about 200nm, Ce 3+ / Ce 4+ The molar ratio is 2.2:1; the selected aluminum silicate fiber is the same as that in Example 1; the selected dispersant is the same as that in Example 1; and the selected binder is polyethylene glycol.

[0061] Examples 3-6 are the same as Example 1, except that the raw material ratios are as shown in Table 1.

[0062] Table 1 Ratio of raw materials used in Examples 3-6

[0063]

[0064] Comparative Example 1

[0065] The raw material ratio is as follows: 83.5% zirconium oxide, 5.5% yttrium oxide, 2% cerium oxide, 3.5% magnesium oxide, 0.5% niobium oxide, 1% dispersant, and 4% binder.

[0066] The preparation process comprises the following steps:

[0067] (1) Powder mixing: Zirconia, yttrium oxide, cerium oxide, magnesium oxide and niobium oxide are ball-milled and mixed in a certain proportion for 3 hours and then spray-dried.

[0068] (2) Calcination: The powder dried in step (2) was calcined at 1100° C. for 7 h.

[0069] (3) Slurry preparation and dispersion: The calcined powder is dispersed to a particle size D50 of less than 0.3 μm and D90 of less than 0.5 μm, and a certain proportion of dispersant and binder are added and stirred to obtain a slurry.

[0070] (4) Granulation: Same as Example 1

[0071] The limitations of the raw materials are the same as those in Example 1.

[0072] Comparative Example 2

[0073] The raw material ratio is as follows: 80% zirconium oxide, 4% yttrium oxide, 2% cerium oxide, 4% magnesium oxide, 7% aluminum silicate fiber, 0.5% dispersant, and 2.5% binder.

[0074] The preparation process comprises the following steps:

[0075] (1) Raw material pretreatment: same as in Example 1

[0076] (2) Powder mixing: Zirconia, yttrium oxide, cerium oxide, magnesium oxide, niobium oxide and aluminum silicate fiber are ball-milled and mixed in a certain proportion for 5 hours and then spray-dried.

[0077] (3) Calcination: The powder dried in step (1) was calcined at 1000° C. for 8 h.

[0078] (4) Slurry preparation and dispersion: The calcined powder is dispersed to a particle size D50 of less than 0.5 μm and D90 of less than 0.7 μm, and a certain proportion of dispersant and binder are added and stirred to obtain a slurry.

[0079] (5) Granulation: Same as Example 1

[0080] The limitations of the raw materials are the same as those in Example 1.

[0081] Comparative Example 3-4: The specific implementation method is the same as Comparative Example 1, except that the raw material ratio is as shown in Table 2.

[0082] Table 2 Ratio of raw material usage in comparative example 3-4

[0083]

[0084]

[0085] Comparative Examples 5, 6, and 7 are similar in implementation to Example 1, except that the raw material characteristics are limited as follows:

[0086] In Comparative Example 5, the aluminum silicate fiber has a diameter of 0.5 μm and an aspect ratio of 10:1; in Comparative Example 6, the aluminum silicate fiber has a diameter of 5 μm and an aspect ratio of 60:1; and in Comparative Example 7, the fiber type is carbon fiber, with a diameter of 1 μm and an aspect ratio of 30:1.

[0087] Performance Testing

[0088] The granulated powders of Examples 1-6 and Comparative Examples 1-6 were pre-pressed at 20 MPa for 30 seconds, and then isostatically pressed at 150 MPa for 1 minute to obtain green bodies. The green bodies were sintered at a sintering temperature of 1350°C, a heating rate of 2°C / min, and a holding time of 4 hours. The green bodies were cooled to room temperature with the furnace to obtain zirconia ceramics for oil and gas wells, and the following tests were performed:

[0089] 1. Fracture toughness and bending strength are tested using Shimadzu AGS-X50KN universal testing machine.

[0090] 2. Wear resistance The friction coefficient of the prepared composite ceramics was tested using an MFT-4000 multifunctional material surface performance testing machine.

[0091] 3. The corrosion resistance should simulate the oil and gas well environment. The sulfur resistance is carried out in a simulated liquid of 10% NaCl and 0.5% NaHS, and the acid resistance is carried out under 5% HCl. The accelerated corrosion test is carried out in a closed environment of a 120℃ high-temperature reactor for 48 hours to verify its corrosion resistance. After the test, the sample is cleaned and weighed to calculate its total weight loss rate to obtain the corrosion resistance.

[0092] 4. Crystal structure analysis: The crystal structure information was obtained by X-ray diffractometer, model Bruker D8Advance. The content of tetragonal phase and cubic phase was obtained by full spectrum fitting of TOPAS software.

[0093] 5. Oxygen vacancy test analysis: Bruker EMX Plus electron paramagnetic resonance spectrometer.

[0094] The test results are shown in Tables 3, 4 and Figure 1 shown.

[0095] Table 3 Key physical and chemical indicators of the embodiments and comparative examples

[0096]

[0097]

[0098] Table 4 Performance test results of embodiments and comparative examples

[0099]

[0100] From Tables 3 and 4, we can see that:

[0101] (1) Influence of component content:

[0102] Comparative Example 1 does not add aluminum silicate fiber, and the lack of fiber reinforcement effect leads to increased brittleness, weak crack propagation resistance, inability to control oxygen vacancy distribution, and reduced fracture toughness, bending strength, and corrosion resistance;

[0103] In Comparative Example 2, the aluminum silicate fiber content is too high (7%), and the excessive fiber causes interface defects, destroys the continuity of the matrix, reduces corrosion resistance, increases surface roughness, increases the friction coefficient to 0.52, deteriorates mechanical properties, increases friction loss, and reduces applicability;

[0104] In Comparative Example 3, the content of oxide dopants (yttrium oxide, cerium oxide) is not within the range, resulting in too low oxygen vacancies, unbalanced phase structure, and high material brittleness (fracture toughness is reduced to 6.6);

[0105] In Comparative Example 4, a large amount of yttrium oxide was added, resulting in a cubic phase ratio far exceeding the normal range and overall performance degradation.

[0106] (2) Influence of raw material characteristics:

[0107] In comparative example 5, the diameter of the aluminum silicate fiber is 0.5 μm, and the aspect ratio is 10:1; in comparative example 6, the diameter of the aluminum silicate fiber is 5 μm, and the aspect ratio is 60:1; in comparative example 7, the fiber type is carbon fiber, with a diameter of 1 μm and an aspect ratio of 30:1. Combining the performance test results of comparative examples 5-7, it is found that:

[0108] If the fiber diameter is too thin, the strength is insufficient and it is easy to agglomerate. If it is too thick, the interface bonding is poor. 1μm-3μm balances the strength, interface and process. If the aspect ratio is too short, the crack propagation resistance decreases and the enhancement is ineffective. If it is too long, it is difficult to disperse and arrange in a directional manner. Random distribution leads to anisotropy and increased strength volatility. 20:1-50:1 ensures stress transfer and process controllability.

[0109] (3) Impact of process:

[0110] In Comparative Example 2, one-step ball milling was used to disperse ZrO 2 , Y 2 O 3 、CeO 2 , Nb 2 O 5 When mixed with aluminum silicate fibers, the fibers hinder the diffusion of oxides, resulting in uneven dispersion and loss of interface control, which leads to a significant decrease in the overall performance of the material.

[0111] As shown in Figure 1, a symmetrical and narrow oxygen vacancy characteristic peak is presented in the range of 3480–3520 Gauss, indicating that the oxygen vacancy concentration is moderate through the compounding of various oxides and the interface confinement effect of aluminum silicate fibers, which is the material in H 2 S / CO 2 Provides long-term corrosion resistance in the environment.

Claims

1. A zirconium oxide composite powder, characterized in that: include: Zirconia solid solution containing yttria, cerium oxide, and aluminum silicate fibers.

2. The zirconium oxide composite powder according to claim 1, characterized in that: Calculated by mass percentage, it comprises: 85-94% of the zirconium oxide solid solution containing yttrium oxide and cerium oxide, 3-5.2% of magnesium oxide, 1.5-4.5% of the aluminum silicate fiber, and 0.5-0.8% of niobium oxide.

3. The zirconium oxide composite powder according to claim 1, characterized in that: The zirconium oxide solid solution containing yttrium oxide and cerium oxide comprises 80-85% of zirconium oxide, 2.5-6% of yttrium oxide and 2-3% of cerium oxide.

4. The zirconium oxide composite powder according to claim 1, characterized in that: The fiber diameter of the aluminum silicate fiber is selected from 1-3 μm, and the aspect ratio is selected from 20:1-50:

1.

5. The zirconium oxide composite powder according to claim 2, characterized in that: The purity of the zirconium oxide is ≥99.9%, and the average particle size is 30-100nm; the purity of the yttrium oxide is ≥99.9%, and the average particle size is 100-200nm; the purity of the cerium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of the magnesium oxide is ≥99.5%, and the average particle size is 100-500nm; the purity of the niobium oxide is ≥99.5%, and the average particle size is 100-300nm; the crystal of the zirconium oxide is monoclinic, and the specific surface area is 50-100m 2 / g; Ce in the cerium oxide 3+ / Ce 4+ The molar ratio is 1.5-2.5:

1.

6. The zirconium oxide composite powder according to claim 1, characterized in that: In the zirconium oxide composite powder, the tetragonal zirconium oxide accounts for 79-91%, and the cubic zirconium oxide accounts for 9-21%.

7. The method for preparing the zirconium oxide composite powder according to any one of claims 1 to 6, characterized in that: The method comprises a powder mixing step, wherein the powder mixing step comprises: firstly ball-milling and mixing zirconium oxide, yttrium oxide, cerium oxide, magnesium oxide and niobium oxide, and then adding aluminum silicate fiber and mixing evenly to obtain a mixture.

8. The method for preparing zirconium oxide composite powder according to claim 7, characterized in that: The method comprises a raw material pretreatment step, a powder mixing step, a calcination step, a slurry preparation and dispersion step, and a granulation step; The raw material pretreatment step includes: acid washing the aluminum silicate fiber to remove surface impurities, washing with water until neutral, and then drying; The calcination step comprises: calcining the mixture at 800-1200° C. for 5-8 hours to obtain a calcined powder; The slurry preparation and dispersion step comprises: dispersing the calcined powder to a particle size D50 less than 0.5 μm and D90 less than 0.8 μm, and then adding a dispersant and a binder and stirring to obtain a slurry; The granulation step comprises: spray drying the slurry to remove water therein and obtain granulated powder, wherein the particle size of the granulated powder is 30-70 μm.

9. The method for preparing zirconium oxide composite powder according to claim 8, characterized in that: In the slurry preparation and dispersion step, the amount of the dispersant is 0.5-1.5%, and the amount of the binder is 2-3.6% by weight; the dispersant is selected from ammonium polyacrylate; and the binder is selected from one of polyvinyl alcohol, glycerol, and polyethylene glycol.

10. Use of the zirconium oxide composite powder according to any one of claims 1 to 6 in oil and gas wells.

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