Impeller material for titanium dioxide waste acid regeneration device, impeller and preparation method of impeller

Abstract

The invention discloses an impeller material for a titanium dioxide waste acid regeneration device, an impeller and a preparation method of the impeller material, the impeller material comprises the following components in percentage by mass: 85-92% of silicon carbide matrix, 5-8% of nano aluminum oxide and 2-4% of rare earth oxide, and the service life of the impeller under a strong corrosion / scouring working condition containing ferrous sulfate crystals is remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to an impeller material, an impeller and a preparation method thereof for a titanium dioxide waste acid regeneration device. Background Art

[0002] In the titanium dioxide waste acid regeneration device, the impeller of the forced circulation pump is subjected to long-term chemical corrosion and physical erosion by high-concentration sulfuric acid and ferrous sulfate crystals (FeSO4.H2O). The service life of the impeller of traditional materials (such as high-silicon cast iron and Hastelloy) is only 4-6 months, resulting in frequent equipment shutdown and replacement, which is costly and affects production efficiency. Existing technology defects: High silicon cast iron impeller: low hardness (HV500-600), prone to groove wear under crystal erosion; Hastelloy impeller: Insufficient corrosion resistance, intergranular corrosion leads to structural embrittlement and blade collapse; Conventional silicon carbide materials: poor thermal shock resistance and prone to cracking under complex working conditions. Summary of the invention

[0003] The purpose of the present invention is to provide an impeller material, an impeller and a preparation method thereof for a titanium dioxide waste acid regeneration device, which significantly improves the service life of the impeller under strong corrosion / scouring conditions containing ferrous sulfate crystals.

[0004] The impeller material for a titanium dioxide waste acid regeneration device provided by the present invention comprises, by mass percentage, 85%-92% of a silicon carbide matrix, 5%-8% of nano-aluminum oxide, and 2%-4% of a rare earth oxide.

[0005] Furthermore, the rare earth oxide is yttrium oxide.

[0006] The present invention also provides an impeller for a titanium dioxide waste acid regeneration device, wherein the impeller is made of the impeller material as described above.

[0007] Furthermore, the impeller surface is laser clad with a tungsten carbide coating.

[0008] Furthermore, the thickness of the tungsten carbide coating is 50-100 μm.

[0009] The present invention also provides a method for preparing the impeller for the titanium dioxide waste acid regeneration device as described above, comprising the steps of: S1: Provide 85%-92% silicon carbide powder, 5%-8% nano alumina powder, and 2%-4% rare earth oxide powder by mass percentage; S2: preparing polyvinyl alcohol with a mass of 2% of the total mass of the silicon carbide powder, nano-alumina powder and rare earth oxide powder in step S1 and dissolving it in deionized water, stirring and dissolving after heating to obtain a binder with a volume fraction of 5%; S3: adding silicon carbide powder, nano-alumina powder, rare earth oxide powder and adhesive into the ball mill in sequence, and then performing low-speed coarse grinding and high-speed fine grinding in sequence to obtain slurry; S4: Slowly pour the slurry into a closed container; S5: filtering the slurry through a 200-mesh sieve; S6: spray drying and evaporating the slurry filtered in step S5 to obtain spherical granulated powder with fluidity; S7: Preform the spherical granulated powder by dry pressing at 100 MPa, and then form it by 3D printing or cold isostatic pressing at 300 MPa; S8: sintering at 2100° C. in an argon atmosphere to obtain an impeller blank; S9: Ultra-precision machining is performed on the impeller blank to obtain an impeller sample; S10: The impeller sample is subjected to surface laser cladding of tungsten carbide coating.

[0010] Furthermore, the rare earth oxide is yttrium oxide.

[0011] Furthermore, in step S9, the impeller blank is processed by ultra-precision, and the dynamic balance level reaches G6.3.

[0012] Furthermore, in step S10, the hardness HRA of the carbide coating is greater than or equal to 92. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a flowchart of a method for preparing an impeller for a titanium dioxide waste acid regeneration device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0015] The invention provides an impeller material for a titanium dioxide waste acid regeneration device, comprising, by mass percentage, 85%-92% of a silicon carbide matrix, 5%-8% of nano-alumina and 2%-4% of a rare earth oxide.

[0016] The rare earth oxide is yttrium oxide.

[0017] The present invention also provides an impeller for a titanium dioxide waste acid regeneration device, and the impeller adopts the impeller material as mentioned above.

[0018] The impeller surface is laser clad with tungsten carbide coating.

[0019] The thickness of the tungsten carbide coating is 50-100μm.

[0020] It is worth noting that the impeller includes blades and a shaft core, and the blade thickness adopts a gradient design, 8-10mm at the inlet end and 12-15mm at the outlet end.

[0021] The present invention also provides a method for preparing an impeller for a titanium dioxide waste acid regeneration device as described above, comprising the steps of: S1: Provide 85%-92% silicon carbide powder, 5%-8% nano alumina powder, and 2%-4% rare earth oxide powder by mass percentage; S2: preparing polyvinyl alcohol with a mass of 2% of the total mass of the silicon carbide powder, nano-alumina powder and rare earth oxide powder in step S1 and dissolving it in deionized water, stirring and dissolving after heating to obtain a binder with a volume fraction of 5%; S3: adding silicon carbide powder, nano-alumina powder, rare earth oxide powder and adhesive into the ball mill in sequence, and then performing low-speed coarse grinding and high-speed fine grinding in sequence to obtain slurry; S4: Slowly pour the slurry into a closed container; S5: filtering the slurry through a 200-mesh sieve; S6: spray drying and evaporating the slurry filtered in step S5 to obtain spherical granulated powder with fluidity; S7: Preform the spherical granulated powder by dry pressing at 100 MPa, and then form it by 3D printing or cold isostatic pressing at 300 MPa; S8: sintering at 2100° C. in an argon atmosphere to obtain an impeller blank; S9: Ultra-precision machining is performed on the impeller blank to obtain an impeller sample; S10: The impeller sample is subjected to surface laser cladding of tungsten carbide coating.

[0022] The rare earth oxide is yttrium oxide.

[0023] In step S9, the impeller blank is processed by ultra-precision, and the dynamic balance level reaches G6.3.

[0024] In step S10 , the hardness HRA of the carbide coating is greater than or equal to 92.

[0025] By optimizing the impeller material components, the service life of the impeller under strong corrosion / scouring conditions containing ferrous sulfate crystals has been significantly improved. The material provides wear resistance through the silicon carbide matrix, nano-alumina enhances corrosion resistance and toughness, and rare earth oxides optimize the microstructure, achieving a balance between high temperature resistance, corrosion resistance and long life.

[0026] It is worth noting that in step S3, 0.5–1% sodium hexametaphosphate Na6[(PO3)6] can be added as a dispersant to reduce the surface energy and inhibit agglomeration by adsorbing on the powder surface. The dispersant needs to be added slowly and stirred continuously to avoid excessive local concentration.

[0027] It is worth noting that the low-speed coarse grinding in step S3 refers to the initial stage of ball milling (the first 6 hours): it is mainly used to break up large particle agglomerates and coarsely crush, and its goal is to quickly reduce the particle size of the powder (such as decomposing from agglomerates to submicron level), and the speed range is 300-350 rpm; its purpose is to reduce the kinetic energy, reduce excessive crushing of the powder, and avoid generating too many fine particles or nano-fragments; promote the crushing of large particles, and gradually disintegrate agglomerates through low-speed rolling friction; energy consumption control, low energy consumption at low speed, suitable for long-term coarse grinding.

[0028] Key points for this step: With a high ball-to-material ratio (15:1) and larger zirconia balls (5 mm), the synergistic effect of impact force and grinding force is utilized; the slurry fluidity (such as Blaine viscosity) is regularly tested. If the viscosity drops significantly, it indicates that the coarse grinding is completed.

[0029] In addition, high-speed fine grinding refers to the later stage of ball milling (last 4-6 hours), which is used to refine the powder particle size to the target range (such as D50 ≤0.8 μm). Its purpose is to achieve uniform dispersion and high dispersibility of the powder. The speed range is 350-400 rpm, with higher centrifugal force, increasing the shear force and impact force of the ball on the powder, promoting fine grinding; shortening the grinding time, accelerating energy transfer through high-speed motion, and improving efficiency; avoiding excessive crushing, it is necessary to balance the speed and time to prevent the silicon carbide grains from being over-crushed (affecting the strength of the material).

[0030] Key points for this step: Use small diameter zirconia balls (3 mm) and increase the number of balls to increase the grinding surface area; monitor the temperature (≤40°C) and suspend ball milling to dissipate heat when necessary.

[0031] It is worth noting that in step S1, the particle size of silicon carbide is 0.5-1μm, and the particle size of aluminum oxide is 0.05-0.1μm. Silicon carbide uses large particles to have high strength and wear resistance. Silicon carbide is used as the main crystal phase, and its coarse particles (0.5-1μm) provide excellent compressive strength and wear resistance, which can withstand high-speed fluid erosion and particle wear in the waste acid regeneration device. At the same time, the large particles form a stable three-dimensional network structure to reduce the risk of cracking caused by sintering shrinkage.

[0032] Small particles of alumina can act as toughening and dispersion strengthening. Nanoscale particles of alumina (0.05–0.1 μm) can be evenly distributed in the gaps between silicon carbide particles, improving the fracture toughness of the material through dislocation pinning and crack deflection. At the same time, small particles form a tight bonding layer with the silicon carbide surface, reducing interface defects and stress concentration.

[0033] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. Impeller material for titanium dioxide waste acid regeneration device, characterized in that: The invention comprises, by mass percentage, 85%-92% of silicon carbide matrix, 5%-8% of nano-aluminum oxide and 2%-4% of rare earth oxide.

2. The impeller material for the titanium dioxide waste acid regeneration device according to claim 1, characterized in that: The rare earth oxide is yttrium oxide.

3. An impeller for a titanium dioxide waste acid regeneration device, characterized in that: The impeller adopts the impeller material as claimed in claim 2.

4. The impeller for the titanium dioxide waste acid regeneration device according to claim 3, characterized in that: The impeller surface is laser-clad with a tungsten carbide coating.

5. The impeller for the titanium dioxide waste acid regeneration device according to claim 4, characterized in that: The thickness of the tungsten carbide coating is 50-100 μm.

6. The method for preparing an impeller for a titanium dioxide waste acid regeneration device according to claim 5, characterized in that: Includes steps: S1: Provide 85%-92% silicon carbide powder, 5%-8% nano alumina powder, and 2%-4% rare earth oxide powder by mass percentage; S2: preparing polyvinyl alcohol with a mass of 2% of the total mass of the silicon carbide powder, nano-alumina powder and rare earth oxide powder in step S1 and dissolving it in deionized water, stirring and dissolving after heating to obtain a binder with a volume fraction of 5%; S3: adding silicon carbide powder, nano-alumina powder, rare earth oxide powder and adhesive into the ball mill in sequence, and then performing low-speed coarse grinding and high-speed fine grinding in sequence to obtain slurry; S4: Slowly pour the slurry into a closed container; S5: filtering the slurry through a 200-mesh sieve; S6: spray drying and evaporating the slurry filtered in step S5 to obtain spherical granulated powder with fluidity; S7: Preform the spherical granulated powder by dry pressing at 100 MPa, and then form it by 3D printing or cold isostatic pressing at 300 MPa; S8: sintering at 2100° C. in an argon atmosphere to obtain an impeller blank; S9: Ultra-precision machining is performed on the impeller blank to obtain an impeller sample; S10: The impeller sample is subjected to surface laser cladding of tungsten carbide coating.

7. The method for preparing an impeller for a titanium dioxide waste acid regeneration device according to claim 6, characterized in that: The rare earth oxide is yttrium oxide.

8. The method for preparing an impeller for a titanium dioxide waste acid regeneration device according to claim 6, characterized in that: In step S9, the impeller blank is processed by ultra-precision, and the dynamic balance level reaches G6.

3.

9. The method for preparing an impeller for a titanium dioxide waste acid regeneration device according to claim 6, characterized in that: In step S10 , the hardness HRA of the carbide coating is greater than or equal to 92.

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