A front shield of a slurry pump and a preparation method thereof

Abstract

The present application provides a kind of slag pump front guard plate and preparation method thereof, belong to the field of casting of rock slag pump front guard plate, including the following steps: step 1) preparation of preform;Preform is ceramic preform, and can improve the flow velocity of liquid metal;Step 2) the preform is placed in slag pump front guard plate mold, then the liquid metal is poured into the slag pump front guard plate mold, so that the liquid metal fills the slag pump front guard plate mold, while wrapping the preform, and infiltrating into the specified structure of preform, to obtain the front guard plate rough casting;Wherein, the liquid metal is the liquid metal of high-hardness wear-resistant alloy;Step 3) the front guard plate rough casting is heat treated and processed, to obtain the slag pump front guard plate.The ceramic preform of helical structure has high hardness and strength itself, and the crack cannot penetrate the ceramic. At the same time, there is metallurgical bonding between the high-hardness wear-resistant alloy matrix and the ceramic during pouring, and the bonding force is large, which can resist the crack propagation of high-hardness alloy cracking and improve the fracture toughness of the front guard plate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of casting of front shroud plates of rock-breaking slurry pumps, and particularly relates to a front shroud plate of a slurry pump and a preparation method thereof. BACKGROUND

[0002] As an important mechanical equipment widely used in mining, power plants, dredging, metallurgy, chemical industry, building materials and petroleum industries, a slurry pump mainly functions to increase the energy of solid-liquid mixed medium through rotation of an impeller, so as to realize conveying of the medium. In the working process of the slurry pump, the front shroud plate as one of the key flow-through components undertakes the important task of protecting the pump body and preventing solid particles from directly impacting the impeller. Therefore, the quality and performance of the front shroud plate are directly related to the overall operation efficiency and service life of the slurry pump.

[0003] The centrifugal casting technology has been widely applied in the preparation of the front shroud plate of the slurry pump due to its unique advantages. It is a technology and method of injecting liquid metal into a high-speed rotating mold and using centrifugal force to make the liquid metal fill the mold and form a casting. This technology has the following characteristics: the centrifugal force helps the liquid metal to be uniformly distributed in the radial direction, reduces defects such as pores and slag inclusions, and improves the mechanical and physical properties of the casting. It can produce cylindrical inner holes without cores, especially suitable for producing long pipe-shaped castings, which reduces the ratio of the wall thickness to the length or diameter of the casting and simplifies the production process. When forming the casting, the centrifugal force can improve the filling capacity of the metal, making it easier to form a thin-walled structure.

[0004] The existing front shroud plate usually adopts a single alloy by centrifugal casting. However, when the centrifugal casting speed is high, the carbide of the single alloy will be enriched on the outside of the front shroud plate, and the internal stress will form cracks on the front shroud plate, resulting in poor fracture toughness of the front shroud plate. When the centrifugal casting speed is low, the outer layer carbide content will be low, and the hardness and wear resistance of the front shroud plate will be insufficient. Therefore, the existing front shroud plate of the slurry pump has the problem of insufficient mechanical properties. SUMMARY

[0005] Therefore, the application provides a front shroud plate of a slurry pump and a preparation method thereof, and the main purpose is to improve the mechanical properties of the front shroud plate of the slurry pump.

[0006] In order to solve the above problems, on the one hand, the application provides a preparation method of a front shroud plate of a slurry pump, which comprises the following steps:

[0007] Step 1) preparing a preform; the preform is a ceramic preform and can improve the flow speed of the liquid metal;

[0008] Step 2) placing the preform into a slag pump front shroud mold, then pouring liquid metal into the slag pump front shroud mold, so that the liquid metal fills the slag pump front shroud mold, wraps the preform, and infiltrates into the set structure of the preform, to obtain a front shroud roughcast; wherein the liquid metal is a high-hardness wear-resistant alloy liquid metal;

[0009] Step 3) heat treating and processing the front shroud roughcast to obtain a slag pump front shroud.

[0010] Further, in the step 1), the preform has a spiral structure;

[0011] Preferably, the diameter of the preform is 6-8 mm;

[0012] Preferably, the preform has 3-5 layers of spiral structure;

[0013] Preferably, the thickness of the preform is 1 / 2-3 / 4 of the thickness of the slag pump front shroud mold;

[0014] Preferably, the central axis of the spiral structure coincides with the central axis of the slag pump front shroud mold.

[0015] Further, the preparation step of the preform comprises:

[0016] sintering the ceramic raw material in a mold, and obtaining the preform after cooling;

[0017] Preferably, the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide, and titanium nitride;

[0018] Preferably, the mold is a spiral structure ceramic mold;

[0019] Preferably, the sintering temperature is 1800-2300℃, and the sintering time is 20-24 h.

[0020] Further, in the step 1), the diameter of the preform is 6-8 mm; and / or

[0021] The preform has 3-5 layers of spiral structure.

[0022] Further, in the step 2), the raw material components of the high-hardness wear-resistant alloy, in terms of mass percentage, are as follows: C: 3.3-3.7 wt%, Si: 5.3-5.7 wt%, Al: 0.4-0.8 wt%, B: 0.1-0.3 wt%, V: 8.5-9.0 wt%, Nb: 0.4-0.8 wt%, Mo: 2.3-2.7 wt%, N: 0.06-0.09 wt%, La+Ce: 0.2-0.5 wt%, and the balance is Fe.

[0023] Further, in the step 2), further comprising a step of preparing the metal liquid:

[0024] The primary smelting step: the primary smelting of other raw material components except rare earth, and the mother alloy ingot is obtained after pouring;

[0025] The casting step: refining treatment is performed on the mother alloy ingot, and the steel ingot is obtained after melting and pouring; wherein, rare earth is added during the refining treatment;

[0026] The secondary smelting step: the secondary smelting of the steel ingot, and the metal liquid is obtained after melting.

[0027] Further, in the primary smelting step, the vacuum electric frequency induction furnace is used for primary smelting; preferably, the primary smelting temperature is 1530-1550℃; the primary smelting time is 2-2.5h; and / or

[0028] In the casting step, the refining treatment temperature is 1530-1550℃; the refining treatment time is 1.5-2h; and / or

[0029] In the secondary smelting step, the vacuum electric frequency induction furnace is used for secondary smelting; preferably, the secondary smelting temperature is 1530-1550℃; the secondary smelting time is 2-2.5h.

[0030] Further, in the step 2), the metal liquid is poured into the slag pump front baffle mold by centrifugal casting;

[0031] Preferably, the temperature of the centrifugal casting is 1520-1550℃;

[0032] Preferably, the initial centrifugal speed is 600-800r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 800-1000r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 1000-1200r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 1200-1500r / min.

[0033] Further, in the step 3), the heat treatment of the front baffle rough blank includes: the front baffle rough blank is sequentially subjected to normalizing treatment and tempering treatment;

[0034] Preferably, the normalizing treatment includes: heating the front baffle rough blank to 750-800℃ at a rate of 3-5℃ / h, holding for 1-2h, then heating the front baffle rough blank to 1050-1100℃ at a rate of 1-1.5℃ / h, holding for 2-3h, and cooling to room temperature to obtain the front baffle rough blank after normalizing treatment;

[0035] Preferably, the tempering treatment comprises: heating the normalized front shroud rough blank to 200-250℃ at 1-1.5℃ / h, keeping for 2-3h, and cooling to room temperature to obtain the front shroud of the slurry pump.

[0036] In another aspect, the present application provides a front shroud of a slurry pump, the front shroud of the slurry pump being a preform, the preform being infiltrated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform in a spiral structure.

[0037] Preferably, the microstructure of the front shroud of the slurry pump comprises martensite, austenite and carbide, the martensite being in a lath shape; from the core to the surface of the front shroud of the slurry pump, the volume fraction of the carbide gradually increases.

[0038] Preferably, the volume fraction of the carbide on the surface of the front shroud of the slurry pump is 67-70%.

[0039] Preferably, the carbide comprises VC, M7C3 and Mo2C; the VC is in a spherical shape and forms a coherent crystal face with the austenite; the M7C3 is in a skeleton shape.

[0040] Further, the surface hardness of the front shroud of the slurry pump is ≥70HRC, and the impact toughness is ≥8J / cm2. 2 ;

[0041] Preferably, the front shroud of the slurry pump is obtained by the preparation method of the front shroud of the slurry pump according to any one of the above.

[0042] Compared with the prior art, the present application has at least the following beneficial effects:

[0043] 1. The application provides a preparation method of a front baffle plate of a slurry pump, which comprises the following steps: preparing a ceramic preform with a spiral structure, placing the preform in a front baffle plate mold of the slurry pump, pouring a high-hardness wear-resistant alloy liquid into the front baffle plate mold of the slurry pump, so that the high-hardness wear-resistant alloy liquid fills the front baffle plate mold of the slurry pump, and a front baffle plate rough blank is obtained; and then, the front baffle plate rough blank is subjected to heat treatment and processing, and a front baffle plate of the slurry pump is obtained. According to the method, the ceramic preform is added to the front baffle plate, on the one hand, the ceramic material has high hardness and strength, and cracks are difficult to penetrate the ceramic material, meanwhile, the high-hardness wear-resistant alloy base and the ceramic material are metallurgically combined during pouring, and the binding force is large, so that the crack propagation of the high-hardness alloy is resisted, and the fracture toughness of the front baffle plate is improved; on the other hand, the preform is beneficial to increasing the flow speed of the metal liquid, ensuring the density of the high-hardness wear-resistant alloy base, increasing the flow force of the alloy, being beneficial to improving the combination ability between the alloy and the ceramic material, realizing strong support to the outer high-hardness wear-resistant alloy, ensuring the high hardness and high wear resistance of the outer high-hardness wear-resistant alloy, and thus ensuring that the front baffle plate of the slurry pump has high fracture toughness, high hardness and high wear resistance.

[0044] 2. Further, the preform adopts a spiral structure, the spiral shape has a good flow guiding effect on the metal liquid, and can guide the fluid to flow along the spiral path efficiently; meanwhile, the spiral structure can increase the turbulence degree of the fluid, so as to reduce the local friction resistance and improve the flow efficiency, and thus being beneficial to improving the combination ability between the alloy and the ceramic material.

[0045] 3. Further, the high-hardness wear-resistant alloy liquid pouring is poured by using a variable-speed centrifugal casting process, which is beneficial to making the carbide small under the action of the centrifugal force, so as to play a second phase to further improve the synergistic protection effect on the base structure, that is, to play the role of second phase strengthening, and thus to improve the hardness and wear resistance; meanwhile, the variable-speed centrifugal casting process is beneficial to removing the gas and slag in the high-hardness wear-resistant alloy liquid, compensating the feeding of the riser, and reducing the defects of the prepared front baffle plate of the slurry pump; the centrifugal casting process has the effect of increasing the centrifugal force of the metal melt, and has the characteristics of accelerating the flow of the melt, and is beneficial to the preform to play the role of guiding the fluid to flow along the spiral path efficiently and the turbulence degree, and thus being beneficial to improving the high structural density, high strength and excellent wear resistance of the front baffle plate.

[0046] 4. Further, in the pouring process, the centrifugal acceleration makes the carbide (formed in situ between vanadium, niobium, molybdenum and carbon in the metal liquid) deviate to the direction of the outer surface of the front baffle plate, when the carbide particles are accumulated on the outer surface, their movement will stop, and thus a relatively uniform carbon-rich layer is formed on the outer surface of the front baffle plate of the slurry pump, and thus the wear resistance of the surface of the front baffle plate of the slurry pump is improved.

[0047] 5. In another aspect, the present application provides a slurry pump front shroud obtained by the above preparation method, the slurry pump front shroud comprising a preform and a high-hardness wear-resistant alloy base wrapped around the preform; wherein the preform is a ceramic preform with a spiral structure; the microstructure of the slurry pump front shroud comprises martensite, austenite and carbide, the martensite is in the form of lath; from the core to the surface of the slurry pump front shroud, the volume fraction of the carbide gradually increases; the volume fraction of the carbide on the surface of the slurry pump front shroud is 67-70%; the carbide comprises VC, M7C3 and Mo2C; the VC is in the form of a sphere and forms a coherent crystal face with the austenite; the M7C3 is in the form of a skeleton; the surface hardness of the slurry pump front shroud is ≥70HRC, and the impact toughness is ≥8J / cm2. 2 ; wherein the ceramic preform with a spiral structure has high hardness and strength, cracks cannot penetrate the ceramic, and at the same time, there is a metallurgical bond between the high-hardness wear-resistant alloy base and the ceramic during pouring, the bonding force is large, and can resist the crack propagation of the high-hardness alloy, thereby improving the fracture toughness of the front shroud. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. The drawings in the following description are only exemplary, and other embodiment drawings can be derived from the provided drawings without creative labor for those skilled in the art.

[0049] Figure 1 is a schematic diagram of the spiral structure ceramic preform in the present application; wherein, Figure 1 a is a top view of the preform, Figure 1 b is a cross-sectional view of one half of the slurry pump front shroud, Figure 1 c is a schematic diagram of the preform placed in the slurry pump front shroud template;

[0050] Figure 2 is a cross-sectional microstructure diagram of the slurry pump front shroud of Example 1 of the present application from the core to the surface layer;

[0051] Figure 3 is a cross-sectional microhardness change diagram of the slurry pump front shroud of Example 1 of the present application from the core to the surface layer;

[0052] Figure 4 is a cross-sectional microstructure and precipitated phase size comparison diagram of the slurry pump front shroud of Example 2 of the present application;

[0053] Figure 5 is the grain size and impact toughness of the slurry pump front shroud of Example 2 of the present application at different positions;

[0054] Figure 6is a surface light microscope contrast chart of the front shroud of the slurry pump of embodiment 1 and embodiment 3 of the present application;

[0055] Figure 7 is a hardness contrast chart of different parts of the front shroud of the slurry pump of embodiment 1 and embodiment 3 of the present application;

[0056] Figure 8 is a contrast chart of impact toughness and 100-hour wear weight loss of the front shroud of the slurry pump of embodiment 1 and comparative example 1 of the present application;

[0057] Figure 9 is the near-surface tissue morphology of the front shroud of the slurry pump of embodiment 1 and comparative example 2 of the present application;

[0058] Figure 10 is a contrast chart of the surface layer friction coefficient of the front shroud of the slurry pump of embodiment 1 and comparative example 2 of the present application;

[0059] Figure 11 is the wear damage tissue morphology of the front shroud of the slurry pump of embodiment 1 and comparative example 3 of the present application;

[0060] Figure 12 is a contrast chart of impact toughness of different parts of the front shroud of the slurry pump of embodiment 1 and comparative example 4 of the present application;

[0061] The reference signs are: 1-high-hardness wear-resistant alloy, 2-preform, 3-mold of the front shroud of the slurry pump. DETAILED DESCRIPTION

[0062] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. The drawings in the following description are only exemplary, and for those skilled in the art, other implementation drawings can also be derived from the provided drawings without creative labor.

[0063] In one aspect, the present application provides a preparation method of a front shroud of a slurry pump, comprising the following steps:

[0064] Step 1) sintering treatment of ceramic raw materials in a mold, and obtaining a preform after cooling; the preform is a ceramic preform and has a spiral structure (i.e. a set structure);

[0065] The spiral structure is a disc-shaped spiral structure (i.e. a spiral structure spirally winding at least one turn on a plane, similar to a mosquito-repellent incense structure); the diameter of the preform is 6-8 mm; the number of spiral layers of the preform is 3-5 layers; the thickness of the preform is 1 / 2-3 / 4 of the thickness of the front baffle mold of the slurry pump; the central axis of the spiral structure coincides with the central axis of the front baffle mold of the slurry pump; preferably, the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide and titanium nitride; preferably, the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1800-2300°C; the sintering time is 20-24 h; wherein the diameter of the preform refers to the maximum diameter of the cylinder surrounded by the spiral structure; the number of layers of the preform refers to the number of turns of the spiral structure around the central axis (i.e. the number of turns spirally winding on a plane);

[0066] Step 2) placing the preform in the front baffle mold of the slurry pump, and then pouring the high-hardness wear-resistant alloy liquid metal into the front baffle mold of the slurry pump by centrifugal casting, so that the high-hardness wear-resistant alloy liquid metal fills the front baffle mold of the slurry pump, while wrapping the preform and infiltrating into the spiral structure of the preform, to obtain a front baffle rough casting;

[0067] The central axis of the spiral structure coincides with the central axis of the front baffle mold of the slurry pump; the centrifugal casting temperature is 1520-1550°C; preferably, the initial centrifugal speed is 600-800 r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 800-1000 r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000-1200 r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1200-1500 r / min;

[0068] The preparation of the high-hardness wear-resistant alloy liquid metal comprises the following steps:

[0069] Primary melting step: primary melting of other raw material components except rare earth in a vacuum electric frequency induction furnace, and pouring to obtain a master alloy ingot; wherein the primary melting temperature is 1530-1550°C; the primary melting time is 2-2.5 h;

[0070] Casting step: refining treatment is performed on the master alloy ingot, and after melting, pouring is performed to obtain a steel ingot; wherein rare earth is added during the refining treatment; the refining treatment temperature is 1530-1550°C; the refining treatment time is 1.5-2 h;

[0071] Secondary melting step: secondary melting of the steel ingot in a vacuum electric frequency induction furnace, and after melting, a high-hardness wear-resistant alloy liquid metal is obtained; wherein the secondary melting temperature is 1530-1550°C; the secondary melting time is 2-2.5 h.

[0072] The raw material components of the high-hardness wear-resistant alloy are as follows in percentage by mass: C: 3.3-3.7 wt%, Si: 5.3-5.7 wt%, Al: 0.4-0.8 wt%, B: 0.1-0.3 wt%, V: 8.5-9.0 wt%, Nb: 0.4-0.8 wt%, Mo: 2.3-2.7 wt%, N: 0.06-0.09 wt%, La+Ce: 0.2-0.5 wt%, and the balance being Fe;

[0073] Step 3) performing heat treatment and processing on the front shield rough blank to obtain the front shield of the slurry pump;

[0074] The heat treatment on the front shield rough blank comprises: sequentially performing normalizing treatment and tempering treatment on the front shield rough blank.

[0075] Preferably, the normalizing treatment comprises: heating the front shield rough blank to 750-800 DEG C at a rate of 3-5 DEG C / h, holding for 1-2 h, then heating the front shield rough blank to 1050-1100 DEG C at a rate of 1-1.5 DEG C / h, holding for 2-3 h, and cooling to room temperature to obtain the front shield rough blank after normalizing treatment.

[0076] Preferably, the tempering treatment comprises: heating the front shield rough blank after normalizing treatment to 200-250 DEG C at a rate of 1-1.5 DEG C / h, holding for 2-3 h, and cooling to room temperature to obtain the front shield of the slurry pump.

[0077] Based on the above method, the ceramic preform with a spiral structure is added inside the front shield. On the one hand, the ceramic material has high hardness and strength, and cracks are difficult to penetrate the ceramic. Meanwhile, the high-hardness wear-resistant alloy matrix and the ceramic are metallurgically combined during pouring, and the bonding force is large, which can resist the crack propagation of the high-hardness alloy, thereby improving the fracture toughness of the front shield. On the other hand, the spiral structure of the ceramic is beneficial to increasing the flow speed of the metal liquid, ensuring the density of the high-hardness wear-resistant alloy matrix, and increasing the flow force of the alloy, which is beneficial to improving the bonding capacity between the alloy and the ceramic, realizing strong support on the outer high-hardness wear-resistant alloy, ensuring the high hardness and high wear resistance of the outer high-hardness wear-resistant alloy, thereby ensuring that the front shield of the slurry pump has high fracture toughness, high hardness and high wear resistance.

[0078] Based on the above components of high-hardness wear-resistant alloy, Al is dissolved in the matrix, which can improve the activity of C in austenite and the martensite transformation temperature. Among them, the improvement of the activity of C is beneficial to the in-situ self-generation of multi-scale ceramic particles (i.e. carbides) such as VC, Cr7C3, Fe7C3 and Mo2C, etc. These carbides are beneficial to the realization of second phase strengthening, and can effectively refine the grains, thereby improving the mechanical properties of the front shield of the slurry pump through second phase strengthening and fine-grain strengthening; the increase of the martensite transformation temperature can increase the content of lath martensite in the matrix during air cooling, thereby improving the strength and hardness of the matrix; among them, the in-situ self-generation is due to the low Gibbs free energy of the formation of carbides such as VC, NbC and Mo2C, which ensures that the carbides are directly formed during casting, rather than being formed by solid state phase transformation from the matrix.

[0079] For the front shield of the slurry pump of the present application, the degree of alloying is high, more alloying elements can form more carbides with C, and the size of the carbides is also getting larger and larger, which changes from fine globular to coarse rod-like, leading to stress concentration and preferential failure, i.e. leading to the decrease of the strength and toughness of the front shield of the slurry pump; the greater the alloying, the greater the solidification temperature range of the alloy, and the greater the viscosity, therefore, rare earth elements La and Ce are added in the composition, and the grain refinement is realized through the synergistic effect of Al element and rare earth. This is because the atomic radius of rare earth is larger than that of aluminum, and the property is relatively active, which is easy to fill the surface defects of the alloy phase in the aluminum melt pool, so that the surface tension on the interface between the new and old phases is reduced, and the growth rate of the crystal nucleus is improved; at the same time, it can also form a surface active film between the grain and the molten liquid, preventing the growth of the generated grains, i.e. under the synergistic effect of Al element and rare earth, the grain size of the carbide is smaller (for example, VC, Cr7C3, Mo2C is micron scale, and Cr 23 C6 is nanometer scale), thereby improving the toughness of the front shield of the slurry pump.

[0080] On the other hand, the present application provides a front shield of a slurry pump, which comprises a preform, and the preform is impregnated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform with a spiral structure.

[0081] Preferably, the microstructure of the front shield of the slurry pump comprises martensite, austenite and carbide, the martensite is in the form of lath; from the core to the surface of the front shield of the slurry pump, the volume fraction of the carbide gradually increases; the volume fraction of the carbide on the surface of the front shield of the slurry pump is 67-70%; the carbide comprises VC, M7C3 and Mo2C; the VC is in the form of globular, and forms a coherent crystal face with the austenite; the M7C3 is in the form of skeleton.

[0082] Further, the surface hardness of the front shield of the slurry pump is ≥70HRC, and the impact toughness is ≥8J / cm 2 ;

[0083] Preferably, the slag pump front shield is obtained by the preparation method of any one of the slag pump front shields described above.

[0084] The slag pump front shield has a high volume fraction of carbides on the surface, which can improve the wear resistance of the surface of the slag pump front shield; VC can improve the strength and hardness of the slag pump front shield, and forms a coherent interface between the spherical VC and the surrounding matrix, and the skeleton-like Cr7C3 and Fe7C3 are both beneficial to the synergistic deformation during the wear process, thereby inhibiting the peeling of the material matrix during the wear process; high alloying is beneficial to increasing the martensite transformation temperature, thereby increasing the content of the plate-like martensite and refining the size of the martensite during air cooling, thereby improving the strength and toughness of the slag pump front shield.

[0085] The application will be further described below with reference to specific examples.

[0086] The raw material components of the high-hardness wear-resistant alloy of the examples and the comparative examples are shown in Table 1.

[0087] Table 1 shows the raw material components (wt%) of the high-hardness wear-resistant alloy of the examples and the comparative examples of the application.

[0088] C Si Al B V Nb Mo N Rare earth Fe Example 1 3.5 5.5 0.6 0.2 8.7 0.6 2.5 0.08 0.3 Remain Example 2 3.3 5.3 0.5 0.1 8.6 0.3 2.3 0.06 0.2 Remain Example 3 3.5 5.5 0.6 0.2 8.7 0.6 2.5 0.08 0 Remain Comparative Example 3 2 5.5 0.6 0.2 6.5 0.6 2.5 0.08 0.3 Remain

[0089] Example 1

[0090] The present example provides a preparation method of a slag pump front shield, which specifically comprises the following steps:

[0091] Step 1) sintering treatment of ceramic raw materials in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0092] Preferably, the diameter of the preform is 8 mm; the number of spiral layers of the preform is 4 layers; the thickness of the preform is 1 / 2 of the thickness of the slag pump front shield mold; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering treatment temperature is 1950℃; the sintering treatment time is 22h;

[0093] Step 2) placing the preform in the slag pump front shield mold, and the central axis of the spiral structure coincides with the central axis of the slag pump front shield mold; then pouring the high-hardness wear-resistant alloy liquid metal into the slag pump front shield mold by centrifugal casting, so that the high-hardness wear-resistant alloy liquid metal fills the slag pump front shield mold, simultaneously wrapping the preform and infiltrating into the spiral structure of the preform, to obtain a front shield rough blank;

[0094] The centrifugal casting temperature is 1540 DEG C; the initial centrifugal speed is 650 r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850 r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100 r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250 r / min; and the centrifugal casting time is 22 min;

[0095] The preparation of the high-hardness wear-resistant alloy liquid includes the following steps:

[0096] The primary smelting step is that, according to the raw material components in Table 1 of Example 1, the primary smelting of the raw materials except rare earth is carried out in a vacuum electric frequency induction furnace, and a mother alloy ingot is obtained after pouring; the primary smelting temperature is 1540 DEG C; and the primary smelting time is 2 h;

[0097] The casting step is that the mother alloy ingot is subjected to refining treatment, and then is poured after melting to obtain a steel ingot; the rare earth is added during the refining treatment; the refining treatment temperature is 1540 DEG C; and the refining treatment time is 1.6 h;

[0098] The secondary smelting step is that the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace, and a high-hardness wear-resistant alloy liquid is obtained after melting; the secondary smelting temperature is 1540 DEG C; and the secondary smelting time is 2 h;

[0099] Step 3) the front baffle rough blank is heated to 770 DEG C at a rate of 4 DEG C / h under room temperature, and then heated to 1080 DEG C at a rate of 1.3 DEG C / h after being kept for 1.5 h, and then cooled to room temperature after being kept for 2.5 h, to obtain a front baffle rough blank after normalizing treatment; the front baffle rough blank after normalizing treatment is subjected to tempering treatment, the tempering treatment is to heat to 230 DEG C at a rate of 1 DEG C / h, keep for 2.5 h, and then directly air-cooled to room temperature, and then machined to obtain the front baffle of the slurry pump.

[0100] The top view of the preform prepared in the example and the sectional view of the front baffle of the slurry pump are shown in Figure 1 It can be seen that the preform 1 with a spiral structure is impregnated and wrapped with a high-hardness wear-resistant alloy (matrix) 2, the central axis of the preform 1 coincides with the central axis of the front baffle mold 3 of the slurry pump; the microstructure and the microhardness of the front baffle of the slurry pump from the core to the surface are respectively as shown in Figure 2 and Figure 3As shown, it can be found that the more and finer dispersed distribution of the carbide content from the core to the surface, and the higher the hardness, which is due to the use of centrifugal casting method to make the carbide migrate to the surface of the front baffle of the slurry pump, and the centrifugal force also makes the size of the carbide more fine, and the fine carbide plays the role of second phase strengthening, which is beneficial to improve the hardness of the surface of the front baffle; at the same time, the spiral structure of the ceramic preform is beneficial to increase the flow speed of the molten metal, ensure the density of the high-hardness wear-resistant alloy matrix, and increase the flow force of the alloy, which is beneficial to improve the binding capacity between the alloy and the ceramic, realize the strong support to the outer layer of high-hardness wear-resistant alloy, and further improve the surface hardness.

[0101] Example 2

[0102] The embodiment provides a preparation method of a front baffle of a slurry pump, and specifically comprises the following steps:

[0103] Step 1) sintering treatment is performed on the ceramic raw material in a mold, and a preform is obtained after cooling; the preform is a spiral structure ceramic preform;

[0104] Preferably, the sintering treatment temperature is 2200 DEG C, and the sintering treatment time is 24 h.

[0105] Step 2) the preform is placed in the front baffle mold of the slurry pump, and the central axis of the spiral structure is coincided with the central axis of the front baffle mold of the slurry pump; then the molten metal of the high-hardness wear-resistant alloy is poured into the front baffle mold of the slurry pump by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the front baffle mold of the slurry pump, wraps the preform, and infiltrates into the spiral structure of the preform, to obtain a front baffle rough blank;

[0106] Preferably, the centrifugal casting temperature is 1550 DEG C, the initial centrifugal speed is 650 r / min, the centrifugal speed is increased to 850 r / min when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100 r / min when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250 r / min when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, and the centrifugal casting time is 23 min.

[0107] Preferably, the preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0108] Primary smelting step: according to the raw material components of Example 2 in Table 1, the raw material components except rare earth are subjected to primary smelting in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after pouring; wherein the primary smelting temperature is 1550℃; the primary smelting time is 2.5h;

[0109] Casting step: the master alloy ingot is subjected to refining treatment, and after melting, a steel ingot is obtained by pouring; wherein rare earth is added during the refining treatment; the refining treatment temperature is 1550℃; the refining treatment time is 1.8h;

[0110] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace, and a high-hardness wear-resistant alloy liquid metal is obtained after melting; wherein the secondary smelting temperature is 1550℃; the secondary smelting time is 2.5h;

[0111] Step 3) the front shield rough blank is heated to 780℃ at a rate of 4.5℃ / h, and after holding for 1.3h, the front shield rough blank is heated to 1070℃ at a rate of 1.5℃ / h, and after holding for 2.2h, it is cooled to room temperature to obtain a normalized front shield rough blank; the normalized front shield rough blank is then subjected to tempering treatment, which is heated to 220℃ at a rate of 1.5℃ / h, and after holding for 2.4h, it is directly air-cooled to room temperature, and then machined to obtain a slurry pump front shield.

[0112] The microstructure and precipitated phase (carbide) size of the slurry pump front shield prepared in this example from the core to the surface of the skin are compared as shown in Figure 4 The grain size and impact toughness at different positions are shown in Figure 5 It can be found that the carbide size becomes smaller and smaller from the core to the surface, and the impact toughness becomes higher and higher, which is because the fine carbide can significantly refine the grains and disperse the impact stress concentration effect, thereby improving the comprehensive mechanical properties; at the same time, due to the high hardness and strength of the ceramic material, the crack is difficult to penetrate the ceramic, and the high-hardness wear-resistant alloy matrix and the ceramic are metallurgically combined during pouring, and the bonding force is large, which can resist the crack propagation of the high-hardness alloy, thereby improving the impact toughness of the front shield.

[0113] The above two examples are preferred examples adopting the necessary features and preferred technical features of the present application, and the following examples are examples adopting the necessary features and non-preferred technical features.

[0114] Example 3

[0115] The present example provides a preparation method of a slurry pump front shield, which specifically comprises the following steps:

[0116] Step 1) sintering treatment is performed on the ceramic raw material in a mold, and a preform is obtained after cooling; the preform is a ceramic preform with a spiral structure;

[0117] wherein the diameter of the preform is 8mm; the number of spiral layers of the preform is 4 layers; the thickness of the preform is 1 / 2 of the thickness of the front baffle mold of the slurry pump; the ceramic raw material is titanium carbide; the mold is a spiral structure ceramic mold; preferably, the sintering treatment temperature is 1850℃; the sintering treatment time is 20h;

[0118] Step 2) placing the preform into the front baffle mold of the slurry pump, the central axis of the spiral structure coincides with the central axis of the front baffle mold of the slurry pump; then pouring the high-hardness wear-resistant alloy liquid metal into the front baffle mold of the slurry pump through centrifugal casting, so that the high-hardness wear-resistant alloy liquid metal fills the front baffle mold of the slurry pump, at the same time, wrapping the preform and infiltrating into the spiral structure of the preform, to obtain a front baffle rough blank;

[0119] wherein the centrifugal casting temperature is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000r / min; the centrifugal casting time is 23min;

[0120] wherein the preparation of the high-hardness wear-resistant alloy liquid metal comprises the following steps:

[0121] primary smelting step: according to the raw material components in Table 1, the raw material components except rare earth are subjected to primary smelting in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after pouring; wherein the primary smelting temperature is 1540℃; the primary smelting time is 2h;

[0122] casting step: the master alloy ingot is subjected to refining treatment, and after melting, pouring is carried out to obtain a steel ingot; wherein rare earth is added during the refining treatment; the refining treatment temperature is 1540℃; the refining treatment time is 1.6h;

[0123] secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace, and after melting, a high-hardness wear-resistant alloy liquid metal is obtained; wherein the secondary smelting temperature is 1540℃; the secondary smelting time is 2h;

[0124] Step 3) the front baffle rough blank is heated to 770℃ at a rate of 4℃ / h, and after holding for 1.5h, the front baffle rough blank is heated to 1080℃ at a rate of 1.3℃ / h, and after holding for 2.5h, it is cooled to room temperature to obtain a front baffle rough blank after normalizing treatment; then the front baffle rough blank after normalizing treatment is subjected to tempering treatment, the tempering treatment is to heat to 230℃ at a rate of 1℃ / h, hold for 2.5h, directly air cool to room temperature, and then machine to obtain a front baffle of a slurry pump.

[0125] The surface defects of the front shield of the slurry pump prepared in the present example and the hardness from the core to the surface were compared with those of the front shield of the slurry pump prepared in Example 1, respectively, as shown in Figure 6 and Figure 7 It can be found that the surface composition segregation of the front shield of the slurry pump of the present example and the hardness decrease more, which is due to the fact that the rotation speed is increased too fast during centrifugal casting of the present example, which easily causes composition segregation near the surface, thereby resulting in large hardness change from the core to the surface of the prepared front shield of the slurry pump, which can cause stress concentration and accelerate the fracture thereof.

[0126] Comparative Example 1

[0127] The present comparative example provides a preparation method of a front shield of a slurry pump, which specifically comprises the following steps:

[0128] Step 1) pouring the molten high-hardness wear-resistant alloy into a front shield of a slurry pump mold by centrifugal casting to fill the front shield of the slurry pump mold with the molten high-hardness wear-resistant alloy, so as to obtain a front shield rough casting;

[0129] The temperature of the centrifugal casting is 1540℃; the initial centrifugal rotation speed is 650r / min; the centrifugal rotation speed is increased to 850r / min when the centrifugal casting reaches 1 / 4 of the thickness of the front shield of the slurry pump; the centrifugal rotation speed is increased to 1100r / min when the centrifugal casting reaches 1 / 2 of the thickness of the front shield of the slurry pump; the centrifugal rotation speed is increased to 1250r / min when the centrifugal casting reaches 3 / 4 of the thickness of the front shield of the slurry pump; and the time of the centrifugal casting is 22min.

[0130] The preparation of the molten high-hardness wear-resistant alloy comprises the following steps:

[0131] Primary melting step: according to the raw material components of Example 1 in Table 1, the primary melting of the raw material components except rare earth is carried out in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after pouring; wherein the temperature of the primary melting is 1540℃; and the time of the primary melting is 2h;

[0132] Casting step: the master alloy ingot is subjected to refining treatment, and after melting, pouring is carried out to obtain a steel ingot; wherein rare earth is added during the refining treatment; the temperature of the refining treatment is 1540℃; and the time of the refining treatment is 1.6h;

[0133] Secondary melting step: the steel ingot is subjected to secondary melting in a vacuum electric frequency induction furnace, and the molten high-hardness wear-resistant alloy is obtained after melting; wherein the temperature of the secondary melting is 1540℃; and the time of the secondary melting is 2h;

[0134] Step 3) the front shield rough blank is loaded into the furnace at room temperature, and then heated to 770℃ at a rate of 4℃ / h, kept for 1.5h, then heated to 1080℃ at a rate of 1.3℃ / h, kept for 2.5h, and then cooled to room temperature to obtain the front shield rough blank after normalizing treatment; the front shield rough blank after normalizing treatment is subjected to tempering treatment, the tempering treatment is heating to 230℃ at a rate of 1℃ / h, kept for 2.5h, and then directly air-cooled to room temperature, and then machined to obtain the front shield of the slurry pump.

[0135] The impact toughness of the front shield of the slurry pump prepared in Example 1 is compared with that of the front shield of the slurry pump prepared in the comparative example 1, as shown in the table. Figure 8 As can be seen from the table, the high-hardness wear-resistant alloy lacks ceramic preform, and the crack propagation resistance of the high-hardness wear-resistant alloy is insufficient, the internal crack of the high-hardness wear-resistant alloy will quickly lose stability and expand, and then the impact toughness is poor, and the lack of ceramic preform will also reduce the support of the high-hardness wear-resistant alloy, so the wear weight loss of the comparative example is more, and the wear performance is reduced.

[0136] Comparative example 2

[0137] The comparative example provides a preparation method of a front shield of a slurry pump, which specifically comprises the following steps:

[0138] Step 1) sintering treatment is performed on the ceramic raw material in the mold, and the preform is obtained after cooling; the preform is a cylindrical ceramic preform;

[0139] Preferably, the diameter of the preform is 8mm; the thickness of the preform is 1 / 2 of the thickness of the front shield mold of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering treatment temperature is 1950℃; the sintering treatment time is 22h;

[0140] Step 2) the preform is placed in the front shield mold of the slurry pump, and the central axis of the preform coincides with the central axis of the front shield mold of the slurry pump; then the metal liquid of the high-hardness wear-resistant alloy is poured into the front shield mold of the slurry pump by centrifugal casting, so that the metal liquid of the high-hardness wear-resistant alloy fills the front shield mold of the slurry pump, simultaneously wrapping the preform, and infiltrating into the spiral structure of the preform, to obtain the front shield rough blank;

[0141] Preferably, the centrifugal casting temperature is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front shield of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front shield of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front shield of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0142] Preferably, the preparation of the metal liquid of the high-hardness wear-resistant alloy comprises the following steps:

[0143] Once smelting step: according to the raw material components of example 1 in table 1, other raw material components except rare earth are smelted in a vacuum electric frequency induction furnace, and a mother alloy ingot is obtained after pouring; wherein, the temperature of once smelting is 1540℃; the time of once smelting is 2h;

[0144] Casting step: the mother alloy ingot is refined and treated, and after melting, a steel ingot is obtained by pouring; wherein, rare earth is added in the process of refining and treating; the temperature of refining and treating is 1540℃; the time of refining and treating is 1.6h;

[0145] Secondary smelting step: the steel ingot is smelted in a vacuum electric frequency induction furnace, and a high-hardness wear-resistant alloy liquid metal is obtained after melting; wherein, the temperature of secondary smelting is 1540℃; the time of secondary smelting is 2h;

[0146] Step 3) the front shield rough blank is loaded into the furnace at room temperature, then heated to 770℃ at a rate of 4℃ / h, and after holding for 1.5h, heated to 1080℃ at a rate of 1.3℃ / h, and after holding for 2.5h, cooled to room temperature to obtain the front shield rough blank after normalizing treatment; the front shield rough blank after normalizing treatment is tempered, the tempering treatment is to heat to 230℃ at a rate of 1℃ / h, hold for 2.5h, and directly air cool to room temperature, and then machined to obtain the front shield of the slurry pump.

[0147] The near outer layer surface microstructure of the comparative example and example 1 is as shown in Figure 9 It can be found that the ceramic preform of the comparative example is changed from a spiral shape to a cylindrical preform, and the driving force for the metal melt during solidification is smaller, so the size of the outer layer carbide is larger than that of the example, and the average friction coefficient is lower than that of example 1, and the test results are shown in Figure 10 .

[0148] Comparative example 3

[0149] The comparative example provides a preparation method of a front shield of a slurry pump, which specifically comprises the following steps:

[0150] Step 1) sintering treatment is performed on the ceramic raw material in a mold, and a preform is obtained after cooling; the preform is a ceramic preform with a spiral structure;

[0151] Wherein, the diameter of the preform is 8mm; the number of spiral layers of the preform is 4 layers; the thickness of the preform is 1 / 2 of the thickness of the mold of the front shield of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering treatment temperature is 1950℃; the sintering treatment time is 22h;

[0152] Step 2) placing the preform into the slag pump front baffle mold, the central axis of the spiral structure coincides with the central axis of the slag pump front baffle mold; then pouring the high-hardness wear-resistant alloy liquid metal into the slag pump front baffle mold by centrifugal casting, so that the high-hardness wear-resistant alloy liquid metal fills the slag pump front baffle mold, at the same time, wrapping the preform and infiltrating into the spiral structure of the preform, to obtain a front baffle rough casting;

[0153] The centrifugal casting temperature is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the slag pump front baffle, the centrifugal speed is increased to 1250r / min; and the centrifugal casting time is 22min.

[0154] The preparation of the high-hardness wear-resistant alloy liquid metal includes the following steps:

[0155] Primary melting step: according to the raw material components in Table 1 of the comparative example 3, the primary melting of the raw materials except rare earth is carried out in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after pouring; wherein the primary melting temperature is 1540℃; and the primary melting time is 2h.

[0156] Casting step: the master alloy ingot is subjected to refining treatment, and after melting, the steel ingot is obtained by pouring; wherein rare earth is added during the refining treatment; the refining treatment temperature is 1540℃; and the refining treatment time is 1.6h.

[0157] Secondary melting step: the steel ingot is subjected to secondary melting in a vacuum electric frequency induction furnace, and a high-hardness wear-resistant alloy liquid metal is obtained after melting; wherein the secondary melting temperature is 1540℃; and the secondary melting time is 2h.

[0158] Step 3) loading the front baffle rough casting into the furnace at room temperature, then heating the front baffle rough casting to 770℃ at a rate of 4℃ / h, holding for 1.5h, then heating the front baffle rough casting to 1080℃ at a rate of 1.3℃ / h, holding for 2.5h, and then cooling to room temperature to obtain a front baffle rough casting after normalizing treatment; then the front baffle rough casting after normalizing treatment is subjected to tempering treatment, the tempering treatment is heating to 230℃ at a rate of 1℃ / h, holding for 2.5h, and then directly air cooling to room temperature, and then machining to obtain a slag pump front baffle.

[0159] The comparative example and the embodiment are compared in terms of the wear microscopic morphology of the front baffle Figure 11As shown, it can be found that the base alloy component range of the present comparative example is not without the high-hard wear-resistant alloy described in the present application. The lower V and Cr contents in the alloy result in less carbide content and insufficient surface hardness, causing poor wear resistance of the front baffle surface.

[0160] Comparative Example 4

[0161] The present comparative example provides a preparation method of a front baffle of a slurry pump, specifically comprising the following steps:

[0162] Step 1) sintering treatment of ceramic raw materials in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0163] Preferably, the temperature of the sintering treatment is 1950°C; the time of the sintering treatment is 22h;

[0164] Step 2) placing the preform in a slurry pump front baffle mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front baffle mold; then pouring the metal liquid of the high-hard wear-resistant alloy into the slurry pump front baffle mold through centrifugal casting, so that the metal liquid of the high-hard wear-resistant alloy fills the slurry pump front baffle mold, simultaneously wrapping the preform and infiltrating into the spiral structure of the preform, to obtain a front baffle rough blank;

[0165] Preferably, the temperature of the centrifugal casting is 1540°C; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the slurry pump front baffle, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the slurry pump front baffle, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the slurry pump front baffle, the centrifugal speed is increased to 1250r / min; the time of the centrifugal casting is 22min;

[0166] Preferably, the preparation of the metal liquid of the high-hard wear-resistant alloy comprises the following steps:

[0167] Primary melting step: according to the raw material components in Table 1, primary melting of the raw material components except rare earth in a vacuum electric frequency induction furnace, and pouring to obtain a master alloy ingot; wherein the temperature of the primary melting is 1540°C; the time of the primary melting is 2h;

[0168] Casting step: refining treatment of the master alloy ingot, melting and pouring to obtain a steel ingot; wherein rare earth is added during the refining treatment; the temperature of the refining treatment is 1540°C; the time of the refining treatment is 1.6h;

[0169] Secondary melting step: the steel ingot is subjected to secondary melting in a vacuum electric frequency induction furnace, and a molten metal of the high-hardness wear-resistant alloy is obtained after melting; wherein, the temperature of the secondary melting is 1540 DEG C; the time of the secondary melting is 2h;

[0170] Step 3) the front shield rough blank is heated to 770 DEG C at a rate of 4 DEG C / h at room temperature, and then heated to 1200 DEG C at a rate of 1.3 DEG C / h after holding for 1.5h, and then cooled to room temperature, to obtain the front shield rough blank after normalizing treatment; the front shield rough blank after normalizing treatment is subjected to tempering treatment, the tempering treatment is heating to 300 DEG C at a rate of 1 DEG C / h, holding for 2.5h, and then directly air cooling to room temperature, and then machining, to obtain the front shield of the slurry pump.

[0171] The front shield of the slurry pump prepared in the comparative example and the front shield of the slurry pump prepared in example 1 are compared in terms of impact toughness as shown in the table. Figure 12 As shown in the table, the normalizing temperature and the tempering temperature of the comparative example are both higher than the temperature range of the present application, so that the growth of carbide is accelerated during the heat treatment, which is not conducive to the strength and toughness.

[0172] It is easily understood by those skilled in the art that the advantageous technical features of the above-mentioned modes can be freely combined and superimposed without conflict.

[0173] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application. The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of manufacturing a front shroud for a slurry pump, characterized in that, The method comprises the following steps: Step 1) preparing a preform; the preform is a ceramic preform and can improve the flow speed of the metal liquid; Step 2) placing the preform in a slurry pump front shield mold, then pouring the metal liquid into the slurry pump front shield mold, so that the metal liquid fills the slurry pump front shield mold and wraps the preform and infiltrates into the set structure of the preform, to obtain a front shield rough blank; wherein the metal liquid is a metal liquid of high-hardness wear-resistant alloy; Step 3) performing heat treatment and processing on the front shield rough blank to obtain a slurry pump front shield; The preform has a spiral structure spirally winding at least one loop on a plane; the number of spiral layers of the preform is 3-5; wherein the number of spiral layers of the preform is the number of loops spirally winding on a plane. The preparation step of the preform comprises: sintering treatment of a ceramic raw material in a mold, and obtaining the preform after cooling; the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide and titanium nitride.

2. The method for preparing the slurry pump front guard plate according to claim 1, characterized in that, In the step 1), the diameter of the preform is 6-8 mm.

3. The method for preparing the slurry pump front guard plate according to claim 1, characterized in that, The thickness of the preform is 1 / 2-3 / 4 of the thickness of the slurry pump front shield mold.

4. The method for preparing the slurry pump front guard plate according to claim 1, characterized in that, The central axis of the spiral structure coincides with the central axis of the slurry pump front shield mold.

5. The method of claim 1, wherein the front shroud of the slurry pump is made of a material selected from the group consisting of: carbon steel, stainless steel, and duplex stainless steel. The mold is a ceramic mold with a spiral structure.

6. The method of claim 1, wherein the front shroud of the slurry pump is made of a material selected from the group consisting of: carbon steel, stainless steel, and duplex stainless steel. The sintering temperature is 1800-2300 DEG C; the sintering time is 20-24 h.

7. The method of claim 1, wherein the front shroud of the slurry pump is made of a material selected from the group consisting of: carbon steel, stainless steel, and duplex stainless steel. In the step 2), the raw material components of the high-hardness wear-resistant alloy are as follows in terms of mass percentage: C: 3.3-3.7 wt%, Si: 5.3-5.7 wt%, Al: 0.4-0.8 wt%, B: 0.1-0.3 wt%, V: 8.5-9.0 wt%, Nb: 0.4-0.8 wt%, Mo: 2.3-2.7 wt%, N: 0.06-0.09 wt%, La+Ce: 0.2-0.5 wt%, and the balance is Fe.

8. The method for preparing the slurry pump front guard plate according to claim 7, characterized in that, In the step 2), the preparation step of the metal liquid is further included: Primary smelting step: primary smelting of other raw material components except rare earth, and pouring to obtain a master alloy ingot; Casting step: refining treatment is performed on the master alloy ingot, and after melting, pouring is performed to obtain a steel ingot; wherein rare earth is added during the refining treatment; Secondary smelting step: secondary smelting of the steel ingot, and after melting, the metal liquid is obtained.

9. The method of claim 8, wherein the front shroud of the slurry pump is prepared by, In the primary smelting step, a vacuum electric frequency induction furnace is used for primary smelting; the primary smelting temperature is 1530-1550 DEG C; the primary smelting time is 2-2.5 h; and / or In the casting step, the refining treatment temperature is 1530-1550 DEG C; the refining treatment time is 1.5-2 h; and / or In the secondary smelting step, a vacuum electric frequency induction furnace is used for secondary smelting; the secondary smelting temperature is 1530-1550 DEG C; the secondary smelting time is 2-2.5 h.

10. The method for preparing the slurry pump front guard plate according to claim 1, characterized in that, In the step 2), the metal liquid is poured into the slurry pump front shield mold by centrifugal casting; The temperature of the centrifugal casting is 1520-1550℃; the initial centrifugal speed is 600-800r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 800-1000r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000-1200r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1200-1500r / min.

11. The method of making a slurry pump front shroud of claim 1, wherein, In the step 3), the heat treatment of the front baffle rough blank comprises: sequentially performing normalizing treatment and tempering treatment on the front baffle rough blank.

12. The method for preparing the slurry pump front guard plate according to claim 1, characterized in that, The normalizing treatment comprises: heating the front baffle rough blank to 750-800℃ at a rate of 3-5℃ / h, maintaining for 1-2h, then heating the front baffle rough blank to 1050-1100℃ at a rate of 1-1.5℃ / h, maintaining for 2-3h, and cooling to room temperature to obtain the front baffle rough blank after normalizing treatment; The tempering treatment comprises: heating the front baffle rough blank after normalizing treatment to 200-250℃ at a rate of 1-1.5℃ / h, maintaining for 2-3h, and cooling to room temperature to obtain the front baffle of the slurry pump.

13. A front shroud for a slurry pump, characterized in that The front baffle of the slurry pump is obtained by the preparation method of the front baffle of the slurry pump according to any one of claims 1-12; the front baffle of the slurry pump comprises a preform, and the preform is infiltrated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform with a spiral structure.

14. The front baffle of the slurry pump according to claim 13, the microstructure of the front baffle of the slurry pump comprises martensite, austenite and carbide, the martensite is in the form of lath; from the core to the surface of the front baffle of the slurry pump, the volume fraction of the carbide gradually increases; The volume fraction of the carbide on the surface of the front baffle of the slurry pump is 67-70%; The carbide comprises VC, M7C3 and Mo2C; the VC is in the form of sphere and forms a coherent crystal face with the austenite; the M7C3 is in the form of skeleton.

15. The slurry pump front shroud of claim 13, wherein, The surface hardness of the front guard plate of the slag slurry pump is greater than or equal to 70HRC, and the impact toughness is greater than or equal to 8J / cm 2 .

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