Preparation method of composite ceramic pump

Abstract

The invention discloses a preparation method of a composite ceramic pump. The preparation method comprises the following steps: (1) obtaining raw materials; (2) adding a binder into the mixture of the silicon powder and the carbon black, and granulating; (3) mixing and stirring a mixture of silicon carbide particles and silicon carbide powder with the granules in the step (2), adding a dispersing agent and a binding agent, and finally adding a curing agent; (4) casting in a plaster mold, and presetting curing time and temperature; (5) after curing, taking out and continuously carrying out heat preservation; (6) feeding the blank subjected to heat preservation into a sintering furnace, vacuumizing, introducing nitrogen, preserving heat at 600 DEG C for 4-12 hours in a nitrogen atmosphere, preliminarily finishing nitriding at 1200-1350 DEG C, cooling along with the furnace, and taking out; (7) polishing the surface of the sintered block, and paving a layer of silicon powder; and (8) feeding into a furnace chamber, vacuumizing, starting to heat, heating to 1400 DEG C, preserving heat, continuously heating to 1600-1700 DEG C, preserving heat, reacting the residual silicon with the added carbon, simultaneously keeping the introduction of nitrogen, and cooling along with the furnace after sintering is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic pumps, and in particular to a method for preparing a composite ceramic pump by utilizing carbon-nitrogen reaction sintering. Background Art

[0002] In recent years, ceramic materials have been increasingly used in industrial applications due to their high hardness, good wear resistance, and corrosion resistance, especially in the newly emerging field of composite ceramic pumps. Currently, the most commonly used ceramic types are silicon nitride ceramics, silicon carbide ceramics, and silicon nitride-bonded silicon carbide ceramics. In practical applications, these three types of ceramic materials each have their own advantages and disadvantages. Single silicon nitride and silicon carbide ceramic structural parts are relatively brittle, and cracks can easily spread, causing the entire structure to fail. Silicon nitride-bonded silicon carbide ceramics prepared by nitridation reactions generally have weak bonding strength and relatively weak wear resistance. They wear more when conveying large-particle slurries and often fail to reach the preset service life, which greatly limits the application of this type of ceramic material in the field of composite ceramic pumps. Summary of the Invention

[0003] The purpose of the present invention is to address the above-mentioned shortcomings and defects of the prior art and provide a method for preparing a composite ceramic pump, which improves the fracture toughness of the ceramic material while still having good wear resistance, and can extend the effective use time of ceramic structural parts under harsh conditions.

[0004] A method for preparing a composite ceramic pump comprises the following steps:

[0005] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0006] 55wt%-75wt% mixture of silicon carbide particles and silicon carbide powder,

[0007] Silicon powder and carbon black mixture 10wt%-30wt%,

[0008] Binder 15wt%,

[0009] Dispersant 0.3wt%,

[0010] Curing agent 0.5wt%;

[0011] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0012] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0013] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0014] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0015] (6) The green body after heat preservation is sent to the sintering furnace, first evacuated, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling in the furnace;

[0016] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0017] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0018] In a preferred embodiment of the present invention, the particle size of the silicon carbide particles is 20-80 mesh, and the particle size of the silicon carbide powder is 150-325 mesh.

[0019] In a preferred embodiment of the present invention, the particle size of the silicon powder is 200-325 mesh.

[0020] In a preferred embodiment of the present invention, the binder includes at least one of phenolic resin, epoxy resin, silica sol, and gum arabic.

[0021] In a preferred embodiment of the present invention, the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate, and sodium hexametaphosphate.

[0022] In a preferred embodiment of the present invention, in step (1), the raw materials comprise the following components by weight percentage:

[0023] Silicon carbide particles and silicon carbide powder mixture 65wt%,

[0024] Silicon powder and carbon black mixture 20wt%,

[0025] Binder 15wt%,

[0026] Dispersant 0.3wt%,

[0027] Curing agent 0.5wt%.

[0028] In a preferred embodiment of the present invention, in the mixture of silicon powder and carbon black, the weight ratio of silicon powder to carbon black is 3:1.

[0029] In a preferred embodiment of the present invention, in step (6), the heating rate is reduced when the temperature exceeds 900°C.

[0030] In a preferred embodiment of the present invention, in the mixture of silicon carbide particles and silicon carbide powder, the weight ratio of the silicon carbide particles to the silicon carbide powder is 7:3.

[0031] Due to the adoption of the above technical solution, the present invention combines the advantages of silicon carbide reaction sintering and nitridation reaction sintering, while maintaining high wear resistance, it improves the fracture toughness of the ceramic material, making this type of ceramic material suitable for more application scenarios and can be used in composite ceramic pumps. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 The present invention is a process flow chart of a method for preparing a composite ceramic pump. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0035] The terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The singular forms "a," "the," and "the" used in this invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms "first", "second", "third", etc. may be used to describe various information in the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0037] See also Figure 1 As shown, a method for preparing a composite ceramic pump includes the following steps:

[0038] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0039] 55wt%-75wt% mixture of silicon carbide particles and silicon carbide powder,

[0040] Silicon powder and carbon black mixture 10wt%-30wt%,

[0041] Binder 15wt%,

[0042] Dispersant 0.3wt%,

[0043] Curing agent 0.5wt%;

[0044] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0045] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0046] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0047] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0048] (6) The green body after heat preservation is sent to the sintering furnace, first evacuated, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling in the furnace;

[0049] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0050] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0051] The particle size of the silicon carbide particles is 20-80 mesh, the particle size of the silicon carbide powder is 150-325 mesh, and the particle size of the silicon powder is 200-325 mesh. The binder includes at least one of phenolic resin, epoxy resin, silica sol, and gum arabic. The dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate, and sodium hexametaphosphate.

[0052] In the mixture of silicon powder and carbon black, the weight ratio of silicon powder to carbon black is 3:1.

[0053] In the mixture of silicon carbide particles and silicon carbide powder, the weight ratio of the silicon carbide particles to the silicon carbide powder is 7:3.

[0054] The present invention mainly reflects the advantages of the product from three properties: density, fracture toughness, and wear resistance. The calculation of the three properties is as follows:

[0055] Calculation of ceramic density:

[0056] The bulk density of sintered ceramics was measured using the Archimedes drainage method. The bulk density of the sintered sample was calculated using the following formula:

[0057]

[0058] Where: ρ is the sample volume density, unit: g / cm 3 ; m1 is the dry weight of the sample, unit is g; m2 is the floating weight of the sample, unit is g; m3 is the wet weight of the sample, unit is g; ρwater is the density of deionized water, unit is g / cm 3 .

[0059] Fracture toughness calculation:

[0060] The SENB method is used to test the fracture toughness of the sample. The prepared sample strips are placed on a universal testing machine for testing, and then the fracture toughness of the material is calculated using the formula.

[0061]

[0062] Where: KIC: fracture toughness (MPa·m 1 / 2 );

[0063] P: Maximum load when the specimen breaks (N);

[0064] L: span (mm);

[0065] W: sample width (mm);

[0066] h: specimen height (mm);

[0067] a: depth of specimen notch (m);

[0068] Wear rate calculation:

[0069] Wear volume is measured using an MMH-5 three-body abrasive wear tester, using 7-150 mesh quartz sand, a test load of 40N, a rotational speed of 50 rpm, and 20 abrasion cycles per specimen, each lasting 5 hours. A larger wear volume value indicates poorer wear resistance. The ratio of wear volume to total specimen volume is the wear rate.

[0070] The following is further explained with reference to the following examples and comparative examples.

[0071] Example 1

[0072] A method for preparing a composite ceramic pump comprises the following steps:

[0073] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0074] Silicon carbide particles and silicon carbide powder mixture 75wt%,

[0075] Silicon powder and carbon black mixture 10wt%,

[0076] Binder 15wt%,

[0077] Dispersant 0.3wt%,

[0078] Curing agent 0.5wt%;

[0079] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0080] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0081] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0082] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0083] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0084] (6) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0085] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0086] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0087] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0088] The product properties obtained in this embodiment are as follows:

[0089] Density: 2.87g / cm 3 ;

[0090] Fracture toughness: 2.9 MPa·m 1 / 2 ;

[0091] Wear resistance test, the loss is 0.56%.

[0092] Example 2

[0093] A method for preparing a composite ceramic pump comprises the following steps:

[0094] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0095] Silicon carbide particles and silicon carbide powder mixture 70wt%,

[0096] Silicon powder and carbon black mixture 15wt%,

[0097] Binder 15wt%,

[0098] Dispersant 0.3wt%,

[0099] Curing agent 0.5wt%;

[0100] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0101] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0102] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0103] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0104] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0105] (6) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0106] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0107] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0108] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0109] The product properties obtained in this embodiment are as follows:

[0110] Density: 2.91g / cm 3 ;

[0111] Fracture toughness: 3.1MPa·m 1 / 2 ;

[0112] Wear resistance test, the loss is 0.59%.

[0113] Example 3

[0114] A method for preparing a composite ceramic pump comprises the following steps:

[0115] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0116] Silicon carbide particles and silicon carbide powder mixture 65wt%,

[0117] Silicon powder and carbon black mixture 20wt%,

[0118] Binder 15wt%,

[0119] Dispersant 0.3wt%,

[0120] Curing agent 0.5wt%;

[0121] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0122] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0123] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0124] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0125] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0126] (6) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0127] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0128] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0129] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0130] The product properties obtained in this embodiment are as follows:

[0131] Density: 2.95g / cm3 ;

[0132] Fracture toughness: 3.30 MPa·m 1 / 2 ;

[0133] Wear resistance test, the loss is 0.57%.

[0134] Example 4

[0135] A method for preparing a composite ceramic pump comprises the following steps:

[0136] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0137] Silicon carbide particles and silicon carbide powder mixture 60wt%,

[0138] Silicon powder and carbon black mixture 25wt%,

[0139] Binder 15wt%,

[0140] Dispersant 0.3wt%,

[0141] Curing agent 0.5wt%;

[0142] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0143] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0144] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0145] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0146] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0147] (6) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0148] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0149] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0150] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0151] The product properties obtained in this embodiment are as follows:

[0152] Density: 2.93g / cm 3 ;

[0153] Fracture toughness: 3.17 MPa·m 1 / 2 ;

[0154] Wear resistance test, the loss is 0.62%.

[0155] Example 5

[0156] A method for preparing a composite ceramic pump comprises the following steps:

[0157] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0158] Silicon carbide particles and silicon carbide powder mixture 55wt%,

[0159] Silicon powder and carbon black mixture 30wt%,

[0160] Binder 15wt%,

[0161] Dispersant 0.3wt%,

[0162] Curing agent 0.5wt%;

[0163] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0164] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0165] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0166] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0167] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0168] (6) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0169] (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0170] (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0171] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0172] The product properties obtained in this embodiment are as follows:

[0173] Density: 2.90g / cm 3 ;

[0174] Fracture toughness: 2.74 MPa·m 1 / 2 ;

[0175] Wear resistance test, the loss is 0.71%.

[0176] Comparative Example 1

[0177] A method for preparing a composite ceramic pump comprises the following steps:

[0178] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0179] Silicon carbide particles and silicon carbide powder mixture 65wt%,

[0180] Silicon powder and carbon black mixture 20wt%,

[0181] Binder 15wt%,

[0182] Dispersant 0.3wt%,

[0183] Curing agent 0.5wt%;

[0184] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0185] (2) mixing the silicon powder and carbon black mixture with the silicon carbide particles and silicon carbide powder mixture, stirring, adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0186] (3) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0187] (4) After solidification, take it out and continue to keep it warm at a temperature of 150-200°C;

[0188] (5) The green body after heat preservation is sent to the sintering furnace, first vacuumed, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling with the furnace. When the temperature exceeds 900 ° C, the heating rate is reduced;

[0189] (6) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder;

[0190] (7) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0191] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0192] The performance of the product obtained in this comparative example is as follows:

[0193] Density: 2.94g / cm 3 ;

[0194] Fracture toughness: 2.87 MPa·m 1 / 2 ;

[0195] Wear resistance test, the loss is 0.65%.

[0196] Comparative Example 2

[0197] A method for preparing a composite ceramic pump comprises the following steps:

[0198] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0199] Silicon carbide particles and silicon carbide powder mixture 65wt%,

[0200] Silicon powder and carbon black mixture 20wt%,

[0201] Binder 15wt%,

[0202] Dispersant 0.3wt%,

[0203] Curing agent 0.5wt%;

[0204] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0205] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0206] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0207] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0208] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0209] (6) Assemble the green body on the trolley and spread a layer of metallic silicon powder on the surface of the green body;

[0210] (7) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

[0211] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0212] The performance of the product obtained in this comparative example is as follows:

[0213] Density: 2.87g / cm 3 ;

[0214] Fracture toughness: 2.4 MPa·m1 / 2 ;

[0215] Wear resistance test, the loss is 0.67%.

[0216] Comparative Example 3

[0217] A method for preparing a composite ceramic pump comprises the following steps:

[0218] (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage:

[0219] Silicon carbide particles and silicon carbide powder mixture 65wt%,

[0220] Silicon powder and carbon black mixture 20wt%,

[0221] Binder 15wt%,

[0222] Dispersant 0.3wt%,

[0223] Curing agent 0.5wt%;

[0224] The particle size of silicon carbide particles is 20-80 mesh, the particle size of silicon carbide powder is 150-325 mesh, and the particle size of silicon powder is 200-325 mesh;

[0225] (2) adding a binder to a mixture of silicon powder and carbon black for granulation;

[0226] (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity;

[0227] (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h;

[0228] (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C;

[0229] (6) The green body after insulation is sent to the sintering furnace, first evacuated, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600℃ for 4-12h, and the nitriding is initially completed at 1200-1350℃. Then the temperature is raised to 1400℃ and kept for 3-6h. The heating rate is reduced and the temperature is continued to be raised to 1600-1700℃, and the insulation time is 8-12h, so that the remaining silicon reacts with the added carbon. At the same time, the nitrogen is kept introduced. After sintering is completed, it is cooled with the furnace and the sintering is completed.

[0230] The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic; the dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate and sodium hexametaphosphate.

[0231] The performance of the product obtained in this comparative example is as follows:

[0232] Density: 2.96g / cm 3 ;

[0233] Fracture toughness: 3.1MPa·m 1 / 2 ;

[0234] Wear resistance test, the loss is 0.92%.

[0235] According to the above comparative example: the fracture toughness of the ceramic material prepared by the nitrogen-carbon reaction method increases with the increase of the amount of silicon powder and carbon black granulated powder added, reaching a maximum value of 3.3MPa·m when it reaches 20w%. 1 / 2 Compared with the control group in Example 1 which did not carry out preliminary granulation, its fracture toughness increased by 13%, indicating that the preliminary granulation of silicon powder and carbon powder is beneficial to the sintering performance. Compared with Example 2 which did not carry out preliminary nitriding sintering and only carried out siliconizing reaction, the density and fracture toughness of the sample increased by 3% and 27% respectively. Compared with the components in Example 3 which did not carry out siliconizing but only carried out nitriding reaction, the difference in fracture toughness is not much, and the density and wear resistance are greatly improved. Therefore, the ceramic material of the present invention which utilizes nitrogen-carbon reaction combines the advantages of two sintering technologies, improving the fracture toughness of the material while maintaining good wear resistance.

[0236] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite ceramic pump, characterized in that: The steps include: (1) Obtaining raw materials, the raw materials comprising the following components by weight percentage: 55wt%-75wt% mixture of silicon carbide particles and silicon carbide powder, Silicon powder and carbon black mixture 10wt%-30wt%, Binder 15wt%, Dispersant 0.3wt%, Curing agent 0.5wt%; (2) adding a binder to a mixture of silicon powder and carbon black for granulation; (3) mixing and stirring the mixture of silicon carbide particles and silicon carbide powder with the granules prepared in step (2), adding a dispersant and a binder, continuing to stir, and finally adding a curing agent to maintain fluidity; (4) Casting in a plaster mold, presetting the curing time and temperature, the curing temperature is 40-80°C, and the curing time is 12-20h; (5) After solidification, take out and continue to keep warm at a temperature of 150-200°C; (6) The green body after heat preservation is sent to the sintering furnace, first evacuated, then nitrogen is introduced, and in a nitrogen atmosphere, it is kept at 600 ° C for 4-12 hours, and the nitriding is initially completed at 1200-1350 ° C. It is taken out after cooling in the furnace; (7) Grind the surface of the sintered block, place it on a trolley, and assemble it, then spread a layer of silicon powder; (8) Use a material cart to deliver the assembled composite ceramic pump blank into the furnace chamber, first evacuate the chamber, then start heating to 1400°C, keep warm for 3-6 hours, reduce the heating rate and continue heating to 1600-1700°C, keep warm for 8-12 hours, so that the remaining silicon reacts with the added carbon, while keeping nitrogen flowing. After sintering is completed, cool with the furnace and sintering is completed.

2. The method for preparing a composite ceramic pump according to claim 1, characterized in that: The particle size of the silicon carbide particles is 20-80 meshes, and the particle size of the silicon carbide powder is 150-325 meshes.

3. The method for preparing a composite ceramic pump according to claim 1, characterized in that: The particle size of the silicon powder is 200-325 mesh.

4. The method for preparing a composite ceramic pump according to claim 1, characterized in that: The binder includes at least one of phenolic resin, epoxy resin, silica sol and gum arabic.

5. The method for preparing a composite ceramic pump according to claim 1, characterized in that: The dispersant includes at least one of polyethylene glycol 200, HPMA, sodium tripolyphosphate, and sodium hexametaphosphate.

6. The method for preparing a composite ceramic pump according to claim 1, characterized in that: In step (1), the raw materials include the following components by weight percentage: Silicon carbide particles and silicon carbide powder mixture 65wt%, Silicon powder and carbon black mixture 20wt%, Binder 15wt%, Dispersant 0.3wt%, Curing agent 0.5wt%.

7. The method for preparing a composite ceramic pump according to claim 1, characterized in that: In the mixture of silicon powder and carbon black, the weight ratio of silicon powder to carbon black is 3:

1.

8. The method for preparing a composite ceramic pump according to claim 1, characterized in that: In step (6), the heating rate is reduced when the temperature exceeds 900°C.

9. The method for preparing a composite ceramic pump according to claim 1, characterized in that: In the mixture of silicon carbide particles and silicon carbide powder, the weight ratio of the silicon carbide particles to the silicon carbide powder is 7:3.

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