Spraying type cylinder sleeve for drilling mud pump

Abstract

The invention provides a spraying type cylinder sleeve for a drilling mud pump, and relates to the field of mud pumps. The cylinder sleeve comprises an outer sleeve and a lining, and the lining is attached to the inner wall of the outer sleeve in a spraying mode. The outer sleeve is prepared from the following raw materials in parts by weight: 60 to 70 parts of zirconium oxide, 30 to 40 parts of modified silicon nitride, 20 to 30 parts of modified silicon carbide, 5 to 10 parts of graphite oxide, 5 to 10 parts of chromic oxide, 10 to 20 parts of molybdenum oxide, 5 to 10 parts of nickel powder, 5 to 10 parts of molybdenum powder, 5 to 10 parts of rare earth metal oxide, 5 to 10 parts of ammonium polyacrylate and 5 to 10 parts of binder; the modified silicon nitride is a compound formed by coating the surfaces of silicon nitride particles with aluminum hydroxide; the modified silicon carbide is a compound formed by coating the surfaces of silicon carbide particles with aluminum hydroxide. The cylinder sleeve has the advantages of excellent mechanical property, good corrosion resistance, high temperature resistance and long service life.

Description

Technical Field

[0001] The invention relates to the field of mud pumps, and in particular to a spray-coated cylinder liner for a drilling mud pump. Background Art

[0002] The mud pump cylinder liner is the core component of the hydraulic end of the mud pump, which directly cooperates with the piston to achieve the compression and transportation of the mud. The mud pump cylinder liner usually adopts a double-layer metal design (such as a bimetallic cylinder liner), with the outer layer of high-strength carbon steel providing support and the inner layer of wear-resistant materials such as high-chromium cast iron to resist mud erosion. This composite structure balances strength and wear resistance, ensuring that the cylinder liner operates stably under high pressure and high temperature environments. The cylinder liner and the piston form a closed volume chamber, and through the reciprocating motion of the piston, the low-pressure mud is compressed into a high-pressure fluid to achieve energy conversion. Its inner surface needs to withstand the high-speed friction of the piston ring, and the outer surface cooperates with the cooling system to prevent thermal stress deformation.

[0003] Although the technology of mud pump cylinder liners is relatively mature, there are still the following technical bottlenecks, such as insufficient wear resistance: traditional high-chromium cast iron cylinder liners are prone to wear in mud with high sand content, and the surface hardness (HRC60-62) is difficult to meet the requirements of extreme working conditions. Corrosion resistance defects: acidic mud can easily cause chemical corrosion on the surface of the cylinder liner, forming grooves and cracks. High temperature resistance shortcomings: high temperature mud (>80℃) can easily soften the cylinder liner material, reducing sealing and life. Insufficient rigidity: thin-walled cylinder liners (5-9mm) are easy to deform under high pressure, resulting in mud leakage and pump pressure drop. Heat treatment process: uneven quenching causes fluctuations in the hardness of the inner sleeve, affecting the consistency of wear resistance and other problems.

[0004] Patent 201710113476.X discloses a zirconia ceramic cylinder liner material and a preparation method thereof, which includes 65-85% zirconia, 3-5% yttrium oxide, 2.5-4.5% neodymium oxide, 1-5% graphite and 5-10% molybdenum carbide; wherein the graphite and molybdenum carbide need to be soaked in dilute nitric acid first, and then separated into solid and liquid. The composite addition of yttrium oxide and neodymium oxide significantly improves the density of zirconia ceramics, and rare earth oxides can improve the wettability of the material, ultimately achieving the effect of reducing the sintering temperature. Graphite and molybdenum carbide are soaked in dilute nitric acid, which can significantly reduce the friction coefficient of zirconia ceramics at 120°C. Although this solution can reduce the friction coefficient of the cylinder liner at high temperatures and reduce the sintering temperature, its mechanical strength and corrosion resistance still need to be improved. Summary of the invention

[0005] The object of the present invention is to provide a spray-coated cylinder liner for a drilling mud pump, which has excellent mechanical properties, good corrosion resistance, high temperature resistance and long service life.

[0006] The present invention solves the technical problem by adopting the following technical solutions.

[0007] On the one hand, an embodiment of the present invention provides a spray-coated cylinder liner for a drilling mud pump, wherein the cylinder liner comprises an outer sleeve and an inner sleeve, wherein the inner sleeve is attached to the inner wall of the outer sleeve by spraying; The outer jacket comprises the following raw materials by weight: 60-70 parts of zirconium oxide, 30-40 parts of modified silicon nitride, 20-30 parts of modified silicon carbide, 5-10 parts of graphite oxide, 5-10 parts of chromium oxide, 10-20 parts of molybdenum oxide, 5-10 parts of nickel powder, 5-10 parts of molybdenum powder, 5-10 parts of rare earth metal oxide, 5-10 parts of ammonium polyacrylate, and 5-10 parts of a binder; The modified silicon nitride is a composite formed by coating aluminum hydroxide on the surface of silicon nitride particles; the modified silicon carbide is a composite formed by coating aluminum hydroxide on the surface of silicon carbide particles.

[0008] In some embodiments of the present invention, the lining comprises the following raw materials by weight: 30-40 parts of tungsten carbide, 20-30 parts of cobalt powder, 30-40 parts of aluminum oxide, and 10-20 parts of titanium oxide.

[0009] In some embodiments of the present invention, the modified silicon nitride is prepared by the following method: The silicon nitride powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 10-20 minutes, standing, and filtering to obtain the modified silicon nitride. In some embodiments of the present invention, the modified silicon carbide is prepared by the following method: The silicon carbide powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 10-20 minutes, standing, and filtering to obtain the modified silicon carbide. In some embodiments of the present invention, the molar ratio of silicon nitride, yttrium nitrate and sodium aluminate is 1:0.5:(2-3), and the molar ratio of silicon carbide, yttrium nitrate and sodium aluminate is 1:0.5:(2-3). In some embodiments of the present invention, the rare earth metal oxide is a mixture of one or more of lanthanum oxide, yttrium oxide, and cerium oxide.

[0010] In some embodiments of the present invention, the binder is one or more of polyvinyl alcohol, carboxyl cellulose, methyl cellulose, and ethyl cellulose.

[0011] In some embodiments of the present invention, the outer jacket is made by the following method: S1, after mixing all the raw materials evenly, adding them into a ball mill, ball milling, sieving, spray granulation, to obtain a material, wherein the particle size of the material is less than 400 mesh; S2, adding the material into the mold, placing it in an electric field for 1-2 minutes, and then performing cold isostatic pressing to obtain a jacket blank; wherein the electric field treatment is a high-voltage pulse electric field with an electric field strength of 15-20 kV / cm and a pulse frequency of 300-500Hz.

[0012] S3, placing the jacket blank in a sintering furnace, sintering at 1600-1800° C. for 4-5 hours, cooling down, taking the blank out of the furnace, and cooling it to room temperature to obtain the jacket.

[0013] The ball mill is used to grind the raw materials and control the particle size of the raw materials. The smaller the particle size of the raw materials, the tighter the raw materials are compacted during cold isostatic pressing, and the tighter the outer shell is. After the materials are added to the mold, they are treated with a high-voltage pulse electric field to activate the molecules in the raw materials. Then, during the cold isostatic pressing process, intermolecular forces are formed between the metal molecules, increasing the connectivity between molecules. Then, during the high-temperature calcination process, the movement between molecules is enhanced, and the strength and density of the alloy formed are increased.

[0014] In some embodiments of the present invention, the liner is made by the following method: The inner wall of the outer jacket is roughened by sandblasting, cleaned by ultrasonic in an ethanol aqueous solution, air-dried, and set aside; The raw material powder of the prepared lining is sent into the supersonic flame spraying system, and the first coating is sprayed on the inner wall of the outer jacket, roughened by sandblasting, and cleaned; wherein the parameters of the supersonic flame spraying are: flame speed 1800-2000m / s, spraying particle speed: 300-500m / s, particle size of the raw material powder is 10-30um, and spraying distance is 150-200mm.

[0015] The raw material powder for the lining is prepared and sent to a plasma spraying system, and sprayed on the surface of the first coating to obtain a second coating; wherein the parameters of the plasma spraying are: arc power 20-30kw, spraying distance 80-100mm, and particle size of the raw material powder 50-100um.

[0016] Polishing is performed to obtain the inner lining.

[0017] The inner wall of the outer jacket is now formed by supersonic flame spraying, which has low porosity, good density, and excellent corrosion resistance and high temperature resistance. Subsequently, the second coating formed by plasma spraying on the surface of the first coating has a larger porosity than the first coating; the gradient pores formed by the first coating and the second coating can effectively alleviate the problem of thermal stress concentration caused by friction and high temperature on the surface of the second coating. Because the pores provide space for thermal expansion and deformation in a high temperature environment, the interfacial stress concentration caused by the obstruction of thermal expansion between particles is alleviated. Secondly, the second coating with a large porosity can absorb a certain amount of lubricating oil / grease, forming an oil seal on the surface of the second coating, further reducing the friction coefficient. At the same time, the first coating has fewer pores, which can prevent other substances from further entering the lining, thereby extending the service life of the entire cylinder sleeve.

[0018] In some embodiments of the present invention, the thickness of the first coating layer is 200-300 um, the thickness of the second coating layer is 100-200 um, and the thickness of the lining layer is 300-500 um.

[0019] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: The cylinder sleeve provided by the present invention comprises an outer sleeve and an inner sleeve, wherein the outer sleeve is composed of zirconium oxide, modified silicon nitride, modified silicon carbide, graphite oxide, chromium oxide, molybdenum oxide, nickel powder, molybdenum powder, rare earth metal oxide, ammonium polyacrylate, and a binder. Modified silicon nitride and silicon carbide can improve the mechanical properties of the cylinder sleeve: aluminum hydroxide is used to wrap silicon nitride and silicon carbide. During the high-temperature calcination process, the aluminum hydroxide wrapped in the outer layer will decompose into aluminum oxide and adhere to silicon carbide and silicon nitride. It can serve as a connecting bridge between silicon nitride, silicon carbide and raw materials, and can also be filled in the molecules of silicon nitride and silicon carbide to improve the compactness of the cylinder sleeve outer sleeve, thereby improving the mechanical strength. On the other hand, the modified silicon carbide and silicon nitride have good wettability with the remaining metal oxides and are easier to disperse evenly.

[0020] The addition of rare earth metal oxides, together with silicon nitride, silicon carbide and aluminum oxide, further improves the compactness of the jacket. Graphite oxide is a layered structure, which can be deeply graphitized during high-temperature calcination. The layered structure gradually transforms into a honeycomb structure, which is dispersed between the metal molecules, plays a reinforcing role and improves the mechanical strength of the jacket.

[0021] The lining is attached to the inner wall of the outer sleeve by spraying. The lining is composed of tungsten carbide, cobalt powder, aluminum oxide, titanium oxide and other raw materials. The coating formed by spraying has excellent corrosion resistance, smooth surface, small friction coefficient at high temperature, good wear resistance, and can effectively extend the service life of the cylinder liner at high temperature. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0024] Example 1 According to the proportions in Table 1, prepare the raw materials for the jacket of each embodiment 1: Table 1 Ratio of raw materials of jacket (parts by weight)

[0025] In Table 1, the modified silicon nitride is prepared by the following method: Silicon nitride powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 20 minutes, standing, and filtering to obtain the modified silicon nitride. The molar ratio of silicon nitride, yttrium nitrate, and sodium aluminate is 1:0.5:2.

[0026] Modified silicon carbide is prepared by the following method: The silicon carbide powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 20 minutes, standing, and filtering to obtain the modified silicon carbide. The molar ratio of silicon carbide, yttrium nitrate, and sodium aluminate is 1:0.5:2.

[0027] The rare earth metal oxide of Example 1-2 is yttrium oxide, that of Example 3-4 is lanthanum oxide, and that of Example 5 is a mixture of yttrium oxide and lanthanum oxide, and the mass ratio of the two is 1:1.

[0028] According to the proportions in Table 2, prepare the raw materials for the lining of each embodiment: Table 2 Ratio of raw materials for lining (parts by weight)

[0029] The cylinder sleeves of Examples 1-5 were prepared as follows: S1, after mixing all the raw materials evenly, adding them into a ball mill, ball milling, sieving, spray granulation, to obtain a material, wherein the particle size of the material is less than 400 mesh; S2, adding the material to the mold, placing it in an electric field for 1 minute, and then cold isostatic pressing to obtain a jacket blank; wherein the electric field treatment is a high-voltage pulse electric field with an electric field strength of 15kV / cm and a pulse frequency of 300Hz. wherein the cold isostatic pressing pressure is 1500kg / cm 2 , static pressure time is 20min.

[0030] S3, placing the jacket blank in a sintering furnace, sintering at 1800° C. for 5 hours, cooling at a cooling rate of 100° C., and cooling to room temperature to obtain the jacket.

[0031] S4, roughening the inner wall of the outer jacket by sandblasting, cleaning it by ultrasonic wave in ethanol water solution, air drying it and setting it aside; S5, prepare the raw material powder of the lining, send it into the supersonic flame spraying system, spray it on the inner wall of the outer jacket to obtain the first coating, sandblast it for roughening, and clean it; wherein the parameters of the supersonic flame spraying are: flame speed 1800-2000m / s, spraying particle speed: 300-500m / s, raw material powder particle size 10-30um, spraying distance 200mm.

[0032] S6, prepare the raw material powder of the lining, send it into the plasma spraying system, spray it on the surface of the first coating to obtain the second coating; wherein the parameters of the plasma spraying are: arc power 20-30kw, spraying distance 100mm, particle size of the raw material powder 50-100um.

[0033] S7, polishing to obtain an inner lining, that is, the cylinder sleeve of Example 1-5.

[0034] The thickness of the first coating layer is set to 250+10um, the thickness of the second coating layer is set to 150+10um, and the overall thickness of the lining is set to 400+10um. According to the thickness of the first coating layer and the second coating layer, the total mass of the powder raw materials used in steps S5 and S6 is calculated, and the proportion of each raw material is shown in Table 2.

[0035] Example 6 The difference from Example 1 is that in this example, the rare earth metal oxide is a mixture of yttrium oxide and lanthanum oxide, and the mass ratio of the two is 1: 1. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0036] Example 7 The difference from Example 1 is that in this example, the rare earth metal oxide is a mixture of yttrium oxide and lanthanum oxide, and the mass ratio of the two is 1: 1. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0037] Example 8 The difference from Example 1 is that in this example, the rare earth metal oxide is a mixture of yttrium oxide and cerium oxide, and the mass ratio of the two is 1: 1. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0038] Example 9 The difference from Example 1 is that in this example, the rare earth metal oxide is a mixture of lanthanum oxide and cerium oxide, and the mass ratio of the two is 1: 1. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0039] Example 10 The difference from Example 1 is that in this example, the rare earth metal oxide is a mixture of lanthanum oxide, cerium oxide and cerium oxide, and the mass ratio of the three is 1:1:1. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0040] Embodiment 11 The difference from Example 1 is that in this example, carboxyl cellulose is used instead of polyvinyl alcohol, and the remaining raw material ratios and preparation methods are the same as those in Example 1.

[0041] Example 12 The difference from Example 1 is that in this example, methyl cellulose is used instead of polyvinyl alcohol, and the remaining raw material ratios and preparation methods are the same as those in Example 1.

[0042] Embodiment 13 The difference from Example 1 is that in this embodiment, in step S2 of preparing the cylinder liner, the treatment time in the pulse electric field is 2 min, the electric field strength is 20 kV / cm, and the pulse frequency is 500 Hz. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0043] Embodiment 14 The difference from Example 1 is that in this embodiment, in step S2 of preparing the cylinder liner, the treatment time in the pulse electric field is 1.5 min, the electric field strength is 15 kV / cm, and the pulse frequency is 300 Hz. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0044] Embodiment 15 The difference from Example 1 is that in this embodiment, in step S2 of preparing the cylinder liner, the treatment time in the pulse electric field is 2 min, the electric field strength is 10 kV / cm, and the pulse frequency is 400 Hz. The rest of the raw material ratios and preparation methods are the same as those in Example 1.

[0045] Comparative Example 1 The difference from Example 1 is that silicon nitride and silicon carbide are not modified, and the remaining raw material proportions and preparation methods are the same as those of Example 1.

[0046] Comparative Example 2 The difference from Example 1 is that no graphite oxide is added, and the remaining raw material ratios and preparation methods are the same as those of Example 1.

[0047] Comparative Example 3 The difference from Example 1 is that in step S2, pulse electric field treatment is not performed, and the remaining raw material proportions and preparation methods are the same as those in Example 1.

[0048] Comparative Example 4 The difference from Example 1 is that, when spraying the lining, only plasma spraying is used, and the rest of the raw material ratios and preparation methods are the same as those of Example 1.

[0049] Comparative Example 5 The difference from Example 1 is that when spraying the lining, only supersonic flame spraying is used, and the remaining raw material ratios and preparation methods are the same as those of Example 1.

[0050] Experimental example The cylinder liners of the embodiment and the comparative example were used as experimental objects to conduct the following tests, and the results are shown in Table 3. Among them, at 80°C, a hydraulic system was used to simulate the actual working pressure (7000psi) of the mud pump, and the cylinder liners were accelerated by high-frequency pressure cycles to test their service life.

[0051] Table 3 Performance of each cylinder liner

[0052] It can be concluded from Table 3 that in Comparative Example 1, silicon nitride and silicon carbide were not modified, and the Vickers hardness of the cylinder liner was lower than that of the embodiment, and the bending strength was also smaller than that of the embodiment. Similarly, in Comparative Example 2, graphite oxide was not added, and the mechanical properties of the cylinder liner were also worse than those of the embodiment. In Comparative Example 3, the raw materials were not pulse treated, and the mechanical properties of the cylinder liner were also reduced. In Comparative Examples 4-5, only plasma spraying or supersonic flame spraying was performed on the liner, and its mechanical properties were not much different from those of Example 1, but its service life was shorter because of the lack of a gradient pore structure, its heat resistance was poor, and its service life at high temperature was correspondingly shortened.

[0053] Using the spraying parameters and raw materials of the lining in Example 1, plasma spraying and supersonic flame spraying were performed on the inner walls of the two groups of outer jackets to obtain samples. The porosity of the first coating and the second coating was then tested by X-ray CT scanning. The results are shown in Table 4.

[0054] Table 4 Porosity of the first coating and the second coating

[0055] It can be concluded from Table 4 that according to the spraying method of Example 1, the porosity of the first coating and the second coating obtained are different.

[0056] In summary, the cylinder liner provided by the present invention includes an outer jacket and an inner liner, wherein the outer jacket is composed of zirconium oxide, modified silicon nitride, modified silicon carbide, graphite oxide, chromium oxide, molybdenum oxide, nickel powder, molybdenum powder, rare earth metal oxides, ammonium polyacrylate, and a binder. Modified silicon nitride and silicon carbide can improve the mechanical properties of the cylinder liner: aluminum hydroxide is used to wrap silicon nitride and silicon carbide. During the high-temperature calcination process, the aluminum hydroxide wrapped in the outer layer will decompose into aluminum oxide and adhere to silicon carbide and silicon nitride. It can serve as a connecting bridge between silicon nitride, silicon carbide and raw materials, and can also be filled in the molecules of silicon nitride and silicon carbide to improve the compactness of the cylinder liner outer jacket, thereby improving the mechanical strength. On the other hand, the modified silicon carbide and silicon nitride have good wettability with the remaining metal oxides and are easier to disperse evenly.

[0057] The addition of rare earth metal oxides, together with silicon nitride, silicon carbide and aluminum oxide, further improves the compactness of the jacket. Graphite oxide is a layered structure, which can be deeply graphitized during high-temperature calcination. The layered structure gradually transforms into a honeycomb structure, which is dispersed between the metal molecules, plays a reinforcing role and improves the mechanical strength of the jacket.

[0058] The lining is attached to the inner wall of the outer sleeve by spraying. The lining is composed of tungsten carbide, cobalt powder, aluminum oxide, titanium oxide and other raw materials. The coating formed by spraying has excellent corrosion resistance, smooth surface, small friction coefficient at high temperature, good wear resistance, and can effectively extend the service life of the cylinder liner at high temperature.

[0059] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A spray-coated cylinder liner for a drilling mud pump, characterized in that: The cylinder sleeve comprises an outer sleeve and an inner sleeve, and the inner sleeve is attached to the inner wall of the outer sleeve by spraying; The outer jacket comprises the following raw materials by weight: 60-70 parts of zirconium oxide, 30-40 parts of modified silicon nitride, 20-30 parts of modified silicon carbide, 5-10 parts of graphite oxide, 5-10 parts of chromium oxide, 10-20 parts of molybdenum oxide, 5-10 parts of nickel powder, 5-10 parts of molybdenum powder, 5-10 parts of rare earth metal oxide, 5-10 parts of ammonium polyacrylate, and 5-10 parts of a binder; The modified silicon nitride is a composite formed by coating aluminum hydroxide on the surface of silicon nitride particles; the modified silicon carbide is a composite formed by coating aluminum hydroxide on the surface of silicon carbide particles.

2. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The lining comprises the following raw materials by weight: 30-40 parts of tungsten carbide, 20-30 parts of cobalt powder, 30-40 parts of aluminum oxide, and 10-20 parts of titanium oxide.

3. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The modified silicon nitride is prepared by the following method: The silicon nitride powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 10-20 minutes, standing, and filtering to obtain the modified silicon nitride.

4. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The modified silicon carbide is prepared by the following method: The silicon carbide powder is dispersed in an ethanol aqueous solution, yttrium nitrate and a surfactant are added, mixed evenly, and the pH value is adjusted to 12-13; then, sodium aluminate solution is added dropwise under stirring; after the addition is completed, stirring is continued for 10-20 minutes, standing, and filtering to obtain the modified silicon carbide.

5. The spray-coated cylinder liner for a drilling mud pump according to claim 3 or 4, characterized in that: The molar ratio of silicon nitride, yttrium nitrate and sodium aluminate is 1:0.5:(2-3), and the molar ratio of silicon carbide, yttrium nitrate and sodium aluminate is 1:0.5:(2-3).

6. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The rare earth metal oxide is a mixture of one or more of lanthanum oxide, yttrium oxide and cerium oxide.

7. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The binder is one or more of polyvinyl alcohol, carboxyl cellulose, methyl cellulose and ethyl cellulose.

8. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The outer jacket is made by the following method: S1, after mixing all the raw materials evenly, adding them into a ball mill, ball milling, sieving, spray granulation, and obtaining the material; S2, adding the material into the mold, placing it in an electric field for 1-2 minutes, and then performing cold isostatic pressing to obtain a jacket blank; S3, placing the jacket blank in a sintering furnace, sintering at 1600-1800° C. for 4-5 hours, cooling down, taking the blank out of the furnace, and cooling it to room temperature to obtain the jacket.

9. The spray-coated cylinder liner for a drilling mud pump according to claim 1, characterized in that: The lining is prepared by the following method: The inner wall of the outer jacket is roughened by sandblasting, cleaned by ultrasonic in an ethanol aqueous solution, air-dried, and set aside; The raw material powder of the lining is prepared and sent into a supersonic flame spraying system, and the first coating is sprayed on the inner wall of the outer jacket, and the coating is roughened by sandblasting and cleaned; The raw material powder of the lining is prepared and fed into a plasma spraying system, and sprayed on the surface of the first coating to obtain a second coating; Polishing is performed to obtain the inner lining.

10. The spray-coated cylinder liner for a drilling mud pump according to claim 9, characterized in that: The thickness of the first coating is 200-300um, the thickness of the second coating is 100-200um, and the thickness of the lining is 300-500um.

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