Hydrogen engine powder metallurgy valve seat ring and preparation method thereof

Abstract

The invention discloses a hydrogen engine powder metallurgy valve seat ring and a preparation method thereof, and belongs to the technical field of powder metallurgy manufacturing, the valve seat ring is composed of a Fe-based alloy matrix and a working face magnetron sputtering plating layer, and the valve seat ring is prepared from, by mass, 0.6%-1.2% of C, 4.0%-7.0% of Cr, 0.8%-1.2% of Ti, 0.8%-1.2% of Nb, 2.5%-5.8% of V, 2.0%-4.0% of W, 3.5%-7.0% of Mo, 2.0%-2.5% of Co, 1.5%-2.0% of Mn, 1.0%-2.0% of Al and the balance Fe. 1.0%-1.5% of a solid lubricant and the balance of Fe, and the particle size is 100-120 meshes. The hydrogen engine powder metallurgy valve seat ring has the advantages that the hydrogen engine powder metallurgy valve seat ring is prepared through the warm pressing-die wall lubrication technology and the like, has excellent hardness and strength, high compactness, corrosion resistance, high abrasion resistance, high-temperature performance, hydrogen embrittlement resistance and hydrogen corrosion resistance and is suitable for hydrogen engines of automobiles, ships, military heavy equipment and the like.

Description

Technical Field

[0001] The invention belongs to the field of powder metallurgy manufacturing of key parts of gas fuel engines, and in particular relates to a powder metallurgy valve seat ring of a hydrogen engine and a preparation method thereof. Background Art

[0002] Hydrogen has the characteristics of abundant sources, high calorific value, fast flame propagation speed, wide ignition limit, small ignition energy, and strong diffusion ability. When hydrogen burns in the air, it only produces water and a very small amount of nitrogen monoxide, which has a good environmentally friendly effect. Hydrogen can also be mixed with natural gas, gasoline, and diesel fuels to improve the power loss caused by low energy density or lean combustion and improve fuel economy. In summary, from the perspective of economy, power, and emission performance, hydrogen is an ideal engine fuel. At present, hydrogen is considered to be the most promising alternative fuel for automobile engines. As a clean energy, it has been gradually applied to the engines of automobiles, ships, and military heavy equipment, with obvious energy-saving and environmental protection effects.

[0003] For hydrogen engines, the water produced by hydrogen combustion will dilute the lubricating oil along with the blowby gas, thereby increasing the water content of the lubricating oil, aggravating the rust and wear of the engine friction pair, and reducing the reliability of the engine. At the same time, in a high temperature environment, the engine parts will be damaged by hydrogen embrittlement and hydrogen corrosion due to the infiltration of hydrogen, which significantly reduces the mechanical properties and service life of metal parts.

[0004] The valve seat and valve are one of the important friction pairs of the engine. The function of the valve seat is to control the entry of fuel gas and the discharge of exhaust gas. The valve seat and valve cooperate to seal the combustion chamber to reduce the wear of the valve, and withstand the impact and wear of the valve in the high temperature environment; as well as the erosion and oxidation of the intake and exhaust flow. That is, when serving at high temperatures, it not only has to withstand high temperature and high stress impact, but also has to be corroded by exhaust gas, which is very easy to cause wear, deformation, burning, and even fracture failure. The valve seat is one of the vulnerable parts of the engine. When it is severely worn, it will cause the valve to sink too much and the airtightness is poor, which will cause failure and damage. The quality, performance and reliability of the valve seat directly affect the fuel consumption, power, efficiency and service life of the engine.

[0005] The main performance requirements of existing valve seat inserts are high strength, wear resistance, corrosion resistance, high temperature resistance, etc., in order to ensure the normal operation of gasoline engines, diesel engines, natural gas engines and alcohol fuel engines. However, there is currently a lack of valve seat insert materials and preparation technologies that meet the basic performance requirements of valve seat inserts and are resistant to hydrogen embrittlement and hydrogen corrosion for hydrogen engines. Summary of the invention

[0006] In view of the shortcomings of the performance of valve seat rings in existing traditional fuel engines and the requirements of the harsh working environment of valve seat rings in hydrogen fuel engines, the present invention aims to provide an Fe-based powder metallurgy valve seat ring that is resistant to high temperature, wear, hydrogen embrittlement and hydrogen corrosion, and contains alloy elements such as Ti, Co, V, Mo, W, Nb, Mn, Al and Cr, which is suitable for engines of hydrogen fuel vehicles, ships and military heavy equipment.

[0007] The main technical contribution of the present invention is the design of alloy powder materials used for valve seat rings of hydrogen engines and valve seat ring preparation technology adapted thereto, which solves the problems of wear and corrosion of valves and seat rings, hydrogen embrittlement and hydrogen corrosion caused by high speed, high temperature and repeated impact in a hydrogen environment, thereby extending the service life of the valve seat rings.

[0008] The technical solution of the present invention is as follows: a powder metallurgy valve seat ring for a hydrogen engine, which is composed of a Fe-based alloy substrate and a working surface magnetron sputtering coating, and the valve seat ring is composed of by mass fraction.

[0009] C: 0.6-1.2%, Cr: 4.0%-7.0%, Ti: 0.8%-1.2%, Nb: 0.8%-1.2%, V: 2.5%-5.8%, W: 2.0%-4.0%, Mo: 3.5%-7.0%, Co: 2.0%-2.5%, Mn: 1.5%-2.0%, Al: 1.0%-2.0%, solid lubricant 1.0%-1.5%, balance Fe, particle size is 100 mesh-120 mesh;

[0010] The magnetron sputtering coating includes a Ni transition layer with a thickness of 0.1 μm-0.4 μm and a functional Cr / Ni coating with a thickness of 1.0 μm-1.5 μm.

[0011] Preferably, the solid lubricant is one or both of MnS and MoS2.

[0012] A preparation method of a hydrogen engine powder metallurgy valve seat ring, a manufacturing process flow of a hydrogen engine powder metallurgy valve seat ring: batching → powder mixing → mold wall lubrication → warm pressing → sintering → heat treatment → finishing → magnetron sputtering transition layer + functional coating → inspection → packaging;

[0013] S1. Mixing ingredients: mixing different metal alloy powders in proportion to form alloy powder, the powder particle size is 100-120 mesh, and adding one or two of solid lubricants MnS and MoS2;

[0014] S2. Mixing powder: dry mixing for 30-80 minutes on a two-dimensional mixer, adding 0.15% by mass of a mold wall lubricant, and lubricating the mold wall in the female mold cavity of the valve seat;

[0015] S3, warm pressing: during powder pressing, the negative template is floated twice, double-layer filler is used, the temperature is 140℃, and the pressure is 500MPa~900MPa;

[0016] S4, sintering: the formed valve seat ring green body is placed in a push rod furnace, and pre-sintered at 650℃~800℃×1.0~2.0h in N2 protective atmosphere, and then sintered at 1000℃~1150℃×1.5~2.5h. After sintering and natural cooling, the desired sintered product is obtained;

[0017] S5. Heat treatment: heat treatment is carried out in a box furnace, the quenching process is 860℃~880℃×0.5~1.0h; the tempering temperature is 220℃~250℃×1.0h;

[0018] S6, finishing: the valve seat is finished by CNC machine tools;

[0019] S7, transition layer: magnetron sputtering with Ar as protective gas, Ni as target, the distance between target and valve seat insert substrate is 70mm-90mm, deposition pressure is 0.1Pa-1.0Pa, target bias voltage is 200V-1000V, target current density is 5mA / cm 2 -10mA / cm 2 , power density is 3W / cm 2 -30W / cm 2 , the deposition rate is 200nm / min~400nm / min, the temperature is 180℃, and the thickness of the Ni transition layer is 0.1μm-0.4μm;

[0020] S8, functional coating: magnetron sputtering with Ar as protective gas, target material is Cr / Ni, the distance between target material and valve seat insert substrate is 70mm-90mm, deposition pressure is 0.1Pa-1.0Pa, target bias voltage is 200-1000V, target current density is 6mA / cm 2 -10mA / cm 2 , power density is 3W / cm 2 -30W / cm 2 , the deposition rate is 300nm / min~600nm / min, the temperature is 200℃, and the thickness of the Cr / Ni functional coating is 1.0μm-1.5μm;

[0021] S9, Inspection and Packaging: After the finished products are inspected and qualified, they are packaged and put into storage.

[0022] Preferably, the lubricant is Zn[CH3(CH2) 16 COO]2.

[0023] Preferably, the valve seat ring density is 7.3 g / cm 3 ~7.4g / cm 3 , tensile strength is 720MPa~740MPa, impact toughness is 9.5J / cm 2 ~10.5J / cm 2， The hardness after heat treatment is 40HRC~50HRC.

[0024] Preferably, the crushing strength is 1150MPa-1280MPa, and in the wear-resistant bench test at 900°C, the rotation speed r=2000r / min, the valve sinking amount after 1000 hours is 100μm-150μm, and the interference is 80μm-100μm.

[0025] Preferably, after the transition layer and the functional coating are prepared by magnetron sputtering, the amount of hydrogen absorbed is 0.02 mg / L to 0.05 mg / L.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The hydrogen engine valve seat ring alloy powder of the present invention contains elements such as C, Ti, Co, Ni, Cr, Mo, W, etc., and has high strength, hardness, toughness, wear resistance, good high temperature performance and corrosion resistance;

[0028] Co can improve high-temperature strength, thermal fatigue resistance, high-temperature sulfur corrosion resistance and oxidation resistance, increase the nucleation rate of carbides such as M2C, reduce their growth rate, and allow carbides to precipitate in a fine and dispersed state, and can stably exist at high temperatures, playing a strengthening role; Co can also improve the high-temperature sulfur corrosion resistance of the valve seat ring, improve the morphology and distribution of second phases such as Cr, W, and Mo, and improve wear resistance; Ni not only has excellent high-temperature resistance, corrosion resistance, and oxidation resistance, but also can work together with elements such as Cr to further improve the high-temperature performance and corrosion resistance of the alloy.

[0029] The hydrogen engine valve seat ring of the present invention contains alloy elements such as Nb, V, Co, W, Mo, Cr, etc., which can be micro-alloyed with Fe-based alloys, which is conducive to forming a multi-element alloy matrix and fine and dispersed metal compounds, and produces comprehensive strengthening effects such as solid solution strengthening, fine grain strengthening and dispersion strengthening, which can meet the service conditions under high temperature and hydrogen fuel conditions and ensure the normal operation of the hydrogen engine; at high temperature, in addition to forming a solid solution with Fe, the above alloy elements can also form fine and round high-melting point carbides such as NbC, TiC, VC, WC, MoC, Cr7C3, etc. These carbides are very stable at the sintering temperature (1100°C to 1200°C) of the Fe-based alloy powder, and are dispersedly distributed in the crystal and on the grain boundary, which inhibits the growth of grains and hinders the movement of dislocations. The solid solution strengthening, fine grain strengthening and dispersion strengthening effects are very significant, and the high-temperature strength and wear resistance of the valve seat ring are greatly improved.

[0030] Elements such as Ti, Mo, Al, Cr, V, and W can not only reduce hydrogen diffusivity and solubility, reduce hydrogen permeation, and prevent hydrogen embrittlement, but also inhibit the generation of CH4 and prevent hydrogen corrosion, greatly improving the service performance of hydrogen engine valve seat rings and extending their service life.

[0031] 2. Using warm pressing + die wall lubrication technology, the density of sintered powder metallurgy valve seat ring reaches

[0032] 7.3g / cm 3 ~7.4g / cm 3 , ensuring the valve seat has high strength, hardness and wear resistance;

[0033] 3. The warm pressing-die wall lubrication iron-based powder metallurgy valve seat ring provided by the present invention has a tensile strength of 720MPa-740MPa, an impact toughness of 9.5J / cm2-10.5J / cm2, and a hardness of 40HRC-50HRC;

[0034] 4. The crushing strength after heat treatment is 1150MPa~1280MPa. After 1000 hours of wear-resistant bench test at 900℃ (speed r=2000r / min), the valve sinking amount is 100μm-150μm and the interference is 80μm-100μm;

[0035] 5. The hydrogen absorption of the transition Ni layer and the functional Cr / Ni coating prepared by the magnetron sputtering technology of the hydrogen engine valve seat ring of the present invention is 0.02mg / L-0.05mg / L, which can further improve the hardness, strength, wear resistance, resistance to hydrogen embrittlement and hydrogen corrosion of the working surface of the valve seat ring;

[0036] The hydrogen engine powder metallurgy valve seat ring prepared by the present invention has excellent compactness, corrosion resistance, high wear resistance, high temperature performance, resistance to hydrogen embrittlement and hydrogen corrosion, and can be used in hydrogen engines such as automobiles, ships and military heavy equipment. Including but not limited to natural gas (CNG, LNG), LPG gas, oil and gas hybrid, fuel engine valve seat ring working conditions under high temperature, dry friction, impact, gas corrosion and other service conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0038] Figure 1 This is the metallographic structure diagram of the sintered valve seat ring of the present invention;

[0039] Figure 2 This is the metallographic structure diagram of the valve seat ring in the quenched and tempered state of the present invention.

[0040] Figure 1 The microstructure is mainly composed of pearlite, a small amount of martensite and carbide; Figure 2 The microstructure after heat treatment is tempered troostite, pearlite and dispersed carbide particles. This composite strengthening structure not only meets the strength, hardness and density requirements of the valve seat ring, but also has certain plasticity, impact toughness, high temperature performance, corrosion resistance, hydrogen embrittlement resistance and hydrogen corrosion resistance, and has excellent comprehensive performance. DETAILED DESCRIPTION

[0041] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0042] Embodiment 1:

[0043] The chemical composition (mass fraction, %) of a hydrogen engine powder metallurgy valve seat ring is as follows: C: 1.0%, Cr: 5.0%, Ti: 1.0%, Nb: 1.2%, V: 5.5%, W: 4.0%, Mo: 7.0%, Co: 2.0%, Mn: 1.5%, Al: 1.5%, solid lubricant 1.2%, balance Fe, particle size is 110 mesh. The high temperature resistant, wear resistant, hydrogen embrittlement resistant and hydrogen corrosion resistant magnetron sputtering coating includes a Ni transition layer and a functional Cr / Ni coating. The solid lubricant is MnS.

[0044] The powder metallurgy valve seat ring for hydrogen engine is prepared according to the process flow of batching → powder mixing → mold wall lubrication → warm pressing → sintering → heat treatment → finishing → magnetron sputtering transition layer + functional coating → inspection → packaging.

[0045] Different metal alloy powders were mixed in the above proportions to form alloy powder, the powder particle size was 110 mesh, and 1.2% of solid lubricant MnS was added, and dry-mixed for 60 minutes on a two-dimensional mixer.

[0046] Add 0.15% by mass of die wall lubricant Zn[CH3(CH2) 16 COO]2. Lubricate the mold wall in the female mold cavity of the valve seat.

[0047] During the powder molding and pressing, the negative template is floated twice and double-layer filler is used, and the temperature is 140°C and the pressure is 900MPa.

[0048] The formed valve seat green body is placed in a push rod furnace and manufactured by pre-sintering + sintering method under N2 protective atmosphere. Pre-sintering is first performed at 750℃×1.5h, and then sintering is performed at 1150℃×2.5h. After sintering and natural cooling, the desired sintered product is obtained.

[0049] Heat treatment is carried out in a box furnace, and the quenching process is at a temperature of 870°C×0.5~1.0h; the tempering temperature is 220°C×1.0h.

[0050] The valve seat is finely processed by a CNC machine tool.

[0051] The magnetron sputtering uses Ar as the protective gas, Ni as the target material, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.45 Pa, the target bias voltage is 400 V, and the target current density is 7 mA / cm 2 , power density is 10W / cm 2 , the deposition rate is 300nm / min, the temperature is 180℃, and the thickness of the Ni transition layer is 0.4μm.

[0052] The magnetron sputtering uses Ar as the protective gas, the target material is Cr / Ni, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.1 Pa, the target bias voltage is 8000 V, and the target current density is 80 mA / cm 2 , power density is 20W / cm 2 , the deposition rate is 500nm / min, the temperature is 200℃, and the thickness of the Cr / Ni functional coating is 1.5μm.

[0053] Inspection and packaging: After the finished products are inspected and qualified, they are packaged and put into storage.

[0054] After testing, its density is 7.4g / cm 3 , tensile strength is 740MPa, impact toughness is 10.2J / cm 2， The hardness is 47HRC and the crushing strength is 1280MPa. At 900℃, after 1000 hours of engine bench test, the sinking amount is 100μm and the interference is 85μm. The hydrogen absorption amount is 0.02mg / L.

[0055] Embodiment 2:

[0056] The chemical composition (mass fraction, %) of a hydrogen engine powder metallurgy valve seat ring is as follows: C: 1.0%, Cr: 5.5%, Ti: 1.0%, Nb: 1.0%, V: 5.0%, W: 3.5%, Mo: 7.0%, Co: 2.0%, Mn: 1.5%, Al: 1.5%, solid lubricant 1.5%, balance Fe, particle size is 110 mesh. The high temperature resistant, wear resistant, hydrogen embrittlement resistant and hydrogen corrosion resistant magnetron sputtering coating includes a Ni transition layer and a functional Cr / Ni coating. The solid lubricant is MoS2.

[0057] The powder metallurgy valve seat ring for hydrogen engine is prepared according to the process flow of batching → powder mixing → mold wall lubrication → warm pressing → sintering → heat treatment → finishing → magnetron sputtering transition layer + functional coating → inspection → packaging.

[0058] Different metal alloy powders are mixed in a certain proportion to form alloy powder with a powder particle size of 110 meshes, and 1.4% of solid lubricant MoS2 is added, and dry mixing is carried out on a two-dimensional mixer for 60 minutes.

[0059] Add 0.15% by mass of die wall lubricant Zn[CH3(CH2) 16 COO]2, lubricate the mold wall in the female mold cavity of the valve seat.

[0060] During the powder molding and pressing, the negative template is floated twice and double-layer filler is used, and the temperature is 140°C and the pressure is 900MPa.

[0061] The formed valve seat green body is placed in a push rod furnace and manufactured by pre-sintering + sintering method under N2 protective atmosphere. Pre-sintering is first performed at 750℃×1.5h, and then sintering is performed at 1150℃×2.5h. After sintering and natural cooling, the desired sintered product is obtained.

[0062] Heat treatment is carried out in a box furnace, and the quenching process is at a temperature of 870°C×0.5~1.0h; the tempering temperature is 220°C×1.0h.

[0063] The valve seat is finely processed by a CNC machine tool.

[0064] The magnetron sputtering uses Ar as the protective gas, Ni as the target material, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.45 Pa, the target bias voltage is 400 V, and the target current density is 7 mA / cm 2 , power density is 10W / cm 2 , the deposition rate is 300nm / min, the temperature is 180℃, and the thickness of the Ni transition layer is 0.25μm.

[0065] The magnetron sputtering uses Ar as the protective gas, the target material is Cr / Ni, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.1 Pa, the target bias voltage is 8000 V, and the target current density is 80 mA / cm 2 , power density is 20W / cm 2 , the deposition rate is 500nm / min, the temperature is 200℃, and the thickness of the Cr / Ni functional coating is 1.4μm.

[0066] Inspection and packaging: After the finished products are inspected and qualified, they are packaged and put into storage.

[0067] After testing, its density is 7.3g / cm 3 , tensile strength is 735MPa, impact toughness is 10.0J / cm 2， The hardness is 46HRC and the crushing strength is 1200MPa. At 900℃, after 1000 hours of engine bench test, the sinking amount is 120μm and the interference is 90μm. The hydrogen absorption amount is 0.04mg / L.

[0068] Example 3

[0069] The chemical composition (mass fraction, %) of a powder metallurgy valve seat ring for a hydrogen engine is as follows: C: 1.2%, Cr: 6.0%, Ti: 1.2%, Nb: 1.2%, V: 5.0%, W: 3.5%, Mo: 7.0%, Co: 2.5%, Mn: 2.0%, Al: 1.5%, solid lubricant 1.5%, balance Fe, particle size 70-90 mesh. The high temperature resistant, wear resistant, hydrogen embrittlement resistant and hydrogen corrosion resistant magnetron sputtering coating includes a Ni transition layer and a functional Cr / Ni coating. Solid lubricant

[0070] 0.80%MnS+0.70%MoS2.

[0071] The powder metallurgy valve seat ring for hydrogen engine is prepared according to the process flow of batching → powder mixing → mold wall lubrication → warm pressing → sintering → heat treatment → finishing → magnetron sputtering transition layer + functional coating → inspection → packaging.

[0072] Different metal alloy powders are mixed in a certain proportion to form alloy powder with a powder particle size of 110 mesh, and 1.5% solid lubricant (0.80% MnS+0.70% MoS2) is added, and dry-mixed on a two-dimensional mixer for 60 minutes.

[0073] Add 0.15% by mass of die wall lubricant Zn[CH3(CH2) 16 COO]2, lubricate the mold wall in the female mold cavity of the valve seat.

[0074] During the powder molding and pressing, the negative template is floated twice and double-layer filler is used, and the temperature is 140°C and the pressure is 900MPa.

[0075] The formed valve seat green body is placed in a push rod furnace and manufactured by pre-sintering + sintering method under N2 protective atmosphere. Pre-sintering is first performed at 750℃×1.5h, and then sintering is performed at 1150℃×2.5h. After sintering and natural cooling, the desired sintered product is obtained.

[0076] Heat treatment is carried out in a box furnace, and the quenching process is at a temperature of 870°C×0.5~1.0h; the tempering temperature is 220°C×1.0h.

[0077] The valve seat is finely processed by a CNC machine tool.

[0078] The magnetron sputtering uses Ar as the protective gas, Ni as the target material, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.45 Pa, the target bias voltage is 400 V, and the target current density is 7 mA / cm 2 , power density is 10W / cm 2 , the deposition rate is 300nm / min, the temperature is 180℃, and the thickness of the Ni transition layer is 0.15μm.

[0079] The magnetron sputtering uses Ar as the protective gas, the target material is Cr / Ni, the distance between the target material and the valve seat insert substrate is 80 mm, the deposition pressure is 0.1 Pa, the target bias voltage is 8000 V, and the target current density is 80 mA / cm 2 , power density is 20W / cm 2 , the deposition rate is 500nm / min, the temperature is 200℃, and the thickness of the Cr / Ni functional coating is 1.2μm.

[0080] Inspection and packaging: After the finished products are inspected and qualified, they are packaged and put into storage.

[0081] After testing, its density is 7.3g / cm 3 , tensile strength is 725MPa, impact toughness is 9.7J / cm 2，The hardness is 44HRC and the crushing strength is 1250MPa. At 900℃, after 1000 hours of engine bench test, the sinking amount is 120μm and the interference is 85μm. The hydrogen absorption amount is 0.05mg / L.

[0082] Comparative Example 1:

[0083] The difference between Comparative Example 1 and Example 1 is that except that the Ni transition layer and Cr / Ni functional coating are not deposited on the working surface of the valve seat insert by magnetron sputtering, all other factors such as the chemical composition of the valve seat insert, the process flow, steps and technical parameters are the same as those of Example 1.

[0084] Comparative Example 2:

[0085] The difference between Comparative Example 2 and Example 2 is that except that the Ni transition layer and Cr / Ni functional coating are not deposited on the working surface of the valve seat insert by magnetron sputtering, all other factors such as the chemical composition of the valve seat insert, the process flow, steps and technical parameters are the same as those of Example 2.

[0086] Comparative Example 3:

[0087] The difference between Comparative Example 3 and Example 3 is that except that the Ni transition layer and Cr / Ni functional coating are not deposited on the working surface of the valve seat insert by magnetron sputtering, all other factors such as the chemical composition of the valve seat insert, the process flow, steps and technical parameters are the same as those of Example 3.

[0088] Hydrogen embrittlement and hydrogen corrosion of valve seat inserts are caused by hydrogen infiltration, so testing the amount of hydrogen absorbed by the valve seat inserts is an important criterion for determining whether the valve seat inserts of hydrogen engines can work normally.

[0089] By comparing the discharge method, capacity method and weight method, it is found that the capacity method is more accurate, quick and economical to test the hydrogen absorption.

[0090] The patent of the present invention uses a volumetric method to test the hydrogen absorption of the valve seat ring embodiment and the comparative example (Table 1). The results show that the hydrogen absorption of the valve seat ring prepared by the complete process of the present invention is close to 0, which can effectively inhibit the occurrence of hydrogen embrittlement and resist hydrogen corrosion.

[0091]

[0092]

[0093] Table 1 Performance of valve seat inserts of the embodiments and comparative examples.

[0094] The technical scope of the present invention is not limited to the contents in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A powder metallurgy valve seat ring for a hydrogen engine, characterized in that: The valve seat insert is composed of a Fe-based alloy substrate and a working surface magnetron sputtering coating. The valve seat insert is composed of the following by mass fraction: C: 0.6-1.2%, Cr: 4.0%-7.0%, Ti: 0.8%-1.2%, Nb: 0.8%-1.2%, V: 2.5%-5.8%, W: 2.0%-4.0%, Mo: 3.5%-7.0%, Co: 2.0%-2.5%, Mn: 1.5%-2.0%, Al: 1.0%-2.0%, solid lubricant 1.0%-1.5%, balance Fe, particle size is 100 mesh-120 mesh; The magnetron sputtering coating includes a Ni transition layer with a thickness of 0.1 μm-0.4 μm and a functional Cr / Ni coating with a thickness of 1.0 μm-1.5 μm.

2. A powder metallurgy valve seat ring for a hydrogen engine according to claim 1, characterized in that: The solid lubricant is one or two of MnS and MoS2.

3. A method for preparing a powder metallurgy valve seat insert for a hydrogen engine, which uses a powder metallurgy valve seat insert for a hydrogen engine as described in claim 2, characterized in that: Manufacturing process of powder metallurgy valve seat ring for hydrogen engine: batching → powder mixing → mold wall lubrication → warm pressing → sintering → heat treatment → finishing → magnetron sputtering transition layer + functional coating → inspection → packaging; S1. Mixing different metal alloy powders according to proportion to form alloy powder, the powder particle size is 100-120 mesh, and one or two of solid lubricants MnS and MoS2 are added; S2. Mixing powder: dry mixing for 30-80 minutes on a two-dimensional mixer, adding 0.15% by mass of a mold wall lubricant, and lubricating the mold wall in the female mold cavity of the valve seat; S3, warm pressing: during powder pressing, the negative template is floated twice, double-layer filler is used, the temperature is 140℃, and the pressure is 500MPa~900MPa; S4, sintering: the formed valve seat ring green body is placed in a push rod furnace, and pre-sintered at 650℃~800℃×1.0~2.0h in N2 protective atmosphere, and then sintered at 1000℃~1150℃×1.5~2.5h. After sintering and natural cooling, the desired sintered product is obtained; S5. Heat treatment: heat treatment is carried out in a box furnace, the quenching process is 860℃~880℃×0.5~1.0h; the tempering temperature is 220℃~250℃×1.0h; S6, finishing: the valve seat is finished by CNC machine tools; S7, transition layer: magnetron sputtering with Ar as protective gas, Ni as target, the distance between target and valve seat insert substrate is 70mm-90mm, deposition pressure is 0.1Pa-1.0Pa, target bias voltage is 200V-1000V, target current density is 5mA / cm 2 -10mA / cm 2 , power density is 3W / cm 2 -30W / cm 2 , the deposition rate is 200nm / min~400nm / min, the temperature is 180℃, and the thickness of the Ni transition layer is 0.1μm-0.4μm; S8, functional coating: magnetron sputtering with Ar as protective gas, target material is Cr / Ni, the distance between target material and valve seat insert substrate is 70mm-90mm, deposition pressure is 0.1Pa-1.0Pa, target bias voltage is 200-1000V, target current density is 6mA / cm 2 -10mA / cm 2 , power density is 3W / cm 2 -30W / cm 2 , the deposition rate is 300nm / min~600nm / min, the temperature is 200℃, and the thickness of the Cr / Ni functional coating is 1.0μm-1.5μm; S9, Inspection and Packaging: After the finished products are inspected and qualified, they are packaged and put into storage.

4. The method for preparing a powder metallurgy valve seat ring for a hydrogen engine according to claim 3, characterized in that: The lubricant is Zn[CH3(CH2) 16 COO]2.

5. The method for preparing a powder metallurgy valve seat ring for a hydrogen engine according to claim 4, characterized in that: The valve seat ring density is 7.3g / cm 3 ~7.4g / cm 3 , tensile strength is 720MPa~740MPa, impact toughness is 9.5J / cm 2 ~10.5J / cm 2， The hardness after heat treatment is 40HRC~50HRC.

6. The method for preparing a powder metallurgy valve seat ring for a hydrogen engine according to claim 5, characterized in that: The crushing strength is 1150MPa~1280MPa, the wear-resistant bench test is carried out at 900℃, the rotation speed is r=2000r / min, and the valve sinking amount is 100μm-150μm and the interference is 80μm-100μm after 1000 hours.

7. The method for preparing a powder metallurgy valve seat ring for a hydrogen engine according to claim 5, characterized in that: After the transition layer and the functional coating are prepared by magnetron sputtering, the hydrogen absorption amount is 0.02mg / L to 0.05mg / L.

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