Preparation method of in-situ reinforced 420 stainless steel feed

Abstract

The invention discloses a preparation method of an in-situ reinforced 420 stainless steel feed, which comprises the following steps: S1, stirring and dissolving a silane coupling agent in absolute ethyl alcohol to obtain A1; s2, adding polycarbosilane, copper nitrate or copper acetate into the A1, and then stirring and dissolving to obtain A2; s3, stirring and mixing A2 and a high-molecular binder to obtain A3; and S4, the A3 and water vapor combined atomized 420 stainless steel powder are subjected to internal mixing, crushing and granulation, and the in-situ reinforced 420 stainless steel feed is obtained. The added silane can enable polycarbosilane, copper nitrate or copper acetate to be uniformly combined with the high-molecular binder, and then the polycarbosilane, the copper nitrate or the copper acetate and the high-molecular binder are uniformly mixed with the water-gas combined atomized 420 stainless steel powder. When the in-situ reinforced 420 stainless steel cutting tool is prepared in the next step, the polycarbosilane is thermally decomposed into silicon carbide particles, and the silicon carbide particles can be uniformly dispersed in the 420 stainless steel product, so that the maximum reinforcing effect is achieved; meanwhile, copper nitrate and copper acetate are thermally decomposed into copper particles which can be well dispersed in the 420 stainless steel product, and the maximum antibacterial effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of strengthened stainless steel, and in particular to a method for preparing in-situ strengthened 420 stainless steel feedstock. Background Art

[0002] 420 stainless steel is a martensitic stainless steel. Unlike austenitic and ferritic stainless steels, it can obtain higher strength and hardness through heat treatment. Therefore, it can be widely used in industrial fields that require hardness, wear resistance and a certain degree of corrosion resistance, such as knives.

[0003] The use of traditional methods such as casting and machining to prepare complex-shaped 420 stainless steel parts has the problems of complex process, high cost and low production efficiency. Metal powder injection molding (MIM) is a technology that combines powder metallurgy and plastic injection molding. It is suitable for the production of complex-shaped products with high product precision and high production efficiency. The use of MIM technology to prepare complex-shaped 420 stainless steel products can give full play to the advantages of this process in industrial mass production, thereby promoting the application of MIM technology and 420 stainless steel.

[0004] It is difficult to evenly add additives such as silicon carbide and copper to stainless steel metal powders using traditional MIM processes. Due to the large size of the added particles, most of the particles obtained are large particles in the micron range. In response to this problem, this patent proposes to use additive precursor in-situ decomposition generation technology to improve the performance of stainless steel products. Under certain conditions, the smaller the particles, the less additives can be used to achieve the same uniform distribution. By taking advantage of powder metallurgy, the problem of uneven distribution of additives can also be solved.

[0005] The molecular weight of polycarbosilane is 1000-2000. Under the protection of inert gas, it begins to decompose above 400°C and cracks to form silicon carbide above 1000°C. Silicon carbide powder is prepared by thermal decomposition of polycarbosilane, a silicon carbide precursor, and copper powder is prepared by thermal decomposition of copper nitrate and copper acetate precursors, which have high dispersibility. The silicon carbide powder prepared by this method improves the strength, hardness and wear resistance of MIM products. The copper powder prepared by thermal decomposition of the precursor can be well dispersed in MIM products to achieve the maximum antibacterial effect. Summary of the invention

[0006] The present invention provides a method for preparing an in-situ strengthened 420 stainless steel feedstock. The prepared in-situ strengthened 420 stainless steel feedstock has the advantages of uniform distribution and fine particles, and can be well dispersed in stainless steel products to achieve the maximum enhanced antibacterial effect. To achieve the above purpose, the present invention adopts the following technical scheme:

[0007] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the polymer binder comprises the following components in percentage by mass:

[0008] Polyoxymethylene 78-86%;

[0009] High-density polyethylene 3-9%;

[0010] Ethylene-vinyl acetate copolymer 2-7%;

[0011] Solid paraffin 1.8-4%;

[0012] Surfactant 0.7~2.6%;

[0013] Microcrystalline wax 1-2.5%;

[0014] Polyvinyl alcohol 1-3%;

[0015] Antioxidant 0.2~0.5%.

[0016] Polyoxymethylene has good fluidity and high green strength after injection, and is not easy to deform. It can be quickly catalytically decomposed into formaldehyde in an acidic atmosphere, thereby achieving rapid degreasing and high production efficiency. The chemical stability of high-density polyethylene and ethylene-vinyl acetate copolymer can ensure that the degreased blank has sufficient strength during catalytic degreasing and does not deform. Paraffin wax fills the gaps between powders to reduce viscosity and improve feed fluidity. Microcrystalline wax can effectively reduce the viscosity of the binder and act as a lubricant. Polyethylene glycol improves the compatibility of the polymer binder components, reduces the separation of the two phases, and also acts as a lubricant.

[0017] A method for preparing an in-situ strengthened 420 stainless steel feedstock, characterized in that the in-situ strengthened 420 stainless steel feedstock comprises the following components in percentage by mass:

[0018] Water-gas combined atomization 420 stainless steel powder 82.5-92%;

[0019] Copper nitrate or copper acetate powder or more 0.2% to 4%;

[0020] Polycarbosilane 0.05% to 4%;

[0021] Ethanol 4-10%;

[0022] Silane coupling agent 0.5~3%.

[0023] A method for preparing in-situ strengthened 420 stainless steel feed material, characterized in that it comprises the following steps:

[0024] S1 and a silane coupling agent are stirred and dissolved in anhydrous ethanol to obtain A1;

[0025] Add polycarbosilane, copper nitrate or copper acetate to S2 and A1, and then stir and dissolve to obtain A2;

[0026] S3, A2 and a polymer binder are stirred and mixed to obtain A3;

[0027] S4, A3 and water vapor are combined to atomize 420 stainless steel powder for internal mixing, crushing and granulation to obtain in-situ strengthened 420 stainless steel feed.

[0028] A method for preparing an in-situ strengthened 420 stainless steel feedstock, characterized in that, in step S4, the A3 and the water vapor co-atomized 420 stainless steel powder are mixed in a mixer, and the mixing process parameters are:

[0029] The rotor speed is 30-40 rpm;

[0030] The mixing temperature is 180-190°C;

[0031] Refining for 60 to 90 minutes.

[0032] According to the method for preparing an in-situ strengthened 420 stainless steel feed, an in-situ strengthened 420 stainless steel cutting tool is prepared, which is characterized by comprising the following steps:

[0033] B1. Injection: the in-situ strengthened 420 stainless steel feed is added into an injection machine, and the injection machine injects the in-situ strengthened 420 stainless steel feed into the cavity of a cutting tool mold, and demolds to obtain a cutting tool injection green body, the injection temperature is 190° C., and the mold temperature is 95° C.;

[0034] B2, degreasing: the injection green body is subjected to oxalic acid catalytic degreasing treatment to form a degreasing body, the degreasing environment temperature is controlled to be 135°C, the acid passing time is 8h, and the acid feeding speed is: 9g / min;

[0035] B3, sintering: sintering the degreased blank to form a sintered blank; the sintering temperature is 1320°C, the holding time is 8h, the sintering atmosphere is N2, the partial pressure is 10kPa, and the blank is cooled with the furnace;

[0036] B4. Heat treatment: heat treatment of the sintered blank; 1000°C for 30 min, quenching with 10% salt water, and then tempering at 200°C;

[0037] B5. Sharpening: sharpening the sintered blank after heat treatment to obtain a reinforced antibacterial stainless steel cutting tool.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The in-situ strengthened 420 stainless steel cutting tool is prepared by metal injection molding, which is easy to achieve the dispersion and uniform distribution of hardening and antibacterial elements, and is more conducive to the full play of hardening and antibacterial effects;

[0040] 2. The feed material is degreased by oxalic acid catalysis, and the degreased ash billet has good shape retention.

[0041] 3. The in-situ strengthened 420 stainless steel cutting tool has high dimensional accuracy and excellent mechanical properties. It can be mass-produced with little or no subsequent machining and low cost. DETAILED DESCRIPTION

[0042] Example 1

[0043] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the polymer binder comprises the following components in parts by weight:

[0044] Polyoxymethylene 78%;

[0045] High-density polyethylene 9%;

[0046] Ethylene-vinyl acetate copolymer 5%;

[0047] Solid paraffin 2%;

[0048] Stearic acid 1.5%;

[0049] Microcrystalline wax 1%;

[0050] Polyvinyl alcohol 3%;

[0051] Antioxidant AO-3 0.5%.

[0052] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the in-situ strengthened 420 stainless steel feedstock comprises the following components in percentage by mass:

[0053] 420 stainless steel powder 85.5%;

[0054] Polycarbosilane 2%;

[0055] Copper nitrate 4%;

[0056] Ethanol 6%;

[0057] Silane coupling agent A-151 2.5%.

[0058] A method for preparing an in-situ strengthened 420 stainless steel feed material comprises the following steps:

[0059] S1 and silane coupling agent A-151 are stirred and dissolved in anhydrous ethanol to obtain A1;

[0060] Add copper nitrate and polycarbosilane to S2 and A1, and then stir and dissolve to obtain A2;

[0061] S3, A2 and a polymer binder are stirred and mixed to obtain A3;

[0062] S4, A3 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 30rpm, mixing temperature 190℃, mixing for 70min. Then stop heating, cool, crush and granulate to obtain feed material.

[0063] Example 2

[0064] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the polymer binder comprises the following components in parts by weight:

[0065] Polyoxymethylene 81%;

[0066] High-density polyethylene 6%;

[0067] Ethylene-vinyl acetate copolymer 7%;

[0068] Solid paraffin 1.8%;

[0069] Pentaerythritol stearate 1%;

[0070] Microcrystalline wax 2%;

[0071] Polyvinyl alcohol 1%;

[0072] Antioxidant AO-14 0.2%.

[0073] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the in-situ strengthened 420 stainless steel feedstock comprises the following components in percentage by mass:

[0074] 420 stainless steel powder 82.5%;

[0075] Polycarbosilane 4%;

[0076] Copper acetate 0.5%;

[0077] Ethanol 10%;

[0078] Silane coupling agent KH-550 3%.

[0079] A method for preparing an in-situ strengthened 420 stainless steel feed material comprises the following steps:

[0080] S1 and silane coupling agent KH-550 were stirred and dissolved in anhydrous ethanol to obtain A1;

[0081] Add polycarbosilane and copper acetate to S2 and A1, and then stir and dissolve to obtain A2;

[0082] S3, A2 and a polymer binder are stirred and mixed to obtain A3;

[0083] S4, A3 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed of 40rpm, mixing temperature of 190℃, mixing for 60min. Then stop heating, cool, crush and granulate to obtain feed material.

[0084] Example 3

[0085] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the polymer binder comprises the following components in parts by weight:

[0086] Polyoxymethylene 82%;

[0087] High-density polyethylene 4%;

[0088] Ethylene-vinyl acetate copolymer 3%;

[0089] Solid paraffin 4%;

[0090] Zinc stearate 2.6%;

[0091] Microcrystalline wax 1.5%;

[0092] Polyvinyl alcohol 2.5%;

[0093] Antioxidant AO-4 0.2%;

[0094] Antioxidant AO-430.2%.

[0095] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the in-situ strengthened 420 stainless steel feedstock comprises the following components in percentage by mass:

[0096] 420 stainless steel powder 92%;

[0097] Polycarbosilane 1%;

[0098] Copper nitrate 2%;

[0099] Ethanol 4%;

[0100] Silane coupling agent KH-564 1%.

[0101] A method for preparing an in-situ strengthened 420 stainless steel feed material comprises the following steps:

[0102] S1 and silane coupling agent KH-564 were stirred and dissolved in anhydrous ethanol to obtain A1;

[0103] Add polycarbosilane and copper nitrate to S2 and A1, and then stir and dissolve to obtain A2;

[0104] S3, A2 and a polymer binder are stirred and mixed to obtain A3;

[0105] S4, A3 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 30rpm, mixing temperature 180℃, mixing for 90min. Then stop heating, cool, crush and granulate to obtain feed material.

[0106] Example 4

[0107] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the polymer binder comprises the following components in parts by weight:

[0108] Polyoxymethylene 86%;

[0109] High-density polyethylene 3%;

[0110] Ethylene-vinyl acetate copolymer 2%;

[0111] Solid paraffin 3%;

[0112] Pentaerythritol stearate 1%;

[0113] Zinc stearate 0.7%;

[0114] Microcrystalline wax 2.5%;

[0115] Polyvinyl alcohol 1.5%;

[0116] Antioxidant AO-46 0.3%.

[0117] A method for preparing an in-situ strengthened 420 stainless steel feedstock, wherein the in-situ strengthened 420 stainless steel feedstock comprises the following components in percentage by mass:

[0118] 420 stainless steel powder 87%;

[0119] Polycarbosilane 3%;

[0120] Copper acetate 0.2%;

[0121] Copper nitrate 2.8%;

[0122] Ethanol 6%;

[0123] Silane coupling agent A-174 0.5%;

[0124] Silane coupling agent KH-560 0.5%.

[0125] A method for preparing an in-situ strengthened 420 stainless steel feed material comprises the following steps:

[0126] S1, silane coupling agent A-174 and KH-560 are stirred and dissolved in anhydrous ethanol to obtain A1;

[0127] Add polycarbosilane, copper acetate and copper nitrate to S2 and A1, and then stir and dissolve to obtain A2;

[0128] S3, A2 and a polymer binder are stirred and mixed to obtain A3;

[0129] S4, A3 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed of 40rpm, mixing temperature of 185℃, mixing for 80min. Then stop heating, cool, crush and granulate to obtain feed material.

[0130] Comparative Example 1

[0131] The polymer binder in this comparative example is the same as that in Example 1.

[0132] Compared with Example 1, the 420 stainless steel feedstock in this comparative example does not contain polycarbosilane and copper nitrate, and the proportions of other components remain unchanged.

[0133] A method for preparing 420 stainless steel feed material comprises the following steps:

[0134] S1 and silane coupling agent A-151 are stirred and dissolved in anhydrous ethanol to obtain A1;

[0135] S2, A1 and a polymer binder are stirred and mixed to obtain A2;

[0136] S3, A2 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 30rpm, mixing temperature 190℃, mixing for 70min. Then stop heating, cool, crush and granulate to obtain feed material.

[0137] Comparative Example 2

[0138] The polymer binder in this comparative example is the same as that in Example 2.

[0139] Compared with Example 2, the 420 stainless steel feedstock in this comparative example does not contain polycarbosilane and copper acetate, and the proportions of other components remain unchanged.

[0140] The method for preparing the 420 stainless steel feed of this comparative example comprises the following steps:

[0141] S1 and silane coupling agent KH-550 were stirred and dissolved in anhydrous ethanol to obtain A1;

[0142] S2, A1 and a polymer binder are stirred and mixed to obtain A2;

[0143] S3, A2 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 40rpm, mixing temperature 190℃, mixing for 60min. Then stop heating, cool, crush and granulate to obtain feed material.

[0144] Comparative Example 3

[0145] The polymer binder in this comparative example is the same as that in Example 3.

[0146] Compared with Example 3, the 420 stainless steel feedstock in this comparative example does not contain polycarbosilane and copper nitrate, and the proportions of other components remain unchanged.

[0147] The method for preparing the 420 stainless steel feed of this comparative example comprises the following steps:

[0148] S1 and silane coupling agent KH-564 were stirred and dissolved in anhydrous ethanol to obtain A1;

[0149] S2, A1 and a polymer binder are stirred and mixed to obtain A2;

[0150] S3, A2 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 30rpm, mixing temperature 180℃, mixing for 90min. Then stop heating, cool, crush and granulate to obtain feed material.

[0151] Comparative Example 4

[0152] The polymer binder in this comparative example is the same as that in Example 4.

[0153] Compared with Example 4, the 420 stainless steel feedstock in this comparative example does not contain polycarbosilane, copper nitrate and copper acetate, and the proportions of other components remain unchanged.

[0154] The method for preparing the 420 stainless steel feed of this comparative example comprises the following steps:

[0155] S1, silane coupling agent A-174 and KH-560 are stirred and dissolved in anhydrous ethanol to obtain A1;

[0156] S2, A1 and a polymer binder are mixed to obtain A2;

[0157] S3, A2 and 420 stainless steel powder are mixed, crushed and granulated to obtain feed material, and the mixing process parameters are: rotor speed 30rpm, mixing temperature 190℃, mixing for 70min. Then stop heating, cool, crush and granulate to obtain feed material.

[0158] According to the method for preparing an in-situ strengthened 420 stainless steel feed, an in-situ strengthened 420 stainless steel cutting tool is prepared, comprising the following steps:

[0159] B1. Injection: the in-situ strengthened 420 stainless steel feed is added into an injection machine, and the injection machine injects the in-situ strengthened 420 stainless steel feed into the cavity of a cutting tool mold, and demolds to obtain a cutting tool injection green body, the injection temperature is 190° C., and the mold temperature is 95° C.;

[0160] B2, degreasing: the injection green body is subjected to oxalic acid catalytic degreasing treatment to form a degreasing body, the degreasing environment temperature is controlled to be 135°C, the acid passing time is 8h, and the acid feeding speed is: 9g / min;

[0161] B3, sintering: sintering the degreased blank to form a sintered blank; the sintering temperature is 1320°C, the holding time is 8h, the sintering atmosphere is N2, the partial pressure is 10kPa, and the blank is cooled with the furnace;

[0162] B4. Heat treatment: heat treatment of the sintered blank; 1000°C for 30 min, quenching with 10% salt water, and then tempering at 200°C;

[0163] B5. Sharpening: sharpening the sintered blank after heat treatment to obtain a reinforced antibacterial stainless steel cutting tool.

[0164] The antibacterial stainless steel cutting tools were tested by the "adhesive film method" proposed by the Japan Food Analysis Center, and Escherichia coli and Staphylococcus aureus were cultured and observed on the surface of the samples at 35°C for 24 hours.

[0165] Table 1 The tensile strength, hardness and antibacterial performance test results of the in-situ strengthened 420 stainless steel cutting tools prepared by the in-situ strengthened 420 stainless steel feed materials of Examples 1-4 and the 420 stainless steel cutting tools of Comparative Examples 1-4.

[0166]

[0167] Table 1 shows that the cutting tools prepared in the four embodiments have good antibacterial properties. The comparative example does not add copper nitrate and copper acetate, but the surfactant zinc stearate is decomposed into uniformly dispersed ultrafine zinc particles at high temperature, which has a certain antibacterial effect.

[0168] Table 1 shows that the mechanical properties of the cutting tools prepared in the four embodiments are greatly improved compared with those without adding polycarbosilane.

[0169] The above description is only a specific embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent transformation made by the present invention, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. A method for preparing in-situ strengthened 420 stainless steel feed, characterized in that: The following steps are involved: S1 and a silane coupling agent are stirred and dissolved in anhydrous ethanol to obtain A1; Add polycarbosilane, copper nitrate or copper acetate to S2 and A1, and then stir and dissolve to obtain A2; S3, A2 and a polymer binder are stirred and mixed to obtain A3; S4, A3 and water vapor are combined to atomize 420 stainless steel powder for internal mixing, crushing and granulation to obtain in-situ strengthened 420 stainless steel feed.

2. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: The silane coupling agents are A-151, A-171, A-172, A-174, A-186, KH-550, KH-560, KH-561, KH-563, and KH-564.

3. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: The in-situ strengthened 420 stainless steel feed material comprises the following components in percentage by weight: 82.5-92% of water-gas combined atomized 420 stainless steel powder, 0.2-4% of one or more powders of copper nitrate or copper acetate, 1-4% of polycarbosilane, 4-10% of ethanol, and 0.5-3% of silane coupling agent.

4. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: More than 95% of the particle sizes of the water-gas combined atomized stainless steel powder are within the range of 7 to 10 μm.

5. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: The polymer binder comprises the following components in percentage by mass: 78-86% of polyoxymethylene, 3-9% of high-density polyethylene, 2-7% of ethylene-vinyl acetate copolymer, 1.8-4% of solid paraffin, 0.7-2.6% of surfactant, 1-2.5% of microcrystalline wax, 1-3% of polyvinyl alcohol and 0.2-0.5% of antioxidant.

6. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 5, characterized in that: The surfactant is one or more combinations of stearic acid, pentaerythritol stearate and zinc stearate.

7. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 5, characterized in that: The antioxidant is one or more combinations of AO-3, AO-4, AO-14, AO-15, AO-43 and AO-46.

8. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: The mass ratio of the polymer binder to the water-gas-co-atomized 420 stainless steel powder is 1:

9.

9. The method for preparing an in-situ strengthened 420 stainless steel feedstock according to claim 1, characterized in that: In step S4, the A3 and the water vapor atomized 420 stainless steel powder are mixed in a mixer, and the mixing process parameters are: the rotor speed is 30-40 rpm, the mixing temperature is 180-190° C., and the heating is stopped after mixing for 60-90 minutes.

10. According to the method for preparing an in-situ strengthened 420 stainless steel feed, an in-situ strengthened 420 stainless steel cutting tool is prepared, characterized in that: The following steps are involved: B1. Injection: the in-situ strengthened 420 stainless steel feed is added into an injection machine, and the injection machine injects the in-situ strengthened 420 stainless steel feed into the cavity of a cutting tool mold, and demolds to obtain a cutting tool injection green body, the injection temperature is 190° C., and the mold temperature is 95° C.; B2, degreasing: the injection green body is subjected to oxalic acid catalytic degreasing treatment to form a degreasing body, the degreasing environment temperature is controlled to be 135°C, the acid passing time is 8h, and the acid feeding speed is: 9g / min; B3, sintering: sintering the degreased blank to form a sintered blank; the sintering temperature is 1320°C, the holding time is 8h, the sintering atmosphere is N2, the partial pressure is 10kPa, and the blank is cooled with the furnace; B4. Heat treatment: heat treatment of the sintered blank; 1000°C for 30 min, quenching with 10% salt water, and then tempering at 200°C; B5. Sharpening: sharpening the sintered blank after heat treatment to obtain a reinforced antibacterial stainless steel cutting tool.

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