Sterilizing stainless steel composite pipe and preparation method thereof

Abstract

The invention relates to the technical field of stainless steel pipes, and provides a sterilization stainless steel composite pipe and a preparation method thereof.The stainless steel composite pipe sequentially comprises a copper pipe layer and a stainless steel pipe layer from inside to outside, a brazing material layer is arranged outside the copper pipe layer, and the stainless steel pipe is composed of, by weight, 18%-20% of Cr, 6%-8% of Ni, 2.0%-4.0% of Cu, 0.4%-0.8% of Mo, 1%-2% of Mn, 0.8%-1.5% of Si, 0.7%-1.0% of Ag, 0.05%-0.08% of Zn, 0.05% < = Sc + Ce < = 0.06%, 0.03% < = C and the balance Fe and other inevitable impurities. Through the technical scheme, the problem of poor sterilization effect of the stainless steel pipe in the related technology is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel pipes, and specifically, to a bactericidal stainless steel composite pipe and a preparation method thereof. Background Art

[0002] The bactericidal stainless steel composite pipe is a multi-layer pipe structure, and its main structure usually uses stainless steel as the base material because stainless steel itself has good corrosion resistance and mechanical properties (such as strength and toughness). In order to improve the bactericidal effect of the stainless steel composite pipe, a material layer with bactericidal function is often added through a composite process.

[0003] However, this method of coating a bactericidal coating on the surface of the stainless steel pipe has some problems: for example, during long-term use, due to the low bonding strength between the coating and the pipe substrate, it is easy to fall off due to factors such as flowing water scouring and friction, and the antibacterial effect is difficult to maintain.

[0004] Therefore, it is necessary to propose a bactericidal stainless steel composite pipe to improve the antibacterial property of the stainless steel pipe, extend the service life of the steel pipe, and ensure the normal transportation of fluids. Summary of the Invention

[0005] The present invention proposes a bactericidal stainless steel composite pipe and a preparation method thereof, which solves the problem of poor bactericidal effect of stainless steel pipes in related technologies.

[0006] The technical solution of the present invention is as follows: The present invention proposes a bactericidal stainless steel composite pipe. The stainless steel composite pipe comprises a copper pipe layer and a stainless steel pipe layer from the inside to the outside in sequence. A brazing filler metal layer is arranged outside the copper pipe layer. The stainless steel pipe is composed of the following components by weight percentage: Cr 18% - 20%, Ni 6% - 8%, Cu 2.0% - 4.0%, Mo 0.4% - 0.8%, Mn 1% - 2%, Si 0.8% - 1.5%, Ag 0.7% - 1.0%, Zn 0.05% - 0.08%, 0.05% ≤ Sc + Ce ≤ 0.06%, C ≤ 0.03%, and the balance is Fe and other inevitable impurities.

[0007] As a further technical solution, the mass ratio relationship of Sc, Ce, and Cu is Cu:(Ce / Sc) = 3 - 4:1 and Ce / Sc = 1.

[0008] In the present invention, Cu itself has certain antibacterial properties. By limiting the mass ratio of Sc, Ce, and Cu, it can have a beneficial effect on the microstructure of the stainless steel composite pipe, reduce the attachment sites of bacteria, and better improve the antibacterial effect of the stainless steel composite pipe.

[0009] As a further technical solution, the copper tube is composed of the following components by weight percentage: Fe 1.8% - 2.5%, P 0.01% - 0.2%, Ti 0.01% - 0.1%, Sn 0.01% - 0.2%, and the balance is copper and other inevitable impurities.

[0010] As a further technical solution, the brazing filler metal is composed of the following components by weight percentage: Sn 2% - 3%, Cu 1.0% - 1.5%, Cd 0.5% - 1.3%, Bi 1% - 1.5%, and the balance is Ag and other inevitable impurities.

[0011] As a further technical solution, the particle size of the brazing filler metal is 100 μm.

[0012] In the present invention, the combined action of each element in the silver-based brazing filler metal can improve the wettability and adhesion between the brazing filler metal and the stainless steel tube and the copper tube, increase the interfacial bonding force, and improve the welding strength.

[0013] As a further technical solution, the thickness of the brazing filler metal layer is 0.04 mm - 0.05 mm.

[0014] As a further technical solution, the thickness of the copper tube is 0.4 - 0.6 mm.

[0015] The present invention also provides a method for preparing a sterilizing stainless steel composite tube, comprising the following steps: S1. A brazing filler metal layer is provided on the outer surface of the copper tube to obtain a pretreated copper tube; S2. The pretreated copper tube is inserted into the stainless steel tube, and one end is sealed by welding to obtain a sealed steel tube; S3. The sealed steel tube is evacuated and heated and welded to obtain a sterilizing stainless steel composite tube.

[0016] As a further technical solution, the process of the heating and welding is as follows: First, it is heated to 350 - 450 °C at a rate of 10 - 15 °C / min for the first heat treatment for 0.5 - 1.0 h, then heated to 650 - 700 °C at a rate of 18 - 24 °C / min for the second heat treatment for 15 - 20 min, and finally heated to 920 - 980 °C at a rate of 25 - 30 °C / min for the third heat treatment for 15 - 20 min.

[0017] In the present invention, through the heating in three stages, the brazing filler metal can be better homogenized, its fluidity can be increased, deep alloying can be promoted, and it can better ensure the full welding between the brazing filler metal and the copper tube and the stainless steel tube, ensure the stability of the welding quality, achieve a higher welding strength, and better meet the requirements of actual use.

[0018] As a further technical solution, during the evacuation, the vacuum degree is 4.5×10 -4 ~5×10 -4 Pa.

[0019] As a further technical solution, the pressure during the heating and soldering is 0.8~1.2 MPa.

[0020] The working principle and beneficial effects of the present invention are as follows: In the present invention, the copper tube is located inside the stainless steel composite tube. Copper has good thermal conductivity, which can enable the composite tube to have a good heat transfer effect when transporting hot media, etc., and can quickly and evenly transfer heat. At the same time, copper itself also has a certain bactericidal effect, which synergistically with components such as silver, zinc, and cerium in the outer-layer stainless steel to further improve the bactericidal ability of the composite tube. The brazing filler metal can better brazing-join the copper tube and the stainless steel tube together, ensuring the structural stability and sealing performance of the composite tube. The stainless steel tube, as the outer layer of the composite tube, provides high strength, high hardness, and good corrosion resistance, can protect the internal copper tube, and the surface of the stainless steel tube is smooth and easy to clean. Specific Embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0022] In the following embodiments and comparative examples: The particle size of the brazing filler metal is 100 μm.

[0023] Embodiment 1 The stainless steel tube is composed of the following components by weight percentage: Cr 18%, Ni 6%, Cu 2.0%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Sc + Ce = 0.05% (Sc:Ce = 1:4), C 0.02%, and the rest are Fe and other inevitable impurities.

[0024] The brazing filler metal is composed of the following components by weight percentage: Sn 2%, Cu 1.0%, Cd 0.5%, Bi 1%, and the balance is Ag and other inevitable impurities.

[0025] The copper tube is composed of the following components by weight percentage: Fe 1.8%, P 0.01%, Ti 0.01%, Sn 0.01%, and the rest are copper and other inevitable impurities.

[0026] A preparation method of a bactericidal stainless steel composite pipe, comprising the following steps: S1. Spraying a brazing filler metal with a thickness of 0.04 mm on the outer surface of a copper pipe with a thickness of 0.4 mm to obtain a pretreated copper pipe; S2. Inserting the pretreated copper pipe into a stainless steel pipe and sealing one end to obtain a sealed steel pipe; S3. Vacuumizing the sealed steel pipe to 4.5×10 -4 Pa, heating and welding under a pressure of 0.8 MPa, and then cooling to 100 °C to complete welding, obtaining a bactericidal stainless steel composite pipe; The specific process of the heating and welding is: heating to 980 °C at a rate of 25 °C / min for the third heat treatment for 30 min.

[0027] Example 2 The stainless steel pipe is composed of the following components by weight percentage: Cr 20%, Ni 8%, Cu 4.0%, Mo 0.8%, Mn 2%, Si 1.5%, Ag 1.0%, Zn 0.08%, Sc + Ce = 0.06% (Sc:Ce = 1:5), C 0.03%, and the balance is Fe and other inevitable impurities; The brazing filler metal and the copper pipe are the same as those in Example 1; A preparation method of a bactericidal stainless steel composite pipe, comprising the following steps: S1. Spraying a brazing filler metal with a thickness of 0.05 mm on the outer surface of a copper pipe with a thickness of 0.6 mm to obtain a pretreated copper pipe; S2. Inserting the pretreated copper pipe into a stainless steel pipe and sealing one end to obtain a sealed steel pipe; S3. Vacuumizing the sealed steel pipe to 5×10 -4 Pa, heating and welding under a pressure of 1.2 MPa, and then cooling to 100 °C to complete welding, obtaining a bactericidal stainless steel composite pipe; The specific process of the heating and welding is: heating to 920 °C at a rate of 30 °C / min for the third heat treatment for 40 min.

[0028] Example 3 Compared with Example 1, the difference in this example is only that the stainless steel pipe in this example is composed of the following components by weight percentage: Cr 18%, Ni 6%, Cu 2.0%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Sc + Ce = 0.05% (Sc:Ce = 1:1), C 0.02%, and the balance is Fe and other inevitable impurities.

[0029] Example 4 Compared with Example 1, the difference in this example is only that the stainless steel pipe in this example is composed of the following components by weight percentage: Cr 18%%, Ni 6%%, Cu 4.0%%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Sc + Ce = 0.05% (Sc:Ce = 1:1), C 0.02%, and the balance is Fe and other inevitable impurities.

[0030] Example 5 Compared with Example 3, the difference in this example is only that the brazing filler metal in this example is composed of the following components by weight percentage: Sn 3%, Cu 1.5%, Cd 1.3%, Bi 1.5%, and the balance is Ag and other inevitable impurities.

[0031] Example 6 Compared with Example 3, the difference in this example is only that the brazing filler metal in this example is composed of the following components by weight percentage: Sn 2%, Cu 1.0%, Cd 0.5%, and the balance is Ag and other inevitable impurities.

[0032] Example 7 Compared with Example 3, the difference in this example is only that the brazing filler metal in this example is composed of the following components by weight percentage: Sn 2%, Cu 1.0%, Bi 1%, and the balance is Ag and other inevitable impurities.

[0033] Example 8 Compared with Example 3, the difference in this example is only that the specific heating and welding process in this example is as follows: The specific heating and welding process is: First, heat up to 650°C at a rate of 18°C / min for the first heating treatment for 15 min, and finally heat up to 980°C at a rate of 25 - 30°C / min for the second heating treatment for 15 min.

[0034] Example 9 Compared with Example 3, the difference in this example is only that the specific heating and welding process in this example is as follows: The specific heating and welding process is: First, heat up to 350°C at a rate of 10°C / min for the first heating treatment for 0.5 h, then heat up to 650°C at a rate of 18°C / min for the second heating treatment for 15 min, and finally heat up to 980°C at a rate of 25°C / min for the third heating treatment for 15 min.

[0035] Example 10 Compared with Example 3, the difference in this example is only that the heating and welding process in this example is specifically as follows: The heating and welding process is specifically as follows: First, heat up to 450 °C at a rate of 15 °C / min for the first heat treatment for 1.0 h, then heat up to 700 °C at a rate of 24 °C / min for the second heat treatment for 20 min, and finally heat up to 980 °C at a rate of 30 °C / min for the third heat treatment for 20 min.

[0036] Example 11 Compared with Example 3, the difference in this example is only that the heating and welding process in this example is specifically as follows: The heating and welding process is specifically as follows: First, heat up to 350 °C at a rate of 10 °C / min for the first heat treatment for 0.5 h, then heat up to 650 °C at a rate of 10 °C / min for the second heat treatment for 15 min, and finally heat up to 980 °C at a rate of 25 °C / min for the third heat treatment for 15 min.

[0037] Example 12 Compared with Example 3, the difference in this example is only that the heating and welding process in this example is specifically as follows: The heating and welding process is specifically as follows: First, heat up to 350 °C at a rate of 10 °C / min for the first heat treatment for 0.5 h, then heat up to 650 °C at a rate of 30 °C / min for the second heat treatment for 15 min, and finally heat up to 980 °C at a rate of 25 °C / min for the third heat treatment for 15 min.

[0038] Comparative Example 1 The stainless steel pipe is composed of the following components by weight percentage: Cr 18%%, Ni 6%%, Cu 2.0%%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Ce 0.05%, C 0.02%, and the rest are Fe and other inevitable impurities.

[0039] Comparative Example 2 The stainless steel pipe is composed of the following components by weight percentage: Cr 18%%, Ni 6%%, Cu 2.0%%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Sc 0.05%, C 0.02%, and the rest are Fe and other inevitable impurities.

[0040] Comparative Example 3 The stainless steel pipe is composed of the following components by weight percentage: Cr 18%, Ni 6%, Cu 2.0%, Mo 0.4%, Mn 1%, Si 0.8%, Ag 0.7%, Zn 0.05%, Sc + Ce = 0.1% (Sc:Ce = 1:4), C 0.02%, and the balance is Fe and other inevitable impurities.

[0041] Experimental Example 1 According to the test methods specified in GB / T 42675-2023 "Antibacterial Stainless Steel Welded Pipes and Fittings", the inhibitory effects of the stainless steel composite pipe samples of Examples 1 to 4 and Comparative Examples 1 to 3 against Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC 6538P) were determined, and the determination results are shown in Table 1.

[0042] Table 1

[0043] As can be seen from Table 1, compared with Comparative Examples 1 to 3, the antibacterial rates of Escherichia coli in the stainless steel composite pipes of Examples 1 to 4 in the present invention are as high as 98.4% - 99.9%, and the antibacterial rates of Staphylococcus aureus are as high as 98.2% - 99.5%.

[0044] Experimental Example 2 The bond shear strength of the stainless steel composite pipes prepared in Example 3 and Examples 6 to 12 was tested according to the method in GB / T 31940-2015 "Dual-Metal Composite Corrosion-Resistant Steel Pipes for Fluid Transportation", and the test results are shown in Table 2.

[0045] Table 2

[0046] The bond shear strength of the stainless steel composite pipes in Example 3 and Examples 6 to 12 of the present invention is as high as 173 - 217 MPa, improving the welding strength of the stainless steel pipe composite pipes.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A sterilization stainless steel composite tube, characterized in that: The stainless steel composite tube is composed of a copper tube layer and a stainless steel tube layer from the inside to the outside, a brazing material layer is arranged outside the copper tube layer, and the stainless steel tube is composed of the following components in weight percentage: Composition: Cr18%~20%, Ni 6%~8%, Cu 2.0%~4.0%, Mo 0.4%~0.8%, Mn 1%~2%, Si 0.8%~1.5%, Ag 0.7%~1.0%, Zn 0.05%~0.08%, 0.05%≤Sc+Ce≤0.06%, C≤0.03%, the rest are Fe and other unavoidable impurities.

2. A sterilization stainless steel composite tube according to claim 1, characterized in that: The mass ratio of Sc, Ce and Cu is Cu: (Ce / Sc) = 3-4:1 and Ce / Sc = 1.

3. The sterilization stainless steel composite tube according to claim 1, characterized in that: The solder layer is composed of the following components in weight percentage: Sn 2%-3%, Cu 1.0%-1.5%, Cd 0.5%-1.3%, Bi 1%-1.5%, and the balance is Ag and other inevitable impurities.

4. The sterilization stainless steel composite tube according to claim 1, characterized in that: The thickness of the solder layer is 0.04 mm to 0.05 mm.

5. The sterilization stainless steel composite tube according to claim 1, characterized in that: The thickness of the copper tube is 0.4-0.6 mm.

6. The sterilization stainless steel composite tube according to claim 1, characterized in that: The copper tube is composed of the following components in weight percentage: Fe 1.8%-2.5%, P 0.01%-0.2%, Ti 0.01%-0.1%, Sn 0.01%-0.2%, and the rest is copper and other inevitable impurities.

7. The method for preparing a sterilized stainless steel composite tube according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, providing a brazing material layer on the outer surface of the copper tube to obtain a pretreated copper tube; S2, inserting the pretreated copper tube into the stainless steel tube, and sealing one end to obtain a sealed welded steel tube; S3, evacuating the sealed and welded steel pipe, and heating and welding it to obtain a sterilized stainless steel composite pipe.

8. The method for preparing a sterilized stainless steel composite tube according to claim 7, characterized in that: The heating welding process is: firstly, heating to 350-450°C at a rate of 10-15°C / min for a first heating treatment for 0.5-1.0h, then heating to 650-700°C at a rate of 18-24°C / min for a second heating treatment for 15-20min, and finally heating to 920-980°C at a rate of 25-30°C / min for a third heating treatment for 15-20min.

9. The method for preparing a sterilized stainless steel composite tube according to claim 7, characterized in that: When the vacuum is drawn, the vacuum degree is 4.5×10 -4 ~5×10 -4 Pa.

10. The method for preparing a sterilized stainless steel composite tube according to claim 7, characterized in that: The pressure during the heating and welding is 0.8-1.2 MPa.

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