Method for providing protection for metal joint

Abstract

The invention provides a method for providing protection for a metal joint. The method comprises the steps that an aluminum metal piece makes contact with a copper metal piece to form electric connection; the surface of the contact part of the aluminum metal part and the copper metal part is coated with a coating so as to provide protection for the contact part, and the coating comprises one of polyurethane, acrylic ester or polyolefin elastomer. The coating is used for protecting the connection site, so that the effects of resisting moisture and salt mist and keeping the resistance at the connection site stable can be achieved.

Description

Technical Field

[0001] The present disclosure relates to the chemical industry field. Specifically, the present disclosure relates to a method for providing protection to the connection of metals. Background Art

[0002] Due to the low price and light weight of aluminum enameled wire, aluminum enameled wire is increasingly used to replace copper enameled wire. For example, in the motor winding, the cost of aluminum enameled wire is even as low as one-fifth of that of copper enameled wire. In addition, currently, the cold-pressed terminals used to connect enameled wires are mostly made of copper. When the aluminum enameled wire is electrically connected to the copper terminal, if there are some chemical media such as water or salt in the environment, due to the different activities, the two are extremely likely to form a primary battery effect, and then the aluminum wire at the connection site undergoes electrochemical corrosion. In addition, the large current under the working state will cause the resistance at the connection site to increase, and at the same time generate high temperature, which will further exacerbate the corrosion process, form a vicious cycle, and ultimately lead to the failure of the electrical connection.

[0003] In some engineering applications, operators will choose to use adhesives to apply glue at the connection site between the enameled wire and the terminal to slow down and avoid the above situation. However, since the connection site between the enameled wire and the terminal usually has a size of only dozens of micrometers, the existing adhesives are difficult to fill and adhere to this connection site. Moreover, the corrosion resistance of the adhesive is limited. When the adhesive cures, due to the large curing shrinkage stress generated by itself, this will also cause the resistance at the connection site to increase and exacerbate the temperature rise effect. Summary of the Invention

[0004] In order to solve the above problems and defects, the present disclosure proposes a method for providing protection to the connection of metals. This method can provide a protective effect on the contact part between the copper metal part and the aluminum metal part.

[0005] Based on this, according to an embodiment of the present disclosure, a method for providing protection to the connection of metals is proposed, including: bringing an aluminum metal part into contact with a copper metal part to form an electrical connection; applying a coating on the surface of the contact part between the aluminum metal part and the copper metal part to provide protection to the contact part, wherein the coating includes one of the following: polyurethane, acrylate, or polyolefin elastomer.

[0006] By using the above conformal coating to provide protection at the connection site, the effects of moisture resistance, salt spray resistance, and maintaining the stability of the resistance at the connection site can be achieved.

[0007] In one embodiment, the aluminum metal part is the aluminum core of the enameled wire, and the copper metal part is the copper component of the cold-pressed terminal.

[0008] In one embodiment, the method further includes: curing at room temperature for 24 hours to 72 hours.

[0009] In one embodiment, the viscosity of the coating is less than 2000 cps.

[0010] In one embodiment, the solid content of the coating is less than 50%.

[0011] In one embodiment, the wire diameter of the enameled wire is from 0.24 mm to 0.45 mm.

[0012] In one embodiment, the coating further comprises any one or more of the following solvents: xylene, ethylbenzene, propyl acetate, butyl acetate, methyl ethyl ketone, toluene, or methylcyclohexane. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In conjunction with the accompanying drawings and with reference to the following detailed description, the features, advantages, and other aspects of the embodiments of the present disclosure will become more apparent. Several embodiments of the present disclosure are shown herein in an illustrative rather than restrictive manner. In the drawings:

[0014] Figure 1 An exemplary flow chart of a protection method according to an embodiment of the present disclosure is shown.

[0015] Figure 2 A three-dimensional schematic diagram of coating a coating between a cold-pressed terminal and an enameled wire according to an embodiment of the present disclosure is shown.

[0016] Figure 3 A top view of coating a coating between a cold-pressed terminal and an enameled wire according to an embodiment of the present disclosure is shown.

[0017] Figure 4 Results of damp heat test and temperature shock test on an enameled wire with a wire diameter of 0.3 mm are shown.

[0018] Figure 5 Results of damp heat test and temperature shock test on an enameled wire with a wire diameter of 0.4 mm are shown.

[0019] Figure 6 Results of salt spray test on an enameled wire with a wire diameter of 0.3 mm are shown.

[0020] Figure 7 Results of salt spray test on an enameled wire with a wire diameter of 0.4 mm are shown. DETAILED DESCRIPTION

[0021] In the following detailed description of the preferred embodiments, reference will be made to the accompanying drawings that form a part of this disclosure. The accompanying drawings illustrate, by way of example, specific embodiments that can implement this disclosure. The exemplary embodiments are not intended to exhaust all embodiments according to this disclosure. In the specification, the same or similar reference numerals indicate the same or similar components. It is understood that other embodiments can be utilized and structural modifications can be made without departing from the scope of this disclosure. Therefore, the following detailed description is not restrictive, and the scope of this disclosure is defined by the appended claims.

[0022] As used herein, the terms "comprising," "including," and similar terms should be understood as open-ended terms, i.e., "including / including but not limited to," indicating that other elements can also be included. The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment," and so on.

[0023] This disclosure provides a method for protecting the connection of metals. Figure 1 An exemplary flowchart of this method according to an embodiment of this disclosure is shown. This method includes steps S10 - S20.

[0024] Step S10: Bring an aluminum metal part into contact with a copper metal part to form an electrical connection.

[0025] Step S20: Apply a coating to the surface of the contact portion between the aluminum metal part and the copper metal part to provide protection to the contact portion, where the coating includes one of the following: polyurethane, acrylate, or polyolefin elastomer.

[0026] Additionally, this method further includes curing at room temperature for 24 hours to 72 hours.

[0027] In this embodiment, the aluminum metal part is the aluminum core of an enameled wire, and the copper metal part is the copper component of a cold - pressed terminal. This disclosure proposes that by using the above - mentioned conformal coating for protection at the connection site, the effects of moisture resistance, salt - fog resistance, and maintaining a stable resistance at the connection site can be achieved. Figure 2 and Figure 3 respectively show a three - dimensional schematic view and a top - view of applying a coating 300 to the contact portion between the cold - pressed terminal 100 and the enameled wire 200. The protective effect of this coating on the metal connection can be confirmed by the following experimental results.

[0028] This disclosure selects two coatings 1A27NSLU and ITW 2104 containing polyurethane, two coatings 1B66NS and 1B73 containing acrylate, one coating 1B51NSLU containing polyolefin elastomer, and one adhesive 4538 for experiments. In the experiments, refer to Figure 2 and Figure 3, First, apply the coating on the surface of the connection site between the cold-pressed terminal and the enameled wire, with the coating dosage for each site being 0.01 g - 0.02 g. Subsequently, conduct a damp heat test or a temperature shock test, and finally test the contact resistance of the connection site to examine the protection effect. Figure 4 Shows the test results for enameled wires with a wire diameter of 0.3 mm. It can be found that when using coatings containing polyurethane, acrylate, or polyolefin elastomer for protection, after undergoing damp heat or temperature shock tests, the change in the contact resistance of the connection site is relatively small, less than 20%. When using the adhesive 4538 for protection, the change in the contact resistance of the connection site is relatively large, even exceeding 20%. If no protection measures are taken at the connection site, that is Figure 4 the blank group shown in Figure 5 shows the test results for enameled wires with a wire diameter of 0.4 mm, and the test results are similar to those Figure 4 obtained.

[0029] In another experiment, the present disclosure selects two coatings 1A27NSLU and ITW 2104 containing polyurethane, two coatings 1B66NS and 1B73 containing acrylate, one coating 1B51NSLU containing polyolefin elastomer, and conducts experiments in combination with a blank control group. In the experiment, referring to Figure 2 and Figure 3 , First, apply the coating on the surface of the connection site between the cold-pressed terminal and the enameled wire, with the coating dosage for each site being 0.01 g - 0.02 g. Subsequently, place the sample in a salt spray environment for a long time, and test the contact resistance of the connection site to examine the protection effect. Figure 6 Shows the test results for enameled wires with a wire diameter of 0.3 mm. It can be found that when using coatings containing polyurethane, acrylate, or polyolefin elastomer for protection, the contact resistance hardly changes within 96 hours. When the test time is increased to 312 hours, the change in the contact resistance is still relatively small, not exceeding the change upper limit of 20%. On the contrary, if no protection measures are taken at the connection site, that is Figure 6 the blank group shown in Figure 7 shows the test results for enameled wires with a wire diameter of 0.4 mm, and the test results are similar to those Figure 6 obtained.

[0030] Through the above experiments, it can be proved that the coating containing polyurethane, acrylate, or polyolefin elastomer has a protective effect on the connection site, and the use of such coating for protection can pass the wet heat test, temperature shock test, and aging test. Optionally, the wire diameter of the enameled wire to which the coating is applied is 0.24mm-0.45mm. If the wire diameter of the enameled wire is too small, it is difficult to form a reliable electrical connection between it and the terminal, even if the coating has a small protective effect on the connection site. If the wire diameter of the enameled wire is too large, the electrical connection formed between it and the terminal is sufficiently reliable, and the protective effect of the coating on the connection site is not obvious.

[0031] Optionally, in order to be suitable for a small-sized connection site between a terminal and an enameled wire, the coating material proposed in the present disclosure has a low viscosity. Specifically, the viscosity of the coating material is less than 2000 cps.

[0032] Optionally, in order to reduce the curing stress of the coating during the curing process and thus avoid damaging the electrical connections of the metal, the solid content of the coating proposed in the present disclosure is less than 50%.

[0033] Optionally, the coating proposed in the present disclosure may further include any one or more of the following solvents: xylene, ethylbenzene, propyl acetate, butyl acetate, methyl ethyl ketone, toluene, or methylcyclohexane. The solvent can adjust the viscosity of the coating to achieve optimal process performance.

[0034] It should be noted that the above examples are only specific embodiments of the present invention, and the present invention is obviously not limited to the above examples, and there are many similar variations. All variations directly derived or associated from the contents disclosed by the technicians in this field should fall within the protection scope of the present invention.

Claims

1. A method for providing protection for the joint of metals, comprising: bringing an aluminum metal part into contact with a copper metal part to form an electrical connection; applying a coating on the surface of the contact part between the aluminum metal part and the copper metal part to provide protection for the contact part, wherein the coating comprises one of the following: polyurethane, acrylate, or polyolefin elastomer.

2. The method according to claim 1, wherein the aluminum metal part is an aluminum wire core of an enameled wire, and the copper metal part is a copper component of a cold-pressed terminal.

3. The method according to claim 1, further comprising: curing at room temperature for 24 hours to 72 hours.

4. The method according to claim 1, wherein, The viscosity of the coating is less than 2000 cps.

5. The method according to claim 1, wherein, The solid content of the coating is less than 50%.

6. The method according to claim 2, wherein The wire diameter of the enameled wire is 0.24 mm to 0.45 mm.

7. The method according to claim 1, wherein, The coating further comprises any one or more of the following solvents: xylene, ethylbenzene, propyl acetate, butyl acetate, methyl ethyl ketone, toluene, or methyl cyclohexane.

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