A noise-reducing liquid heating vessel and a method of manufacturing a heating base plate therefor

Abstract

The application relates to a noise reduction liquid heating container and a preparation method of a heating base plate thereof. The liquid heating container comprises a container body and a heating device. The container body comprises the heating base plate. The heating base plate comprises a stainless steel base layer and a PVD coating layer. The PVD coating layer is prepared on the first surface of the stainless steel base layer by using a vacuum sputtering coating technology. The coating layer has a compact structure and good surface flatness. The coating layer can seal the pores on the first surface of the stainless steel base layer. The surface of the heating base plate located in the container body has excellent smoothness and compactness. The volume of the bubbles formed in the heating process of the heating container is greatly reduced. In turn, the noise generated by the explosion of large bubbles is reduced, and the use experience is improved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a method for preparing a noise-reducing liquid heating container and its heating base. Background Technology

[0002] When a heating container is used to heat a liquid inside, as the liquid temperature rises, the gas remaining on the inner surface of the container expands due to the temperature, weakening its adhesion to the surface and forming bubbles of varying sizes that gradually enter the liquid. These bubbles rise, expanding further and converging into larger bubbles. When these larger bubbles reach a certain pressure difference, they burst, producing noise, as seen in common kettles, health-preserving kettles, and industrial liquid heating furnaces. Simultaneously, larger bubbles may also burst upon leaving the heating plate, causing vibrations in the container's base or inner wall, generating noise. This noise significantly reduces user comfort, and the violent bursting of bubbles can easily cause liquid spillage, posing a risk of burns and scalds.

[0003] Some advanced silent electric kettles on the market have noise reduction functions, but these generally only optimize the mechanical structure to reduce noise propagation and vibration, without fundamentally reducing noise generation. For example: 1) Patents CN217185662U, CN209932406U, and CN206080154 all use a soundproof cover, but this increases the kettle's footprint, and steam can transfer heat to the cover, posing a risk of burns when people touch it. 2) Patents CN217185662U, CN219229608U, and CN209219949U use a vibration damping mechanism, which reduces noise to some extent by decreasing kettle vibration. However, this also increases the kettle's footprint and has the disadvantages of complex structure and high manufacturing costs. 3) Patent CN210130706U incorporates an electric stirring device inside the kettle to reduce the generation of bubbles. However, this increases processing and usage costs, increases energy consumption, and makes the kettle difficult to clean, thus reducing the user experience.

[0004] Therefore, it is essential to develop a noise-reducing heating container that does not increase the volume of the heating container and is easy to use. Summary of the Invention

[0005] The main objective of this invention is to solve the technical problem of reducing noise and improving the user experience of the heating container without increasing its volume.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] This application provides a noise-reducing liquid heating container, comprising:

[0008] The container body includes a heating base plate, which includes a stainless steel base layer and a PVD coating layer. The stainless steel base layer has a first surface and a second surface opposite to each other. The PVD coating layer is located inside the container body and is disposed on the first surface of the stainless steel base layer.

[0009] A heating device, located outside the container body and in contact with the second surface of the stainless steel base layer, is used to heat the container body.

[0010] As a further improvement of this application, the thickness of the PVD coating layer is 0.8 μm to 10 μm.

[0011] As a further improvement to this application, the PVD coating layer includes:

[0012] A functional coating is provided on the first surface of the stainless steel base layer to seal the pores of the first surface of the stainless steel base layer.

[0013] A base coat is applied between the first surface of the stainless steel substrate and the functional coating to increase the adhesion between the functional coating and the first surface of the stainless steel substrate.

[0014] As a further improvement of this application, the thickness of the functional coating is 0.6 to 8 mm, and the thickness of the undercoat is 0.2 to 2 mm.

[0015] As a further improvement of this application, the underlayer is prepared from any one or more of Ti, Cr, Zr, Ta, Al, Ag, Si or stainless steel; the functional coating includes at least one of Ti, Cr, Zr, Ta, Al, stainless steel, chromium nitride, titanium nitride, zirconium nitride, tantalum nitride, aluminum nitride, aluminum oxide, silicon oxide, chromium oxide, zirconium oxide, tantalum oxide, titanium oxide, and carbon film.

[0016] As a further improvement to this application, the carbon film is a diamond-like carbon (DLC) film.

[0017] As a further improvement of this application, the underlayer is a Cr layer, and the functional coating is an alternating layer of CrN film and SiO2 film; or, the underlayer is a Zr layer, and the functional coating includes a ZrN film and a ZrO2 film, wherein the Zr layer is sequentially composed of a ZrN film and a ZrO2 film.

[0018] To achieve the above objectives, this application also provides a method for preparing the heating chassis described above, comprising the following steps:

[0019] S1. Etching process: Plasma is used to etch the first surface of the stainless steel substrate;

[0020] S2. Coating process: Vacuum sputtering coating technology is used to sequentially deposit the underlayer and functional coating on the first surface of the etched stainless steel substrate.

[0021] As a further improvement of this application, in step S1, the bias voltage for etching is -300V to -50V, the current of the ion source for etching is 0.5A to 100A, the gas used for etching is argon, and the flow rate of the argon is 50sccm to 200sccm.

[0022] As a further improvement to this application, a post-coating processing method is also included: using plasma to etch the surface of the functional coating of the heated chassis.

[0023] The beneficial effects of this application are as follows: It provides a noise-reducing liquid heating container, comprising: a container body and a heating device. The container body includes a heating base, which includes a stainless steel base and a PVD coating layer. The PVD coating layer can seal the pores on the first surface of the stainless steel base, reducing the roughness of the first surface of the stainless steel base, and giving the surface of the heating base located inside the container body excellent smoothness and density. A method for preparing the heating base is also provided. The PVD coating layer is prepared on the first surface of the stainless steel base using vacuum sputtering deposition technology. This film layer has a dense structure and good surface flatness, greatly reducing the number of large bubbles formed on the heating base and significantly reducing the average volume of the bubbles. This fundamentally reduces the noise generated by the bursting of large bubbles, thereby improving the user experience of the heating container. Attached Figure Description

[0024] Figure 1 Microscopic images of the surface morphology of the heating chassis of Comparative Example 1(a) and Example 1(b) as observed under a microscope;

[0025] Figure 2 The diagram shows the formation and changes of bubbles inside electric kettles prepared from the heating plates of Comparative Example 1(a) and Example 1(b) as the temperature rises. Detailed Implementation

[0026] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to specific embodiments.

[0028] Commonly available heating containers include electric kettles and health-preserving kettles. Their heating plates are typically made of food-grade stainless steel (such as 304 stainless steel). Stainless steel undergoes rolling, annealing, deep drawing, and polishing processes to achieve a bright, smooth surface. However, considering factors such as processing level and cost, conventional polishing can only guarantee smoothness and reduce surface roughness to a certain extent. Microscopic observation of the stainless steel heating plate surface reveals numerous microscopic defects such as micro-grooves, processing lines, deep holes, and cracks. (Refer to...) Figure 1 (a) These microscopic defects easily cause dissolved gases to remain on the surface of the stainless steel heating plate. When heating the liquid, the stainless steel heating plate, connected to the heating device, experiences a preferential temperature rise. When the temperature reaches a certain level, the gas remaining on the surface of the stainless steel heating plate expands, forming bubbles of varying sizes. A pressure difference exists between the top and bottom of these bubbles, forcing them to rise continuously. During this rise, the bubbles continuously converge and expand. When the pressure difference reaches a certain level, the bubbles burst, generating noise. The rougher the surface of the heating plate, the larger the bubbles, and the more large bubbles are formed. These large bubbles are also more likely to burst directly when leaving the heating plate, causing vibrations in the heating container and generating noise. The more large bubbles there are, the larger their volume, and the louder the noise. Therefore, to reduce noise during liquid heating, it is necessary to reduce the generation of large bubbles, i.e., further reduce the surface roughness of the inner wall of the heating container, mainly the heating plate, to reduce the formation of larger surface defects and make the surface microstructure as uniform as possible.

[0029] To address the aforementioned technical problems, this application provides a noise-reducing liquid heating container, comprising: a container body and a heating device, wherein: the container body includes a heating base, the heating base includes a stainless steel base and a PVD coating layer, the stainless steel base has opposing first and second surfaces, and the PVD coating layer is located inside the container body and disposed on the first surface of the stainless steel base; the heating device is located outside the container body and in contact with the second surface of the stainless steel base, for heating the container body. The PVD coating layer has a dense surface, effectively sealing microscopic defects on the first surface of the stainless steel base, greatly reducing gas adhering to the heating base, thereby reducing noise caused by bubble bursting during liquid heating.

[0030] In one optional embodiment, the thickness of the PVD coating layer is 0.8 μm to 10 μm. Within this thickness range, the PVD coating layer effectively seals microscopic defects on the first surface of the stainless steel substrate without affecting the thermal conductivity of the heating chassis. The PVD coating layer includes a functional coating and a primer layer, wherein the functional coating is disposed on the first surface of the stainless steel substrate to seal pores on the first surface; the primer layer is located between the first surface of the stainless steel substrate and the functional coating to increase the adhesion between the functional coating and the first surface of the stainless steel substrate. Preferably, the thickness of the functional coating is 0.6 to 8 μm, and the thickness of the primer layer is 0.2 to 2 μm.

[0031] In an optional embodiment, the underlayer is prepared from any one or more combinations of Ti, Cr, Zr, Ta, Al, Ag, Si, or stainless steel; the functional coating includes at least one film layer selected from Ti, Cr, Zr, Ta, Al, stainless steel, chromium nitride, titanium nitride, zirconium nitride, tantalum nitride, aluminum nitride, aluminum oxide, silicon oxide, chromium oxide, zirconium oxide, tantalum oxide, titanium oxide, and carbon film. The functional coating material selected in this embodiment has excellent biocompatibility, corrosion resistance, high temperature resistance, and wear resistance, which can improve the service life of the heating container and achieve long-term cost reduction. Preferably, the carbon film is a diamond-like carbon (DLC) film. The above materials have very good chemical stability and biocompatibility, will not cause harm to the human body, and have a certain bactericidal effect, which can reduce the number of harmful bacteria in water to a certain extent.

[0032] In one specific implementation, the underlayer is a Cr layer, and the functional coating is an alternating layer of CrN film and SiO2 film; or, the underlayer is a Zr layer, and the functional coating includes a ZrN film and a ZrO2 film, wherein the Zr layer is sequentially composed of a ZrN film and a ZrO2 film.

[0033] This application also provides a method for preparing a heating chassis, comprising the following steps: S1, etching process: etching the first surface of a stainless steel substrate using plasma; S2, coating process: sequentially depositing an underlayer and a functional coating on the etched first surface of the stainless steel substrate using vacuum sputtering coating technology to obtain the heating chassis. The etching process serves to clean and activate the first surface of the stainless steel substrate using plasma, facilitating the deposition of a PVD coating layer on the first surface of the stainless steel substrate.

[0034] In an optional implementation, in step S1, the bias voltage for etching is -300V to -50V, the current of the ion source for etching is 0.5A to 100A, the gas used for etching is argon, and the flow rate of the argon is 50sccm to 200sccm.

[0035] In an optional implementation, in step S2, the temperature in the coating process is controlled below 250°C, the negative bias voltage applied to the stainless steel heating base is set to -150V to -80V, the flow rate of argon gas introduced under vacuum is 50sccm to 200sccm, the flow rate of oxygen gas is 20sccm to 100sccm, and the flow rate of nitrogen gas is 100sccm to 300sccm.

[0036] In an optional embodiment, the fabrication method of the heating chassis further includes a post-coating treatment process: plasma bombardment of the surface of the functional coating of the heating chassis. The purpose of the post-coating treatment process is to use plasma to remove large surface particles generated during the coating process and further to form a uniform surface morphology at the nanoscale of the functional coating. Preferably, in the post-coating treatment process: the etching bias voltage is -1000V to -80V, the current of the ion source used for etching is 2A to 120A, the etching gas is argon, and the argon flow rate is 50sccm to 200sccm.

[0037] To verify the excellent performance of the technical solution of this application, the following embodiments are also provided.

[0038] Comparative Example 1

[0039] The commonly used 304 stainless steel heating base.

[0040] Example 2

[0041] After polishing the surface of the 304 stainless steel heating base (similar to Comparative Example 1), the first surface of the stainless steel heating base was subjected to the following steps in sequence: cleaning, drying, placing it in a vacuum coating equipment, vacuuming, heating, etching process, coating process, cooling, and removal to obtain the heating base. Wherein:

[0042] In the etching process: the argon gas flow rate under vacuum is set to 80 sccm, the current of the ion source for etching is set to 80 A, and the negative bias voltage applied to the stainless steel heating plate is gradually reduced from -100V to -250V. After reaching -250V, the negative bias voltage is maintained for 60 minutes to complete the plasma etching process. High-energy plasma is used to bombard and etch the metal surface, removing rust, activating the surface, and improving coating adhesion.

[0043] Coating process:

[0044] Step 1: Deposit a Cr underlayer on the first surface of the stainless steel heating base. Use a metal Cr target as the cathode. Set the negative bias voltage applied to the stainless steel heating base to -120V. The argon gas flow rate introduced under vacuum atmosphere is 300 sccm. Deposit the Cr underlayer using vacuum DC magnetron sputtering technology. The thickness of the deposited Cr underlayer is 500 nm.

[0045] Step 2: Deposit a CrN film on the Cr substrate. Set the negative bias voltage on the stainless steel heating base to -100V, adjust the argon gas flow rate to 120sccm, and simultaneously introduce 180sccm of high-purity nitrogen gas. Use a metal Cr target as the cathode and deposit the CrN film using pulsed magnetron sputtering technology. The thickness of the CrN film is 30nm.

[0046] Step 3: Deposit a SiO2 film on the CrN film. Set the negative bias voltage on the stainless steel heating base to -50V, adjust the argon gas flow rate to 215 sccm, and simultaneously introduce 50 sccm of high-purity oxygen. Deposit the SiO2 film using a metal elemental silicon target via magnetron sputtering. The thickness of the SiO2 film is 30 nm.

[0047] Step four: Repeat steps two and three 15 times in sequence until a SiO2 film is deposited on the surface, resulting in a heating base. The multilayer film structure avoids the surface arcing problem caused by excessively thick SiO2 film growth, and at the same time, it helps to further reduce surface roughness and reduce internal stress in the film.

[0048] The temperature in the overall coating process described above is controlled below 250℃. Furthermore, food residue left in the health-preserving kettle may produce acidic substances that can damage the substrate. When applied to the health-preserving kettle, SiO2 effectively isolates the stainless steel substrate from these acidic substances. The SiO2 film layer has better oxidation resistance and high-temperature properties, thus protecting the stainless steel substrate and extending the service life of the heating base.

[0049] Example 3

[0050] After polishing the surface of the 304 stainless steel heating base (similar to Comparative Example 1), the first surface of the stainless steel heating base was subjected to the following steps in sequence: cleaning, drying, placing it in a vacuum coating equipment, vacuuming, heating, etching process, coating process, post-coating treatment process, cooling, and removal to obtain the heating base. Wherein:

[0051] In the etching process: the argon gas flow rate under vacuum is set to 80 sccm, the current of the ion source for etching is set to 100A, and the negative bias voltage applied to the stainless steel heating plate is gradually reduced from -100V to -250V. After reaching 250V, the negative bias voltage is maintained for 45 minutes to complete the plasma etching process. Plasma etching utilizes high-energy ion bombardment to remove rust from the metal surface, activates the surface, and improves coating adhesion.

[0052] Coating process:

[0053] Step 1: Deposit a Zr substrate on the first surface of the stainless steel heating base. Set the negative bias voltage applied to the stainless steel heating base to -200V, and introduce argon gas at a flow rate of 250 sccm in a vacuum atmosphere. Use a metal Zr target as the cathode and deposit the Zr substrate using magnetron sputtering technology. The thickness of the deposited Zr substrate is 200 nm.

[0054] Step 2: Deposit a ZrN film on the Zr substrate. Set the negative bias voltage on the stainless steel heating base to -100V, adjust the argon gas flow rate to 250 sccm, and simultaneously introduce 80 sccm of high-purity nitrogen gas. Deposit the ZrN film using a metal Zr target via magnetron sputtering. The thickness of the ZrN film is 600 nm.

[0055] Step 3: Deposit a ZrO2 film on the ZrN film. Set the negative bias voltage on the stainless steel heating base to -55V, adjust the argon gas flow rate to 215 sccm, and simultaneously introduce high-purity oxygen at 85 sccm. Deposit the ZrO2 film using a metal Zr target via magnetron sputtering. The thickness of the ZrO2 film is 300 nm.

[0056] Post-coating process: The negative bias voltage applied to the stainless steel heating base is set to -800V, the argon gas flow rate introduced under vacuum atmosphere is 250sccm, the current of the etching ion source is set to 80A, and high-energy Ar ions are used to bombard the ZrO2 film surface to achieve a nanoscale surface engraving morphology and make it uniformly distributed, finally obtaining a heating base with a nanoscale engraving morphology.

[0057] The temperature in the overall coating process described above is controlled below 250℃. Furthermore, ZrO2 has a certain bactericidal effect, releasing reactive oxygen species (ROS) which can disrupt bacterial cell walls.

[0058] The surface morphology of the heating chassis of Comparative Example 1 and Example 1 was observed under a microscope, such as... Figure 1 (a) and Figure 1 As shown in (b), the surface of commonly used 304 stainless steel chassis has many micro-defects such as micro-grooves, processing lines, deep holes, and cracks.

[0059] To verify the excellent noise reduction function of the heating chassis with PVD coating layer of this application, electric kettles of the same model were also prepared from the heating chassis of Example 1, Example 1, and Example 2 for comparison. The specific process is as follows:

[0060] 1L of tap water was added to each of the three electric kettles. Besides dissolving in the water, the gas also remained on the inner walls and defective areas of the kettle's base. Since the kettles were the same model, differing only in the surface coating of the heating plate, the contact area between the water and the inner wall was the same. The difference in the amount of residual gas in the two kettles depended on the difference in the amount of gas remaining on the heating plate surface. The three kettles were heated simultaneously, and the formation and changes in bubbles were observed as the temperature increased. A noise test was also conducted. Figure 2 The diagram illustrates the formation and changes of bubbles inside electric kettles prepared using the heating plates of Comparative Example 1 and Example 1, respectively, as the temperature rises. Figure 2 (a) is an electric kettle made from the heating plate of Comparative Example 1. Figure 2 (b) An electric kettle prepared using the heating plate of Example 1. Observation showed that as the water temperature inside the electric kettle gradually increased, at the same temperature, compared to Comparative Example 1, the electric kettle prepared using the heating plate of Example 1 produced fewer bubbles on its heating plate, and the bubbles were smaller, thus generating less noise. Therefore, the PVD coating layer of this application plays a positive role in noise reduction during the liquid heating process of the liquid heating container.

[0061] During the experiment, the noise level of the electric kettle during heating was also tested. When the water temperature was heated to 50℃~70℃, the noise level of the electric kettle prepared in Comparative Example 1 was 57dB~75dB, and the noise level of the electric kettle prepared in Example 1 was 43dB~58dB. When the water temperature was heated to 90℃~100℃, the noise level of the electric kettle prepared in Comparative Example 1 was 52dB~64dB, and the noise level of the electric kettle prepared in Example 2 was 46dB~51dB.

[0062] In summary, this application provides a noise-reducing liquid heating container, comprising: a container body and a heating device. The container body includes a heating base, which includes a stainless steel base and a PVD coating layer. The PVD coating layer is prepared on the first surface of the stainless steel base using vacuum sputtering deposition technology. This coating layer has a dense structure and good surface smoothness. The PVD coating layer can seal the pores on the first surface of the stainless steel base, reducing the roughness of the first surface of the stainless steel base, so that the surface of the heating base located inside the container body has excellent smoothness and density. Without changing the mechanical structure of the liquid heating container, the PVD coating layer of this application can effectively seal the pores on the surface of the stainless steel base, reduce the volume of residual gas, and reduce the size of bubbles, thereby greatly reducing the pressure on the upper and lower surfaces of the bubbles, the rising speed, and delaying the time for the bubbles to converge into large bubbles. This effectively reduces the noise generated by the bursting of large bubbles, without occupying additional space, and improves the user experience of the heating container.

[0063] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0064] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this application.

Claims

1. A noise-reducing liquid heating container, characterized in that, include: The container body includes a heating base plate, which includes a stainless steel base layer and a PVD coating layer. The stainless steel base layer has a first surface and a second surface opposite to each other. The PVD coating layer is located inside the container body and is disposed on the first surface of the stainless steel base layer. A heating device is located outside the container body and in contact with the second surface of the stainless steel base layer, for heating the container body; The PVD coating layer includes: A functional coating is provided on the first surface of the stainless steel base layer to seal the pores of the first surface of the stainless steel base layer. A base coat is applied between the first surface of the stainless steel substrate and the functional coating to increase the adhesion between the functional coating and the first surface of the stainless steel substrate. The underlayer is a Cr layer, and the functional coating is an alternating layer of CrN film and SiO2 film; or; The base layer is a Zr layer, and the functional coating includes a ZrN film layer and a ZrO2 film layer, with the Zr layer having a ZrN film layer and a ZrO2 film layer in sequence.

2. The noise-reducing liquid heating container according to claim 1, characterized in that, The thickness of the PVD coating layer is 0.8μm to 10.0µm.

3. The noise-reducing liquid heating container according to claim 1, characterized in that, The thickness of the functional coating is 0.6~8.0µm, and the thickness of the undercoat is 0.2~2.0µm.

4. The noise-reducing liquid heating container according to claim 1, characterized in that, The heating chassis is prepared by the following steps: S1. Etching process: Plasma is used to etch the first surface of the stainless steel substrate; S2. Coating process: Vacuum sputtering coating technology is used to sequentially deposit an underlayer and a functional coating on the first surface of the etched stainless steel substrate to obtain a heating chassis.

5. The noise-reducing liquid heating container according to claim 4, characterized in that, In step S1, the etching bias voltage is -300V to -50V, the current of the etching ion source is 0.5A to 100A, the etching gas is argon, and the argon flow rate is 50sccm to 200sccm.

6. The noise-reducing liquid heating container according to claim 4 or 5, characterized in that, It also includes post-coating processing: using plasma to bombard the surface of the functional coating on the heated chassis with ions.

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