Hair iron
Carbonized silicon ceramic heating plates in hair straighteners enhance heating efficiency by direct contact with hair, addressing slow heating issues and reducing wait times.
Patent Information
- Application Number
- CN202422089331.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2034-08-27
AI Technical Summary
The heating structure of traditional permators has thermal energy loss, resulting in slow temperature rise and long waiting time for users.
The silicon carbide ceramic heating plate is used as a heating device. The silicon carbide ceramic heating plate is used to directly contact the hair through the silicon carbide ceramic heating plate to reduce the process of heat conduction to the metal parts, and the silicon carbide ceramic heating plate is used to quickly conduct heat to the hair surface.
It significantly improves the heating speed of the perm, reduces user waiting time, reduces power consumption, and improves the convenience of use.
Smart Images
Figure CN223094998U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of hair styling appliances, and particularly to a hair straightener. Background Art
[0002] At present, there are various forms of hair straighteners on the market. Among them, hair straighteners and curling irons that straighten hair by opening and closing two clamping plates are widely used. They mainly heat and shape hair through heating components. In the heating structure of traditional hair straighteners, generally, heating elements are arranged in metal components (plate bodies or cylindrical bodies). After the heating elements are energized to generate heat, the heat is conducted to the surface of the metal components, and the heat on the surface of the metal components is used for hair straightening. However, during the heat conduction process, there is heat energy loss, resulting in a slow temperature rise rate of the metal components. Users usually need to wait for a long time from turning on to being able to use, which is not convenient for users. Summary of the Utility Model
[0003] The main purpose of the utility model is to propose a hair straightener, aiming to improve the temperature rise rate when using the hair straightener to reduce the waiting time of users.
[0004] To achieve the above purpose, the hair straightener proposed by the utility model includes:
[0005] Two clamping arms, one end of the two clamping arms is hinged to each other, and each clamping arm is provided with a mounting position facing the other clamping arm, and the mounting positions of the two clamping arms are arranged oppositely;
[0006] An electric control device, arranged on the clamping arm; and
[0007] Two silicon carbide ceramic heating plates, each silicon carbide ceramic heating plate is provided with a wiring part at both ends to be electrically connected to the electric control device through the wiring part. The two silicon carbide ceramic heating plates are respectively arranged at the two mounting positions to clamp hair together when the two clamping arms are closed.
[0008] Optionally, the silicon carbide ceramic heating plate includes a heating plate body and an insulating layer arranged on the surface of the heating plate body. The heating plate body is installed at the mounting position and is provided with the wiring part. The insulating layer of each silicon carbide ceramic heating plate is located on the side of its heating plate body facing the other silicon carbide ceramic heating plate to contact hair through the insulating layer.
[0009] Optionally, the insulating layer and the heating plate body are integrally sintered and formed.
[0010] Optionally, clamping protrusions are provided at both ends of the silicon carbide ceramic heating plate. The hair straightener further includes two mounting seats which are respectively disposed at both ends of the silicon carbide ceramic heating plate and are provided with insertion holes that are in plug-in fit with the clamping protrusions. The mounting seats are mounted on the clamping arms.
[0011] Optionally, the hair straightener further includes a battery and a charging member. Both the battery and the charging member are electrically connected to the electronic control device, and the charging member is located on one of the clamping arms.
[0012] Optionally, a plurality of protrusions are formed on the surface of any one of the silicon carbide ceramic heating plates facing the other silicon carbide ceramic heating plate, and the protrusions on the two silicon carbide ceramic heating plates are arranged staggeredly.
[0013] Optionally, the protrusions are in the shape of long strips extending along the length direction of the clamping arms and extend from one end of the silicon carbide ceramic heating plate to the other end, and the plurality of protrusions are arranged in sequence in the width direction of the clamping arms.
[0014] Optionally, the width of the protrusions on any one of the silicon carbide ceramic heating plates gradually decreases in the direction facing the other silicon carbide ceramic heating plate.
[0015] Optionally, the surface of any one of the silicon carbide ceramic heating plates facing the other silicon carbide ceramic heating plate has a plurality of regions. The plurality of regions all extend from one end of the silicon carbide ceramic heating plate to the other end and are arranged in sequence in the width direction of the clamping arms. Each region is provided with a plurality of protrusions, and the plurality of protrusions in the same region are arranged in sequence in the length direction of the clamping arms, and the protrusions of adjacent two regions are arranged staggeredly.
[0016] Optionally, one of the silicon carbide ceramic heating plates forms a concave arc surface, the generatrix of the concave arc surface extends along the length direction of the clamping arm, and the other silicon carbide ceramic heating plate forms a convex arc surface adapted to the concave arc surface.
[0017] Optionally, the silicon carbide ceramic heating plate is in a spiral shape extending along the length direction of the clamping arm, and the two silicon carbide ceramic heating plates have the same helix direction so that when the two clamping arms are closed, the two silicon carbide ceramic heating plates are mutually engaged.
[0018] Optionally, the surfaces of the two silicon carbide ceramic heating plates facing each other are both flat surfaces.
[0019] The technical solution of the present utility model uses a silicon carbide ceramic heating plate as the heating device of the hair straightener, and directly contacts the hair with the silicon carbide ceramic heating plate. In this way, the heat generated by the silicon carbide ceramic heating plate can be quickly conducted to its surface for contacting the hair. Compared with the traditional heating structure, the process of the heating device conducting heat to the metal parts is reduced, thereby reducing heat loss, enabling the surface of the silicon carbide ceramic heating plate contacting the hair to quickly rise to the hair straightening temperature, significantly improving the heating speed when using the hair straightener, reducing the waiting time for the user from turning on the hair straightener to being able to use it, and also being beneficial to reducing power consumption, which greatly facilitates the user's use. Description of the Drawings
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.
[0021] Figure 1 Structural schematic diagram of an embodiment of the hair straightener of the present utility model;
[0022] Figure 2 For Figure 1 Exploded view of the hair straightener in
[0023] Figure 3 For Figure 2 Enlarged view of part A in
[0024] Figure 4 For Figure 2 Enlarged view of part B in
[0025] Figure 5 For Figure 1 Cross-sectional view of the hair straightener in
[0026] Figure 6 Structural schematic diagram of another embodiment of the hair straightener of the present utility model;
[0027] Figure 7 Structural schematic diagram of yet another embodiment of the hair straightener of the present utility model;
[0028] Figure 8 Structural schematic diagram of still another embodiment of the hair straightener of the present utility model.
[0029] Explanation of the reference numerals in the drawings:
[0030] 10. Clamping arm; 11. Mounting position; 12. Accommodating part; 13. Avoidance groove; 14. Rotating groove; 15. Shaft hole; 16. Groove; 17. Rotating convex part; 20. Silicon carbide ceramic heating plate; 21. Wiring part; 22. Convex part; 24. Concave arc surface; 25. Convex arc surface; 26. Clamping convex; 30. Electric control device; 40. Mounting base; 41. Jack; 51. Battery; 52. Charging part; 54. Lever; 55. Power button; 56. Rotating shaft; 57. Protective cover.
[0031] The realization, functional features and advantages of the purpose of the present utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments
[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.
[0033] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.
[0034] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.
[0035] The present utility model provides a hair curler.
[0036] In the embodiments of the present utility model, as Figures 1 to 5As shown in the figure, the hair straightener includes an electric control device 30, two clamping arms 10, and two silicon carbide ceramic heating plates 20. One ends of the two clamping arms 10 are hinged to each other. Each clamping arm 10 is provided with a mounting position 11 facing the other clamping arm 10, and the mounting positions 11 of the two clamping arms 10 are arranged oppositely; the electric control device 30 is arranged on the clamping arm 10; at both ends of each silicon carbide ceramic heating plate 20, there are wiring parts 21, so as to be electrically connected to the electric control device 30 through the wiring parts 21. The two silicon carbide ceramic heating plates 20 are respectively arranged at the two mounting positions 11, so as to clamp the hair together through the two silicon carbide ceramic heating plates 20 when the two clamping arms 10 are closed.
[0037] In this embodiment, the electric control device 30 has circuit structures such as a controller and a power supply circuit, etc. The specific circuit structure can refer to the prior art, and the present utility model will not elaborate on it one by one. Optionally, the circuit device also has a power cord for connecting to an external power supply; or the electric control device 30 has a power interface for connecting the power cord.
[0038] The silicon carbide ceramic heating plate 20 is made of silicon carbide ceramic material, so that the silicon carbide ceramic heating plate 20 is a conductive structure and has a certain resistance value, so that the whole silicon carbide ceramic heating plate 20 is a heating element. At least one wiring part 21 is provided at each end of the silicon carbide ceramic heating plate 20. Connect the wiring parts 21 at both ends of the silicon carbide ceramic heating plate 20 to the power supply circuit (the wiring part 21 at one end of the silicon carbide ceramic heating plate 20 is connected to the positive pole of the power supply, and the wiring part 21 at the other end is connected to the negative pole of the power supply). After the power is turned on, the current flows through the silicon carbide ceramic heating plate 20, thereby converting electrical energy into heat energy, so that the silicon carbide ceramic heating plate 20 generates heat. The wiring part 21 can be located at the end face of the silicon carbide ceramic heating plate 20 or spaced from the end face of the silicon carbide ceramic heating plate 20.
[0039] Among them, the silicon carbide ceramic heating plate 20 can be made by mixing silicon carbide powder as the main sintering phase raw material with one or more conductive phase raw materials such as titanium nitride powder, zirconium nitride powder, titanium carbonitride powder, titanium carbide powder, zirconium carbide powder, thallium carbide powder, hafnium carbide powder, titanium boride powder, zirconium boride powder, molybdenum silicide powder, and tungsten carbide powder, and then molding and sintering according to the designed shape. For example, silicon carbide powder, yttrium oxide powder, aluminum oxide powder, and titanium boride powder can be uniformly mixed according to a certain mass ratio, then water is used as a solvent, and they are uniformly mixed using a ball mill, then spray-dried, the dried powder and paraffin are heated and kneaded according to a certain mass ratio, poured into a hot die-casting machine to complete hot die-casting molding. After the green body is dried, it is put into a sintering furnace for sintering and molding to obtain the silicon carbide ceramic heating plate 20.
[0040] The technical solution of the present utility model uses a silicon carbide ceramic heating plate 20 as the heating device of the hair straightener, and directly contacts the hair with the silicon carbide ceramic heating plate 20. In this way, the heat generated by the silicon carbide ceramic heating plate 20 can be quickly conducted to its surface for contacting the hair. Compared with the traditional heating structure, the process of the heating device conducting heat to the metal components is reduced, thereby reducing heat loss, enabling the surface of the silicon carbide ceramic heating plate 20 contacting the hair to quickly rise to the hair straightening temperature, significantly improving the heating speed when using the hair straightener, reducing the waiting time for the user from turning on the hair straightener to being able to use it, and also being beneficial to reducing power consumption, which greatly facilitates the user.
[0041] In some embodiments, the silicon carbide ceramic heating plate 20 includes a heating plate body and an insulating layer provided on the surface of the heating plate body. The heating plate body is installed at the installation position 11 and is provided with a wiring portion 21. The insulating layer of each silicon carbide ceramic heating plate 20 is located on the side of its heating plate body facing another ceramic heating body to contact the hair through the insulating layer. This can avoid the risk of short circuit when the two silicon carbide ceramic heating plates 20 come into contact with each other or misclip the electrical conducting device, improving the use safety. Of course, in other embodiments, when sintering and forming the silicon carbide ceramic heating plate 20, the silicon carbide ceramic heating plate 20 can also be set as a multi-layer structure so that the resistance of the surface layer is greater than that of the inner layer.
[0042] In some embodiments, the insulating layer and the heating plate body are integrally sintered and formed. This can improve the reliability of the insulating layer, reduce the risk of detachment, and also improve the heat conduction effect. When forming, the silicon carbide ceramic matrix can be formed first, then the insulating ceramic slurry containing silicon dioxide is evenly coated on the surface of the ceramic matrix, and then the silicon carbide ceramic matrix coated with the insulating ceramic slurry is placed in a high-temperature sintering furnace at 1000 - 12000 °C for sintering to obtain the silicon carbide ceramic heating plate 20 with an insulating layer.
[0043] Among them, the shape of the silicon carbide ceramic heating plate 20 has various types. For example, in some embodiments, the surfaces of the two silicon carbide ceramic heating plates 20 facing each other are both flat surfaces. That is, the silicon carbide ceramic heating plate 20 is in a flat plate shape. In this way, the structure of the silicon carbide ceramic heating plate 20 can be simple and it is convenient for production and forming.
[0044] In other embodiments, please refer to Figure 6 or Figure 7 , a plurality of convex portions 22 are formed on the surface of any one silicon carbide ceramic heating plate 20 facing another silicon carbide ceramic heating plate 20, and the convex portions 22 on the two silicon carbide ceramic heating plates 20 are arranged staggeredly. That is, when the two clamping arms 10 are closed, the convex portions 22 on the two silicon carbide ceramic heating plates 20 are mutually engaged, and the hair can be straightened into a curved shape, which is convenient for the user to shape the hair texture.
[0045] Among them, the shape of the convex portion 22 has a variety of forms. For example, in one embodiment, please refer to Figure 6 , the convex portion 22 is in the shape of a long strip extending along the length direction of the clamping arm 10, and extends from one end of the silicon carbide ceramic heating plate 20 to the other end. A plurality of convex portions 22 are arranged in sequence in the width direction of the clamping arm 10. This is beneficial for users to shape wavy hairstyles. Optionally, the width of the convex portion 22 on any one silicon carbide ceramic heating plate 20 gradually decreases in the direction towards the other silicon carbide ceramic heating plate 20. That is, the convex portion 22 is generally triangular, so that the degree of hair bending can be adjusted during use, which is beneficial to reducing hair damage.
[0046] Different from the above-mentioned long-strip convex portion 22, in other embodiments, please refer to Figure 7 , the surface of any one silicon carbide ceramic heating plate 20 facing the other silicon carbide ceramic heating plate 20 has a plurality of regions. The plurality of regions all extend from one end of the silicon carbide ceramic heating plate 20 to the other end, and are arranged in sequence in the width direction of the clamping arm 10. Each region is provided with a plurality of convex portions 22. The plurality of convex portions 22 in the same region are arranged in sequence in the length direction of the clamping arm 10, and the convex portions 22 of adjacent two regions are staggered from each other. Specifically, each convex portion 22 is generally in the shape of a square, so that it is convenient for users to shape hair texture during use.
[0047] In still other embodiments, please refer to Figure 8 , one of the silicon carbide ceramic heating plates 20 is formed with a concave arc surface 24, the generatrix of the concave arc surface 24 extends along the length direction of the clamping arm 10, and the other silicon carbide ceramic heating plate 20 is formed with a convex arc surface 25 adapted to the concave arc surface 24, so as to facilitate users to shape hair texture.
[0048] In still other embodiments, the silicon carbide ceramic heating plate 20 is in a spiral shape extending along the length direction of the clamping arm 10 (not shown in the figure). The spiral directions of the two silicon carbide ceramic heating plates 20 are the same, so that when the two clamping arms 10 are closed, the two silicon carbide ceramic heating plates 20 are mutually engaged, so as to facilitate curling the hair into a spiral shape.
[0049] In some embodiments, please refer to Figures 2 to 5 , clamping protrusions 26 are provided at both ends of the silicon carbide ceramic heating plate 20. The hair curling iron further includes two mounting seats 40. The two mounting seats 40 are respectively disposed at both ends of the silicon carbide ceramic heating plate 20, and are provided with insertion holes 41 that are inserted and matched with the clamping protrusions 26. The mounting seats 40 are mounted on the clamping arms 10. That is, during installation, the two mounting seats 40 can be respectively installed at both ends of the silicon carbide ceramic heating plate 20 first, so that the clamping protrusions 26 are snapped into the corresponding insertion holes 41 of the mounting seats 40, and then the silicon carbide ceramic heating plate 20 and the two mounting seats 40 are installed at the installation position 11. After the mounting seats 40 are fixed to the housing of the clamping arms 10, the silicon carbide ceramic heating plate 20 can be fixed on the clamping arms 10. Such a structure is simple and convenient for installation, which is beneficial to reducing the production cost of the hair curling iron.
[0050] In some embodiments, the hair straightener further includes a battery 51 and a charging member 52. Both the battery 51 and the charging member 52 are electrically connected to the electronic control device 30. The charging member 52 is located on one of the clamping arms 10. In this way, the silicon carbide ceramic heating plate 20 can be powered by the battery 51, which is convenient for short-term use when going out. Moreover, when the battery 51 is used for power supply, the voltage used by the hair straightener can be relatively small, and even if an insulating layer is not provided on the silicon carbide ceramic heating plate 20, the safety can be ensured. Among them, the charging member 52 can be a charging interface (such as a USB Type-C interface) or a wireless charging coil.
[0051] Optionally, the charging member 52 is provided on the end face (the tail end) of the clamping arm 10 away from the silicon carbide ceramic heating plate 20, so that the space at the tail end of the clamping arm 10 can be fully utilized.
[0052] In some embodiments, one of the clamping arms 10 is provided with a receiving portion 12 bulging toward the other clamping arm 10, and the other clamping arm 10 is provided with an avoidance groove 13 corresponding to the receiving portion 12. When the two clamping arms 10 are closed, the receiving portion 12 partially extends into the avoidance groove 13, and the battery 51 is provided inside the receiving portion 12. In this way, the space utilization rate of the clamping arm 10 without the battery 51 can be improved. While making the battery 51 have a large capacity, the overall size of the hair straightener can be prevented from being too large, which is convenient for storage and carrying.
[0053] In some embodiments, one of the clamping arms 10 is provided with a rotating groove 14 and a shaft hole 15 penetrating through opposite side walls of the rotating groove 14. The other clamping arm 10 is provided with a rotating convex portion 2217. The shaft hole 15 penetrates at least one side surface of the clamping arm 10, and a groove 16 is provided on the surface of the clamping arm 10 at the shaft hole 15. The hair straightener further includes a rotating shaft 56 and a protective cover 57. The rotating shaft 56 is installed in the shaft hole 15 and passes through the rotating convex portion 2217, so that the rotating convex portion 2217 is rotatably installed in the rotating groove 14, and the protective cover 57 covers the groove 16. In this way, during installation, the rotating convex portion 2217 can be first inserted into the rotating groove 14, then the rotating shaft 56 can be inserted into the shaft hole 15 and the hole of the rotating convex portion 2217 from the outside of the clamping arm 10, and finally the protective cover 57 can be covered on the groove 16 to cover the rotating shaft 56 inside. In this way, the assembly of the two clamping arms 10 can be facilitated.
[0054] In some embodiments, the hair straightener further includes a protection switch and a lever 54. The protection switch is electrically connected to the electronic control device 30. The lever 54 is connected to the protection switch and is located at the tail end of the clamping arm 10. In this way, when it is idle, the protection switch can be toggled to the off state through the lever 54, avoiding the situation of accidentally touching the power button 55 to start the hair straightener. And setting the lever 54 at the tail end of the clamping arm 10 can reduce the risk of accidental touch.
[0055] The above are only the preferred embodiments of the present utility model, and do not thus limit the patent scope of the present utility model. Any equivalent structural transformation made under the inventive concept of the present utility model by using the content of the specification and drawings of the present utility model, or any direct / indirect application in other related technical fields shall be included within the patent protection scope of the present utility model.
Claims
1. A hair straightening iron, characterized in that, Comprising: Two clamping arms, one ends of the two clamping arms are hinged to each other, each clamping arm is provided with a mounting position facing the other clamping arm, and the mounting positions of the two clamping arms are arranged oppositely; An electric control device, provided on the clamping arm; and Two silicon carbide ceramic heating plates, at both ends of each silicon carbide ceramic heating plate are provided with wiring parts for electrically connecting with the electric control device through the wiring parts, and the two silicon carbide ceramic heating plates are respectively arranged at the two mounting positions, so as to clamp hair jointly by the two silicon carbide ceramic heating plates when the two clamping arms are closed.
2. The hair curler according to claim 1, characterized in that, The silicon carbide ceramic heating plate comprises a heating plate body and an insulating layer provided on the surface of the heating plate body, the heating plate body is mounted at the mounting position and is provided with the wiring part, and the insulating layer of each silicon carbide ceramic heating plate is located on the side of its heating plate body facing the other silicon carbide ceramic heating plate for contacting hair through the insulating layer.
3. The hair straightening device according to claim 2, characterized in that, The insulating layer and the heating plate body are integrally sintered and formed.
4. The hair straightening iron according to claim 1, wherein, Both ends of the silicon carbide ceramic heating plate are provided with clamping protrusions, the hair straightener further comprises two mounting seats, the two mounting seats are respectively arranged at both ends of the silicon carbide ceramic heating plate and are provided with insertion holes for inserting and cooperating with the clamping protrusions, and the mounting seats are mounted on the clamping arm.
5. The hair straightening iron according to claim 1, characterized in that, The hair straightener further comprises a battery and a charging part, the battery and the charging part are both electrically connected with the electric control device, and the charging part is located on one of the clamping arms.
6. The hair straightening device according to claim 1, characterized in that On the surface of any one of the silicon carbide ceramic heating plates facing the other silicon carbide ceramic heating plate, a plurality of convex parts are formed, and the convex parts on the two silicon carbide ceramic heating plates are arranged staggeredly.
7. The hair straightening iron according to claim 6, wherein The convex parts are in a long strip shape extending along the length direction of the clamping arm and extend from one end of the silicon carbide ceramic heating plate to the other end, and the plurality of convex parts are arranged in sequence in the width direction of the clamping arm.
8. The hair curler according to claim 7, wherein, The width of the convex parts on any one of the silicon carbide ceramic heating plates gradually decreases in the direction facing the other silicon carbide ceramic heating plate.
9. The hair straightening iron according to claim 6, characterized in that, On the surface of any one of the silicon carbide ceramic heating plates facing the other silicon carbide ceramic heating plate, there are a plurality of regions, the plurality of regions all extend from one end of the silicon carbide ceramic heating plate to the other end and are arranged in sequence in the width direction of the clamping arm, each region is provided with a plurality of the convex parts, the plurality of convex parts in the same region are arranged in sequence in the length direction of the clamping arm, and the convex parts of adjacent two regions are arranged staggeredly.
10. The hair straightening iron according to claim 1, characterized in that, One of the silicon carbide ceramic heating plates forms a concave arc surface, the generatrix of the concave arc surface extends along the length direction of the clamping arm, and the other silicon carbide ceramic heating plate forms a convex arc surface adapted to the concave arc surface; Or, the silicon carbide ceramic heating plate is in a spiral shape extending along the length direction of the clamping arm, and the two silicon carbide ceramic heating plates have the same helix direction, so that when the two clamping arms are closed, the two silicon carbide ceramic heating plates are mutually engaged; Or, the surfaces of the two silicon carbide ceramic heating plates facing each other are both flat surfaces.