METHOD FOR PREPARING CERAMIC STRIP HEATER WITH IMPROVED FIXING EFFECT

Abstract

A method for improving fixing effect of a ceramic strip heater is performed as follows. An electrode material is applied to each end of an upper surface of an alumina ceramic substrate by printing, followed by drying and sintering to form an electrode. A heating paste is applied to the upper surface of the alumina ceramic substrate by printing to connect two electrodes on both ends of the alumina ceramic substrate, followed by drying and sintering to form a heating filament. A glass paste is applied to a lower surface of the alumina ceramic substrate by printing, followed by drying and sintering to form a first glass layer. Another glass paste is applied onto the heating paste by printing, followed by drying and sintering to form a second glass layer, so as to arrive at the ceramic strip heater.

Claims

1. A method for preparing a ceramic strip heater, comprising: (S1) applying an electrode material on each of two ends of an upper surface of an alumina ceramic substrate by printing, followed by drying and sintering to form an electrode; (S2) applying a heating paste onto the upper surface of the alumina ceramic substrate by printing to connect two electrodes on the two ends of the upper surface of the alumina ceramic substrate, followed by drying and sintering to form a heating filament; (S3) applying a first glass paste on a lower surface of the alumina ceramic substrate by printing, followed by drying and sintering to form a first glass layer; and (S4) applying a second glass paste on the heating filament by printing, followed by drying and sintering to form a second glass layer, so as to produce the ceramic strip heater.

2. The method of claim 1, wherein in step (S1), a main component of the electrode material is AgPt.

3. The method of claim 2, wherein in step (S1), a temperature of the drying is 100-150 C., and a temperature of the sintering is 830-880 C.

4. The method of claim 1, wherein in step (S2), a main component of the heating paste is AgPt; and a temperature coefficient of resistance (TCR) of the heating paste is 200-600 ppm/ C.

5. The method of claim 4, wherein in step (S2), a temperature of the drying is 100-150 C., and a temperature of the sintering is 830-880 C.

6. The method of claim 1, wherein in step (S3), a solid part of the first glass paste comprises higher than 40 wt. % of Al.sub.2O.sub.3, 18 wt. % of SiO.sub.2, 15 wt. % of B.sub.2O.sub.3, 5 wt. % of ZnO and 15 wt. % of BaO; and a solid content of the first glass paste is 70 wt. %; and in step (S4), a solid part of the second glass paste comprises higher than 40 wt. % of Al.sub.2O.sub.3, 18 wt. % of SiO.sub.2, 15 wt. % of B.sub.2O.sub.3, 5 wt. % of ZnO and 15 wt. % of BaO; and a solid content of the second glass paste is 70 wt. %.

7. The method of claim 6, wherein in steps (S3)-(S4), a temperature of the drying is 100-150 C., and a temperature of the sintering is 800-860 C.

8. The method of claim 7, wherein in step (S3), the first glass paste is applied in 1 layer by a 325-mesh 40-m screen, and a thickness of the first glass layer is 8-10 m.

9. The method of claim 7, wherein in step (S4), the second glass paste is applied in 5-7 layers by a 200-mesh 40-82 m screen; and a total thickness of the second glass layer is 60-80 m.

10. The method of claim 1, wherein in step (S4), the first glass layer is placed on a support during the sintering of the second glass layer.

11. The method of claim 10, wherein the support comprises a base plate and at least two beams; and the at least two beams are arranged in parallel at upper surfaces of two ends of the base plate, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a structural diagram of a ceramic strip heater according to an embodiment of the present disclosure.

[0029] FIG. 2 is a structural diagram of a support according to an embodiment of the present disclosure.

[0030] In Figures: 1, first glass layer; 2, alumina ceramic substrate; 3, electrode; 4, heating filament; 5, second glass layer; 6, support; 7, base plate; and 8, beam.

DETAILED DESCRIPTION OF EMBODIMENTS

[0031] The present disclosure provides a method for preparing a ceramic strip heater with improved fixing effect (as shown in FIG. 1), including the following steps. [0032] (S1) An electrode material is applied to each of two ends of an upper surface of an alumina ceramic substrate 2 by printing, where a main component of the electrode material is AgPt. The electrode material is a paste with uniform color and good weldability. After the printing, the alumina ceramic substrate 2 is dried in a drying oven at 100-150 C., and sintered at 830-880 C. in a sintering furnace to form an electrode 3, which is silvery and glossy. [0033] (S2) A heating paste is applied onto the upper surface of the alumina ceramic substrate 2 by printing to connect two electrodes 3 on the two ends of the upper surface of the alumina ceramic substrate 2. A main component of the heating paste is AgPt, and the heating paste is uniform color paste. A temperature coefficient of resistance (TCR) of the heating paste is 200-600 ppm/ C. After that, the alumina ceramic substrate 2 is dried in the drying oven at 100-150 C., and sintered at 830-880 C. in the sintering furnace to form a heating filament 4, which is configured to generate heat after energization. The heating filament 4 is examined to ensure that there is no short circuit and open circuit at the surface. In addition, a resistance of the heating filament 4 is detected by a resistance tester. [0034] (S3) A first glass paste is applied onto a lower surface of the alumina ceramic substrate 2 by printing to slow down heat dissipation from the lower surface of the alumina ceramic substrate 2, where a solid part of the first glass paste includes higher than 40 wt. % of Al.sub.2O.sub.3, 18 wt. % of SiO.sub.2, 15 wt. % of B.sub.2O.sub.3, 5 wt. % of ZnO and 15 wt. % of BaO, and a solid content of the first glass paste is 70 wt. %. The first glass paste is applied in 1 layer by a 325-mesh 40-m screen, and a thickness of the first glass layer is 8-10 m. After printing, the alumina ceramic substrate 2 is placed in the 100-150 C. drying box to dry, followed by sintering in the sintering furnace to form a first glass layer 1, where a temperature of the sintering is 800-860 C. After sintering, the first glass layer 1 is uniform and transparent. Specifically, for the formation of the first glass layer 1, an edge of the alumina ceramic substrate 2 has a protective edge with a width of 4 mm which is not coated with the first glass paste, that is, not the whole lower surface of the alumina ceramic substrate 2 is coated with the first glass paste. [0035] (S4) A second glass paste is applied onto the heating paste in 5-7 layers by printing for insulation and heat conduction. A solid part of the second glass paste is the same as the first glass paste in step (S3). The second glass paste is applied in 5-7 layers by using a 200-mesh 40-m screen, and a total thickness of the second glass layer is 60-80 m. After that, the alumina ceramic substrate 2 is dried in the drying oven at 100-150 C., and sintered at 800-860 C. in the sintering furnace to form a second glass layer 5.

[0036] In this embodiment, in order to avoid surface quality impact caused by the first glass layer 1 directly touching a kiln roller conveyor, in step (S4), the first glass layer 1 is placed on a support 6 during the sintering of the second glass layer 5. The support 6 includes a base plate 7 and at least two beams 8. Two beams 8 are arranged in parallel at upper surfaces of two ends of the base plate 7, respectively. An edge of each of two ends of the alumina ceramic substrate 2 has a protective edge with a width of 4 mm which is not coated with the second glass paste. A distance between the two beams 8 is larger than a length of the first glass layer 1. Specifically, during the sintering, a bottom surface of the base plate 7 is placed on the kiln roller conveyor, and the protective edge is placed on the two beams 8, so as to prevent the first glass layer 1 from contacting the support 6, which will affect the surface quality of the first glass layer 1 during the sintering. In other embodiments, the two beams 8 are arranged in parallel at the upper surfaces of two ends of the base plate 7. The edge of each of two ends of the alumina ceramic substrate 2 has a protective edge with a width of 4 mm which is not coated with the second glass paste, respectively. The distance between the two beams 8 is larger than a width of the first glass layer 1. In other embodiments, the two beams 8 are arranged in parallel at the two ends of the base plate 7 or the upper surfaces of two ends of the base plate 7. An edge around the alumina ceramic substrate 2 has a protective edge with a width of 4 mm which is not coated with the second glass paste.