JPS63190282A - Ceramic cooker for electromagnetic cooking - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ceramic cooker, particularly a ceramic pot, used in combination with an induction heater for electromagnetic cooking.

[Conventional technology]

As shown in Fig. 2, conventional ceramic pots for induction cooking are made by coating the inner and outer surfaces of the circumferential wall 2 and the inner surface of the bottom 3 of the unglazed pot body 1, so that the unglazed surface is exposed. Metal such as aluminum, titanium, silver, etc. is applied to the outer surface of the bottom part 3.
[Problems to be solved by the invention] - The above-mentioned electromagnetic cooking pot does not generate heat by applying paste, baking, gas plasma spraying, vacuum evaporation, etc. to form a heat-generating metal layer. Since the metal layer 5 was exposed, high-temperature oxidation, rusting, corrosion, etc. occurred. Also,
Moisture containing salt seeps into the main body through cracks in the salt layer on the inner surface of the pot, reaches the adhesive interface of the metal layer, where it repeatedly evaporates and condenses as the pot heats and cools. The decomposition products corroded the metal layer from the back side, causing the metal layer to come loose from the pot body.

If the metal layer becomes partially oxidized or corroded, the electric resistance becomes uneven and heat generation becomes uneven, and the local high-temperature oxidation progresses even further, causing 1-induction damage if the metal layer is accidentally heated. Partial red heat occurs before the safety device on the heater side is activated, and the metal layer of the pot cracks and burns out, rendering it unusable.

In addition, if the metal layer is partially liberated, the heat of the liberated portions will not be transmitted to the pot body, causing abnormal temperature rise, resulting in high-temperature oxidation or burnout, which will also result in uneven heat generation and empty air. ◎ Normally, the potting agent is not applied, but in this invention, the potting agent is applied not only to the inner surface of the pot body but also to the entire outer surface of the bottom. After firing the powder layer,
A heat-generating metal layer is provided on the outer surface of the bottom by depositing metal such as aluminum, titanium, silver, etc. by gas plasma spraying, vacuum evaporation, or the like.

Finally, a protective layer made of a chemically stable inorganic material by gas plasma spraying or vapor deposition is provided to cover the heat generating metal layer. Because it is enclosed between the material and the protective layer, high-temperature oxidation and corrosion hardly occur. In addition, water seeping into the pot body is blocked by the aqueous layer and does not reach the adhesive interface of the heat-generating metal layer, making it difficult for the heat-generating metal layer to separate.

The reason why the powder layer is not used as the surface protective layer is that the heat-generating metal layer cannot withstand the firing temperature of the powder. In addition, the reason why a powder layer is used as the base of the heat-generating metal layer is due to economic reasons (Example). 3, and a powder layer 4 is provided on the inner and outer surfaces thereof. A heating metal layer 5 made of aluminum coated to a thickness of 100 to 200 microns by gas plasma spraying is provided on the outer surface of the bottom part 3 in a range of 21 to 22 centimeters in diameter, and further on the outer surface. The main component is alpha alumina (αA1203) or f'L, and the thickness is 50 to 150 microns.
A protective layer 6 with a porosity of less than 20% is applied by gas plasma spraying.

- If the porosity of the protective layer 6 is too large, water may permeate and corrode the heat-generating metal layer 5. - Adjust the spraying distance of the material so that it is 20% or less. Example As mentioned above, a heat-generating metal layer 5 made of aluminum in the amount shown in Table 1 and 49% alpha. A protective layer 6 made of alumina or alpha alumina containing 3% titanium oxide was deposited. In addition, as a comparative example, a pot with only the protective layer 6 removed was manufactured. 1.5 liters of water was placed in the pots of the above embodiments and comparative examples, and the pots were placed on an induction heater for electromagnetic cooking. The temperatures at four locations A, B, O, and D on the bottom shown in the figure were measured using thermocouples, and the power consumption of the heater was measured. The results are shown in Table 2. Note that the distance between the top surface of the heater and the bottom surface of the pot was approximately 4 mm.

Table 2 From this test result, even when the pot is used properly,
In the comparative example, a high temperature of up to 500°C appears, indicating a large heat loss that is not effectively transferred to the water load in the pot and is dissipated to the outside world, whereas in the example, the surface temperature is low at a maximum of 300″C, In addition, the temperature of 500°C in the comparative example is close to the melting point of aluminum, 659°C, and even after repeated use, the heat-generating metal It can be easily inferred that the oxidation of the layer progresses considerably.Next, if the pot is left empty or the contents are burnt, the life of the pot will be shortened, but a test was conducted to investigate this. First, I put 0.5 liters of water and 2 slices of kirimochi (10 pieces) in 6 pots.
0 grams) was placed on a 1.2 kilowatt induction heater, and heating was continued until the water evaporated and the contents were burnt. Next, clean the inside of the pot, add 1.5+J liters of water, place it on the induction heater, turn on the power, and bring it to a boil.
After 0 minutes, the power was turned off, and when the temperature had cooled to 150°C, the power was turned on again, and this operation was repeated the number of times shown in Table 3. During this time, if the water in the pot decreased, I replenished it. Finally, the empty pot was placed on the induction heater, and the empty cooking was continued for the time shown in Table 3 to determine whether the pot would partially become red hot.

The above test results can be judged as follows. During the first ill burning operation, in the comparative example, deterioration of the heat-generating metal layer due to high-temperature oxidation occurred, whereas in the example, This kind of deterioration.

It almost didn't happen.

During the next repeated heating operation while containing water, in the comparative example, the above-mentioned deterioration did not grow, but the heat-generating metal layer peeled off at the adhesive interface due to moisture that permeated through the bottom of the pot and reached the heat-generating metal layer. In contrast, in the example, although the number of repeated heating was greater than in the comparative example, such deterioration, growth and peeling of the heat-generating metal layer was small.

During the final dry cooking operation, in the comparative example, the deterioration and peeling of the heat-generating metal 1 had reached its limit, so the bottom of the pot became partially red hot after 100 minutes and 70 minutes of heating, respectively, making the pot unusable. However, in the example, there was little deterioration or peeling of the heat-generating metal layer, so red heat did not occur on the bottom of the pot even after continued heating for 120 minutes. The adhesive interface of the heat-generating metal layer is effectively blocked by effectively blocking water that permeates through, and the protective layer on the outer surface effectively prevents deterioration of the heat-generating metal layer from the outer surface. I can understand.

〔Effect of the invention〕

As described above, according to the present invention, the heat lost from the surface of the heat-generating metal layer is limited, heating efficiency is increased, and...
Protects the heat-generating metal layer from its inner and outer surfaces to prevent high-temperature oxidation, rust, and
It can prevent corrosion, peeling, etc., extend its lifespan, and prevent damage due to dry cooking or scorching.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an embodiment of the present invention, FIG. 2 is a partial sectional view of a conventional example, and FIG. 3 is a bottom view showing temperature measurement points in a heating test. l... Pot body, 3... Bottom, 4... Yuyaku layer, 5
・Pa heating metal layer, 6...protective layer.

Claims (1)

[Claims] (1) Apply yam to the entire outer surface of the bottom of a ceramic cooker, provide a heat-generating metal layer on the yume on the outer surface of the bottom of the cooker, and then cover this heat-generating metal layer with a chemically stable inorganic material. A ceramic cooker for electromagnetic cooking coated with a protective layer formed by gas plasma welding or vapor deposition.