JPH06116701A - Thermally sprayed heating element for composite particle and its production - Google Patents

Abstract

PURPOSE:To provide the thermally sprayed heating element which is inexpensive and is a stable and high additive value by thermally spraying conductive composite particles to a base material. CONSTITUTION:The composite particles consisting of insulating or semiconductor particles coated with an conductive material or the composite particles consisting of the conductive particles coated with a insulating or conductive material are thermally sprayed onto the surface of the base material which is an insulator to form the thermally sprayed film to be electrically heated, by which the thermally sprayed heating element is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal spray heating element for energizing and generating heat, and more particularly to a thermal spray heating element obtained by thermal spraying composite particles obtained by coating a conductive material, an insulating material or a semiconductor material into respective particles.

[0002]

2. Description of the Related Art Conventional heating elements are formed by applying processing techniques such as coating, sintering, sheathing, vapor deposition, and thermal spraying of metal, carbon, conductive ceramics, and a mixture of the conductive material and insulating material according to their characteristics. It was manufactured. However, when forming a heating element by thermal spraying of metal, for example, the resistivity is usually on the order of 10 ⁻⁴ , so to obtain a predetermined resistance value, the length of the heating element is lengthened (using a jig or the like). Moreover, it was necessary to reduce the cross-sectional area, but there was a problem that the power density was particularly small because the thickness was limited. Further, the metal spray material is expensive, about 10,000 yen / kg. On the other hand, conductive ceramics such as TiO ₂ have problems in electrical characteristics and durability.

Documents disclosing such a technique include Japanese Patent Laid-Open No. 59-94394 and Japanese Patent Publication No. 2-56425. On the other hand, there is a method for forming a metal-ceramic composite coating in Japanese Patent Laid-Open No. 64-8260. This is mainly a method of manufacturing a composite coating, and since electroless plating is the main component, it is only a limited metal and conductive ceramics etc. are not possible. There is concern about the impact. Further, the evaluation of the characteristics of the heating element by applying electric power is also a drawback.

[0004]

[SUMMARY OF THE INVENTION] is to establish a technique for the technical essence apparent resistivity of the can be controlled to 10 ^-3 to 10 ^0. When this technique is achieved, a predetermined resistance value can be easily obtained because the three elements of resistivity, length, and cross-sectional area can be arbitrarily changed. Further, in order to be electrically stable, it is important that the conductive substance is continuous, and it is necessary for uniform heating that the ratios thereof are approximately the same from a macro perspective. Therefore, it is an object of the present invention to provide a high value-added thermal spray heating element capable of satisfying the above-mentioned various requirements and a manufacturing method thereof.

[0005]

In order to solve the above problems, in the present invention, an insulating base material and a composite particle composed of insulating or semiconductor particles coated with a conductive substance on the surface of the base material are sprayed. A thermal spray heating element consisting of the formed thermal spray coating, or an insulating base material and a thermal spray coating formed by spraying composite particles consisting of electrically conductive particles coated with an insulating or semiconductor substance on the surface of the base material. This is a thermal spray heating element.

Further, in the present invention, on the surface of the base material of the insulator,
Composite particles consisting of insulating or semiconductor particles coated with a conductive material, or composite particles consisting of conductive particles coated with an insulating or semiconductor material are sprayed to form a sprayed coating that produces heat when energized. This is a method for manufacturing a thermal spray heating element. As described above, in the present invention, a heat-generating body is formed by applying electric power to the thermal spray coating formed by thermal spraying the composite material (particles) obtained by coating the surface of the ceramic particles with the conductive material.

In the above, the coating film can be manufactured by plating, mechanical alloying, sputtering, etc., and the film thickness can be changed to about 0.1 μm to 20 μm. Conductive substances include metals, alloys and B ₄ C, TiC, W
C, ZrC, TiB ₂ , Mo ₂ B ₅ , TiN, AlN,
Conductive ceramics such as MoSi ₂ and SnO, Pb
Conductive oxides such as O ₂ , ReO ₂ and V ₂ O ₃ can be used. The particle size of the insulating or semiconductor particles is about 10 to 75 μm, and the insulating material (particles) is Al ₂ O ₃ or TiO _2.
2 , ZrO ₂ , CaO, Y ₂ O ₃ , Cr ₂ O ₃ , Mg
O, MnO, etc., and their respective mixtures, and the semiconductor material is Sn, Se, Te, SiC, GaN, ZnS, P.
For example, bS.

[0008]

Function: For example, 30μ coated with 1μm metal
Assuming that the film thickness is 100 μm in the thermal spraying process using m composite particles, 30 μm particles are reduced to 1/2 and laminated to form a 15 μm lamella, and 6 particles are arranged in the radial direction. For example, if only the coating layer is taken, the total film thickness becomes 6 μm. This is about 1 compared to the case of metal alone
This means that a resistance value that is seven times higher can be obtained. Also, since the coating layer is three-dimensionally continuous, it is electrically stable,
Macroscopically, the ratio of the conductive material is about the same, and uniform heating is performed. Further, the apparent resistivity also changes by changing the coating film thickness.

On the other hand, the thermal spray material of metal is expensive at about 10,000 yen / kg, but since inexpensive ceramic is used as the core,
The proportion of metal is small and the cost is low. Therefore, without performing complicated thermal spraying, the thermal spraying of the composite particles makes it possible to easily obtain a heater of any shape that can be used in a household power source.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 A mechanical alloying method was used in which particles of Al ₂ O ₃ + 2.3TiO ₂ having an average particle diameter of 27.5 μm were mixed with Ni powder having an average particle diameter of 1.3 μm as a conductive material at a ratio of 10: 3 wt%. I coated. Composite particles having a Ni film thickness of about 2 μm were obtained. 25A SUS3 which had already been insulation-treated with Al ₂ O ₃ by plasma spraying method for these composite particles
04, a thermal spray heating element having a film thickness of 80 μm was formed on the outer surface having a length of 10 cm.

FIG. 1 shows a heating device for measuring resistivity using the thermal spray heating element of the composite particles. In FIG. 1, a thermal spray heating element 1 is formed on a main body (SUS304) 2,
The electrodes 3 are attached to both ends of the thermal spray heating element 1, and the ammeter 5
Is connected to the slidac (100V, 10A) 4 via. A thermocouple 6 is installed at the center of the thermal spray heating element 1 to measure the temperature.

When a voltage of 50 V was applied to the electrode 3 attached to the thermal spray heating element 1 by the sliderac 4, a current value of 10 A flowed, and the resistance of the heating element was 5 Ω by the usual method.
Met. From this, the resistivity is calculated to be 0.04Ω
-Cm, and an increase in apparent resistivity about 100 times that of Ni powder alone was obtained.

Next, 5 W with a slidac on the thermal spray heating element.
(5.0V, 1.0A) 20W (10.0V, 2.0
The temperature rising heating experiment of A) was implemented. The result is shown in FIG. 45 ° C. with a power density of 0.05 W / cm ² in 30 minutes,
It was 75 ° C. at 0.2 W / cm ² . Room temperature 28.1
It was ℃. The temperature was measured with a thermocouple 6 attached to the surface of the thermal spray heating element.

[0014]

According to the present invention, the following effects can be obtained. (1) In the present invention, the apparent resistivity of this coating can be arbitrarily controlled by subjecting composite particles coated with a conductive material to thermal spraying. Therefore, the heater can be easily obtained with the household power source, and the range of use is expanded. (2) This coating is electrically stable because it is three-dimensionally continuous with a conductive substance, and is uniformly heated macroscopically. (3) The cost of the composite particles has been reduced by using inexpensive insulating particles for the core. (4) The apparent resistivity increased, resulting in high resistance. Therefore, the heater can be made compact.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a heating experimental apparatus using a thermal spray heating element of the present invention.

FIG. 2 is a graph showing the surface temperature of a thermal spray heating element.

[Explanation of symbols]

1: Thermal spray heating element, 2: Main body (SUS304), 3: Electrode, 4: Slidac, 5: Ammeter, 6: Thermocouple

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Murata 11-1 Haneda-Asahi-cho, Ota-ku, Tokyo Inside EBARA CORPORATION

Claims (3)

[Claims] 1. A thermal spray heating element comprising an insulating base material and a thermal spray coating formed by thermal spraying composite particles composed of insulating or semiconductor particles coated with a conductive substance on the surface of the insulating base material. 2. A thermal spray heating element comprising an insulating base material and a thermal spray coating formed by thermal spraying composite particles comprising conductive particles obtained by coating an insulating or semiconductor material on the surface of the insulating base material. 3. A conductive particle-coated composite particle composed of insulating or semiconductor particles coated with a conductive material, or a composite particle composed of conductive particles coated with an insulating or semiconductor material is sprayed on the surface of a base material of an insulator to generate heat when energized. A method for manufacturing a composite particle thermal spray heating element, which comprises forming a thermal spray coating.