JPS59198690A - Ceramic heater and method of producing same - 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] [Industrial Application Field] The present invention provides a ceramic heater with excellent heat resistance and oxidation resistance.
and its manufacturing method.

[Prior art]

Conventionally, focusing on the high-temperature bone resistance of ceramics, attempts have been made to incorporate functional materials such as heat-generating resistors and sensors into ceramic bodies to improve heat-generating effects, sensitivity, mechanical strength, and the like.

Examples are shown in the attached FIGS. 1 to 6. That is, FIG. 1 is a schematic perspective view of a conventional plate-shaped heating element. In FIG. 1, numeral 1 means a heating resistor, and 2 means a ceramic body (thermal conductor). The heating element shown in FIG. 1 generates high-temperature heat by supplying electricity to the heating element 1, and has various uses. Of course, its shape is not limited to the illustrated plate shape, but can be used in various shapes suitable for various uses, such as a cylindrical shape, a rod shape, and a square shape.

FIG. 2 is a schematic partial cross-sectional view of a conventional glow plug for an internal combustion engine. In FIG. 2, numeral 11 is a heating element made of a high melting point metal material, 2 is the same as in FIG. 1, 6 is a retaining pipe, and 4 is a main body.

Further, FIG. 3 is a schematic cross-sectional view of a heat insulating subchamber of a conventional engine. In FIG. 5, 12 is a heater, 2 is a ceramic body, 5 is a piston, 6 is an auxiliary chamber, 7 is an electrical outlet terminal, 8 is an injection nozzle, and 9 is a body ground.

However, these conventional ceramic heaters mainly use a hot press method as the firing method. Therefore, it has been difficult to manufacture a hot plug as shown in FIG.

The hot press method will be outlined in the attached Figure 4 using a glow plug as an example. That is, FIG. 4 is a process diagram of the conventional hot press method, and in FIG.
It has the same meaning as in the figure, and 21 means a powder compact of the corresponding ceramic material.

In FIG. 4, powder molding of the ceramic material is performed in step (a), installation of 11 is performed in step (b), and step (
C), temperature 1500~1900℃, pressure 200~5o
ol'v/m'', and is heated and sintered by applying pressure from above and below to obtain a product in the form (d).

As shown in Figure 4, in the conventional hot press method, pressure is applied mainly from above and below, so the cross-sectional shape of the mounting opening of the ceramic body becomes a kamabob shape, and the body is pressed through a special holder with a circular outer shape. There were disadvantages such as the inconvenience of connecting with the metal and the possibility of stress concentration occurring in the movable parts during rapid heating, which caused them to be easily damaged. In addition, defects are likely to occur at the joint surfaces of the upper and lower molds, and cracks may occur from the joint surfaces under severe usage conditions. Furthermore, the most important drawback is that high melting point metals have high hardness, so if they are coiled, (C
) The pressurization in the process is obstructed by the heating element, and the powder compact of the ceramic material contained in this element is not sufficiently compressed. Therefore, the enclosed structure has the drawbacks of weak strength, poor thermal conductivity, and large fluctuations in temperature distribution and temperature gradient, and the shape of the heating element is also limited. The heat generation effect could not be fully demonstrated.

[Purpose of the invention]

The present invention was made to eliminate these drawbacks of the conventional techniques, and its purpose is to provide excellent heat resistance and oxidation resistance,
Another object of the present invention is to provide a ceramic heater that can achieve high temperature heating in a short time, and a method for manufacturing the same.

[Structure of the invention]

To summarize the present invention, the first invention of the present invention relates to a ceramic heater, in which a heating element made of a high melting point metal material is built into a heat conductor made of a non-oxide ceramic body. In the ceramic heater, the heating element has an arbitrary three-dimensional shape, and the heating element is embedded in powder of a corresponding ceramic material, and after molding,
It is characterized by being sintered in an inert gas at high temperature and high pressure.

The second invention of the present invention is an invention relating to a method of manufacturing a ceramic heater, which is a ceramic heater in which a heating element made of a high melting point metal material is built into a heat conductor made of a non-oxide ceramic body. A method for manufacturing a heater, which includes the steps of embedding a heating element in powder of a corresponding ceramic material, press-molding it, and sintering it in a high-temperature, high-pressure inert gas. Characterized by/doing.

In the second aspect of the invention, the three steps are essential, and additional steps may be provided. For example, after the pressure forming step, a step of performing pressureless sintering may be added.

According to the manufacturing method of the present invention, the powder compact of the ceramic material contained in the heating element made of a high-melting point metal is also sufficiently compressed under pressure, so that the heating element can be formed into any three-dimensional shape. Nomo (7) Teyoi. For example, it may be a ceramic heater product in the form of a spiral coil, for which the conventional hot pressing method is insufficient. An example is shown in FIG. That is, FIG. 5 is a schematic diagram of an example of the shape of a heating element in a ceramic heater according to the present invention. In FIGS. 5(b) and 5(b), numerals 11 and 2 have the same meanings as in FIG. 2.

The non-oxide type ceramic used in the present invention includes the first to
Any ceramic can be used as long as it can be used in the conventional ceramic heater shown in Figure 3. Examples include silicon nitride and silicon carbide, but silicon nitride yarn is the most suitable. .

The refractory metal material used in the present invention may be any refractory metal or alloy that can be used for the corresponding purpose. Examples include tungsten, molybdenum, tantalum, rhenium and their alloys.

Next, the manufacturing method of the present invention will be specifically explained with reference to the attached FIG. 6. In other words, FIG. 6 is a process diagram of one example of manufacturing a ceramic heater according to the present invention. In Figure 6,
Reference numerals 11 and 21 have the same meanings as in FIG. 4, 22 is a ceramic material powder, and 23 is an elastic body such as a rubber material.

Further, 60 is a ceramic heater semi-finished product, and 40 is a sintering furnace.

Step (a) in FIG. 6 is a powder molding step, in which a container is filled with ceramic material powder 22 and heating element 11, and
Pressurization of about 10 Kg/cni' (usually air pressure)
I do. In step (b), the molded body obtained in steps (,) is shaped by processing and removing the periphery.

Next, firing is performed in step (c) with or without pressureless sintering as desired.

In step (C), the pressurizing and heating device is filled with an inert gas, such as argon gas, and the temperature in this device is usually 1500 to 1900°C and 100°C.
Sintering is carried out at a pressure of 000 Kg/'cyd'.

As shown in step (C) of FIG. 6, in the method of the present invention, pressure is applied from all sides with inert gas. Therefore, even if the heating element has a spiral coil shape or a more complicated shape, the powder compact of the ceramic material contained therein is compressed by applying pressure from at least one direction. Therefore, the lack of compression unlike in the conventional hot pressing method does not occur, and the conventional drawbacks can be overcome.

In addition, unlike the conventional hot press method, sintering is performed mainly by vertical pressure, so the product can be circular in shape and can be attached tightly. On the other hand, there is also the advantage that a ceramic heater having a complicated shape as shown in FIG. 3 can be easily manufactured.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example A tungsten wire was molded into the shape shown in FIG. 5(a), and using silicon nitride powder, powder molding was performed by applying water pressure according to the method shown in FIG.
A glow plug was produced by sintering at q/d.

This was compared with a glow plug made using the conventional normal pressure firing method. Conventional products require 20 seconds to heat up when used,
The temperature only reached 700°C. On the other hand, the one obtained in Example 1 was heated to j-(, 1200℃
can be reached.

Similar results were obtained when other high melting point metal materials were used.

〔Effect of the invention〕

As explained above, the ceramic heater of the present invention has
It has excellent heat resistance and oxidation resistance, has improved mechanical strength due to the fact that the ceramic material is compressed, and also has the advantage of being able to reach high temperatures from room temperature at high speed.

Further, during its manufacture, there is no need to pay attention to the shape of the heat generating element, and a remarkable effect can be achieved in that it can meet a wide range of usage conditions.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view of a conventional plate-shaped heating element, Fig. 2 is a schematic partial cross-sectional view of a conventional glow plug for an internal combustion engine, Fig. 3 is a schematic cross-sectional view of a heat-insulating subchamber of a conventional engine, and Fig. 4 is a schematic cross-sectional view of a conventional glow plug for an internal combustion engine. The figure is a process diagram of a conventional hot press method, Figure 5 is a schematic diagram of an example of the shape of a heating element in a ceramic heater according to the present invention, and Figure 6 is a schematic diagram of an example of the shape of a heating element in a ceramic heater according to the present invention.
The figure is a diagram showing one example of manufacturing a ceramic heater according to the present invention. 1: Heat generating resistor 11: Old high melting point metal element) 12: Heater coil 2: Ceramic body 5: Piston 6: Sub-chamber 8: Injection nozzle 21: Powder compact of ceramic material 22: Powder compact of ceramic material Powder 23:
Elastic body Li: Ceramic heater semi-finished product 40: Sintering furnace Patent applicant Representative of Isuy Automobile Co., Ltd. Hirotoshi Nakamoto Bengami Sho Fig. 2// Fig. 3 Fig. 4 Fig. 6

Claims (1)

[Claims] 1. A ceramic heater in which a heating element made of a high-melting point metal material is built into a heat conductor made of a non-oxide ceramic body, wherein the heating element has an arbitrary three-dimensional shape. 1. A ceramic heater characterized in that the heating element is embedded in powder of a corresponding ceramic material, molded and then sintered in a high-temperature, high-pressure inert gas.
8 2. The ceramic heater according to claim 1, wherein the heating element has a spiral coil shape. In the method of manufacturing a built-in ceramic heater, each of the steps of embedding the heating element in powder of a corresponding ceramic material, press-molding it, and sintering it in a high-temperature, high-pressure inert gas 1. A method for manufacturing a ceramic heater, comprising the steps of: 4. The method for manufacturing a ceramic heater according to claim 3, further comprising adding a step of pressureless sintering after the pressure forming step.