JPH0634276A - Device for pressurized self-combustion synthesis oxidizing atmosphere - Google Patents

Abstract

PURPOSE:To use a pressurized self-combustion synthesis method to synthesize an oxidized ceramic by using an oxidation-resistant porous ceramic material as the material for an insulating cylindrical furnace and an insulating hearth and an oxidation-resistant alloy of platinum and rhodium as the material for an ignition heater and a heating heater. CONSTITUTION:Both an insulating cylindrical furnace 6 and an insulating hearth 8 are formed of an oxidation-resistant porous ceramic material and a combustion furnace is built by mounting the insulating cylindrical furnace 6 and the insulating hearth 8 on a furnace base 9. On the insulating hearth 8 a specimen stand 10 is provided as a means on which to place a material to be processed. An ignition heater 11 and a heating heater 12 both made of an oxidation-resistant alloy of platinum and rhodium are provided; the specimen stand 10 is fitted with the heating heater 12 and over the material to be processed the ignition heater 11 is placed. Through a tubular entry for pressurized gas an argon gas mixture or a nitrogen gas mixture, in either case with an oxygen concentration of up to a maximum of 20%, is injected under pressure up to a pressure of 2,000kg/cm<2>. By applying power to the ignition heater 11 from ignition-heater electrodes 13 the material to be processed is heated and ignited in a manner of self-combustion. When the specimen is hard to ignite, power is applied to the heating heater 12 from heating-heater electrodes 14 so as to urge the start of the self- combustion by preheating the specimen. This device functions as a pressure-isotropic press using a hot oxidizing atmosphere and enables sintering of specimens under pressure at 1,600 deg.C and 2,000kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a ceramics synthesizing apparatus by a pressure self-combustion synthesis method, and more particularly to an apparatus for synthesizing oxide ceramics by a pressure self-combustion synthesis method in an oxidizing atmosphere. .

[0002]

2. Description of the Related Art The self-combustion synthesis method, in which material powder is self-combusted to synthesize ceramics, has attracted attention as a promising method for producing ceramics. In particular, the pressurized self-combustion synthesis method, in which the material powder is self-combusted while being pressurized in a pressure gas medium, has the advantage of being able to produce ceramics with even higher density.

In this pressurized self-combustion synthesis method, it is possible to control the stability of the ceramic material and the characteristics of the produced ceramic by using various pressure gas media such as argon, nitrogen and oxygen. Atmosphere control below has become an important technical issue.

[0004]

However, as the apparatus for carrying out the pressurized self-combustion synthesis method, a hot hot isostatic press modified is mainly used. Since boron nitride or the like is used for the reaction vessel and graphite or the like is used for the heater, an inert gas such as argon or nitrogen is used as the pressure gas medium. Therefore, the furnace chamber has a reducing atmosphere and has been used for manufacturing non-oxide ceramics and the like.

With such a pressurized self-combustion synthesizer, it has been impossible to manufacture oxide ceramics or the like that are sintered in an oxidizing atmosphere.

An object of the present invention is to provide an apparatus for synthesizing oxide ceramics by a pressure self-combustion synthesis method in an oxidizing atmosphere.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a pressurized self-combustion synthesis apparatus in which a pressure-resistant container is provided with an insulating furnace tube and an insulating hearth to define a furnace chamber, and a heater is provided in the furnace chamber. An oxidizing atmosphere pressurized self-combustion synthesizer characterized in that the adiabatic furnace barrel and adiabatic hearth are made of oxidation-resistant porous ceramics, and the ignition heater and the heating heater are made of an oxidation-resistant platinum-rhodium alloy I will provide a.

[0008]

In the apparatus of the present invention, the heat insulating furnace tube and the heat insulating hearth are made of oxidation resistant porous oxide ceramics, and the ignition heater and the heating heater are made of the oxidation resistant platinum-rhodium alloy. Oxygen mixed gas can be used as a pressure gas medium, and pressurized self-combustion synthesis of oxide ceramics is possible by making the furnace chamber an oxidizing atmosphere.

The oxygen concentration of the pressurized gas medium which can be used is preferably 0-20%.

Further, the heat insulating cylinder and the hearth heat insulating material use a porous oxide ceramic material having heat resistance and thermal shock resistance to prevent the high heat during self-combustion from radiating to the pressure vessel side. In addition, it responds to a high heat attack due to a rapid temperature rise during self-combustion.

The heater can heat the furnace chamber to a high temperature. The furnace chamber temperature that can be used is preferably 0.
-1600 ° C.

The apparatus of the present invention can naturally use an inert gas such as argon or nitrogen as a pressure medium due to its structure and material, and it is possible to use a conventional carbide,
It can also be used for pressurized self-combustion synthesis of borides and nitride ceramics.

The apparatus of the present invention is used as a normal hot isostatic press in an oxidizing atmosphere at 1600 ° C. and 2000 kg / cm ^2.
It is also possible to pressure sinter the sample.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An oxidizing atmosphere pressurized self-combustion synthesizer according to the present invention will be described in detail below with reference to FIG.

A heat insulation cylinder (6) and a heat insulation hearth (8) are provided on a furnace table (9) in the pressure vessel (1) to define a combustion furnace. A sample table (10) is provided on the hearth, and an object to be processed is placed thereon. A heating heater (12) is attached to the sample stage, and an ignition heater (11) is attached above the object to be processed. Heaters and ignition heaters include furnace base and lower lid (4)
Are connected to the heating heater electrode (14) and the ignition heater electrode (13) respectively. A thermocouple (15) for measuring the sample temperature is provided in contact with the object to be treated, a thermocouple (16) for controlling the heater is provided in the center of the furnace chamber, and a temperature display controller ( (Not shown).

In the furnace chamber in which the object to be treated is located, a mixed argon gas or a mixed nitrogen gas having an oxygen concentration of up to 20% is added through a pressurized gas introduction pipe penetrating the lower lid and the furnace base.
Press up to kg / cm ² . By energizing the ignition heater from the ignition heater electrode to heat the object to be processed,
Performs self-combustion ignition. In the case of a sample that is difficult to ignite (or when the standard heat of formation and the adiabatic temperature are both low), the heater is energized from the heating heater electrode to preheat the sample to accelerate the start of self-combustion. During this time, by measuring the sample temperature with a thermocouple for measuring the sample temperature,
The sample temperature during the preheating is controlled. Furthermore, when self-combustion starts, the sample temperature rises sharply, confirming the start of the synthesis reaction.

[0017]

EFFECT OF THE INVENTION The apparatus according to the present invention is provided with an oxidizing atmosphere in the furnace chamber of the pressurized self-combusting ceramics synthesis apparatus,
The conventional apparatus has the advantage that it is possible to perform self-combustion under pressure in an oxidizing atmosphere while being unable to synthesize oxide ceramics, and to manufacture high-quality oxide ceramics.

Further, by making the inside of the furnace chamber in an oxidizing atmosphere, it is possible to perform the self-combustion synthesis under the oxidizing atmosphere by the reaction between oxygen in the pressurized gas and the object to be treated. The range of synthetic reactions can also be expanded to obtain a wider variety of products.

The apparatus of the present invention can naturally use an inert gas such as argon or nitrogen as a pressure gas medium due to its structure and material, and it is possible to use conventional carbides, borides, nitride ceramics, etc. It can also be used for pressurized self-combustion synthesis of.

It is also possible to press-sinter the sample at a maximum temperature of 1600 ° C. and 2000 kg / cm ² as a normal hot isostatic press in an oxidizing atmosphere.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an oxidizing atmosphere pressurized self-combustion synthesizer showing an embodiment according to the present invention.

[Explanation of symbols]

 1 Pressure Vessel 2 Yoke Frame 3 Upper Lid 4 Lower Lid 5 Gas Seal 6 Heat Insulation Cylinder 7 Heat Insulation Cylinder Support Casing 8 Heat Insulation Hearth 9 Heat Sink 10 Sample Stage 11 Ignition Heater 12 Heating Heater 13 Ignition Heater Electrode 14 Heating Heater Electrode 15 For Measuring Sample Temperature Thermocouple 16 Thermocouple for heating heater control 17 Thermocouple lead wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F27D 11/02 A 8222-4K

Claims (1)

[Claims] 1. A pressurized self-combustion synthesizer in which a pressure-resistant container is provided with an adiabatic furnace barrel and an adiabatic hearth to define a furnace chamber, and a heater is provided in the furnace chamber. Is composed of an oxidation-resistant porous ceramics, and the ignition heater and the heating heater are made of an oxidation-resistant platinum-rhodium alloy.