DE1671652B2 - PROCESS FOR MANUFACTURING A FIRE-RESISTANT BODY FROM GRAINY SILICON CARBIDE WITH SILICON OXYNITRIDE BOND - Google Patents

Description

J 671 652

atetTffÄ fStSaS Z / f Γ * ■ The ^{test was carried out in a} chamotte capsule

Subsequent heating to? 450 ° C and n ^ h ' ^ Ψ * ™haben *** tunnel kiln fired at SK 15/16,

repeated holding for a period of 5 hours ? ^The J ^e * ^g ™ ^PrÜflm S ^{showed an} 8 ^ute strength

The fired rod showed a st "Festinkeil 5 rt *" for? ^ ^ ^Essential dnhdt-

The Bruchfiäche was uniform erau ^tesü ^ ^{EIL 5 hch} fau, said core having a diameter

In addition to Sil, v; “™ ·, μ ^vo °. ^{20 bls 30} η ™ «which is lighter than the edge part.

and little silicon nitnT very wemg, äSÄ? ^ ^ - Γ ^ ¹ ^ ^{next to} Siüziumoxynitrid

and a small amount of Cristobal! remaining silicon and little cristobalite.

Example II "Example III

From the following mass ^was a test piece prepared in Example I Silicon _on? ^ie ₁ ^ser _JU ^{Prob? The rod was placed in} a chamber furnace heated with molybdenum-silicon small ac fioVn- ' ⁸ ° disihzidheizleitern with a

SSS ^ ^{μ 20 15 Tempe} T ^{m FROM 1350} ° ^{C a} S ^esc raised. The furnace

^X atmosphere was air. It was in for 5 hours

; ⁴ fired in this furnace atmosphere.

^ äs: α-'γα

Total amount ₁₀₅ 2 20 with the exception of a slight hem on the edge

a cylinder with a Twi, ™, "'became evenly gray. In addition to silicon

50 mm and a height " VnT ^^^ ^ SÄ« * ^ ^{nkht Um} ^ ^{set2tes Silizi} - ^d

Claims (3)

1 2 This object is achieved according to the invention by claims: that the body before burning in the oxygen and nitrogen contained atmosphere 1. Process for the production of a refractory in a practically oxygen-free atmosphere on 1250 bodies made of granular silicon carbide with silicon from 5 to 1500 ⁰ C is heated. oxynitride bond, according to which the silicon carbide In the known method in which the mixed with 3 to 20% fine-grain silicon, offset nitrogen-containing compounds added to the body and then formed at one, it has been shown that the in dation on the individual silicon grains ^{at the oxy temperature in the range of 1250 to 1500 0 C} The nitrogen and oxygen-containing atmosphere layer of silicon dioxide is so dense that the sphere is already burned, as a result of which a relatively thin layer marks every further one, so that the body prevents a reaction before burning. At temperatures above in the oxygen and nitrogen of the melting point of silicon and containing lie Siliziumoxynitridbildung which is heated before other Reaksphäre at 1250-1500 ⁰ C at atmospheric in practically oxygen-free atmos-. 15 has the advantage of bursting these thin skins, 2. The method according to claim 1, characterized in that the individual silicon grains are drawn together that substances are added to the offset, melt. As a result, the gases which do not react with the nitrogen and oxygen are split off sufficiently quickly during the heating up with the body, and the atmosphere prevents the heating and burning in an oxygen-containing silicon oxynitride formation as desired.
Atmosphere takes place. The method according to the invention can be 3. The method according to claim 1, characterized in that the offset is characterized by substances that the body is added to at least one which, during heating to 1250 ⁰ C, split off an oxygen-containing atmosphere that does not react with the body, and a sphere, for example air, having furnace 25 that the heating and burning in an oxygen-rapid manner is used. and nitrogenous atmosphere takes place. This procedure must not be confused with the procedure according to the German interpretative document 1182130, in which nitrogen is split off, ic: 30 to the nitrogen atmosphere necessary for the formation \ on The invention relates to a method for producing silicon oxynitride required to come. Much of a refractory body made of granular silicon - it is more about the body a layer of carbide with silicon oxynitride bond, according to which it is formed from gases that do not react with it, silicon carbide with 3 to 20% fine-grain silicon which mixes the immediate entry of the undesirable sauce, the body is shaped and then at 35 substance prevent, so that the formation of a silicon of a temperature in the range of 1250 to 1500 ⁰ C dioxide layer on the silicon grains cannot take place in an atmosphere containing nitrogen and oxygen.
Sphere is burned. Another way of achieving the In German Patents 921,559 and method of the invention is that 929,656, 2,752,258, and 40 of the body heated in the USA. patent in one of at least 1250 ⁰ C aufin "Material and Methods", Nov. 1954, p 83, , an oxygen-containing atmosphere, in which refractory bodies made of silicon carbide are described, for example air, having furnaces which are bonded by silicon nitride. Becomes her. In this case, the temperature of position, makes such, bound with silicon nitride about 1250 ⁰ C for the fact that because of limited silicon carbide, it is necessary, the oxygen-containing in 45 atmosphere can occur no silica consisting essentially of silicon carbide and silicon loading, which in the above- the manner discussed, standing mass has a harmful effect if it is permanently maintained,
to burn in a nitrogen atmosphere. The following is an example for each of the three From the German Auslegeschrift 1182 130 it is possible to carry out the specified also already known that silicon carbide can be reproduced with the silicon method according to the invention, to bind oxynitride, one being the starting material Adds cyanamide compounds. The one in the Zer example I Settlement of the cyanamide compounds released
Nitrogen and that from the furnace atmosphere come from a mass of parts by weight Oxygen reacts with the silicon 711 55 silicon carbide 80 Silicon oxynitride. Such masses can be in silicon, smaller than 60μΐη 20 usual kiln in a nitrogen and oxygen dextrin + totanine 1 burning atmosphere. The water process 4 however, requires the addition of nitrogenous Compounds that prove to be disadvantageous in this respect, 60 total amount 105 As silicon still remaining in the finished bodies, a rod with the dimensions 120 × 120 × 15 mm and, in particular, cristobalite in the outer layer was produced. The rod was left with a pressure of. 800 kg / cm ² pressed. He was then in the dry The invention has the object of providing a dried oven at 105 ⁰ C. The stick was scraped in a process in which the silicon oxynitride is bonded to a tube furnace according to the following firing scheme, without being fired: Mixture of nitrogen-containing compounds added. Heating to 138O ⁰ C in one for about three hours Need to become. Normal quality nitrogen atmosphere with 1.5%