RU778306C - Method of producing articles from metal nitrite - Google Patents

Description

- .j- xi Mte & scjs The invention relates to the field of powder metalurgy. in 1ityosty. dl / pupil products from ny | They can be used in the refractory industry in the smelting and evaporation of metals, in the electrochemical industry as electronic materials in the electrical industry. -. "" .. .. A known method for producing products from titanium nitride by hot pressing, which comprises T1HGh% titanium nitride powder, is subjected to a pressure of 200-300 kg / cm at a temperature of 1900-2. - , ."....--WITH. -gzg, The disadvantage of this method is the need to use sophisticated equipment and large) (trienergy. Another disadvantage inherent in the method of hot pressing of titanium nitride products is a significant 6v s & carbon impregnation of the sintered product when using commonly used graphite molds, which It requires special measures to prevent this contamination (joining of conductive presses of 6 rm and ytrides, thorough coating of the inner surface of the molds with boron and aluminum nitride, etc.). hot pressing should be carried out in a protective (containing nitrogen) or neutral (argon) gas environment. There is a known method of reaction sintering, which consists in the formation of nitride fafai4aToShippered by sintering, that is, all the powders of titanium are pre-filled with nitrogen, which is allowed in front of It contains n6flvsii% titanium nitride idedes with porosity up to 13% g. In this case, titanium hydride samples were used, treated with a hydrogen adaptation length in vacuum at 400-7 (and labeled then at 950-1000 С for 1-2 hours. Nitriding was carried out, starting with, with subsequent raising the temperature and sintering at this temperature for 10-20 hours. The reaction sintering method in this case polyphase (dehydration, sintering, nitriding), trybuet long time (10-20 hours) and requires a large power expenditure. The disadvantage of this method is the need to use complex equipment, in addition, this method does not allow receiving electrodes. At the same time, they have a high porosity (up to 50% volume), which is special for titanium nitride, since porosity is one of the important xaplatcf yorystyk Шх products, and containing nitrogen more than 20% by weight. The best electrodes obtained by this method had a porosity of 30% and the nitrogen content in them was 17.5% by weight. In order to obtain better samples, the 48% percentage, nitrogen content 18.8%, the process needs to be divided into 2 stages: Hydrogenation of the samples, then nitriding. The nitriding degree of the electrodes at 1200 ° C for 90-100 hours was 18.8-19.3% by weight, which is also insufficient. The chemical stability of titanium nitride is such that 5% of titanium nitride is dissolved in a 1: 1 solution of H2S04 in 1 hour. The closest to the claimed method is a method for producing fusible non-organic compounds, which consists in 6, that titanium pressed in the form of porous samples is placed in a sealed vessel and ignited in a nitrogen atmosphere at pressures of 0.5-1000 atm. ignition is carried out by a heated electric spiral; the synthesis is due to the heat of the exothermic reaction of the metal with nitrogen. However, the existing method does not allow the floor 1 to bend products with low porosity and sufficient strength, but ensures the preservation of the shape of the pressed Products. The starting products pressed in the form of a product, with a porosity of 30%, retain the same porosity of the post synthesis. This is due to the fact. that the speed of synthesis (fractions of a second) and temperature up to 2800 ° C. ensuring the chemical transformation of the starting components into the final product, it does not provide sintering of the particles of the final product (that is, the porosity remains the same, there is no shrinkage, densification of the product) due to the fast | 10 Gd of heat sink and temperature reduction. An important qualitative indicator of tyrant nitride products is also the degree of nitriding, which ensures an increase in the melting temperature. The maximum degree of nitriding of products obtained by this method is 19.8% vei. The aim of the invention is to reduce porosity during synthesis to 8-10% by volume. and an increase in the degree of nitriding from 21.5 to 22.6 wt.%. The goal is achieved in that a mixture compressed in the form of a product containing 40-50 wt.% Of the finished product. nitri4: while titanium, before burning, an 8 mixture of titanium and titanium nitride powders is placed with the same ratio of yngredoegs and the synthesis of hydrogen t at a pressure of atm. Mixture, compressed} in the form of an article From TiT powders: ana and titanium nitride, placed in a graphite glass, pour such

the same mixture of powders of titanium and titanium nitride. The synthesis is carried out in a reactor. A tungsten helix initiates the combustion of the powder mixture surrounding the compressed form at a nitrogen pressure of 1000-5000 ytm. The mixture compressed in the form of the article ignites from the burning powder mixture surrounding it. As a result, the mixture of titanium and titanium nitride powders pressed in the form of the product lasts longer; is at high temperatures to, which promotes both complete conversion and better sintering of the particles. For the quality of the product, the process of slowly cooling the product is also important.;: V. .,.

The process proceeds for several seconds, while the temperature arising due to the exothermic reaction of the starting components during synthesis reaches 2500-4000С and is stored in the burning layer of titanium and titanium nitride powders surrounding the pressed article.

The essence of the proposed method is illustrated by the following examples:

Example T. Production of a crucible evaporator. A mixture of titanium powder grade PTM GOST in an amount of 70 g (50 wt.%) Fraction 63 d 100 and titanium nitride in an amount of 70 g {50 wt.%) Was pressed in the form of a crucible with a diameter of 30 mm and a high 70 mm at a density of 0.7 . The preform was placed in a graphite glass with a diameter of 55 mm, a height of 100 mm and filled with a mixture of titanium powders 150 g (0 wt.%) And titanium nitride 150 g (50 wt.%). A graphite beaker was placed in a reactor that was filled with nitrogen until d; aleia 1000 atm. Local ignition of the powders of titanium and titanium nitride surrounding the compressed cylinder was carried out using a tungsten spiral in an area of 5-7 mm. Synthesis lasts 3-4 seconds at a temperature of 2500 ° C. After cooling, the sample is taken out of the reactor. It has the correct geometric shape. Characterization of the obtained crucible: Porosity - 8% by volume 5; Nitrogen content - May 22.6. %

In 1 hour, in a solution of H2S04 (1: 1) at a temperature of 140 ° C, 2% of titanium nitride decomposes.

Example 2, Manufacture of refractory tube 0. A mixture of powdered titanium electrodes of 1 GOST 42 g (60% wt.) And titanium nitride powder 28 g (40% wt.) Was pressed in the form of a tube to a relative density of 0.6. Then, synthesis 5 was carried out analogously to example No. 1, at an azo pressure in the reactor of 5000 atm.

 The characteristic of the obtained refractory tube: the absorption is 13% by volume: the nitrogen content is 21.5% by mass: in 1 hour in a solution of H2SO4 (1: 1) at a temperature of 140 ° C 2 titanium nitrides decompose.

Using the proposed method for producing products from titanium nitride provides compared with the existing 5 methods the following advantages:

- the ability to obtain products with porosity from 8 to 13 (% volume) ensures the strength of the products, improves their quality:

-increase in chemical resistance due to 0 due to high temperatures developing in

2.5 times nitriding process:

-increasing the service life of products in aggregate external media is not less than 2.5 times:

Increasing the content of Bripe5 matters from 21.5 to 22.6 wt.% increases the melting point of products up to 3000 ° C, which is very important in the manufacture of crucibles - evaporators for melting and vaporizing metals (see table).

0 (56) Samsonov G, 6. Nitrides, 1969, Naukova Dumka, p. 157, 1978.

USSR copyright certificate M: 255221, class, cot 6 1/00, 1% 8.

Comparative table of contents and (arakteris yk tygly-evaporator

 -. - .. ..,, t 8

Refractoriness is determined by pouring crucible-evaporators

Formula

 METHOD FOR IMPROVING § SHY1 1 FROM NITRMDM METAL, a Titanium yarn, including the preparation of a charge, compression of a product and synthesis of a finished product by burning a compressed mixture in a nitrogen atmosphere under pressure, cast:) b нр уййАДзгйге- V

:; f riSjSfSjBUsJiii-ik, (bSSiiSSt; i ".-": iifS is:;:

In order to reduce porosity and increase the degree of nitriding, 40-50 wt.% of the finished product are added to the charge; this titanium nitride, the pressed product are placed in the resulting mixture, and the synthesis is carried out under a pressure of 1000-5000 atm. ..