Features of thermogradient gasphase furnaces of the NSC KIPT.

Nowadays NSC KIPT have 15 furnaces of the specified type. They were designed in NSC KIPT first of all for realization of gasphase technologies of carbon - carbon materials reception but maximum universal and allow to solve the following problems:

• To carry out termogradient gaphase impregnation by the pyrocarbon of the porous powder and fiber fillers; to receive products from carbon - carbon materials and graphites on the pyrocarbon binder using this method;
• To carry out isothermal gasphase impregnation of porous materials and products;
• To graphitise and rafinate graphite and carbon materials at temperatures up to 2500-3000 °C in conditions of a radial gradient of temperature or in isothermal conditions.

Basic unit of installations is a vacuum watercooling cylindrical chamber with copper watercooling contactors laying on the same axis, located in the top and bottom . Contactors are executed mobile for indemnification of thermal expansion of products during process. Besides that, the contactor mobility facilitates the preparation installation in the mounting.
Each installation has an independent system of the power supply for heating products containing regulators of a voltage, power transformers of various capacity. The furnaces are equiped by the vacuum system (0.1-0.001 torr), natural gas supplying system.
At gasphase impregnation of products the furnaces are working at the atmospheric pressure of CH4 or at a low pressure, that can be adjusted from 5-10 torr up to atmospheric.
There are systems of inert gases, hydrogen, etc. There is also an automatic control system of the technological processes. The specified system includes maintenance of programmed increase and decrease of furnaces and products temperature, the automatic maintenance of given temperature during the process of gasphase impregnation with required accuracy (in our processes is usually with the accuracy 20-50°Ñ), control of cooling water temperature, alarm system at a deviation of regimes and ets. Temperature control by thermocouples and visually - by the pyrometer is foreseen in all furnaces.

The installations AGAT - 3,2 basically work in a vertical position , but can work and in a horizontal one. With this purpose the vacuum chambers are executed on a hinging suspension and can bend under any corner to a horizontal.

GF-3

GF-2

Type of installation GF-2 GF-3 Sort of an electrical current DC The maximal capacity, KW 1700 1700 Voltage on a heater, V Up to 70 Up to 70 Current on a heater (max), A 25 000 25 000 The sizes of working space - Diameter, mm 1300 3000 - Height, mm 2500 3000 Aperture of a door, mm 1000õ2000 rolling off -

The structure of each installation includes: converter unit of a series ÒÂ9-25000, transformer TMNPU-8000/10PUZ, FROS-3200U4

The installation GF-2 has rolling off on rails a lateral door with contactor entered in it. The installation of a heater and loading of the furnace is carried out while a door is rolled off, then it is to be closed and vacuum chamber is hermetized by the bolt units through the rubber condensation. The vacuum chamber of installation GF-3 consists of half-spherical bottom and cover and cylindrical wall, which are connected through vacuum rubber condensation by bolts. In case of necessity the height of the chamber can be increased by the second cylindrical wall and etc. The loading of the chamber is carried out while the top cover is removed, its weight is ~5 tons. The vacuum chamber (cylindrical wall) is equipped with the hatch, which sizes are sufficient for the man penetration inside the chamber. The vacuum chambers are equipped by the windows allowing to supervise visually the temperature of a product on height and circle of the furnace. At operation the voltage seldom exceeds 10-15 volts, current loading are used maximum.