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HEAT TREATING FURNACES

Methods of powder production

Powder metallurgy is a branch of engineering embracing various methods of producing powders of metals and metal-like compounds, half-finished and finished products made of them without melting the main component.

The technology includes the following operations: metal powders production and preparing charge with the pre-set chemical composition and technological characteristics, forming powders into parts (mainly by pressing), sintering, that is heat-treatment at the temperatures higher than the melting temperature of all the metal or its main components.

Mechanical metals crushing is carried out in whirl, vibration and ball mills.

Another, more perfect method of powder obtaining is spraying of liquid metals. Its virtues are the possibility of effective purification of most impurities, high productivity and economy of the process.

Widely spread is obtaining powders of Fe, Cu, W, Mo by means of high temperature reduction of metal with C or H2.

Hydrometallurgical methods of reduction of these metals with H2is also applied. To obtain the powder of Cu the electrolysis of water solution is often used.

 

MY FUTURE SPECIALITY

I am a student of the Kiev Polytechnical institute. I study at the Physical Engineering Faculty. Our faculty trains specialists for different fields of metallurgy. Metallurgy is a very important branch of national economy. The rate of the development of almost all branches of economy and the speed of scientific and technological progress largely depend on the quantity and quality of metals and alloys of metals. Metallurgy embraces a wide range of subdivisions and scientists conduct research in different directions. Our faculty trains engineers and research workers for such branches of metallurgy as foundry production of ferrous and non-ferrous metals, heat-treatment of metals, physics of metals and powder metallurgy. It is very essential that the engineer who is to be concerned with the selection of metals and alloys in industry should have fundamental knowledge in chemistry, physics, thermodynamics, dynamics and mechanics. He should know the nature of the physical and mechanical properties and characteristics of metals and alloys. The study of microstructure of metals by means of the electron microscope is very important. It is also necessary to study the techniques and processes of changing the physical properties of metals. After graduation we'll have an opportunity to apply our knowledge at metallurgical enterprises to contribute to further growth of metal production in our country or we'll conduct research in metal science to improve quality of metals and alloys and to raise the efficiency of metal production. Many of us will combine their practical work with theoretical study and experimental investigations.

HEAT TREATING FURNACES

 

Heat treating furnaces may be classified into two general categories, batch and continuous, and there are many different types in each group. The simplest furnaces are the direct-fired batch type, with manual controls. Installations for large production lines are more elaborate and are usually continuous furnaces, with automatic programming controls. In some cases controls are included in the furnace for controlling the atmosphere in the working chamber in order to obtain the desired surface condition. In general, the most common heat treatments performed in furnaces are annealing, normalizing, hardening, spheroidizing, tempering, carburizing, and stress relieving. As a rule heat treating furnaces are not designed for temperatures higher than 2000˚F and, in general they operate at from 800˚F to 1600˚F. Insulation is important in maintaining uniform temperatures and the furnaces are built tight to prevent infiltration of air or loss of special atmospheres. For handling batch loads of material to be heat treated, quenched and tempered quench tanks and cranes should be located so that there is a minimum of time expended in transporting material from the furnace to the quenching medium. Furnaces should also be so arranged as to have a second furnace available for taking material after quenching for such additional treatment as may be required. As a rule, three furnaces are used in operations of this type two for heating and one for tempering the work.




Date: 2015-12-24; view: 754


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