TECHNOLOGIES & APPLICATIONS

EQUIPMENT AND TECHNOLOGY FOR COMBINED PLASMA-ASSISTED VACUUM-ARC SURFACE MODIFICATION OF STRUCTURAL STEELS

Purpose

The technology is intended for surface hardening of structural steels and can be used to treat the interacting surfaces of friction pairs - machine and mechanism parts operating at intense dynamic loads, e.g., to enhance the contact strength of gear wheels and the durability of shafts, sleeves, and plungers.

Outline and technical and economic characteristic

The essence of the technology is that with an original plasmogenerator and an electric-arc evaporator used in a unified cycle, on the surface of a part made of structural steel a wear-resistive three-layer composition is formed which consists of an internally nitrided two-layer zone and a coating zone of finely dispersed nitrides of carbonitrides of transition metals, e.g., TiN.

The double-phase nitrided sublayer provides high adhesion of the TiN coating to the substrate, the form stability of the substrate when in contact with a counterbody in the process of friction, and high thermal stability. The surfaces of machine parts made of structural steels subjected to the combined plasma-assisted ion treatment show enhanced resistance to wear and corrosion.

Structure of modified layer of Steel 40X after plasma-assisted vacuum arc treatment

The efficiency of the technology is illustrated by the example of type 40X structural steel (0.4% C, 1.0% Cr, 0.5--0.8% Mn, 0.17--0.37% Si). The plots below present microhardness measurements for a Steel 40X specimen subjected to plasma-assisted ion treatment by the technology under consideration and wear resistance measurements for Steel 40X specimens subjected to various types of treatment.

Testing for wear was performed on a type IP-3 laboratory friction machine without lubrication by the rotor -- plane specimen scheme with a contact load of 30 N and a sliding velocity of 0.36 m/s. The mass lost by the test specimen served as a criterion for wear. The tests have shown that when the surface of steel specimens is modified by the technology proposed, their microhardness increases three or four times and resistance to wear is enhanced four or five times.

Microhardness profile for a Steel 40X specimen subjected to ion nitriding in a non-self-sustained arc discharge followed by plasma-assisted deposition of a TiN coating.

Wear of the surface layers of Steel 40X as a function of the time of dry friction testing performed after various treatments: a - quenching, b - ion nitriding, c - deposition of TiN coating, d - combined treatment by the technology under consideration.

Principal advantages

e technology proposed has the advantage over conventional technologies for plasma-assisted vacuum arc surface modification that it allows one to produce extended multilayer hard structures showing enhanced resistance to wear on structural steels.

Analogs

Technological processes of plasma-assisted vacuum arc surface modification are realized, e.g., on an equipment produced by the Balzers company. After proper modernization, this equipment can be used to effect technologies similar to that proposed.

Development phase

The research and development work on the technology has been completed. A pilot setup intended for industrial realization is currently machined.

Suggestions for collaboration

Collaboration is suggested in the forms as follows:

selling of the technology and equipment
bringing of the technology and equipment to an industrial level
organization of joint production and selling of the products treated by the technology under consideration

Other forms of collaboration are also possible.

For further corresponding please contact:

Nikolai N. Koval
Dr. Sci. (Techn.), Laboratory Head

Phone: (3822) 49-27-92
Fax: (3822) 49-24-10
E-mail: koval@opee.hcei.tsc.ru

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