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Refractory Powder Alloys

#G-995


Manufacturing of New Ni-Co-Cr-based Refractory Powder Alloys for the Strengthening of Coatings and Creating of the Articles Working in Extreme Conditions

Tech Area / Field

  • CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
  • MAT-ALL/High Performance Metals and Alloys/Materials
  • MAT-COM/Composites/Materials

Status
3 Approved without Funding

Registration date
05.03.2003

Leading Institute
Institute of Metallurgy, Georgia, Tbilisi

Collaborators

  • Universität Hamburg / Institut fuer Anorganische ud Angewandte Chemie, Germany, Hamburg\nNational Institute for Materials Science / Advanced Materials Laboratory, Japan, Tsukuba\nUniversity of Missouri-Rolla / Department of Ceramic Engineering, USA, MO, Rolla

Project summary

Improvement of the materials with an ability of working at high temperatures, exceeding 1100 °C, becomes possible if new technological processes of melting and molding are elaborated. The problem may be successfully solved by using a technique of powder metallurgy. By this technique may be fabricated new alloys and composite materials with unique properties, which practically are hardly achievable by well known traditional methods. Especially important role in the production of articles of high strength plays application of powders with obvious high physical-mechanical and technological properties.

At present, fabrication of chromium-nickel, iron-chromium-nickel, chromium-cobalt and other materials by using classical methods of powder metallurgy is realized through sintering of the pressed charges consisting of expensive powders of chromium, nickel, iron, cobalt and other metals. The process is power consuming, and, due to passivity of the surfaces of initial powder particles it is rather difficult to obtain homogenous powder alloys.

One of the most perspective directions for the manufacturing of homogenous powder alloys and composite materials is metal- or hydrogen-thermal co-reduction of chlorides and other compounds of the appropriate metals. An advantage of this method is a comparatively low reduction temperature, rapidity of the process, simplicity of the applied installations and equipment, minimal energy and material consumption, opportunity of using chlorides extracted from the industry wastes, having contained necessary components. Besides, the method makes possible to obtain homogeneous powder alloys. In combination with a widely used method of mechanical alloying, the new technology could undoubtedly have open new ways to the creation of dispersion-strengthened high temperature resistant materials of any composition and unique properties.

Application of homogenous powders as the materials for sputtering of the surfaces allows coating with high rate of evenly distributed components. They have an advantage against the mechanical mixtures of different powders where a difference in mass and ductility promotes their uneven distribution during the plating processes by gas-fire (among them plasma) technique and formation of layered structure.

A great experience has been accumulated by the project team in the field of manufacturing powder metals, alloys, compounds and composite materials by metal-or hydrogen-thermal reduction of chlorides and some other compounds of the appropriate metals. By mechanical alloying of these materials were obtained multipurpose powders of different type, dispersion-strengthened with the particles of refractory compounds (oxides, carbides, etc.).

The goal of the project is:

- Elaboration of the energy capable technology of fabrication powders of refractory alloys based on Ni-Co-Cr, alloyed with some additions (Ti, Nb, Ta, W, V, Mo, Al, etc.) and dispersion-strengthened with nanocrystalline particles of oxide phase (Al2O3, ZrO2, and Y2O3) by using metal- thermal reduction of mostly chloride charge with subsequent dispersion of oxide particles in high power mill.

- Pilot production of powders, investigation of physical-mechanical and technological properties, development of optimal modes for their compacting and covering, investigation of the properties of compacted ingots and covers.

- Definition of the area of practical application of the obtained powders.

Novelty and essence of the project are:

- Investigation of the processes of the formation of powder Ni-Co-Cr alloy and study of the regularities of diffusion, surface and contact phenomena in the system created by oxide compounds with Ni-Co-Cr alloy.

- Elaboration of a technology for the fabrication of new complexly alloyed powder alloys based on Ni-Co-Cr with various content of oxide phase; preparation of the articles and coatings, applied for the work in extreme conditions at high temperatures exceeding 1100 °C.

Expected Results and Application

- The powders based on Ni-Co-Cr alloy, strengthened with nanocrystalline oxides of Al2O3, ZrO2, and Y2O3 will be consisted of the particles of highly homogenous dispersion-strengthened alloys even in the initial state. Their chemical composition, structure and morphological characteristics will ensure the existence of specified properties in the powders as well as in the compacted pieces and covers made of them.

- Unique powders will be created by their composition and properties, which can not be achieved by any other methods; the powders will be applied for the fabrication of the pieces and covers.

- The materials made of the above mentioned powders may be successfully applied in the constructions of power systems, working at high temperatures under the action of static and dynamic loading in strongly aggressive gas atmospheres. Enhancement of reliability and duration of service of such constructions is expected by 25-30%.

Realization of the project is possible through the involvement of 60 % of “weapon” scientists, earlier fulfilling the orders of Defense Institutions. Scientific potential of these scientists will be directed at the creation of peaceful production, in particular, production of new powder materials with unique properties. The elaboration will be implemented at lowest financial expenses if compared with the worldwide expenses necessary for the realization of the similar scientific works.

The results of the project elaboration, ensuring creation of new complexly alloyed dispersion-strengthened powder alloys may be successfully used for the fabrication of articles and coatings, applied for the work in extreme conditions at high temperatures exceeding 1100 °C.

Within the frame of the project, together with a foreign collaborator will be realized the following: exchange of information during the project implementation; joint holding of workshops; preparation of joint publications (patents among them); discussion of the possibilities of application of the project results; partnership in commercialization of the obtained materials.


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