WO2002020196A1

WO2002020196A1 - Method of creating of nanoamorphous materials

Info

Publication number: WO2002020196A1
Application number: PCT/AM2001/000010
Authority: WO
Inventors: Razmik Malkhasyan
Original assignee: Razmik Malkhasyan
Priority date: 2000-09-04
Filing date: 2001-08-22
Publication date: 2002-03-14
Also published as: AU2001283667A1

Abstract

The invention refers to the sphere of material science and nanotechnology, powder metallurgy, applied physics and chemistry. The aim of the invention is to create the single component amorphous nanosize materials and to raise the productivity of the synthesis process. The worked out quantum-chemical technology has allowed to conduct the non-equilibrium processes of the interaction of the amorphizing material and the second reagent under the conditions of the minimal educing of energy (at the room temperatures) and to obtain the amorphous nanosize powders of the single component materials, in particular, metals. The given invention for the first time gives a chance to obtain the single component metals in amorphous nanosize state.

Description

Method of creating of nanoamorphous materials.

The invention refers to the sphere of material science, powder metalurgy, solid physics and applied physics and chemistry.

It is known that amorphous materials are being obtained during the cooling of the different alloys. However, only the alloys of the elements which have a high viscosity or the alloys containing that kind of components turn into amorphous state [ AππeH A.A., XHMHS cτeκjιa. JT. 1974r. ΦH3HHecκHii aHi^HKnoneflH ecKiiH αnoBapt, cTp. 723, 1984r. ]. For instance, S, Si, Se, P, etc. as well as some oxides: SiO₂, GeO₂ and other substancies belong to this class. However, it is impossible to create metals or their alloys through the ordinary cooling method.

It is also known that they obtain the amorphous metal alloys by the method of rapid cooling, i. e. quenching of their alloys [ CyzpyKH K., ΦyΛ3HMopH X., XacHMθτo K. AMopφH ie Meτajiibi, M., 1987r. ], when the metal alloys undergo quenching of 10⁵-10⁶ degree/ sec and more speeds. However it is impossible to obtain the single component metals in amorphous state through this method. It is neither impossible to obtain nanosize powders by this method.

It is also known that they create the amorphous single component metals in nanoamorphous state from the powdrs of oxides of these metals by means of discharge of excited molecules of the second reagent into the metal oxide powder under the low pressure [0,01-0,001 column of Mercury, mm], when their energy exceeds the energy of metal - oxygen bond of the oxide. [Method of Creating of Amorphous Metals, Patent of the Republic of Armenia, N 417, dated 10.27.1994]. However because of low pressure the productivity of this process is not effective and it cannot be used for the creating of all materials irrespective of the value of their educing energy during the transformation. In case the transformation takes place through exothermic way, there is received a crystalline material instead of amorphous one.

This known method is applicable to oxides only, therefore cannot be used for creating of amorphous materials, that have no oxides in solid unit state, and, of course, not all the oxides can turn into amorphous state.

According to the method of creating of amorphous material [Patent of the Republic of Armenia, N 828, claim N 99044], that is closely connected with this suggesting invention, they subject the solid material to the interaction with the excited gaseous reagent under the pressure 0,01-0,001 column of Mercury, mm, in case of some T_cr critical temperature T_cr<0,55T_m, that leads to the formation of the amorphous state, where Tm is a melting point of the given amorphizing material. This T_ent temperature must be less than the minimal value of the energy of the necessary embryo creation for the crystallization of the given amorphizing material.

In the known method the necessity of the gaseous condition of one of the reagents and only its excitation indispensable condition in compulsory conditions of pressure 0.01-0.001 column of Mercury, mm decreases strictly the field of the application of this method. The low productivity of the given method is also its material shortcoming. In some cases when the initial material is a compound of the phase of instillation, it is necessary to reduce the critical temperature or the limit of energy till the energy of overcrystallization of this amorphizing material.

The invention raises a task to enlarge the field of the method of obtaining of amorphous materials, to refuse the presence of one gaseous reagent as a compulsory condition and at the expense of this fact it would be possible to increase sharply the productivity of their obtaining method. Lowering the total capacity of the energy of the process, the most promoting conditions are being created for the creating of nanosize powders by this method, in particular, the single component metals.

The essence of the invention is in the following. In the method of obtaining of amorphous materials, in accordance with which they fed into the reaction zone the amorphizing material in the form of powder and the molecules of the other reagent, that are preliminarily excited till the molecule bond energy of the given amorphizing material are being fed and by the help of interaction transform the material into the amorphous form. According to the invention they perform the interaction by the non- equilibrium mode at the expense of the mechanical-chemical or the other internal excitation energy of one or two both of the reagents (not owing to heat energy), the second reagent also may be both in a gaseous and in a solid unit state in the form of powder, and conduct the process at a temperature lesser than the energy of overcrystallization of the initial material.

The proposing method of obtaining of amorphous form of materials is based on the discovered by us fact which confirms that besides the necessarity of separation of the especially pure chemical interaction and as its result the further transformations that are taking place with the obtaining material, it is also necessary to estimate exactly all the possible heat effects of the overcrystallization of all the initial materials. They as a rule have a more small value than the value of the critical barrier that is necessary for the appearing of crystalline embryo. It is also necessary to take into account that it is feasible to impart an internal energy or excite not only the gaseous material but also the solid materials that gives a possibility to act in conditions of the high pressures.

It is possible to use in this method the powders of two interacting solid materials that may accumulate a sufficient internal energy by the mechanical- chemical or the other method of excitement (of nonheat nature), in order to overcome the first transformation barrier, provided the energy that was educed during the transformation process does not exceed the next activation barrier value of the overcrystallization process.

In this method the limitation concerning the interaction sphere pressure, that may be atmospheric and even more, is taken away and it is clear, that this circumstance increases sharply the productivity of obtaining of the amorphous metals. In any case, it is necessary to use as transforming initial material if only one initial material in the state of solid material, f.e. in the form of powder, and to subject it to chemical transformation through the non-equilibrium method, by the way of dissociation or interaction with the other material, during which these elements will appear in free - atomic or molecular state, and no having the necessary crystallization cannot overcome the second activation barrier of the overcrystallization and turn from amorphous into the crystalline stage.

In this case, the value of the originating material grain is stipulated by the casual unity collection of those free, new obtained atoms or molecules and will also be less than the magnitude of critical embryo R_cr. The critical value of the embryo R_or is being determined by the formula [R_cr =2aN_spec/Δμ], where a is free energy of the grain surface unity, N_spec is specific value of the volume which is fitting a grain particle, Δμ is a change of the chemical potential at the condensation from the gas into the solid state of the given material.

This quantity is variable for the different substancies but does not exceed some dozens of nanometers.

The more Δμ, the less R_cr and f.e. it has the least value (~lnm), for the heavy refractory metals. Therefore the particles with nanosize grain, i.e. the nanoamorphous material is appearing, also including the single component metals, the grain magnitude of which decreases to 1 nanometer.

The amorphous materials are being obtained by the following way. Example:

100 gram of Molybdenum oxide powder (MoO₃) is being placed into the mill, which may be of different kinds (ordinary, planetary or vibrational) and it is being subjected to the breaking up in the presence of the other reagent powders, e.g. molar equivalent quantities of Mg or Al. After the mechanical-chemical treatment during 15-30 minutes an amorphous nanosize material is being obtained.

In order to obtain the pure material, it is necessary during the mechanical- chemical treatment to choose such material as a second reagent (e.g. Sulfur or Hydrogen) that the other appearing product besides the amorphous metal Mo, be gaseous and easily removing ( extracting, e.g. SO₂ or H₂O in the form of steam).

For example, they fed lOOgram of the initial powder of the same MoO₃ into the ordinary spheric mill with the volume 1-21 and treat it, making small in the mill during 2-5 hours with the simultaneous blowing off of the gaseous Hydrogen through the powder. After such a mechanical-chemical treatment the amorphous nanosize metal Mo is being formed as well as in this case some quantity of Molibdenium amorphous oxide is also being appeared.

In any case it is necessary to realize the process in such temperatures, that are less than the energy required for the equivalent overcrystallization (or for appearing of crystalline embryo).

One may to impart to the solid the non-equilibrium internal energy through ultrasound treatment, making small or pressure and by other means instead of use of ordinary or the other kinds of mills.

Claims

This is a method of obtaining of the materials in amorphous state. According to the given method the amorphizing material in powder form and the molecules of the second reagent, which are being excited preliminarily till the bond energy of the molecules of the given amorphizing material, are being fed into the reaction zone, as a result of the interaction the material is being transformed into amorphous form, that differs in the following.

The transformation is being performed by the non-equilibrium method at the expense of mechanical-chemical or other internal excitation energy of one or both of the reagents (not at the expense of heat energy). For all this the second reagent may be both in gaseous and in solid unit state in the form of powder, and the transformation is being performed lesser than the overcrystallization energy of the initial material.