Method for the mechanical activation of powders

Abstract

A method for the mechanical activation of powders is carried out by preparing a hermetically sealable container (5) into which a plurality of spherical bodies and a predetermined quantity of a powder to be activated are introduced. The container (5) is then mounted on a system (1) for the mechanical activation of powders comprising a supporting body (3) suitable for receiving and retaining the container (5). Finally, the system (1) is activated in a condition of quasi-resonance of the supporting body (3).

Description

[0001] METHOD FOR THE MECHANICAL ACTIVATION OF POWDERS FIELD OF THE INVENTION

[0002] The present invention relates to the technical sector of methods for the mechanical processing of materials.

[0003] In particular, the present invention relates to a method for activating powders by applying mechanical stresses, in particular milling.

[0004] STATE OF THE ART

[0005] “Ball milling” is a production process in which one or more materials, generally in powder form, are ground by balls or spheroids confined within an appropriate container made of suitable material set into motion.

[0006] The motion of the balls present inside the container causes significant mechanical stresses on the materials to be ground, inducing different effects.

[0007] The effects observed include intimate mixing of the treated materials, variation in the shape of the particles, increase in the specific surface, reduction in the size of the crystallites until the material is amorphized, metal alloying and the formation of new substances.

[0008] This activation process requires the selection and quantification of many parameters, including the process time, the speed / intensity of movement of the container, the quantity of virgin material to be treated, the size, shape and material of the container, the size and material of the balls, the mass ratio between the milling balls and the material being processed (ball-to-powder mass ratio - BPR), the temperature at which the compound should be, the quantity and type of the process controller (PCA), etc.

[0009] At present, different methods are known which employ various devices for moving containers by applying an oscillating motion; however, they are still affected by disadvantages that reduce the efficiency of use thereof, in terms of both processing times and volumes. In fact, the systems and operating methods currently in use do not allow for the processing of large quantities of material in a short time since they are greatly limited both by the maximum accelerations that can be reached and from the viewpoint of the oscillation frequencies that can be reached.

[0010] Therefore, in the sector there is a strongly felt need to provide new operating methods for processing and activating metallic and non-metallic powders by means of balls, which are capable of overcoming the constraints posed by the prior art while improving overall efficiency thereof. In this context, the technical task at the basis of the present invention is to propose a method that overcomes at least some of the abovementioned drawbacks of the prior art.

[0011] In particular, it is an object of the present invention to provide a method capable of ensuring greater efficiency thanks to the obtainment of large production volumes in a short time.

[0012] The stated technical task and the specified objects are substantially achieved by a method comprising the technical features disclosed in one or more of the appended claims.

[0013] SUMMARY OF THE INVENTION

[0014] According to the present invention, a method for the mechanical activation of powders is shown.

[0015] The method is carried out by preparing a hermetically sealable container.

[0016] A plurality of spherical bodies and a predetermined quantity of the powder to be activated are introduced into the container and it is subsequently sealed.

[0017] The container is then subjected to mechanical forces according to an oscillating motion in a condition of quasi-resonance, preferably in a condition of resonance.

[0018] In particular, this operation can be carried out by mounting the container on a system for the mechanical activation of powders.

[0019] Specifically, the system for the activation of powders is preferably a system comprising an oscillating device, a supporting body and interfacing means.

[0020] The oscillating device has a working plane that can be moved along an oscillation direction and to which the supporting body is coupled.

[0021] The interfacing means are interposed between the working plane and the supporting body and are configured to define a stroke thereof and to exert on it a force proportional to the distance thereof from the working plane. Finally, the system is activated in a condition of quasi-resonance of the supporting body.

[0022] Preferably, the system is activated in a condition of resonance of the supporting body.

[0023] Advantageously, the method proposed herein ensures the rapid activation of the powders with particularly high levels of quality thanks to the placement of the container in quasi-resonance, which makes it possible to maximise the shaking thereof and enables rapid movement with modest energy inputs.

[0024] BRIEF DESCRIPTION OF THE FIGURES

[0025] Figures 1 to 3 show different possible embodiments and configurations of use of a system specifically configured to carry out the method in accordance with the present invention.

[0026] Figures 4 to 6 illustrate some experimental evidence relating to experiments conducted by applying the method claimed here and described below.

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0028] The method of the present invention can be carried out in order to obtain the mechanical activation of powders of varying nature.

[0029] The term “activation” is intended to mean in general terms an operation that has as its result a mechanical modification of the powders which changes at least one characteristic parameter thereof, such as the shape, composition, or size, in particular with the aim of changing the reactivity thereof.

[0030] The term “powder” means any incoherent material in the form, for example, of granules, particles, chips, fragments, flakes or the like of various materials, which include, by way of non-limiting example, metals, metalloids and non-metals, preferably based on aluminium (or alloys thereof, such as series 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 100, 200, 300, 400, 500, 700, 800 or UL40), boron, titanium, magnesium, silicon, steel, or inconel.

[0031] The method is carried out by preparing a hermetically sealable container 5 into which a plurality of spherical bodies and a predetermined quantity of the powder it is desired to activate are introduced.

[0032] Preferably, the spherical bodies used are balls of a material selected in the group consisting of steel, titanium, tungsten carbide, silicon carbide, zirconium oxide, plastic materials, teflon, or a combination thereof.

[0033] The balls preferably have a diameter comprised between 1 mm and 50 mm, more preferably between 1 mm and 20 mm. The process can provide for the use of two different types of balls, i.e. the method can be carried out by inserting into the container 5 spherical bodies having different sizes and preferably having at least two different diameter values and wherein the ratio between the largest diameter of one type of balls and the smallest diameter of the other type of balls is comprised between 1 and 50, preferably between 1 .25 and 5.

[0034] The ratio between the weight of the balls and the weight of the loaded powder mixture is comprised between 1 :1 and 100:1 , preferably between 20:1 and 5:1.

[0035] Alternatively, the balls can be replaced with similar spheroidal elements, rolls, rollers, pins, or a combination thereof, preferably having a volume equal to that of the balls they replace.

[0036] The apparent volume of the spherical bodies relative to the volume of the internal chamber of the container 5 in which they are inserted, or in other words the apparent volumetric filling of the container 5, is comprised between 10 and 90%, preferably between 25 and 75%, even more preferably between 45 and 60%.

[0037] Advantageously, the method can also comprise a step of washing the predetermined quantity of powder to be activated, which is carried out upstream of the introduction thereof into the container 5.

[0038] In this manner it is possible to remove any impurities before carrying out the activation process, thus ensuring a high quality of the final product obtained.

[0039] The method can also comprise a milling step, which can also be carried out upstream of the introduction of the powder to be activated into the container.

[0040] This step, preferably carried out in such a way as to obtain powders of a size equal to or less than 5 mesh, actually represents a pre-processing step suitable for preparing the material for the subsequent activation and selecting the size of the powders to be processed, thus enabling a more homogeneous activation thereof by the spherical bodies.

[0041] Before sealing the container 5, it is also possible to introduce one or more additives into it together with the powder and the spherical bodies, preferably in such a way as to obtain a mass fraction of additives comprised between 0.5% and 90%.

[0042] The powders to be activated can then be processed on their own or in combination with a mass fraction ranging between 0.5% and 90% of one or more additives to be selected from salts (preferably NaCI, KCI, LiCI, CaCI2, YCh, AgCI2, MgCI2, NH4CI, LiF, AIF, CaF2, NH4F, NaF, KF, AgF2), sugars (monosaccharides, preferably glucose or polysaccharides, preferably sucrose), metal oxides (preferably FeaOa, FeaCk, M0O2, M0O3, CuO, CU2O, WO3, BiaOa, Co304, SiO2, NiO, U2O, V2O5), metals or semimetals (preferably Bi, Al, Mg, B, Zn, Sn, Li, Ni), hydroxides (NaOH, KOH, LiOH, AI(OH)3, Ca(OH)2, Mg(OH)2,Cu(OH)2, Fe(OH)2, Fe(OH)3, Zn(OH)2), polymers (preferably PTFE and PE), and graphite. Advantageously, it is also possible to introduce into the container a process control agent (PCA), preferably selected from acetone, pentane, cyclopentane, hexane, cyclohexane, PEG, PPG, isopropyl alcohol, ethyl alcohol or a combination thereof.

[0043] The ratio between the volume of the PCA and the mass of the powders introduced into the container is preferably comprised between 0.1 ml / g and 50 ml / g.

[0044] The addition of the process control agent makes it possible to further and more finely adjust the characteristics of the mechanically activated powder, such as, for example, the particle size and / or purity thereof, since, by acting as a dispersing material inside the mixer, it favours the mechanical activation of the powder mixture and allows better control of the temperature.

[0045] It is also possible to add an inert gas into the container 5 so as to obtain a complete volumetric filling thereof.

[0046] The inert gas can be selected from helium, hydrogen, nitrogen, argon, and a combination thereof and its introduction makes it possible to reduce the probability of ignition of the powder mixture or other collateral processes that may take place in the presence of oxygen and which can reduce the purity of the mechanically activated powder.

[0047] Alternatively, for a similar purpose, the method can comprise connecting the container 5 with a vacuum pump (or a similar pneumatic source) after having sealed it.

[0048] In this context the activation of the vacuum pump allows the residual air inside the container 5 to be removed to generate a vacuum environment inside it, thus contributing to increasing the purity of the final product by avoiding the inclusion of gases.

[0049] Once sealed, the container 5 can be coupled to and be part of a system 1 for the mechanical activation of powders suitable for creating an oscillating system with two masses in which the container 5 (and optionally the element on which it is mounted) defines a first mass and a vibrating component coupled thereto defines a second mass thereof.

[0050] In particular, a system 1 particularly suitable for carrying out the method described here essentially comprises an oscillating device 2, a supporting body 3, interfacing means 4 and a container 5.

[0051] In detail, the oscillating device 2 is a component configured and intended to generate axial vibrations and for this purpose it has a working plane 2a that can be moved along an oscillation direction X through the action of suitable motorised means.

[0052] The oscillating device 2 can thus for example be or comprise a shaker, in particular a shaker of the electrodynamic type, or of the modal or hydraulic type.

[0053] These shakers set a single mass or “worktable” into vertical or horizontal motion with movements of a sinusoidal, random or “impact” type depending on the type and model of shaker used.

[0054] In the case of sinusoidal movement, the accelerations reach as high as 115 G with frequencies ranging from 2 Hz to 6000 Hz.

[0055] Advantageously, it is also possible to carry out the movement of the container 5 according to more complex trajectories, for example by introducing further oscillating devices 2 coupled to the supporting body 3 and configured to cause the movement thereof along different respective oscillation directions X.

[0056] Alternatively, or additionally, it is possible to unbalance the centre of mass of the supporting body 3 and / or of the container 5 relative to an axis of symmetry of the interfacing means 4.

[0057] In other words, in one configuration of use the container 5 can be unbalanced relative to an axis of symmetry of the stresses to which it is subjected, thereby making possible the movement along nonlinear trajectories, also with the use of a single oscillating device 2.

[0058] In this manner, the container 5 is thus moved overall along a trajectory which, despite maintaining a main component along the oscillation axis X, can take on a variety of different shapes, including, for example, an elliptical shape.

[0059] For this purpose, it is possible to provide a supporting body 3 having a surface for receiving / coupling with the container 5 that is inclined relative to the oscillation direction X (as illustrated by way of example in figure 3) and / or the container 5 can be set up by introducing one or more unbalancing masses configured to bring its centre of mass off axis.

[0060] The supporting body 3, which can preferably be made of polymeric or metallic material (aluminium and the alloys thereof, steel, titanium, TieAkV, or another “light” material), is coupled to the working plane 2a.

[0061] The supporting body 3 is specifically configured to house and reversibly retain the container 5, explicitly illustrated for the sake of simplicity of representation solely in figure 1 .

[0062] The container 5 internally defines a working chamber, into which the powders to be activated can be introduced and, to ensure an optimal execution of the activation process (specifically to avoid contaminations of the powders), the method also comprises hermetically sealing the container 5.

[0063] Therefore, it is possible to load the powders into the working chamber, hermetically seal the container 5 and subsequently mount it on the supporting body 3, constraining it thereto.

[0064] The method then comprises mounting the container 5, specifically the sealed container 5 with the powder to be activated inside it and the spherical bodies, on the activation system 1 and in particular on the supporting body 3 thereof.

[0065] The system 1 is then activated in a condition of resonance or quasiresonance of the supporting body 3.

[0066] In other words, the container 5 coupled to the supporting body 3 is moved in a condition of quasi-resonance by the vibrations of the working plane 2a mediated by the interfacing means 4.

[0067] In particular, the expression “quasi-resonance” is meant specifically to indicate a situation in which the supporting body 3 is moved with a stress generated by the working plane 2a having a frequency comprised in a range comprising the resonance frequency and preferably centred on it.

[0068] In particular, the quasi-resonance frequency is equal to the resonance frequency multiplied by a corrective factor having a value comprised between 0.4 and 1.6, preferably between 0.8 and 1.2, even more preferably between 0.9 and 1.1.

[0069] This selection makes it possible to obtain, through the generation of a quasi-resonant oscillating motion for the supporting body 3, a very high multiplication factor of the force, in particular comprised between 2 and 250.

[0070] The interfacing means can comprise, in particular, elastic means (for example springs as illustrated in figure 1 ) configured to exert an elastic force on the supporting body 3, or magnetic elements (for example permanent magnets as illustrated in figure 2) configured to exert a force of a magnetic type on the container 5.

[0071] If the interfacing means 4 are of the elastic type, the springs are specifically configured to exert an elastic force on the supporting body 3 when the oscillating device 2 is active and moves the working plane 2a, while at the same time constraining the supporting body 3 to prevent its detachment.

[0072] In this context, the interfacing means 4 are configured to exert on the supporting body 3 an elastic force whose law can be for example modelled with the following equation:

[0073] F=k*(a-b)

[0074] Wherein F is the force exerted, k is the overall elastic constant of the elastic means, a is the distance between the working plane 2a and the supporting body 3 and b is the length of the elastic means in a rest condition.

[0075] The elastic constant of the springs can be equal for all the springs involved or it can also vary from one spring to the other, preferably maintaining, however, an overall symmetrical configuration. In greater detail, the elastic constant of the springs is calculated from the mass which needs to be shaken and the desired stress frequency and such as to enable the container 5 to be placed at least in a condition of quasi-resonance.

[0076] Therefore, different masses to be shaken can require springs with a different elastic constant in order to operate according to what is provided by the present method.

[0077] Preferably, therefore, each spring can be coupled to the working plane 2a and / or to the supporting body 3, so as to enable the replacement thereof both for operating requirements (to modify the overall elastic constant of the interfacing means 4 in order to adapt the system to process a given powder in an optimal manner) and to be able to easily perform maintenance or repair operations.

[0078] The method can thus comprise a step of determining an optimal elastic constant as a function of one or more characteristics of the powders to be activated (for example as a function of a quantity in terms of mass of the powder to be activated) and selecting a plurality of springs having that elastic constant, then mounting them on the system 1 .

[0079] In this manner, it is possible to operate the system 1 under conditions that are optimal and specifically selected based on the specific characteristics of the powder to be activated.

[0080] If the interfacing means 4 are instead of the magnetic type, they are configured to operate in a manner analogous to what was described above, exerting on the supporting body 3 no longer an elastic force, however, but rather a force of a magnetic type in which the interfacing means 4 are configured to exert on the supporting body 3 a force inversely proportional, in a quadratic manner, to the distance between the latter and the supporting plane (thus defining a relation of inverse quadratic proportionality).

[0081] In particular, in this context the interfacing means 4 comprise a pair of movement magnets, a working magnet 10 and a stationary magnet 11 . The pair of movement magnets is constrained to the supporting body 3 or to the container 5 on opposite walls along the oscillation direction X.

[0082] In other words, the pair of movement magnets comprises a first movement magnet 9a positioned on the portion of the supporting body 3 or container 5 which, during use, is facing the working plane 2 and a second movement magnet 9b disposed on an opposite portion.

[0083] The working magnet 10 is instead coupled / constrained to the working plane 2a and is thus facing the first movement magnet 9a.

[0084] In particular, the first movement magnet 9a and the working magnet 10 are interfaced in such a way as to have the same magnetic poles facing each other, thus causing the generation of a repulsive magnetic force between the two components.

[0085] In a corresponding manner, the stationary magnet 11 is instead facing the second movement magnet 9b and is further secured in a fixed position (being for example mounted on a fixed element F such as the one described above).

[0086] In particular, the second movement magnet 9b and the stationary magnet 11 are likewise interfaced in such a way as to have the same magnetic poles facing each other, thus causing the generation of a repulsive magnetic force between these two components.

[0087] Consequently, in a rest condition of the system 1 , the supporting body 3 or the container 5 (when positioned inside the supporting body 3) are in an equilibrium, retained by the opposing pushes exerted by the working magnet 10 and the stationary magnet 11 .

[0088] The activation in quasi-resonance (or in resonance) of the oscillating device 2 will cause the working plane 2a to move closer to the container 5 and, consequently, an increase in the repulsive push acting between the first movement magnet 9a and the working magnet 10, which will set the container 5 in motion.

[0089] In general, the activation and hence movement of the working plane 2a thus generates a force that is released in a non-rigid manner by the interfacing means 4 on the container 5 (through the supporting body 3), placing it at least in quasi-resonance.

[0090] In this manner, the method proposed here makes it possible to reach extremely high accelerations, even over 250 G, with low energy consumption, thanks also to the possibility of reducing the execution times by virtue of the high accelerations that can be reached by the container in quasi-resonance.

[0091] In greater detail, the activation of the system 1 can be performed specifically in such a way as to apply to the container an average acceleration of between 30 G and 400 G, preferably between 50 G and 200 G, more preferably between 75 and 125 G, with an overall oscillation frequency (i.e. the oscillation frequency of the container 5 set in motion by the vibration of the working plane 2a through the interfacing means 4) of between 5 Hz and 500Hz, preferably between 25 Hz and 400 Hz, even more preferably between 40 Hz and 250 Hz, and for a duration of between 1 and 180 minutes, more preferably between 2.5 and 90 minutes, even more preferably between 5 and 45 minutes.

[0092] During the activation of the system 1 , it is also possible to carry out a step of cooling the container 5, preferably so as to bring it to an operating temperature comprised between -250 °C and +250 °C.

[0093] Advantageously, the mechanical activation under cooling reduces the occurrence of undesirable chemical reactions during the activation process.

[0094] For the same purpose, the activation of the system 1 can be performed by means of a plurality of activations interspersed with at least one pause, and each pause can specifically have a duration comprised between 10 seconds and 20 minutes, preferably comprised between 30 seconds and 10 minutes, even more preferably comprised between 30 seconds and 5 minutes. In this manner one avoids obtaining an overheating of the powders and thus the occurrence of undesirable mechanical-chemical processes during the activation is reduced. In accordance with a further aspect of the present invention, the method can further comprise a step of mixing the powders upstream of the activation thereof.

[0095] In particular, the mixing operation can be carried out by operating in a manner analogous to the one provided for the subsequent activation step, simply by omitting the insertion of the spherical bodies.

[0096] In other words, it is possible to carry out a mixing operation by performing method steps corresponding and analogous to the ones presented above, without inserting the spherical bodies into the container 5, and then to open the latter again, insert the spherical bodies inside it and proceed to carry out the activation process described above.

[0097] In accordance with a further aspect of the present invention, it is also possible to select / modify the specific quasi-resonance frequency of the system 1 so as to optimise it based on the characteristics of the powders to be activated.

[0098] In fact, different powders (thus materials having different chemical and / or physical characteristics) can have a different response to the stress and thus have an optimal response at different frequency values.

[0099] In this context, it is thus possible to single out / identify an optimal working frequency based on at least one chemical and / or physical characteristic of the powders to be activated.

[0100] This optimal frequency represents a frequency of the mechanical stresses to which the powders are subjected which is such as to maximise the effectiveness of the activation process.

[0101] As a function of the optimal working frequency, it is possible to select and provide specific interfacing means 4.

[0102] In other words, the present method comprises selecting and installing interfacing means 4 in the system 1 which are specifically configured to set the quasi-resonance frequency of the supporting body 3 equal to the optimal working frequency.

[0103] In this manner, depending on the characteristics of the powders to be activated, it is possible to select specific interfacing means 4 that will bring the overall quasi-resonance frequency (and thus also the resonance frequency) of the system 1 to values that are optimal for processing those specific powders.

[0104] From an operational standpoint, if the interfacing means 4 are obtained through the elastic means, for example the springs, the procedure just indicated will be carried out by selecting the springs having an elastic constant such as to bring the overall resonance frequency of the system 1 (specifically of the supporting body 3) to the optimal working frequency or in the neighbourhood thereof.

[0105] Advantageously, the present invention achieves the proposed objects, thus overcoming the drawbacks complained of in the prior art and providing the user with a method that promotes the activation of the powders by placing the container 5 into which they are introduced in quasi- resonance.

[0106] The subject matter of the present invention also relates to the powders obtainable with a method for the mechanical activation of powders having one or more of the characteristics presented above.

[0107] Some possible examples of implementation of the process described thus far are provided below, purely by way of representation, along with the relevant experimental results.

[0108] Example 1

[0109] A test mass (thus having testing purposes and in the absence of powders and balls) was subjected to an input acceleration of 3g in a system 1 in which the interfacing means 4 were obtained through elastic means, in particular springs.

[0110] The result obtained corresponds to a peak acceleration of the test mass equal to 84.9g, with an input multiplication factor equal to 27.24, at an oscillation frequency for the working plane 2a equal to 52.50 Hz.

[0111] The form of the response in frequency for this example, which can be observed in the graphs shown in figure 4, is the same as for typical resonance phenomena, and this proves that the proposed method effectively enables even high acceleration values to be obtained with minimal inputs, placing the test mass in resonance. The table below summarises the experimental parameters applied.

[0112] Example 2

[0113] This example shows the response, in frequency, of a container 5 filled with powder and balls (total mass 459.7 g, equal to the sum of the masses of the container, powder, balls and accelerometer used to measure the acceleration values), subjected once again to an input equal to 3g as in the case described in example 1 .

[0114] In this context as well, as may be observed in figure 5, one notes an extremely efficient multiplication of the input in resonance, which enables the jar to reach a peak acceleration of 103.74g (i.e. 34 times the input). Obviously, due to the different value of the mass to be moved compared to example 1 , the resonance frequency in the two cases is also different. Example 3

[0115] Figure 6 shows the combustion of an equal quantity of activated Boron powder (bottom row) when the process of the present invention is applied according to the parameters shown in the table below compared to a quantity of non-activated boron powder (top row).

[0116] The test was performed at room temperature, using a 150 mg sample. The powder was ignited with a hot wire and recorded with a standard video camera.

[0117] Upon observing figure 6, one may note that the activation process significantly increases the velocity of propagation of the flame front. The mean increase in the velocity of combustion of the activated boron compared to the reference powder is equal to over 1800 %. Example 4

[0118] Two samples having the same nominal chemical composition (40% aluminium and 60% magnesium, in mass) were compared. One of the two samples was a simple mixture of the constituents just indicated, whereas the other sample was the product of mechanical activation of the same mixture obtained by carrying out the method claimed according to the parameters below. The first significant experimental result is tied to the energy release of the compositions. Looking at the results of the DTA (Differential Thermal Analysis), one notes that the mechanically activated composition released a total of 8648 J / g (distributed over two peaks) compared to the 7045 J / g of the composition that was simply mixed (+22.75%). The second significant experimental result is tied to the gain of mass of the reaction products of the two samples.

[0119] The gain of mass is tied to the fact that aluminium and magnesium bind to the oxygen in the atmosphere during the combustion reaction.

[0120] On a theoretical level, the complete reaction of the Al 40% - Mg 60% mixture returns products that weigh 175.14% of the reagents. The TG percentage result demonstrates that the activated composition is capable of reacting completely (the TG signal reaches the theoretical limit, it should be noted that any deviations in excess fall within the range of measurement errors); by contrast, the composition that was simply mixed returns products with a weight equal to about 167% of the weight of the reagents. Example 5

[0121] This example shows the impact that the specific oscillation frequency of the working plane 2a (hence the oscillation frequency applied to the container 5) has on the overall efficiency of the activation process. In this example, powders of AI-Bi-NaCI (in respective percentages of 90%- 5%-5%) are activated to produce hydrogen with the parameters shown below. The powders are activated by applying the following operating parameters in a system using springs as the interfacing means 4:

[0122] In both cases, H1 and H2, an activation process of the same duration is carried out in a resonance condition and the container 5 (and thus the powders contained inside it) are subjected to the same acceleration. In this context, with the powders specified above, one observes experimentally a hydrogen production efficiency of 15.94% in case H1 and of 100% in case H2.

[0123] The above highlights that the selection of an optimal working frequency, from the viewpoint of the efficiency of the activation process, is influenced by the specific characteristics of the powders to be activated.

[0124] Consequently, the identification of an optimal working frequency, and the consequent selection of specific interfacing means 4 which allow the resonance frequency of the system 1 to be brought to overlap with it, makes it possible to significantly increase the overall efficiency of the process.

Claims

CLAIMS1 . Method for the mechanical activation of powders comprising the steps of:- preparing a hermetically sealable container (5);- introducing into said container (5) a plurality of spherical bodies and a predetermined quantity of a powder to be activated;- Hermetically sealing said container (5);- Setting up a system (1 ) for the mechanical activation of powders comprising:- an oscillating device (2) with a working plane (2a) that can be moved along an oscillation direction (X);- a supporting body (3) coupled to the working plane (2a) and capable of receiving and holding the container (5);- interfacing means (4) interposed between the working plane (2a) and the supporting body (3), said interfacing means (4) being configured to define a stroke of the supporting body (3) along the direction of oscillation (X) and to exert on said supporting body (3) a force proportional to the distance between the working plane (2a) and the supporting body (3);- coupling the container (5) to the supporting body (3);- activating said system (1 ) in a condition of quasi-resonance of the supporting body (3) in such a way that the container (5) is placed in quasi- resonance.

2. Method according to claim 1 , wherein the activating step is performed in such a way that the system (1 ) is activated in a resonant condition of the supporting body (3) in such a way that the container (5) is resonant.

3. Method according to claim 1 or 2, comprising a step of washing the predetermined amount of powder to be activated upstream of the introduction of said powder into the container (5).

4. Method according to any one of the preceding claims, comprising a step of grinding said predetermined amount of powder to be activated upstream of the introduction of said powder into the container (5).

5. A method according to any one of the preceding claims, comprising a step of introducing one or more additives into said container (5), preferably said step being performed by introducing into said container (5) a mass fraction of additives comprised between 0.5% and 90%.

6. Method according to claim 5, wherein said one or more additives comprise at least one of: salts, sugars, metal oxides, metals, semi-metals, hydroxides or polymers.

7. Method according to any one of the preceding claims, wherein said step of introducing spherical bodies into the container (5) is performed by introducing at least two groups of distinct spherical bodies having different diameters.

8. A method according to any one of the preceding claims, comprising a step of adding an inert gas into said container (5) so as to obtain a complete volumetric filling of said container (5).

9. Method according to any one of the preceding claims 1 to 8, comprising after hermetically sealing the container (5) the steps of:- connecting said container (5) with a vacuum pump;- activating said vacuum pump to generate a vacuum environment in said container (5).

10. A method according to any one of the preceding claims, comprising a step of cooling the container (5) during activation of the system, preferablysaid cooling step being performed so as to bring the container to an operating temperature comprised between -250 °C and +250 °C.

11. Method according to any one of the preceding claims, wherein the activation of the system (1 ) is performed by applying to the container (5) an average acceleration between 30 G and 400 G with an oscillation frequency along the oscillation direction (X) between 5 Hz and 500 Hz for a time between 1 minute and 180 minutes.

12. Method according to any one of the preceding claims, wherein activating the system (1 ) comprises a plurality of activations interspersed with at least one pause, each pause having a duration comprised between 10 seconds and 20 minutes.

13. Method according to any of the preceding claims, comprising the steps of:- Identifying an optimal processing frequency depending on at least one chemical and / or physical characteristic of the powders to be activated;- Selecting and setting up interfacing means (4) configured to set the quasi-resonance frequency of the support body (3) equal to the processing frequency.

14. Powder obtainable by a method for mechanical activation of powders according to any one of the preceding claims.

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