METHOD FOR WETTING A SONOTRODE

Abstract

The method comprising the following steps: a) Providing a first bath of a liquid metal (1) comprising aluminium with a content X and magnesium with a content Y, the magnesium content Y being different to zero, b) Immersing at least partially a sonotrode (3) formed from a material inert to liquid aluminium, in the first bath of liquid metal (1), and c) Applying power ultrasounds to the sonotrode (3) so as to excite the liquid metal (1) until wetting (5) of the sonotrode (3) by the liquid metal (1) is obtained. d) Cooling the first liquid metal (1) of the first bath until solidification of the first liquid metal (1) around the sonotrode (3) is obtained, generating an intimate bond (6) between the sonotrode (3) and the solidified first liquid metal (1) having a bonding strength substantially equal to that of brazing between two metals. e) Machining the solidified first metal (1) in the form of a flange (7) configured for the attachment of a mechanical amplifier and/or of a transducer (4).

Claims

1. Method for using a sonotrode comprising: a) Providing a first bath of a liquid metal comprising aluminium with a content X and magnesium with a content Y, the magnesium content Y being different to zero, b) Immersing at least partially a sonotrode formed from a material inert to liquid aluminium, in the first bath of liquid metal, c) Applying power ultrasounds to the sonotrode so as to excite the liquid metal until wetting of the sonotrode by the liquid metal is obtained, d) Cooling the first liquid metal of the first bath until solidification of the first liquid metal around the sonotrode is obtained, generating an intimate bond between the sonotrode and the solidified first liquid metal having a bonding strength substantially equal to that of brazing between two metals. e) Machining the solidified first metal in the form of a flange configured for the attachment of a mechanical amplifier and/or of a transducer.

2. Method according to claim 1, wherein a) comprises providing a first bath of liquid metal comprising magnesium with a content Y greater than or equal to 0.05%, optionally a content Y greater than 0.5%, and optionally a content Y greater than or equal to 0.7% by weight.

3. Method according to claim 1, wherein the sonotrode immersed in b) is formed from a silicon nitride or silicon oxynitride ceramic, optionally a SiAlON.

4. Method according to claim 1, wherein c) for applying power ultrasounds consists of applying low-frequency ultrasounds, optionally of a frequency between 10 and 40 kHz.

5. Method according to claim 1, wherein a) comprises providing a first bath of liquid metal wherein the liquid aluminium content X is zero.

6. Method according claim 1, wherein a) comprises the provision of a first bath of liquid metal comprising aluminium with a content X different to zero such that the first bath comprises a first liquid aluminium alloy.

7. Method according to claim 1, comprising, after e), f) Immersing the other end of the sonotrode and wetting in the first bath of liquid metal said sonotrode as in c) g) Providing a second bath of a second liquid aluminium alloy, h) Immersing at least partially the sonotrode in the second bath of the second liquid aluminium alloy, i) Applying power ultrasounds to the sonotrode to regenerate the wetting, j) Applying power or measurement ultrasounds to the sonotrode.

8. Method according to claim 7, wherein the second liquid aluminium alloy provided in g) comprises magnesium with a content Y′ between 0 and 0.7% by weight.

9. Method according to claim 7, wherein the second liquid aluminium alloy of the second bath provided in g) is formed from a liquid AlSiMg alloy, the liquid AlSiMg alloy comprising Si with a content of 0.5 to 7% by weight and Mg with a content Y′ of 0 to 0.7% by weight of Mg.

10. Insonification device comprising at least a sonotrode made of ceramic, formed from silicon nitride or silicon oxynitride, a SiAlON, and a flange made of a first aluminium alloy, attached by an intimate bond to the sonotrode obtained using the method according to claim 1.

Description

[0041] Further aspects, aims and advantages of the present invention will emerge more clearly on reading the following description of an embodiment thereof, given by way of non-limiting example and with reference to the appended figures. The figures do not necessarily observe the scale of the elements represented so as to improve the legibility thereof. Hereinafter in the description, for the purposes of simplification, identical, similar or equivalent elements of the various embodiments bear the same reference numbers.

[0042] FIGS. 1 to 3 are an illustration of the schematic diagram of the method for using a sonotrode according to one embodiment of the invention.

[0043] FIGS. 4 to 6 are an illustration of the schematic diagram of the formation of an intimate bond according to one embodiment of the invention.

[0044] FIGS. 7 to 8 are an illustration of the schematic diagram of a further use of the sonotrode wetted according to one embodiment of the invention.

[0045] As illustrated in FIG. 1, a first bath of a liquid metal 1 is prepared in a receptacle 2 such as a crucible. The liquid metal 1 particularly comprises a non-zero content X of liquid aluminium (main component) and a content Y of magnesium of approximately 0.7% by weight according to step a) of the method. A sonotrode 3 made of SiAlON ceramic, which is refractory and inert to liquid aluminium, is then immersed partially in the first bath of liquid metal 1 (step b) FIG. 2). Power ultrasounds are applied via a transducer 4 or a transducer-amplifier assembly to the sonotrode 3 so as to excite same (step c). The power ultrasounds applied are low-frequency ultrasounds, of the order of 20 kHz with a power of 150 W. After a few minutes of this treatment, wetting 5 of the sonotrode 3 is formed, a layer or film of aluminium not suitable for being readily peeled off is indeed found on the surface of the sonotrode 3 (FIG. 3). Further so-called “low-frequency” vibration frequencies particularly between 10 and 40 kHz can be used to excite the liquid metal 1 via the sonotrode 3. Similarly, further power values can be envisaged insofar as they are sufficient to generate the cavitation phenomenon in the liquid metal in a time compatible with industrial methods so as to obtain wetting rapidly.

[0046] According to one alternative embodiment not illustrated, the magnesium content Y in the liquid metal 1 is 0.05, or 0.5% by weight. The sonic treatment time for obtaining wetting is thereby extended compared to that obtained for a magnesium content Y of 0.7% by weight.

[0047] According to one alternative, the same treatment time for obtaining wetting as that obtained with a magnesium content Y of 0.7% by weight is carried out due to the increase in the ultrasound power.

[0048] Moreover, according to a further alternative embodiment, any sonotrode 3 consisting of a material inert to liquid aluminium such as a refractory ceramic of the silicon nitride or silicon oxynitride family is wetted by liquid aluminium by means of this method.

[0049] According to a further alternative embodiment not illustrated, the aluminium content X of the first bath 1 is zero. In this case, the wetting of the sonotrode 3 is obtained with magnesium the content Y whereof is close to 100% by weight. This sonotrode 3 wetted in this way is then immersed in a second bath of a second liquid aluminium alloy in order to be subsequently suitable for carrying ultrasounds without loss of power for a long period.

[0050] According to one option illustrated in FIGS. 4 to 6, the first bath comprising the first liquid aluminium alloy 1, wherein the sonotrode 3 is wetted by applying power ultrasounds (FIG. 4—step c), is allowed to return to ambient temperature (FIG. 5—step d). Once cooled, the first aluminium alloy 1 is solidified around the sonotrode 3, generating an intimate bond 6 between the sonotrode 3 and the solidified alloy 1 (seen in FIG. 5). The intimate bond 6 corresponds to sealing with a perfect bond, without any decohesion and metallurgical continuity between the ceramic and the first aluminium alloy. Then, the sonotrode 3 intimately bonded with the first aluminium alloy 1 is released from the crucible 2 and the solidified alloy 1 is machined by turning and drilling so as to form a cylindrical flange 7 intimately bonded with the ceramic (FIG. 6, step e). The intimate bond 6 between aluminium and SiAlON is formed with similar properties to those obtained upon brazing between two metals. An insonification device 8 is thereby obtained, it enables optimal mechanical coupling between aluminium and the sonotrode 3.

[0051] Obviously, this method can be implemented using alloys of aluminium and magnesium of different compositions, with or without silicon and particularly using an alloy including copper. According to one option illustrated in FIGS. 7 and 8, the sonotrode 3 wetted by liquid aluminium, is removed from the first bath 1 (step f, FIG. 7) to be partially immersed in a second bath of liquid aluminium alloy 1′ (step g, h, FIG. 8). Ultrasounds are applied to the sonotrode 3 with a vibration frequency of 20 kHz and a power of approximately 150 W so as to regenerate the wetting 5 (step i) even in the absence of magnesium in the second liquid aluminium alloy 1′. The second liquid aluminium alloy 1′ is indeed formed from AlSiMg with a content between 0.5 and 7% by weight of Si and a content Y of 0% to 0.7% by weight of Mg. The sonotrode 3 obtained thereby can then be reused for effectively transmitting the power, or measurement, ultrasounds (with frequency of 100 kHz for example) in the second liquid aluminium alloy 1′.

[0052] According to one option not illustrated, the flange 7 in an intimate bond 6 with the sonotrode 3 following step f), FIG. 6, of the method is subsequently used for attaching a transducer 4. The sonotrode 3 attached in this way to the transducer 4 is then wetted in a bath of an aluminium alloy as described above. The ultrasounds emitted by the transducer 4 are then transmitted via the flange 7 to the wetted sonotrode 3 which in turn transmits the ultrasounds to the bath of aluminium alloy with a view to performing tests or treatments of the liquid aluminium for quality casting.

[0053] As such, the present invention relates to a method for using a sonotrode 3 by wetting obtained using aluminium or magnesium, which is inexpensive and simple to carry out. The invention also relates to the formation of an intimate bond 6 between the material of the sonotrode and a solidified aluminium alloy 1′ which is very simple to implement and suitable for producing a flange 7 perfectly sealed to the sonotrode 3, and suitable for long-term use particularly for transmitting measurement or power ultrasounds.

[0054] It is obvious that the invention is not limited to the embodiment described above by way of example but that it includes any technical equivalents and the alternative embodiments of the means described as well as the combinations thereof.