Device intended for implementing an anodization treatment and anodization treatment

Abstract

A device for performing anodizing treatment on a part, the device including a treatment chamber including a part for anodizing together with a counter-electrode situated facing the part to be treated, the part to be treated constituting a first wall of the treatment chamber; a generator, a first terminal of the generator being electrically connected to the part to be treated and a second terminal of the generator being electrically connected to the counter-electrode; and a system for storing and circulating an electrolyte, the system including a storage vessel, different from the treatment chamber, for containing the electrolyte; and a circuit for circulating the electrolyte in order to enable the electrolyte to flow between the storage vessel and the treatment chamber.

Claims

1. A device for performing anodizing treatment on a part, the device comprising: a treatment chamber comprising a part to be treated and a counter-electrode situated facing the part to be treated, the part to be treated constituting a first wall of the treatment chamber and the counter-electrode constituting a wall of the treatment chamber situated facing the first wall; a generator, a first terminal of the generator being electrically connected to the part to be treated and a second terminal of the generator being electrically connected to the counter-electrode; and a system for storing and circulating an electrolyte, the system comprising: a storage vessel, different from the treatment chamber, for containing the electrolyte, the treatment chamber having a volume that is less than the volume of the storage vessel; and a circuit for circulating the electrolyte in order to enable the electrolyte to flow between the storage vessel and the treatment chamber, wherein the counter-electrode is arranged not to be immersed in the electrolyte.

2. The device according to claim 1, further comprising at least one sealing gasket constituting a second wall of the treatment chamber, the second wall being different from the first wall.

3. The device according to claim 1, wherein the system for storing and circulating the electrolyte further includes a pump for driving circulation of the electrolyte through said system.

4. The device according to claim 1, wherein the ratio (volume of the treatment chamber)/(volume of the storage vessel) is less than or equal to 0.2.

5. The device according to claim 1, wherein the circuit for circulating the electrolyte comprises: a first channel for enabling the electrolyte coming from the storage vessel to flow to the treatment chamber; and a second channel for enabling the electrolyte to flow from the treatment chamber to the storage vessel.

6. A method of anodizing a part, the method comprising the following steps: forming a coating on a surface of the part by anodizing treatment using a device according to claim 1, an electrolyte being present in the treatment chamber during the anodizing treatment, and the electrolyte flowing in the electrolyte circulation circuit during the anodizing treatment.

7. The method according to claim 6, wherein the anodizing treatment is micro arc oxidation treatment.

8. The method according to claim 6, wherein during the anodizing treatment: the electrolyte coming from the storage vessel flows to the treatment chamber through a first channel; and the electrolyte flows from the treatment chamber to the storage vessel through a second channel.

9. The method according to claim 6, wherein the electrolyte present in the treatment chamber is continuously renewed during the anodizing treatment.

10. The method according to claim 6, wherein the electrolyte flows in the electrolyte circulation circuit at a flow rate lying in the range 0.1 times to 10 times the volume of the treatment chamber, per minute.

11. The method according to claim 8, wherein it further includes a step of filtering the electrolyte flowing in the second channel prior to its return into the storage vessel.

12. The method according to claim 8, wherein it further includes the following steps: determining at least information relating to the electrolyte flowing in the first channel and/or in the second channel; and modifying at least one characteristic of the anodizing treatment, this modification being performed as a function of the information determined about the electrolyte.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the invention appear from the following description of particular embodiments of the invention, given as non-limiting examples, and with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an embodiment of a device of the invention; and

(3) FIGS. 2 and 3 show other embodiments of devices of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1 shows an embodiment of a device 1 of the invention. The device 1 comprises the part to be treated 3 and a generator 5. The part to be treated 3 is for being subjected to anodizing treatment, preferably micro arc oxidation. The generator 5 serves to perform this anodizing. As shown, a first terminal of the generator 5 is electrically connected to the part 3, and a second terminal of the generator 5 is electrically connected to a counter-electrode 7 situated facing the part 3. The generator 5 is advantageously configured to apply alternating current (AC).

(5) The counter-electrode 7 is preferably made of stainless steel. More generally, it is possible to use any electrically-conductive material for the counter-electrode 7 providing it is compatible with performing anodizing treatment.

(6) The device 1 has a treatment chamber 10 in which the anodizing treatment is to be performed, the part 3 to be treated constituting a first wall of the treatment chamber 10 and the counter-electrode 7 constituting a wall of the treatment chamber that is situated facing the first wall. An electrolyte 11 is present in the treatment chamber 10 between the part 3 and the counter-electrode 7. The electrolyte 11 has a chemical composition that enables the part 3 to be subjected to anodizing treatment. As shown, the counter-electrode 7 is not immersed in the electrolyte 11. The counter-electrode 7 forms a wall of the treatment chamber 10.

(7) Thus, as shown, the part 3 to be treated is not immersed in the electrolyte 11 present in the treatment chamber 10. The part 3 constitutes a wall of the treatment chamber 10 so that only the surface S to be treated of the part 3 is in contact with the electrolyte 11. In the example shown, the part 3 is treated over its entire length, i.e. over its entire longest dimension. Naturally, it would not be beyond the ambit of the present invention for the part to be treated over a fraction only of its length. In the ambit of the invention, it is thus equally possible to perform anodizing treatment over a fraction only of a surface of a part or over an entire surface of a part.

(8) In addition, the treatment chamber 10 comprises two sealing gaskets 13a and 13b situated facing each other and forming two distinct walls of the treatment chamber. As shown, the sealing gaskets 13a and 13b are present at the top and bottom ends of the treatment chamber 10. The gaskets 13a and 13b may be made of flexible material.

(9) Thus, in the embodiment shown of the device 1 the electrolyte 11 used for anodizing is contained between the part 3 and the counter-electrode 7 by static sealing making use of the flexible gaskets 13a and 13b. The treatment chamber 10 thus constitutes a tank of electrolyte 11 for coating the surface S of the part 3. As mentioned above, the treatment chamber 10 has a volume and dimensions that are adapted to the dimensions and to the shape of the surface S to be treated of the part 3. In the example shown, the treatment chamber 10 defines a single compartment.

(10) In addition, the device 1 includes a system 20 for storing and circulating the electrolyte 11. The system 20 comprises a storage vessel 21 in which the electrolyte 11 is stored, with the temperature of the electrolyte 11 stored in the storage vessel being maintained at a value that is determined by a cooling system (not shown). The pH of the electrolyte 11 present in the storage vessel 10 is also maintained at a fixed value. During anodizing treatment, the electrolyte 11 coming from the storage vessel 21 flows along a first channel 23 to the treatment chamber 10. The system 20 also has a second channel 25 enabling the electrolyte 11 to flow from the treatment chamber 10 to the storage vessel 21. The second channel 25 enables the electrolyte 11 present in the treatment chamber 10 to be discharged and returned to the storage vessel 21 where it can be cooled. The electrolyte 11 is caused to circulate through the system 20 by a pump 27. By way of example, the pump 27 may be a pump that is sold under the name YB1-25 by the supplier TKEN.

(11) FIG. 1 includes arrows showing the flow direction of the electrolyte 11. The flow rate of the electrolyte 11 determined by the pump 27 enables the electrolyte 11 in the treatment chamber 10 to be renewed appropriately so as to enable the desired coating to be made by anodizing. It may be advantageous for the pump 27 to cause the electrolyte 11 to flow at a rate that is equal to about one volume of the treatment chamber 10 per minute. More generally, the pump 27 may advantageously cause the electrolyte 11 to flow at a rate lying in the range 0.1 times to 10 times the volume of the treatment chamber 10 per minute.

(12) Advantageously, the flow of electrolyte 11 from the storage vessel 21 to the treatment chamber 10 and from the treatment chamber 10 to the storage vessel 21 is not interrupted throughout the duration of the anodizing treatment. In other words, it is preferred to renew the electrolyte 11 present in the treatment chamber 10 continuously throughout the anodizing treatment.

(13) The first channel 23 may have a diameter d.sub.1 over all or part of its length that is less than or equal to 10 centimeters (cm), e.g. lying in the range 1 cm to 3 cm. The second channel 25 may present a diameter d.sub.2 over all or part of its length that is less than 10 cm, e.g. lying in the range 1 cm to 3 cm. The treatment chamber 10 may have a volume that is less than or equal to 0.5 m.sup.3, e.g. lying in the range 10 cubic decimeters (dm.sup.3) to 40 dm.sup.3. The storage vessel 21 may have a volume greater than or equal to 0.5 m.sup.3, e.g. lying in the range 0.5 m.sup.3 to 2 m.sup.3.

(14) The materials forming the gaskets 13a and 13b, the first channel 23, and the second channel 25 are selected so as to ensure that electricity does not pass between the counter-electrode 7 and the part 3.

(15) The device 1 shown in FIG. 1 serves to perform anodizing treatment on a part by part basis. As shown, the method performed by the device 1 shown in FIG. 1 advantageously does not include a step of masking a portion of the surface S of the part 3 or of putting into place at least one resist on the surface S of the part 3 to be treated.

(16) The final thickness of the coating formed after anodizing treatment measured perpendicularly to the surface of the underlying part may lie in the range 2 micrometers (m) to 200 m.

(17) There follows an example of operating conditions that may be implemented in order to perform micro arc oxidation treatment with a device 1 as described above: imposed current: 40 amps per square decimeter (A/dm.sup.2) to 400 A/dm.sup.2; voltage: 180 volts (V) to 600 V; pulse frequency: 10 hertz (Hz) to 500 Hz; duration of treatment: 10 minutes (min) to 90 min; temperature of the electrolyte in the storage vessel: 17 C. to 30 C. pH of the electrolyte in the storage vessel: 6 to 12; and conductivity of the electrolyte in the storage vessel: 200 millisiemens per meter (mS/m) to 500 mS/m.

(18) In particular, for performing micro arc oxidation treatment, it is possible to use an electrolyte 11 having the following composition: demineralized water; potassium hydroxide (KOH) at a concentration lying in the range 5 grams per liter (g/L) to 50 g/L; sodium silicate (Na.sub.2SiO.sub.3) at a concentration lying in the range 5 g/L to 50 g/L; and potassium phosphate (K.sub.3PO.sub.4) at a concentration lying in the range 5 g/L to 50 g/L.

(19) Nevertheless, the invention is not limited to performing a micro arc oxidation method. A device of the invention may be used for performing any type of anodizing, such as for example sulfuric anodic oxidation (SAO), chromic anodic oxidation (CAO), sulfotartric anodic oxidation (STAO), or sulfo-phosphoric anodic oxidation (SPAO).

(20) By way of example, the treated part may be a blade, e.g. made of titanium, or a pump body. It is also possible to use a device of the invention to repair a layer of anodizing that has been damaged, the device making it possible to perform localized repair with a coating being formed by anodizing solely in the damaged zone.

(21) In a variant that is not shown, it is possible to treat a plurality of distinct parts using a plurality of devices of the invention optionally connected to the same generator. The parts may optionally be treated simultaneously.

(22) The storage vessel 21 is dedicated to storing and renewing the electrolyte and no anodizing treatment is performed therein. By separating the storage vessel 21 from the treatment chamber 10, it is possible to configure devices of the invention so as to perform treatments additional to anodizing, as described in detail below. So far as the inventors are aware, these treatments additional to anodizing are not performed or are not performed in satisfactory manner in methods known in the state of the art.

(23) FIG. 2 shows a variant of the device 1 of the invention. In this example, the device 1 also has a filter device 52 situated between the treatment chamber 10 and the storage vessel 21. The electrolyte present in the second channel 25 flows through the filter device 52 and is returned to the storage vessel 21 after being filtered via the channel 25a. By way of example, using such a filter device 52 advantageously makes it possible to eliminate particles that have not become attached to the anodic layer being formed, thereby purifying the electrolyte 11 before returning it to the treatment chamber 10.

(24) FIG. 3 shows a variant of the device 1 of the invention. The device 1 includes a sensor 60 for determining information about the electrolyte 11 flowing in the first channel 23. As a function of the information it determines, this sensor 60 makes it possible to act on the generator 5 in such a manner as to modify at least one characteristic of the anodizing treatment being performed. In a variant, the sensor may determine information about the electrolyte flowing in the second channel, or indeed it may determine both information about the electrolyte flowing in the first channel and information about the electrolyte flowing in the second channel, so as to modify the anodizing treatment that is being performed as a function of this information. By taking measurements upstream and/or downstream of the treatment chamber 10, this embodiment of the device 1 of the invention advantageously makes it possible to obtain information that is more reliable than the information that can be observed in the reaction chamber, thus making it possible to control the anodizing performed in the treatment chamber in satisfactory manner as a function of the information that has been determined. Typically, the information about the electrolyte that is determined by the sensor may concern one or more of the following parameters: the concentration of metallic species, e.g. aluminum, within the electrolyte, the pH, and the conductivity of the electrolyte. The electrolyte can become laden with metallic species progressively as the anodizing progresses, and this parameter, like the pH or the conductivity of the electrolyte, makes it possible to have an influence on the anodizing treatment that is performed. Direct control over the anodizing being performed may be advantageous in particular for performing anodizing treatments on parts that are to be used in the field of aviation and/or when performing anodizing treatments that are relatively lengthy.

(25) The term including/containing/comprising a should be understood as including/containing/comprising at least one.

(26) The term in the range . . . to . . . should be understood as including the limits.