JP3421457B2 - Method and apparatus for dry treatment of metal surfaces - Google Patents

Description

Detailed Description of the Invention

[0001]

The invention relates to the production or treatment of metal surfaces, which is carried out in a method for the production or treatment of flat products (sheet metal) or hollow bodies (bottles, valves etc.). Regarding the process of.

[0002]

Depending on the part of the production line where the processing steps for the product are carried out, these preparatory steps often comprise surface cleaning, degreasing or activation prior to the subsequent processes. For example, such preparatory steps include annealing; electroplating of zinc, aluminum, tin or their alloys; deposition of organic coatings such as varnishes or paints; deposition of inorganic coatings such as nitride or silicon based films. can do.

Such a step of preparing the surface may also be carried out at the end of the production line, such as immediately before the sheet metal is wound.

The product is made of steel, stainless steel, copper, or aluminum, depending on the ultimate purpose of the product in question (eg, automobile, household appliance, building, or container such as a can). can do.

The most commonly used method for performing these operations for surface preparation is first the liquid phase method.

Examples of this category are in the case of preliminary degreasing, which is carried out with solvents which normally contain chlorine or fluorine, which are subjected to very strict control, or in chemical baths, acids, alkalis or neutrals. Methods involving the degreasing of metal surfaces with an aqueous medium containing the product, which have the drawbacks associated with the wastewater work-up required after washing.

In this connection, a second category of methods for the treatment or preparation of metal surfaces emerges, which is called the "dry method". An example of this category is cleaning the surface with a gas phase plasma using electron radiation under low pressure. This method seems to be very preferable at first glance because it shows great consideration for the environment. It combines two separate operations of electron emission, one is a strong ion bombardment produced under certain conditions by an ionized medium, a cleaning operation by atomization and the other is A method of obtaining the highly reactive use of excited atoms and molecules present in a plasma to make volatile compounds on the surface of sheet metals and with the substances to be removed, ie essentially organic. It is the chemical action of a sexual substance. The gas phase atmosphere generally preferred for this method of pickling under electron emission is to enhance the quality of the gas generating the plasma and to increase the mass of its ions which promote the atomization of this gas. , Containing a high percentage of argon. It is enriched with oxygen and hydrogen in order to use some of the chemistry of the discharge by removing the organics present on the surface of the sheet metal by forming light compounds of the CO _x or CH _y type. .

The high performance of this process cannot hide the main drawback associated with the fact that it is carried out under low pressure and even in vacuum. Since they are relatively incompatible with the treatment of large metal surfaces or high production rates (in the case of industrial production of sheet metal), these pressure conditions undoubtedly suppress their development.

Moreover, the use of such low pressures represents a considerable additional cost.

No. In a French patent application issued 2,697,456, a process under atmospheric pressure is proposed for plasma flux treatment of metal surfaces before soldering or tin plating. The plasma is created by a corona discharge traveling through a microwave source or a port appropriately located in a dielectric located above the member to be treated.

Although this application provides a convenient solution to the problem of fluxing metal surfaces, it has been shown that the proposed process could have been solved, inter alia in the following points.

The yield (ratio between the power introduced to generate the plasma and the concentration of the produced species which actually interacts with the substrate to be treated), or the energy density obtained ( In the case of corona discharge, which reaches only several W per unit volume of the dielectric),
A shorter treatment time is possible-but also as a result of limiting "geometric" factors, in the case of a normal corona discharge the distance between the electrode and the sample is completely definitive. Must be kept small, which causes problems in the case of uneven substrates. In the case of a microwave discharge, it results in the formation of places where a plasma of a defined size is confined by the plasma source-further, a plasma such as that produced by definition in this disclosure is a combination of ionic species and electrons. (I.e., charged species), which is ion bombarded and, in some cases, has been shown to be detrimental to atomization of metal surfaces (e.g., if the metal surface is covered by a coating). It should be unchanged).

In parallel with this, No. 2,692,73
In the French patent application issued at 0-this content is assumed to be incorporated herein-of the production of excited or labile gas molecules acting at substantially atmospheric pressure. A device for was proposed.

[0014]

In this context, the object of the present invention is to provide an improved process for the dry treatment of metal surfaces, which enables:

To operate substantially at atmospheric pressure, to obtain a high degree of flexibility in the distance between the object to be treated and the device used to carry out this treatment, Avoiding contact between charged species and-providing improved energy density giving increased processing rates.

[0016]

To this end, the process for the dry treatment of the surface of at least one metal surface part according to the method of the invention comprises an excited or labile species. In addition, the metal surface portion is treated at a pressure close to the atmospheric pressure by a gas phase treatment atmosphere in which charged species are substantially absent.

The expression "metal surface" as used in the present invention refers to any type of surface, regardless of the size and thickness of the member containing the metal surface portion to be treated,
For example, it may be made of steel, stainless steel, copper or aluminum. Their final industrial application can vary widely, and these metal surfaces can be used, for example, in the field of household appliances, automobiles, commercial gas, or in the building or container industry.

The expression "surface treatment" as used in the present invention refers to any stage for the preparation, cleaning, activation or degreasing of metal surface parts, which stage is the production using such a metal surface. Can be done at different parts of the manufacturing line for objects (whether they are flat, such as sheet metal, or hollow, such as bottles), at the end of the manufacturing line (eg, such sheets). Before winding) or annealing; operations such as electroplating of zinc, aluminum, tin, or alloys thereof; deposition of organic coatings such as varnishes or paints; inorganic coatings such as films based on nitrides or silicon Can be done during manufacturing, before any subsequent steps such as deposition of

The purpose of the application of the surface treatment process according to the invention is therefore, in particular, to facilitate the application of subsequent steps, for example to promote the adhesion of coatings of paint.

The surface treatment method of the present invention can be applied alone or in addition to other surface preparations performed before and after applying the method of the present invention.

"Pressure close to atmospheric pressure" used in the present invention
Represents the pressure in the range of 0.1 × 10 ⁵ Pa to 3 × 10 ⁵ Pa.

The process atmosphere of the present invention differs from a normal plasma atmosphere in that it is substantially free of charged species, ie, ions or electrons.

The gas phase treatment atmosphere can be obtained from a main gas phase mixture, if necessary a neighboring gas phase mixture, the main gas phase mixture being at least 1 for the production of excited or labile gas phase species. Obtained at the gas outlet of one device. Within the device, an initial gas mixture containing an inert gas and / or a reducing gas and / or an oxidizing gas is converted and the adjoining mixture does not pass through the device.

The device of the present invention "excites" the initial gas phase mixture to obtain another gas phase mixture containing unstable or excited gas phase species at the gas outlet of the device.
Configured by any device, the gas phase mixture at the gas outlet is substantially free of charged species. Such excitation can be caused by electron emission, for example of the corona discharge type.

A major component of the process atmosphere containing excited or unstable gas phase species is obtained at the exit of the device, so that it is substantially free of charged species. To assure, this arrangement can be described as "post-discharge". Components near the processing atmosphere that do not pass through the device do not include these fortiori.

Furthermore, this arrangement allows a clear separation between where the main constituents of the atmosphere occur and where it is used, which offers significant advantages in terms of device contamination ( Avoid the various emissions resulting from surface treatment operations from contaminating the inside of the device, eg electrodes). Finally, components that are not treated within the device (eg, within the discharge between the electrodes) benefit from the improved flexibility in terms of "distance" discussed above.

The inert gas is, for example, nitrogen, argon,
It may contain helium, or a mixture of these inert gases. The reducing gas is, for example, hydrogen, CH ₄ ,
It can include natural gas, propane, ammonia, or mixtures of these reducing gases. The oxidizing gas for the portion can include, for example, oxygen, CO ₂ , N ₂ O, H ₂ O, or a mixture of these oxidizing gases. Of course, the listed gases in each category are merely examples and are in no way limiting.

As will be apparent to those skilled in the art, an initial gas mixture of the present invention is provided to obtain a gas phase mixture containing excited or labile gas phase species, called the main gas phase mixture, at the gas outlet of the device. Are processed or converted in at least one device for the production of excited or unstable gas phase species.

It will also be apparent to those skilled in the art that the member having the surface to be treated may be a single device for the production of excited or unstable gas phase species, or parallel across the width of the member. Contacting the main gas phase mixture obtained at the gas outlet of a plurality of devices arranged in. Alternatively, the member is in continuous contact with the main gas phase mixture obtained at the outlet of several devices arranged in series for the production of excited or unstable gas phase species.

The method of the present invention can be applied according to the user's request both when treating only one side of a member to be treated and when treating both sides of the member being treated. it can. In the latter case, the required devices are preferably placed opposite each side of the member.

According to the invention, the near-field mixture can consist of any gas or gas mixture, for example, in order to make it possible to maintain a protective atmosphere around the component, for example , An inert gas or a mixture of inert gases. Further, it may be a reducing gas or an oxidizing gas, or a mixture of gases in one of these three categories.

According to one characteristic of the invention, the neighborhood mixture contains the silane SiH ₄ . Mixtures of this type containing silane are preferably used due to their reducing action on certain metal oxides present on the surface of the component, but also above the component in order to minimize residual oxygen levels. In interaction with residual oxygen from the atmosphere present,
Oxygen depends on the initial gas phase mixture used as a "scavenger" or trapper.

According to one aspect of the invention, the metal surface portion to be treated is heated to a temperature not exceeding 600 ° C,
It is typically heated to room temperature to 600 ° C.

In accordance with one aspect of the present invention, a member having a portion to be treated is provided with a delivery system that traverses the interior space defined by a tunnel or hood assembly for sealing from the ambient atmosphere. Of the plurality of devices arranged parallel to each other across the width of the member, and / or to the gas outlets of the plurality of devices arranged in series. Move to face each other. The tunnel or assembly is connected to seal the device or to contain the device.

Similar considerations as described above can be applied to double-sided processing (in this case, the required number of devices, placed opposite each side of the member).

Depending on the industry in question, the conveying means of the invention can be, for example, a belt or, in the case of sheet metal, a roller.

According to one aspect of the invention, the device in which the initial gas phase mixture is converted is the location of the electron emission generated between the first electrode and the second electrode, the dielectric A layer of material is disposed on the surface of at least one electrode, opposite the other electrode, and the initial gas phase mixture discharges across the electrode.

According to one of the features of the invention, the energy used in the device, modified per unit area of the dielectric, preferably exceeds 1 W / cm ^2.
More preferably, it exceeds W / cm ² .

According to one aspect of the present invention, the processing atmosphere in which the member to be processed is continuously faced along the conveying means is divided into the following areas.

A) An initial gas phase mixture in which at least one device for the production of excited or unstable gas phase species is different from the gas phase mixture which was previously converted by the device in the tunnel or assembly. And / or b) the near gas phase mixture used in the device for the production of excited or unstable gas phase species, prior to the gas phase mixture used in the device in the tunnel or assembly. According to one of the aspects of the present invention, steps a) and b) are:
It may be done in a single device.

It is therefore possible, for example, to use a mixture with increased reducing power from one device to the next.

The invention also relates to a device for the dry surface treatment of at least one metal surface, which is suitable for carrying out the method of the invention, said device of a member having a surface to be treated. A tunnel or hood assembly defining an interior space traversed by means for transporting said tunnel or hood assembly, said tunnel or hood assembly being closed with respect to the surrounding atmosphere, arranged in series and / or parallel, excited or For the production of unstable gas phase species 1
Or at least one tubular gas channel having a shaft formed between an external electrode and an internal electrode, which is hermetically connected to the device or further including the device, and at least 1 One electrode has a dielectric coating facing the other electrode, these electrodes are connected to a high voltage, high frequency power supply, the outer electrode surrounds the dielectric and is a gas called the initial gas. And an outlet for the gas called the main gas, which inlet and outlet are
Extending parallel to the axis and substantially diametrically opposite the other, the gas outlet is open towards the inside of the tunnel or assembly, which tunnel does not pass through the device if necessary The apparatus comprises at least one means for injecting a gas called a nearby gas,
If necessary, it further comprises heating means for heating the member to be treated.

This heating means can be constituted by an infrared lamp existing in the tunnel or convection heating (heating the wall in the tunnel), and the member may be arranged on the heated substrate carrier.

Other features and advantages of the present invention will be apparent from the following description and some aspects provided by non-limiting examples.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a component 1 having a metal surface which is carried and treated by a transport means 2 facing the gas outlet of a device 4 for the production of excited or unstable gas phase species. .

The transport system 2 traverses an interior space 31 defined by a tunnel 3 which is conveniently connected to the device 4 in a sealed manner.

The main gas phase mixture obtained at the outlet 6 of the device 4 is shown schematically at 8. The main gas phase mixture 8 is obtained from the initial gas phase mixture 7 entering the device at its gas inlet 5.

The embodiment shown in FIG. 1 also shows the inlet for the near gas phase mixtures 9, 10. Near gas phase mixture 9,1
The gas phase atmosphere including 0 and the main gas phase mixture 8 constitute the processing atmosphere 30 of the present invention.

The embodiment shown in FIG. 1 shows at 11 and 12 an additional device for the production of excited or unstable gas phase species (not shown), which device is the first device 4. Is arranged in series and continuously faces the member 1.

The device may therefore additionally be provided with another inlet for the near gas phase mixture, as indicated at 13 and 29.

Further, if necessary, the apparatus may be provided with means (not shown) for heating the member 1. This heating means can be constituted by, for example, an infrared lamp in the tunnel, or convection heating (heating the wall of the tunnel). Alternatively, the member may be placed on a heated substrate carrier.

As with the embodiment shown in FIG. 2, the device for this embodiment is cylindrical in shape. It comprises, for example, a first tubular electrode 14 formed by the inner wall surface of a metal block 15, inside of which an assembly containing a tube 16 of a dielectric such as ceramics is arranged concentrically. In FIG. 2, a second electrode 17 is shown on the inner wall surface of the tube 16 with an exaggerated thickness for illustration purposes, but this is deposited by electroplating.

Therefore, the dielectric 16 and the second electrode 1
The assembly comprising 7 defines with the first electrode 14 a tubular gas flow path 18 inside which there is an internal volume 19 in which the coolant circulates. Freon is preferable as the coolant because it is electrically inactive, and exchanged water may be used. The inner gas flow path 18 has an axial dimension of less than 1 m, typically less than 50 cm and a thickness not exceeding 3 mm, typically less than 2.5 mm radial thickness.

The block 15 has two opposing longitudinal elongate gaps 20 and 21, which are respectively the inlet of the excited initial gas into the flow path 18 and the excited or unstable gas. Form an outlet for the main gas stream containing the phase species.

The elongated gaps 20 and 21 are formed in the cavity 18
Over its entire axial length, and in the illustrated embodiment has a height not exceeding the thickness e and is typically substantially equivalent to the thickness. The matrix 15 preferably has a plurality of conduits 22 around the first electrode 14 for the passage of a coolant such as water. The gas inlet 20 is connected to the block 15 so that the initial gas generated from the initial gas source 26 is discharged to 0.
It communicates with a homogenizing chamber or high pressure chamber 23 formed in a housing 24 having a tube 25 for inflowing at a pressure of 1 × 10 ⁵ Pa to ³ × 10 ⁵ Pa. Electrodes 14 and 17 are preferably operated at frequencies above 15 kHz and are connected to a high voltage and high frequency generator 27 which supplies about 10 kW of power. Also, this power delivered from the generator can be expressed as modified for the dielectric surface area (ie, for the unit area of the dielectric electrode).

Gas outlet 21 containing excited gas phase species
The vapor-phase flow utilized in is sent to a user station 28 for treatment of metal surfaces.

One device, such as that described in connection with FIG. 1, is used to implement aspects of the invention.

The apparatus comprises a single device as described in connection with FIG. 2 for producing excited or unstable gas phase species at 4. For this aspect,
A sheet metal of cold rolled low carbon steel having a thickness of 0.2 mm was treated. The processed sample is 10c on each side.
It was a square of m.

The process atmosphere used included the addition of a near gas mixture containing nitrogen and a main gas phase mixture obtained from an initial mixture of nitrogen and 40% hydrogen.

[0060] The initial mixture of nitrogen and hydrogen in the processing amount of each was obtained as 10 m ³ / h and 7m ³ / h. During processing, the steel member is
The temperature was 50 ° C. and the pressure inside the tunnel was maintained at substantially atmospheric pressure levels. The energy density used per square cm of the dielectric was 15 W / cm ² , and the distance between the member and the gas outlet of the device was 10 mm.

Each steel member was processed within 2 mn as it passed by the action of the transport means 2. The surface cleaning properties obtained in this way are tested by the subsequent deposition of silica to evaluate the adhesion of the silica to the steel parts thus treated. The adhesion of 5000 Å deposited silica to this type of steel member was evaluated by a standard test method known as the "Scotch" method.

In this case, the Scotch test was applied as follows.

A silicon deposition was performed and engraved to obtain 100 squares over a 1 cm ² surface area of a steel sample (10 cm × 10 cm). In addition,
Each square has a surface area of about 1 mm ² . After deposition, the adhesive tape was firmly adhered over this area of the surface area of the sheet steel sample and then removed. The test is performed by counting the squares that have been removed and attached to the inside surface of the tape. The results obtained in the post surface cleaning embodiment as described above revealed that 100% of the silica remained on each sheet metal member, which means that the squares transferred to the inner surface of the tape were zero. It corresponds to what was. This result was compared with the result when degreasing was simply performed with a solvent such as hexane without treatment by the method of the present invention. This is 1 from the surface of the untreated metal member.
This resulted in the removal of 00% of the squares, corresponding to no silica squares remaining on the metal part.

Although the present invention has been described with reference to particular embodiments, it will be apparent to those skilled in the art that the present invention is not limited thereto and that modifications and changes can be made within the scope of the present invention.

[Brief description of drawings]

1 shows an example of a suitable device for carrying out the method of the invention.

FIG. 2 is a cross-sectional view showing an example of a device for the production of excited or labile gas phase species suitable for carrying out the method of the invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Member, 2 ... Conveying system, 3 ... Tunnel, 4 ... Device, 5 ... Gas inlet 6 ... Gas outlet, 7 ... Initial gas phase mixture, 8 ... Main gas phase mixture, 9 ... Neighboring gas phase mixture 10 ... Neighboring gas Phase mixture, 11 ... Additional device, 12 ...
Additional device 13 ... Gas inlet, 14 ... First electrode, 15 ... Metal block 16 ... Ceramic tube, 17 ... Second electrode, 18 ... Gas flow path, 20 ... Elongated gap 21 ... Elongated gap, 22 ... Conduit, 23 ... Chamber, 2
4 ... Housing 25 ... Tube, 26 ... Initial gas source, 27 ... Generator, 28 ... User station 29 ... Gas inlet, 30 ... Processing atmosphere, 31 ... Internal space.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Thierry Saint-Angle France, 94230 Cachan, Ryu du Rohan 33 (72) Inventor Stefane Lavia France, 90190 Zif Sur Ibet, Abnyu de Genera Le Leclerc 160, Residence du Parc du Château de Coursel 14 (72) Inventor Daniel Guerlain France, 77500 Shell, Rue Alexandre Biccardba 33, Residence du Barre Fleuri (72) Inventor Christian Larche France, 78280 Guyencourt, Ryu Benoit Frassion 55 (56) References JP-A-5-9768 (JP, A) JP-A-61-293583 (JP, A) Special Flat 3-143930 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) C23F 4/00 C23G 5/00

Claims (5)

(57) [Claims] 1. A method of dry treating at least one metal surface portion of a member, wherein the metal surface portion is treated with a gas phase treatment atmosphere at a pressure close to atmospheric pressure, the gas phase treatment atmosphere being excited. Volatile or unstable species, and substantially free of charged species,
Obtained from a main gas mixture, said main gas mixture comprising at least 1 for the production of excited or labile species.
Obtained at the gas outlet of one device, said device comprising a gas inlet to the flow path of the initial gas mixture to be excited, and
Two opposing longitudinal strips forming the gas outlet
Metal block with a large gap and a cylindrical inner space
And a first electrode arranged on the inner wall surface of the metal block and a dielectric material arranged concentrically in the cylindrical inner space.
And a second electrode formed on the inner wall surface of the tube, the first electrode and the second electrode,
Axial size less than 1 m and radial direction not exceeding 3 mm
A gas flow passage having a thickness, an internal volume existing inside the gas flow passage, a housing having a tube covering the gas inlet, a chamber formed in the housing, and the initial gas mixture. An initial gas source that is generated and a high electric current connected to the first electrode and the second electrode.
A high pressure and high frequency generator, and the initial gas mixture is 0.1 × 10 ⁵ Pa to 3 × 10 ⁵
The pressure of Pa is introduced from the initial gas source into the chamber.
Turn on and operate the generator at a frequency above 15 kHz
Power exceeding 10 kW is applied to the first and second electrodes.
The method comprises the step of changing the initial gas mixture containing an inert gas and / or a reducing gas and / or an oxidizing gas in the device by feeding 2. The method according to claim 1, wherein the gas phase treatment atmosphere is obtained with a main gas mixture and a neighboring gas mixture that does not pass through the device. 3. The method of claim 2, wherein the near gas mixture contains silane SiH ₄ . 4. The method according to claim 1, wherein the member having the metal surface portion to be treated is raised to a temperature not exceeding 600 ° C. 5. The method according to any one of claims 1 to 4.
At least one member suitable for carrying out the method of
A device for dry treatment of a metal surface portion , the gas inlet to the flow path of the initial gas mixture being excited, and
Two opposing longitudinal strips forming the gas outlet
Metal block with a large gap and a cylindrical inner space
And a first electrode arranged on the inner wall surface of the metal block and a dielectric material arranged concentrically in the cylindrical inner space.
And a second electrode formed on the inner wall surface of the tube, the first electrode and the second electrode,
Axial size less than 1 m and radial direction not exceeding 3 mm
A gas flow passage having a thickness of , a housing having a tube that covers the gas inlet and an inner volume existing inside the gas flow passage, a chamber formed in the housing, and the initial gas mixture. An initial gas source that is generated and a high electric current connected to the first electrode and the second electrode.
And a high-frequency generator.
Place