Plasma coating device and method for plasma coating of a substrate

Abstract

The invention relates to a plasma coating device (10) and a method for homogenous coating of a substrate (12). It comprises a particle reservoir (14), a dosing device (16) for dosing the particles (15) contained in the particle reservoir (14), a processing chamber (20) and a transport line (18) to convey particles (15) into the processing chamber (20). The processing chamber pressure (P1) in the processing chamber (20) is lower than the particle reservoir pressure (P2) in the particle reservoir (14).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a Continuation-in-Part patent application under 35 U.S.C. §120 of U.S. patent application Ser. No. 13 / 932,581, filed on Jul. 1, 2013, which claims priority from German Patent Application No. 10 2012 106 078.9, filed on Jul. 6, 2012, which applications are incorporated herein by reference in their entireties.FIELD OF THE INVENTION[0002]The invention relates generally to a plasma coating device, and more specifically to a plasma coating device for coating of a substrate,[0003]Furthermore, the invention generally relates to a method for plasma coating of a substrate.BACKGROUND OF THE INVENTION[0004]The state of the art comprises a diverse series of sample coating methods and devices. The methods may be selected according to the substrate, the layer to be coated thereon and in particular according to the layer thickness. Amongst suitable coating methods are, according to the initial state of the coating material, gas-phase...

AI Technical Summary

Benefits of technology

[0009]The present invention broadly comprises a plasma coating device having a particle reservoir, a dosing device for dosing the particles stored in the particle reservoir, an all-round closed processing chamber, at least one transport line from the particle reservoir to the processing chamber, a suction pump being connected with the processing chamber such that a pressure gradient between the processing chamber and the particle reservoir is settable in such a way that there is a processing chamber pressure in the processing chamber and a particle reservoir pressure in the particle reservoir wherein the processing chamber pressure is lower than the particle reservoir pressure, and a plasma coating torch within the processing chamber that receives at a constant conveying rate the particles from the particle reservoir wherein the constant conveying rate is accurately adjustable by means of the transport line and mechanically or pneumatically generated particle aggregations within the transport line are avoided.

[0010]The present invention also broadly comprises a method for plasma coating of a substrate having the steps of: extracting in a regulated manner particles from a particle reservoir with a dosing device by means of a movable suction lance; supplying the particles via a transport line to a processing chamber, in which a plasma coating torch is provided; and setting a pressure gradient between the processing chamber and the particle reservoir by means of a suction pump connected to the processing chamber such that the pressure gradient determines a delivery rate of particles.

[0011]The object of the present invention is to provide a plasma coating device and a method for plasma coating of a substrate capable of conveying a powder or a mixture of powder and processing gas from a powder reservoir into a processing chamber ensuring a homogeneous, precisely dosed, pulsation-free and time stable powder conveyance between the powder reservoir and the processing chamber.

[0020]The setup of the proposed plasma coating device has the particular advantage that no pumping unit is required in the powder transport line between the powder reservoir and the processing chamber. Furthermore, one can get around of mechanical or pneumatic units in the transport path.

Problems solved by technology

The conveyance of such fine-grained powders is, however, challenging.

Furthermore, fine-grained powders tend to form agglomerates that a processing gas stream may not be able to break up.

Also, the operation of suitable types of pumps often becomes unstable when handling processing gases with high powder contents.

Pumps and conveyance devices are prone to heavy erosion and blockage depending on the powder used.

Also, the properties of the powder material itself have a significant impact.

This process is, however, very complex and not sufficiently reliable for powders prone to agglomeration.

Likewise, the problem remains unaddressed of how a constant extraction rate of deposition material is achieved.

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