Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of coating supply or source outside of primary...
Patent
1996-06-06
1998-09-15
Beck, Shrive
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of coating supply or source outside of primary...
427563, 427574, 427578, 427579, 427585, 4272551, 4272552, 4272555, 4272557, 118719, 118723ER, 118729, C23C 1622
Patent
active
058076158
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to deposits of films containing silicon (for example silicon oxides such as silica or else silicon oxynitrides SiO.sub.x N.sub.y) made on metal surfaces (such as sheet metal) for example with the aim of providing them with a coloration for esthetic reasons, or for providing them with corrosionresistance properties.
2. Description of Related Art
There are currently several deposition techniques making it possible to produce such thin layers of silicon oxide or silicon oxynitride on sheet metal.
Of these, the technique most commonly referred to is that of vapor phase deposition reactions, better known by the generic name of the CVD (chemical vapor deposition) method.
These methods consist in reacting one or more silicon precursor gases, for example silane SiH.sub.4, and an oxidant such as oxygen, on the surface of the sheet metal which has been activated beforehand, the deposition being carried out at atmospheric pressure or at reduced pressure, and at a temperature which is chosen in accordance with the pressure conditions adopted:
when the deposition is carried out at atmospheric pressure, a strong thermal activation of the surface is necessary, and the deposition will therefore be carried out at an elevated temperature, typically of the order of 800.degree. to 1000.degree. C.,
when the deposition is carried out at low pressure, the adopted temperature will be lower, typically between 250.degree. C. and 600.degree. C., according to whether or not the CVD is assisted, for example by an electric discharge in the gas.
Those CVD methods which make it possible to operate at low temperature (as it is often desirable to do) are therefore associated with low pressure conditions. Such low pressure conditions undeniably constitute a constraint and explain the less extensive steel sheets, which are generally in the form of large areas produced in large quantities.
Using such low pressure methods moreover represents a significant extra cost, because of the cost of vacuum equipment and the high level of maintenance which is associated with them.
In this context, the Applicant Company recently proposed, in document FR-A-2,692,598, a method for depositing a layer containing silicon on a metal substrate. This method made it possible, successively or concomitantly, to preactivate the metal surface by dielectric discharge then to deposit a layer containing silicon by exposing the surface thus preactivated to an atmosphere containing a silicon precursor gas. This method was implemented at atmospheric pressure or close to atmospheric pressure.
Although this method undeniably constitutes an improvement over existing techniques, the Applicant Company has demonstrated the fact that it can be improved, in particular in that:
the distance between the sample to be treated and the electrode (the metal sheet may moreover constitute one of the metal electrodes) is critical for obtaining a perfectly homogeneous treatment, which constitutes a constraint when it is necessary to continuously treat sheet metal with variable thickness,
in addition, implementation of the method requires the substrates to pass through the discharge, whence a source of contamination for the electrodes because of the presence of dust or greasy particles at the surface of the substrates,
when the method concomitantly carries out preactivation and deposition, the silicon precursor gas, such as silane, is introduced directly into the discharge, whence the risk of depositing dust (powder) of silica or silicon oxides on the electrodes, which interferes with the operation of the apparatus in question,
finally, the geometrical configuration making it possible to implement this method limited the power density which could be used, increasing the power density beyond this limit running the risk of leading to a delocalization of the ionized cloud.
In a more general context, the Applicant Company recently proposed, in document FR-A-2,692,730, the content of which is assumed to be incorpor
REFERENCES:
patent: 4774062 (1988-09-01), Heinemann
patent: 4951602 (1990-08-01), Kanai
patent: 5114529 (1992-05-01), Masuyama et al.
patent: 5124173 (1992-06-01), Uchiyama et al.
patent: 5458856 (1995-10-01), Marie et al.
Rabia Stephane
Sindzingre Thierry
Beck Shrive
L'Air Liquide Societe Anonyme pour l'Etude et, l'Exploitation de
Meeks Timothy
LandOfFree
Method and device for forming an excited gaseous treatment atmos does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for forming an excited gaseous treatment atmos, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for forming an excited gaseous treatment atmos will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-85191