Coating processes – Direct application of electrical – magnetic – wave – or... – Plasma
Patent
1997-08-11
1998-12-08
Beck, Shrive
Coating processes
Direct application of electrical, magnetic, wave, or...
Plasma
427576, 427577, 427249, 4272552, 20419212, 20419216, C23C 1632, C23C 1634
Patent
active
058466134
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a method of depositing a very hard protective coating on at least one parts
This coating can be a coating of the pseudo diamond-like amorphous carbon type based on carbon and nitrogen, or, alternatively, a titanium-based coating of the TIN or TiCN-type, or even boron nitride (BN) coating.
In all cases, these coatings should be sufficiently hard, heat-stable and adherent.
In order to increase the resistance to wear by friction or abrasion of mechanical parts, in particular those exposed to high stresses, or to protect them against corrosion, attempts have been made for several decades to find protective coatings, amongst which titanium nitride layers or layers obtained by nitridation can be mentioned, for example.
In spite of their intrinsic quality, such layers have not always proved totally satisfactory, particularly in the case of parts which are to withstand very high stresses, in particular mould parts, parts subject to mechanical wear, etc., in particular owing to insufficient adherence above all on the angular portions.
In order to overcome these problems, researchers have already proposed coatings of variable hardness of the so-called pseudo diamond-like amorphous carbon type, substantially containing carbon and hydrogen in variable proportions and, if necessary, doping agents such as silicon, nitrogen, fluorine, boron or metals such as titanium or silver.
Theme coatings, or similar coatings such as titanium carbide or nitride, boron carbide or nitride, etc. which have heat-stability varying between 400.degree. C. and 10000.degree. C., can be obtained by applying different techniques, amongst which the techniques derived from the technique known an CVD (Chemical Vapour Desposition) can be mentioned.
In the conventional CVD technique, a precursor gas containing in particular one or a plurality of hydrocarbons is introduced into a cheer containing the parts to be coated which are raised to a temperature of the order of 800.degree. to 1500.degree. C. At these temperatures, the gases introduced can react chemically with one another and bring about the formation of a thin solid layer which condenses on the hot parts.
With techniques derived from the conventional high-temperature CVD technique, so-called polycrystalline diamond-like carbon layers which have a tetrahedral structure largely similar to that of diamond and are substantially hydrogen-free (following the recombination and elimination of the hydrogen) can be deposited in the presence of an excess of dissociated hydrogen (in particular using a hot filament or in the presence of an electrical discharge produced at high pressure in which there is no ton bombardment),
However, as concerns polycrystalline diamond-like carbon, this technique does not enable very adherent deposits to be produced, in particular owing to the presence of high thermal stresses, and it can only be used for hard materials or ceramics which can withstand temperatures of between 800.degree. and 1500.degree. C.
In order to generalize the use at this technique, specialists have developed the so-called "PECVD" (Plasma Enhanced Chemical Vapour Deposition) or "plasma-assisted CVD technique" in which the temperature can be decreased to a large extent.
Such a coating technique is used in a vacuum chamber associated with a pump system and containing a metal support connected to a high-power generator on which the parts to be coated are placed. The generator can deliver a direct or alternating current operating in the radio-frequency range (13.56 MHz) or the microwave range (2.45 GHz) in order to provide the interior of the chamber with the energy necessary for maintaining an electrical voltage discharge of the order of 10 to 1000 V, which, moreover, increases the temperature of the metal support and the part to be treated to a value of between 150.degree. and 400.degree. C. when the deposit is greater than 1 .mu.m thick.
When this technique is applied, the vacuum chamber is brought beforehand to a pressure of the order of between 10.sup.-4 and 10.sup.-6
REFERENCES:
patent: 5013579 (1991-05-01), Yamazaki
patent: 5104509 (1992-04-01), Buck et al.
patent: 5175020 (1992-12-01), Doellein et al.
International Search Report corresponding to PCT/FR95/01455 Feb. 1996.
7th International Conference on Thin Films, New Delhi, India, Dec. 7-11, 1987, Aiyer, C.R., et al., Effect of Mixing Oxygen or Diboran on the Formation of Amorphous Carbon Films From Methane by R.F. Plasma Chemical Vapour Deposition, pp. 229-232.
Diamonds and Related Materials, Feb. 1995, Switzerland, Vol. 4, No. 2, Kulikovsky, V. Yu, et al., "Preparation of Thin Hard Boron Nitride Films by R.F. Magnetron Sputtering", pp. 113-119.
4th European Conference on Diamond, Diamond-Like and Related Materials, Albufeira, Portugal, Sep. 20-24, 1993, vol. 3, No. 4-6, Dworschak, W., et al., Diamond and Related Materials, Apr., 1994, Switzerland, Growth of Cubic Boron Nitride Coatings in a Magnetic Field Enhanced R.F. Glow Discharge, pp. 338-340.
Le Vide, vol. 41, No. 230, Jan. 1, 1986, Paris, France, H. Michel, et al., Analyse De la Texture De Couches Minces Delitane Et De Nitrure De Titane Obtenues Par P.V.D., pp. 65-69.
Fifteenth IUPAP International Conference on Amorphous Semiconductors; Science and Technology, Cambridge, UK Sep. 6-10, 1993, Journal of Non-Crystalline Solids, Dec., 1993, Netherlands Amaratunga, G.A.J., et al., "Doping of Highly Tetrahedral Amorphous Carbon", pp. 1120-1121.
Beck Shrive
Meeks Timothy
LandOfFree
Method for depositing a hard protective coating 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 for depositing a hard protective coating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for depositing a hard protective coating will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-175047