|Title of Invention||
"A METAL SULPHIDE COATING COMPOSITION"
|Abstract||Disclosed is a metal sulphide coating composition of the formula Where: M is one or more metals selected from: Mo, Ti, W, Nb, Ta, Zr, and Hf; Si is silicon; R is one or more eiemenb selected from; C B, AL V, Cr, Fe, Co, Ni, Sm, Au, Cu, Zn, Sn, Pb. Nr H and O; S is sulphur; F is fluorine; X is 0.2 to 1.5; V is 0.02 to 3, Y is 0 to 4; Z is 0 2 to 6: and. W is 0.01 to 6. and in which X, Y, Z, V & W are given in amounts by atomic ratio The said compositions show good non-stick properties, low hydiophilia and lugh stability.|
|Full Text||TECHNICAL FOLD
The present invention relates to a. low friction coating and to the deposition of low friction coatings by vacuum ion and plasma techniques. oatings have non-stick properties, low hydrophilia and high stability.
The disulph:.des of elements such as Mo and. "W are known to have very low friction properties due to their unique chemical bonding and structure. MoS2 and WS2coa.tings are currently being deposited by vacuum ion and plasma techniques such as magnetron sputtering (MS), plasma assisted chemical vapour deposition (PACVD) and ion beam assisted, deposition (IBAD). MoS4 and WS2 coatings have been used in tribological applications as a solid lubrka.it in aerospace products [M.R. HILTON, P.D. FLEISCHAUER, Surface and Coating Technology, 68/69 (1994) 398; J.S. FRZYBYSZEWSKI, T. SPALVINS, Kasa TN D-5349, July 1969] and other engineering fields such as cuttbg applications [I RECHBER.GER, R- DUBACH, Surface and Coating Technology, 60(1993) 393],
The-deposition process ha.5 always been subject of poor reproduc bility. Different techniques have been applied in order to enhance the reproduc .bility of coaling properties. among them the inclusion of other elements in the structure [M.R. HILTON, Surface and Coating technology, 68/69 (1994) 407;
B.S. STUPP, thin Sclid Films, 84 (1981) 257]. In certain cases the induction of other elements enhanced the coating properties.
General problems inherent to these family of coatings are their thernal and atmospheric instability. The coatings react with water vapour and oxygen transforming the sulphide into an oxide with very different tribological properties. In addition to these problems the maximum useful thickness for the coating lias been always under 2 µm. Thicker coatings tend to suffer sever 2 cracking under working pressure conditions.
Tungsten disulpbide films have had their tribological properties improved by incorporating CFX into a mixture of tungsten and sulphur by pul.se laser deposition [Surface and Coatings Technology Col 76-77, 1995 400-406].
Similarly, fluorinated graphite containing 10-40% F has been added in mixtures to MoS2, 10 improve wear resistance; [SU 601306].
However there remains a need for coatings with improved properties which overcome the limitations of present compositions.
DISCLOSURE OF THE INVENTION
According to the present invention there is provided a metal sulphide coating composition characterised in that the composition further comprises silicon and fluorine.
According to a further aspect of the present invention there is provided a method of depositing a tow fruction metal sulphide coating onto a substrate by a vacuum ion or plasma technique characterised in that silicon and fluorin; or
precursors thereof are introduced into the deposition unit.
According to yet a further aspect of the present invention thers is provided a product coated with a metal sulphide coating composition of. the present invention or a product produced by a method of the invention.
Preferably the deposnion of coatings is by vacuum ion or plasma techniques such as MS, PACVD, IBAD, electron cyclotron resonance (ECFL), arc evaporation (AIL), electron beam evaporation (EBE), laser ablation (LA), ion impiantation (II), or combinations of these techniques.
More particularly the coatings comprises
(a) one or more of the following element: Mo, W, Nb, Ta, Ti,Zr Hf
(e) one or more of the following elements: C, B, Al, V, Cr, Fe, Co, Ni,
Sm, Au, Cu, Zn, Sn, Pb, N, H, C
In one embodiment the invention relates to the deposition of a film in which at least one volume, no matter its size, comprises a chemical composition, as either a single or a plurality cf phases, of the following formula:
where M represents one or several elements as stated in (a)
S represents the sulphur element;
Si represents the silicon element;
F represents the fluorine element;
and R represents one or more of the elements described in (c).
The values of x, y, :z, V and w are within the ranges (by atomic ratio), of:
x= 0.2 to. 1.5
z- 0.2 to 6
v= 0.02 to 3
w= 0.01 to 5
Examples of chemical compositions for coatings described by this inventon include
Tn additior the process could be carried out in different vacuum conditions of gasts and pressure 'N'oble gases (He, Ar, Kr, Xe, Rn) or reactive gases (e.g , H2, 0;, N2, SF6, Si:Fe) or a mixture of them could be used during the deposition process. The process could also be earned out in ultra-high vacuum, without the assistance ol" any or very limited gas or vapour sources.
The metal elements cited in (a) could have been introduced by different means such as thermal evaporation, arc evaporation, electron beam evaporation, laser ablation, magnetron sputtering, plasma assisted chemical vapour deposition, on beam assifrted deposition, ion implantation, which could use different source:; for the elements, such as pure metal target (e.g., Mo, W, Nb, Ta, Zr, Hf, Si) alloys (e.g., Mo/W, Mo/Ti/Zr, Mo/Ti, Zr/Ti) and compounds either solid (e.g. MoS2, WS2, Mo2C, WSi2, WC-Co, WC-Ni), liquid (e.g. WF6.MoF6) or gas (e.g. W(CO)6) or any combination of them.
The sulphur could be introduced by the same or different means as stated for the element of section (a), which could use different sources such as pure sulphur (e.g. S,), metal sulphide (e.g. McS2, WS2, MoWS) or Other sulphur compounds '.e.g. SF6) or any combination of them. The fluorine could be introduced by different means using different precursors such as F2, SF6, C:F4, CF4, C,F6, WF6,MoF6, Si,F6, BF3, NF3, or any combination of them.
The silicon could be introduced as a pure element or as a cornpouinl, for example. Si:F6, Si3N4,SiC or any combination of them. Elements cited in (e) could be introduced by simihir means as (a). (b,\(c) and (d) from appropriated sources (e..g. C from C targets or from C2H2, C2F4 g is, N from N, or NF3) or any combinationof them
All the elements prssem within the coatings described in this invention could be incorporated within the coatings in an homogeneous or inhomogenens way. The coating described in this invention could be a part or the whole of the total deposited film. The composition ot the coating could be homogeneous all the
way from the surface to the interface coating-substrate. The coating could be deposited on to other layers deposited by same, similar or different means and same, similar or different chemical composition and/or structure. The coating could vary its composition from the surface towards the interface. The coating could be a panial or total periodic repetition of different layers. The coating couid be made of different layers without periodic repetitions. The coating could also be subjected to further vacuum and non-vacuum treatments which could imply change; in its original deposited chemical composition and/or structure (e.g. thermal treatment, chemical or electrochemical treatments, radiation or ablation treatments). These treatments could be also included as a part of the general deposition process.
The coating could be produced on one or several in-line deposition units or on one or several isolated-deposition units.
The deposition unit could comprise one or a plurality of coating means and/or sources. Samples to be coated could be static or dynamically noved in
the deposition unit.
The coatings described by the present invention have a low friction
The coatings described by the present invention have lower hydro philia
than the standard metai disuiphide coatings produced previously.
The coatings described by the present invention have good thermal find atmospheric stability which are improved compared to other disuiphide coatings.
The coatings described by the present invention have non-sticky properties.
The coating described by the present invention have good tribobgical properties.
The coatings described by the present invention do not suffer severe cracking during working pressure conditions improving the actual limis of the actual disulphide coatings.
All these properties make possible the use of the coating described by this invention in the following applications: Optic and magnetic recorder media. Aircraft and spacecraft bearings.
Ball bearings, ball screw, gears, cam shafts, valves, fuel injectors, oil and combustion pumps, cylinders and piston rings, as an example in the autonobile and oilier motor industries.
Cutting and forming tools such as drills, end mills, inserts, saws and other tools used in the machining of aluminium, aluminium alloys, copper and copper alloys, inserts, precious metals 'e.g. gold, silver, osmium, indium, platinum, ruthenium, rhodium and palladium), steel, stainless steel, carbon fibres, glass fibres ceramics, metal matrix composites, organic matrix composites, wood, cardboard, plastics and polymers (e.g. plastic packing) or combinations of ouch materials such as cardboard plus polymer (e.g. tetrabrick packing), alurrinium plus polymer (e.g. drink cans),steel plus polymer (e.g. food tins). Stamping, punching and conforming operations in materials as described in the
Coating of mould components such as the mould, injectors, nozzles and valves as an example to enhance demoulding and wear protection.
Operations in textiles and paper industry related to guiding, sliding, machining, cutting, stamping, printing, improving the quality and wear resistance of the tools and elements.
Accordingly, the present invention relates to a metal sulphide coating composition characterized in that the composition further comprises silicon and fluorine.
The invention will be further described by way of exampled only with reference to the following figures in which:
Figure 1 shows a general deposition unit which produces the coating according to the present invention.
Figure 2 illustrates an exampled of in-line deposition unit producing a coating according to the present invention.
Figure 3 shows an example of a PACVD deposition unit according to the present invention where the samples are stationary.
Figure 4 shows an example of a deposition unit based on MS wherein the samples rotates in front of the magnetrons producing a coating deposition according to the present invention.
Figure 5 shows an example of a deposition unit based on a MS and an ECR
sources producias a coating deposition according to the present invention.
Figure 6 shows an example of ion implantation (II) and MS producing a coating deposition according to the present invention.
Figure 7 shows an example of a graded coating composition according to the: present invention; and
Figure 8 shows an example of a multilayered coating with a coaling posl-treatiment according to the present invention.(coaling + gold).
Referring to Figure 1, a deposition unit includes a vacuum charrber 1, which is vacuurred by means of a pumping system 2. The different elements referred within this invention can be introduced separately or by the same means or channels. In general a single or multiplicity of means 3 could incorporate the elements described in (a) on their own or accompanied by other elements. A sir.glc or multiplicity of means 4 could incorporate the suphur on its own or accompanied by other elements. A single or multiplicity of means 5 could introduce the fluorine on its own or accompanied by other eleu.ents. In general a single or multiplicity of means 6 could incorporate silicon on its own or accompanied by other elements. Any other optional element could pe incorporated .n like manner. A single or multiplicity of means 7 could introduce one or more nobie gases on their own or accompanied by other gases or vapours phases. In the system described by this invention the samples due to
be coated 8 are generally situated in a sample holder 9. One or several lines, areas and volumes of energization 10 are normally present within the system. The different elements interact in Those lines, areas or volumes producing the final coating on to the samples and other components surfaces. The energization 10 coule be plasmas generated by different means, particle accelerators temperature heaters, radiation waves or glow discharges processes. the sanples are normally biased by single or different excitation sources 11 in order tc control properties of the deposited films.
Referring to Figure 2, in that in-line system samples 8 are troispc rted in their holder 9 in the direction from 12 to 13. Three chambers 15, 1 and 16 are represented. The chambers are vacuum isolated by gates 14. Each of the: chambers is vacuumed by individual pumping systems 2. In chamber 15 three coating units 20 produce a surface treatment prior to the main deposition. This surface treatment could include etching and/or deposition of one or several intenayers. Coaling units 20 normally are comprised of a main body 18 and a target material 19. One of the most common coating units 20 are the magnetrons, where 18 is the magnetron body and 19 the so called target. Inert gases are introduced through 7. which could also carry reactive gases. The chamber 1 is responsible for the deposition of a coating of the present invention. In the figure three magnetrons are represented. The mugnorons couprises magnetron body 21 and target material 22. The target material could be for example MoS:. Lines 4, 5 and 6 could inject gases such as SFM C2F4 and Si2F6. Line 7 could introduce inert gases such as AT. Chamber 16 represent a
post-deposition treatment where a radiant source 23 irradiates the samples 8 producing a transformation in the deposited coating.
Referring to Figure 3, the deposition chamber 1 is vacuumed by means of a purr-ping systen 2. Samples 8 are situated on to the sample holder 9. Sample lolder 9 is connected to a high frequency power supply 24. plasma discharge is generated between the sample holder 9 and an anode 25 which is earthed 26. The reactants are introduced into the chamber through 3. 4, 5, 6 and 7.
Figure 4, .step view of a deposition chamber 1 which comprises three magnetrons 20. The samples are situated on a sample holder 9 which has two rotation axis 27 and 28 so that the samples could have an uniform coaling by rotating in front of all three magnetrons 20.
Figure 5.. represents a chamber 1 which comprises one magneto n 20 and one electror cyclotron resonance (ECR) unit 29. Highly ionised species create a plasma 10 surrounding the samples 8 7he samples are situatec on to a holder 9 which rotates 2? allowing higher deposition homogeneity.
Figure 6, represents a chamber 1 which comprises magnetron units 20 and an ion. implantatior (II) unit 30. A selected group of ions car. be accelerated by using a suitable magnetic arrangement 31, The growing of the film is mainly performed by the magnetrons 20. A plasma 10 surrounds the samples 8 which are supported by a rotating 27 holder 9. The II unit accelerates the ions up to such energy that they could penetrate into the growing film. This input of energy and new elements is used to control properties such as
composition and structure within the Final deposited film.
Figure 7, is a graph showing the relative concentration, in arbitrary units (a.t.), for different elements in a graded coating according to the present invention.
.'Figure 8. represents a cross section of a multilayered coating according to the present invention. The substrate 32 has beer, coated first with one interlayer 33 which provides good adhesion between the multilayer aad the substrate. The multilayer is composed of alternative layers 34 and 35. Layers 34 could of any composition and structure. Layers 35 have any composition defined by MxSivRySzFw as disclosed in the present invention. A final layer 36 corresponds to a post-treatment which could provide a better aestheric appeal to the final coating, for example, a gold plating.
1. A metal sulphide coating composition comprising silicon and fluorine wherein said coating composition is of the formula
M is one or more metals selected from Mo, Ti, W, Nb, Ta, Zr and Hf;
Si is silicon;
R is one or more elements selected from C, B, Al, V, Cr, Fe, Co, Ni, Sm,
Au, Cu, Zn, Sn, Pb, N, H and O;
S is sulphur;
F is fluorine;
X is 0.2 to 1.5;
V is 0.002 to 3;
Y is 0 to 4;
Z is 0.2 to 6; and
W is 0.01 to 6, and in which X, Y, Z, V & W are given in amounts by
2. A product coated as and when with a metal sulphide coating composition
as claimed in claim 1.
3. A metal sulphide coating composition substantially as herein described
with reference to and as illustrated with reference to the accompanying
|Indian Patent Application Number||3582/DEL/1997|
|PG Journal Number||10/2008|
|Date of Filing||11-Dec-1997|
|Name of Patentee||GENCOA LIMITED|
|Applicant Address||4-D WAVERTREE BOULEVARD SOUTH, WAVERTREE TECHNOLOGY PARK, LIVERPOOL L7 9PF, ENGLAND.|
|PCT International Classification Number||B32B 9/00|
|PCT International Application Number||N/A|
|PCT International Filing date|