Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
  • C23C16/503—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using DC or AC discharges
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2206/00—Materials with ceramics, cermets, hard carbon or similar non-metallic hard materials as main constituents
  • F16C2206/02—Carbon based material
  • F16C2206/04—Diamond like carbon [DLC]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
  • F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
  • F16C2240/60—Thickness, e.g. thickness of coatings
  • F16C2240/64—Thickness, e.g. thickness of coatings in the nanometer range
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer

Definitions

• the invention relates to a diamond-like nanocomposite (DLN) composition having improved (lower) friction properties combined or not with improved (higher) hardness.
• the inven ⁇ tion deals also with an improved process for covering substrates with a layer or film of such a composition in a modified plasma assisted chemical vapour deposition (PACVD) process in vacuum.
• PSVD plasma assisted chemical vapour deposition
• Diamond-like nanocomposite (DLN) mate ⁇ als are related or similar to diamond-like carbon (DLC).
• DLC films (a-C:H, a-C, i-C) display a good combination of high hardness and elasticity, high wear resistance and a low coefficient of friction. Furthermore, because of their chemical inertness, low surface energy and intrinsic smoothness, these films give access to appealing industrial applications such as hard, self-lub ⁇ cating films, eg. for protection of magne ⁇ tic discs and media, sliding parts in motors, space appli ⁇ cations, optical components etc. However, deposited DLC films exhibit much higher internal stresses (above 1 GPa) than DLN films (200-400 MPa), thus impeding good adhesion to the substrate.
• DLC films on substrates may thus require the use of intermediate adhesion promoting layers which is not needed for DLN.
• Another disadvantage of DLC impeding fast commercialisation is the fact that the coefficient of friction of DLC in air increases up to about 0.2 to 0.3 when the relative humidity rises above 50 %
• RH relative humidity
• the friction test for determining this coefficient is described below.
• the composition comprises networks of a-C:H and a-Si:0 wherem the H-concentration is preferably between 40 X and 80 % of the C-concentration. This is different from the composition claimed in U.S. patent 5.466.431.
• the composition can include (be doped with) at least one transition metal of the group lb to 7b and 8 as described in US-patent 5.352,493.
• the controlled incorporation of metals in the DLN structure leads to highly tailorable optical and electrical properties while retaining to a great extent the mechanical and thermal stability.
• the elect ⁇ cal resistivity of the films can be varied.
• the metals Zr, Ti and W are preferred.
• the diamond ⁇ like nanocomposite composition according to the present invention, either doped or undoped with transition metals comprises preferably 30 to 70 at* of C, 20 to 40 at* of H. 5 to 15 at* of Si and 5 to 15 at* of 0, in particular 45 to 70 at* of C, 20 to 35 at* of H. 5 to 10 at* of Si and 5 to 10 at* of 0.
• the composition is generally formed by deposition onto a substrate of any shape and made of glass, ceramics, metal, plastics or semiconductors. It is thus another object of the invention to provide a substrate covered at least in part with a layer of the diamond-like nanocomposite compo ⁇ sition.
• the thickness of the layer is generally between 0.01 ⁇ and 10 ⁇ m although it can be higher than 10 ⁇ m. It has in particular been found that the DLN-composition of the present invention adheres much better to glass than DLC.
• the invention sets also the process parameters for manufac ⁇ turing a covered substrate with the diamond-like nanocompo ⁇ site composition having the friction and hardness proper- ties described above.
• the process according to the inven ⁇ tion for manufacturing a covered substrate is carried out in an improved vacuum chamber and comprises the steps of
• the precursor can be evaporated in step (a) in said chamber during or after introduction, preferably by heating it between 30 °C and 150 °C.
• This evaporation step is also useful for depositing other DLN-compositions out ⁇ side the proportions specified above for C, H, Si and 0.
• the voltage is preferably between 250 and 1000 V and the frequency of the RF-voltage is best choosen between 30 and 1000 kHz.
• the precursor is preferably an organosilicon compound, eg. a polyphenylmethylsiloxane such as triphenylnonamethyl - pentasiloxane.
• an inert gas When introduced in the vacuum chamber for incorporation into the deposited DLN-layer, it is ionised and incorporated by ion bombardment of the growing nano ⁇ composite layer. Finally, when during the deposition process at least one transition metal is codeposited in the composition layer, then this is achieved by ion sputtering (eg. with argon) or by thermal evaporation.
• Tne invention relates also to an improved apparatus as described below for carrying out the deposition process.
• new systems have been conceived for feeding the precursor to the vacuum chamber in a finely divided form, eg. as a vapour or mist and comprising optionally prehea ⁇ ting arrangements for the precursor.
• Figure 1 is a graph showing the low coefficient of friction of an undoped DLN film (or coating) in air at 50 * RH. respectively at 90 * RH.
• Figure 2 is a similar graph for a DLN film doped with about 5 at* Zr.
• Figure 3 is a graph compa ⁇ ng the coefficient of friction of the same doped DLN film as in figure 2 with a DLC film
• Figure 4 is a graph presenting the variation of the coeffi ⁇ cient of friction of an undoped DLN film during a long time when tested in water.
• the base pressure in the vacuum chamber is 3x10 7 mbar and the typi ⁇ cal working pressure is maintained at 1x10" to 1x10 3 mbar by diffusions pumps (controlled with throttle valves).
• the substrates can be cleaned by an in-situ (Ar-) plasma etching process prior to deposition and lasting for 3 to 30 minutes
• the substrate temperature does generally not exceed 200 °C during the deposition process.
• Film thick ⁇ nesses vary generally between 0.1 and 3 ⁇ m and are deter ⁇ mined by stylus profilometry.
• the deposited film With a film thickness of less than about 1 ⁇ m, the deposited film remains transparent (even when coloured) The degree of transparency depends l.a also on the bias voltage applied to the substrate during deposition The deposition rate or film growth rate vanes mostly between 0.5 and 2 ⁇ m/hr
• a preferred liquid precursor is triphenylnonamethylpenta- siloxane in view of depositing a composition as defined in claim 2. It is preferably preheated above 30 °C before or during release in the chamber
• the precursor is delivered to the vacuum chamber eg. through a heat resistant porous body with a porosity of eg. 30 to 50 *.
• the precursor can continuously be metered in small quantities through a tube which delivers it as a vapour or a mist to the porous body
• the precursor can be introduced in batch in an open reservoir which is placed in the chamber before this is put to vacuum
• This reservoir can be electrically heated prior to the start of the deposition process inside the chamber to form the vapour.
• a bundle of alloyed Tungsten filaments is placed as a cathode typically at about -150 V (DC bias voltage) in front of the earthed porous body
• the body itself, with the inlet tube for the precursor at the back side of the porous body may be mounted in the lower part of the chamber
• the filament bundle is convexly bent eg to a half circle in a vertical plane and with a length of 15 to 30 cm
• the current in the cathode filaments is preferably between 50 and 120 A (AC).
• the plasma current (measured between filament bundle and earthed porous body) can then typically amount to about 0.5 to 3 A. Preheating the precursor may offer the advantage that the current needed afterwards in the cathode filaments (for generating the plasma) could be 1owered.
• the distance between the uppermost area of the bent cathode bundle and the substrate is at least about 20 cm.
• the depo- sition occurs from bottom to top through attraction of the plasma ions by the substrate support which is put to a negative RF self-bias voltage of typically about 400 V.
• the RF frequency is preferably much lower than that used according to US patent 5.352,493 ; viz. between 100 and 500 kHz and specifically about 200 to 300 kHz.
• the hysteresis curves are analysed according to the Oliver & Pharr method (W.C. Oliver and G.M. Pharr, Journal of Materials Research 7 (1992), p.1564) and the data are normalised to the data of a Si(111) wafer obtained at the same penetration depth.
• the coefficient of friction ⁇ is continuously measured during the test.
• the relative humidity was thereby monitored at a constant value of either 50 * RH or 90 * RH.
• the measurement is stopped when ⁇ reaches the value of 0.5.
• the wear resistance (life ⁇ time) of the deposited nanocomposite film is expressed as the number of cycles divided by the film thickness. Typical lifetimes range between 100 000 and 300 000 cycles per ⁇ m of film thickness.
• the average compositions (in at*) tested are given in the Table 1 below.
• the real compositions may fluctuate through ⁇ out the film thickness up to 10 * of these average compo- sitions. This means that with an average content of eg. 25 *at H, the real concentration may vary between 22.5 and 27.5 *at H.
• Line 1 (in figure 1) corresponds to the evolution of the friction coefficient for a test in air with RH 50 * and a normal ball load of 5 N for sample A in Table 1.
• Line 2 corresponds to the same test for sample A, but in air with RH 90 *. The test with the higher RH shows even a better friction performance.
• line 3 shows the friction behaviour in air at 90 * RH and line 4 the somewhat better friction behaviour in air at 50 * RH for sample B in Table 1.
• the friction coefficient fluctuates here generally between 0.05 and 0.08 during a test of 10.000 friction cycles with a ball load of 5 N.
• Sample B is doped with 4.1 at* Zr.
• a similar behaviour is obtained with metal doped films with a metal content up to 20 at*.
• An undoped DLN-layer of the same kind, with a thickness of 1.3 ⁇ m, having a hardness of 15 GPa showed a coefficient of friction of approximately 0.05 both in air with a relative humidity of 50 * and under water (as recorded in a ball-on- disk experiment during 100.000 cycles at 10 N normal load with a 6.35 mm diameter 100Cr6 steel bearing ball).
• the coating wear factor k calculated from the profilometric measurement of the wear track area was 2 x IO '7 mm 3 /Nm in air of 50 * RH and only 3.5 x IO '8 mm 3 /Nm under water.
• the ball wear factor, calculated from the worn volume of the steel ball was below 1 x IO '8 m ⁇ rVNm in both cases.
• the film of sample C (see Table 1) on a Si-wafer showed a hardness of 17 GPa and ⁇ varied from 0.05 to 0.06 in a
• the atomic concentrations in Table 1 can be indirectly obtained through Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection (ERD) .
• RBS and ERD yield absolute numbers of the area concentration (in atoms/cm 2 ). They are expressed for sample C in Table 2 below as the atomic area density: AAD (in 10 15 atoms/cm 2 ) .
• Table 2 lists also the corresponding XPS-values (X-Ray Photo-electron Spectroscopy) which indicate the relative value of the concentrations (in *) of the elements (except H and Ar) in sample C The real value correlating to this experimental data are listed in the line "Real". These "Real" values correspond then of course to the at* concentrations listed in Table 2 for sample C.
• the atomic concentrations (by RBS) for C, Si and 0 and Ar are accurate to about 5 * of their value, whereas the at* for H is expected to be correct up to 10* of its value.
• the DLN films according to the invention are of course very suitable for any application or use where the presence of a very low coefficient of friction and at the same time a high hardness are required, in particular in very humid environments or in water.
• the application is thus useful as a low friction coating in prostheses for hip or knee joint replacement, for surgical knives, for razor blades and guide wires. They are also useful as protective coatings on hard disks for computers and on magnetic tapes.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Inorganic Chemistry (AREA)
• Chemical Vapour Deposition (AREA)
• Carbon And Carbon Compounds (AREA)

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• 1997
  • 1997-04-11 US US09/171,614 patent/US6200675B1/en not_active Expired - Lifetime
  • 1997-04-11 AU AU26977/97A patent/AU2697797A/en not_active Abandoned
  • 1997-04-11 JP JP53768997A patent/JP4439594B2/ja not_active Expired - Fee Related
  • 1997-04-11 WO PCT/EP1997/001878 patent/WO1997040207A1/en not_active Ceased
  • 1997-04-11 EP EP97920688A patent/EP0896640B1/en not_active Expired - Lifetime
  • 1997-04-11 DE DE69710324T patent/DE69710324T2/de not_active Expired - Lifetime
  • 1997-04-26 TW TW086105584A patent/TW420724B/zh not_active IP Right Cessation

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