Thermal Annealing Behavior of Si-DLC Ibad Coatings

1996 ◽  
Vol 438 ◽  
Author(s):  
C. G. Fountzoulas ◽  
J. D. Demaree ◽  
L. C. Sengupta ◽  
J. K. Hirvonen

AbstractAmorphous, 700 nm thick, diamond-like carbon coatings containing silicon (Si-DLC), farmed by Ar+ ion beam assisted deposition (IBAD) on silicon substrates, were annealed in air at temperatures ranging from room temperature to 600°C for 30 minutes. RBS analysis showed that the composition of the films remained the same up to 200°C, but at higher temperatures the Si-DLC coatings began to oxidize at the outer surface of the coating, forming a surface layer of SiO2. After in-air annealing at 600°C the coating had been completely converted to SiO2, with no trace of carbon seen by RBS. FTIR spectra of the unannealed coatings showed a very broad mode typical of Si-DLC bonding as well as some absorption features associated with Si and SiO2. Above 200°C the transmission mode shifted to higher frequencies which may be caused by the growth of SiO2 and the decrease of the Si-DLC film thickness. The room temperature ball-on-disk friction coefficient of the coating against a 1/2′′ diameter 440 C steel ball at 1 N load ranged from 0.2 for the original coating up to 0.5 after a 100° anneal and returned to 0.2 after annealing at 200–400°C and fell to 0.12 after a 500°C exposure. The average Knoop microhardness (uncorrected for substrate effects) was 10 GPa (1,000 KHN) for coatings annealed at temperatures as high as 400°C. All coatings up to 500 °C passed the qualitative “Scotch Tape” test.

1997 ◽  
Vol 504 ◽  
Author(s):  
C. G. Fountzoulas ◽  
J. D. Demaree ◽  
L. C. Sengupta ◽  
J. K. Hirvonen ◽  
D. Dimitrov

ABSTRACTHard, adherent, and low-friction silicon-containing diamond-like carbon coatings (Si-DLC) have been synthesized at room temperature by 40 keV (N+ plus N2+), 50%Ar+/50% (N+ plus N2+), and Ar+ ion beam assisted deposition (IBAD) of a tetraphenyl-tetramethyl-trisiloxane oil on silicon and sapphire substrates. X-ray diffraction analysis indicated that all coatings were amorphous. The average coating wear rate and the average unlubricated steel ball-on-disk friction coefficient, μ, decreased with increasing fraction of nitrogen in the ion beam, along with an increase in the average coating growth rate. The Knoop microhardness and nanohardness values of the coatings synthesized by the mixed argon and nitrogen ion beam were higher than the values for the coatings synthesized with 100% nitrogen or 100%argon ion beams. These friction/wear improvements are tentatively attributed to both increased hardening due to greater penetration and ionization induced hardening by the lighter (N) ions and to the presence of Si02 on the surface of N-bombarded samples.


1995 ◽  
Vol 396 ◽  
Author(s):  
Costas G. Fountzoulas

AbstractHard, low-friction silicon-containing diamond-like carbon coatings (Si-DLC), were formed by Ar+ ion beam assisted deposition (IBAD), on 5 in. diameter silicon wafers. The diffusion pump oil precursor (tetraphenyl-tetramethyl-trisiloxane: (C6H5)4(CH3)4Si3O2) was evaporated through seven, 3 mm diameter, closely packed apertures (multinozzle/multi-aperture container) arranged in a hexagonal pattern, approximately 5 mm apart according to mathematical model [1[ developed at ARL describing the spatial distribution of film deposition from nozzles and apertures onto inclined substrates.The ion energy was kept at 40 keV whereas the ion current density and the oil evaporation temperature were varied to produce hard, lubricious and adherent films. The multinozzle array allowed the relatively uniform (± 20%) coverage of the entire 5 in. substrate. The thickness and the microhardness of the films were measured along the rectilinear surface coordinates of the substrate area. Depending on the deposition parameters the standard deviation of the coating thicknesses and Knoop micro-hardness varied from 14 to 30 percent respectively over the substrate. This is a significant improvement from the previously used single nozzle set up where the standard deviation of the coating thickness was 50 to 100 percent for 2 in. diameter substrates. The Knoop microhardness and the sliding friction coefficient of these coatings ranged from 10,000 to 20,000 MPa and 0.04 to 0.2 respectively. These values are in agreement with our previously reported single nozzle results [2].


1997 ◽  
Vol 12 (9) ◽  
pp. 2485-2492 ◽  
Author(s):  
B. K. Daniels ◽  
D. W. Brown ◽  
F. M. Kimock

Protection of glass substrates by direct ion beam deposited diamond-like carbon (DLC) coatings was observed using a commercial pin-on-disk instrument at ambient conditions without lubrication. Ion beam sputter-deposited titanium carbide and boron carbide coatings reduced sliding friction, and provided tribological protection of silicon substrates, but the improvement factor was less than that found for DLC. Observations of unlubricated sliding of hemispherical glass pins at ambient conditions on uncoated glass and silicon substrates, and ion beam deposited coatings showed decreased wear in the order: uncoated glass > uncoated silicon > boron carbide > titanium carbide > DLC > uncoated sapphire. Failure mechanisms varied widely and are discussed. Generally, the amount of wear decreased as the sliding friction decreased, with the exception of uncoated sapphire substrates, for which the wear was low despite very high friction. There is clear evidence that DLC coatings continue to protect the underlying substrate long after the damage first penetrates through the coating. The test results correlate with field use data on commercial products which have shown that the DLC coatings provide substantial extension of the useful lifetime of glass and other substrates.


1988 ◽  
Vol 128 ◽  
Author(s):  
E. P. Donovan ◽  
C. A. Carosella ◽  
D. Van Vechten

ABSTRACTThe annealing behavior of the optical properties of silicon nitride films (Si1-xNx) is described for films fabricated by ion beam assisted deposition. The data are needed for the precise manufacture of optical filters, where the index of refraction must be predicted from deposition parameters and film annealing history.The reflection of homogeneous, amorphous samples deposited on (100) silicon substrates was measured from 500 to 3120 nm. Fits to the interference spectra were obtained over the range 1000 to 3120 nm to obtain the index of refraction vs wavelength as a function of film nitrogen content. Nitrogen atom fraction was varied from.2 to.58 by variation of the incident relative fluxes of nitrogen ion beam current to evaporant silicon flux. The films were annealed in argon at 450 C, 600 C, 750 C, and 1100 C and the measurements repeated. The systematic shifts in index of refraction with annealing temperature are described.


Author(s):  
M Cao ◽  
L Dong ◽  
G Q Liu ◽  
D J Li

ZrN/(Ti, Al)N nanometre multi-layered coatings with different modulation ratios and ion beam fluxes have been synthesized by ion-beam-assisted deposition at room temperature. X-ray diffraction (XRD), a nano indenter, and a profiler were used to characterize the microstructure and mechanical properties of the coatings. The small-angle XRD pattern indicated a well-defined composition modulation and layer structure. The XRD pattern showed a significant mixture of strong ZrN(111) and (Ti,Al)N(111) textures. At an assisted beam flux of 5 mA and modulation ratio of 2:3, the ZrN/(Ti,Al)N multi-layer possessed the highest hardness (30.1GPa) and elastic modulus (361GPa). Its fracture resistance, and residual stress also showed the best results.


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