Plasma coating thickness

To test the corrosion protection conferred by LMP - produced films, glass microscope slides bearing 5000 A - thick layers of aluminium (by vacuum evaporation) were overcoated with P-PHMDSO films. In this experimental series plasma deposits were maintained at thicknesses near 1000 A, and were produced at T ranging from 100 C to about 300 C. Plasma-coated and control samples were placed in a bath of alkaline cleaning fluid (pH 8.5) and Inspected periodically for loss of Al, as described in an earlier publication (5). 

Plasma surface treatment of many polymers, including fabrics, plastics, and composites, often occurs. The production of ultra-thin films via plasma deposition is important in microelectronics, biomaterials, corrosion protection, permeation control, and for adhesion control. Plasma coatings are often on the order of 1 100 nm thick. 

The expansive internal stress in a plasma polymer is a characteristic property that should be considered in general plasma polymers and is not found in most conventional polymers. It is important to recognize that the internal stress in a plasma polymer layer exists in as-deposited plasma polymer layer, i.e., the internal stress does not develop when the coated film is exposed to ambient conditions. Because of the vast differences in many characteristics (e.g., modulus and thermal expansion coefficient of two layers of materials), the coated composite materials behave like a bimetal. Of course, the extent of this behavior is largely dependent on the nature of the substrate, particularly its thickness and shape, and also on the thickness of the plasma polymer layer. This aspect may be a crucial factor in some applications of plasma polymers. It is anticipated that the same plasma coating applied on the concave surface has the lower threshold thickness than that applied on a convex surface, and its extent depends on the radius of curvature. 

In the final stage, after 120s, both the silicon-containing and carbon-containing species have been consumed by the LCVD deposition. In the gas phase, only hydrogen is left in the plasma system and no further deposition occurs. Therefore, it is anticipated that there will be no further thickness growth of the TMS plasma coatings after 120 s. 

Figure 13.15 Changes in thickness and refractive index of TMS plasma coatings with discharge time in a closed reactor system TMS 25 mT, 2 panels of Alclad 7075-T6, DC lOOOV.

Figure 24.4 depicts the change of surface electron energy level as a function of the thickness of a plasma polymer. In this case, plasma polymer of acetylene/N2 was deposited on brass and the contact current was measured against nylon 66. The result indicates the following two important aspects of the surface state First, the surface state electron energy level at a thin-coating thickness is influenced by that of the substrate material but becomes independent of the thickness above a threshold... 

Figure 29.9 ESCA FIs peak intensities for dry and water-immersed CF4 plasma treated plasma polymerization coating of CH4 (on PET) as functions of WjFM values of CH4 plasma polymerization (thickness = 60 nm).

In order to study the effect of the aging after atmospheric exposure on the potential at the inner buried interface of plasma polymer-coated iron, two different plasma-pretreated iron samples were used. For each pretreatment, different TMS plasma polymer thicknesses were studied 20, 50, and 70 nm for Ar + H2 plasma pretreatment, 20, 55, and 115nm for O2 plasma pretreatment. The Scanning Kelvin Probe (SKP) data shown in Figure 33.18 for (Ar + H2) plasma-pretreated and O2 plasma-pretreated samples depicts a correlation between the potential at the inner buried interface and the polymer thickness for respective sample. SKP results showed that the plasma polymer effectively inhibits reoxidation of the interface... 

Figure 34.19 Variation of (a) oxygen enrichment factors and (b) air flux constants as a function of plasma polymer coating thickness, perfluro-1-methyldecalin plasma polymer coatings deposited onto porous polysulfone hollow fibers at A 5.35 x 10 J/kg 6.64 X 10 J/kg and 8.05 x 10 J/kg.

The effects of the composite parameter WjFM on the friction coefficient of the contact lens coated by methane plasma polymer at a fixed coating thickness 31.2nm are shown in Figure 35.3. The friction coefficient, which is the tangential force divided by the normal force, was calculated from the sliding angle of a contact lens placed on a glass plate that was coated with plasma polymer of tetrafluoroethylene (TFE). The friction coefficient of the methane plasma polymerized contact lens is independent of WjFM in the range 2.6-29.1 GJ/kg. 

Figure 35.4 Effect of coating thickness on the frictional coefficient of coating of CH4 plasma polymerization coating.

Similarly, plasma activation of PEEK surfaces with a N2/02 plasma resulted in a significant increase of its wettability, showing a decrease of the contact angle from 85° to 25°. On a plasma-treated PEEK surface, the deposition rate of carbonated calcium phosphate from SBF was much accelerated and coating thickness of up to 50 pm was achieved after 24 days of immersion (Ha et al., 1997). 

Figure 5.25 Contour plots of the depen- hydroxyapatite (Garcia-Alonso, 2009). (Images dence of coating thickness in micrometres (a) courtesy of Dr Diana Garcfa.Alonso Garcia, and crystallinity in percent (b) on statistically Dept of Appl. Phys., Technische Universiteit significant plasma spray parameters selected Eindhoven, The Netherlands.) for low power plasma spraying (LEPS) of...

Gas chromatographic research with plasma-coated silica gel adsorbent and an ultrafiltration test of organic solutes having different molecular sizes have revealed that the polymer appears to have micropores of 2-4 nm in diameter. Control of the dissolution rate of pharmaceuticals by dianging the polymer film thickness was also attempted [72], It was found that propargyl alcohol is a very promising monomer and a few applications of this hydrophilic plasma polymer have been reported [72]. 

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