Sliders, surface coatings

The apparatus for the PFAM film coating on the slider surface is shown in Fig. 1 (a). The film thickness was measured by the TOF-SIMS as shown in Fig. 1 (b). It used a pulsed primary Ga+ ion beam to impact the surface of the PFAM film with an inset energy of 15 keV, an extractor current of 2 fj,A, beam current of 600 pA, a pulse width of 17.5 ns, and a frequency of 10 kHz, respectively. The positive TOF-SIMS spectra on the slider surface is shown in Fig. 2 where the peaks at m/z 31, 50, 69, 100, and 131 in Fig. 2(a) correspond to the positive secondary ion fragments of CF+, CFj, C2F4, and C3F5, respectively. The peak at m/z 469 apparent in Fig. 2(b) corresponds to the ion C12H7F 15O2H+ which is the characteristic ion of PFAM molecules. Therefore, the positive TOF-SIMS spectra demonstrates the existence of PFAM film [24,25]. The thickness of the PFAM film can be determined... 

Chloride interaction films were studied with the Bowden-Leben friction apparatus by Gregory [62]. Steel surfaces were treated with dry chlorine and then a slider was passed over the resulting film, either in the dry condition or lubricated with paraffin oil. Also, steel and platinum, coated with films of FeCl evaporated from ether solution, were rubbed in the presence of paraffin oil. Figure 10-18 shows the behavior... 

The PTV is defined as the loss of energy as the standard rubber-coated slider assembly slides across the test surface and provides a standardised value of slip/skid resistance (CEN EN 13036-4 2011). 

Since the air bearing surface of the slider is carbon-overcoated, the same carbon overcoat was placed on some of the silicon strips to evaluate the PFOM film thickness and ellipsometric measurement procedure on carbon- and non-carbon-overcoated substrates. A nominally 12.5-nm-thick layer of sputtered carbon was deposited on silicon strips, and the strips were dip coated with PFOM. The ellipsometric angles A and T were measured. The two-layer model (two films on an absorbing substrate) was used with the optical constants for the materials listed in table 4.6 in calculating the PFOM thickness from A and T on carbon-overcoated silicon. The apparent... 

Since an additional ellipsometric measurement would be needed to determine the carbon-overcoat thickness, the ellipsometric measurement of PFOM thickness directly on non-carbon-overcoated silicon is more straightforward. Silicon strips and wafers were dip coated with PFOM. The PFOM thickness measnred by ellipsometry and the dIX from XPS are listed in table 4.8. The thickness measured by ellipsometry was divided by the dIX from XPS for each sample (last two columns in table 4.8). The experimentally determined average electron mean free path for PFOM film is X = 2.66 nm. Sliders were dip coated with PFOM at the same conditions as the silicon wafers and strips, and dIX was measured on the air bearing surface of each slider by XPS. These dIX were multiplied by A, = 2.66 nm, as determined above, to estimate the PFOM thickness on the air bearing surface. These results are listed in table 4.9. The concentration of the PFOM solution was 650 ppm, and the withdrawal rate was 1.6 mm/s. 

Tests were done to determine the effects of PFOM concentration and withdrawal rate on the PFOM film thickness deposited on the air bearing surface of sliders. The PFOM film thickness was estimated using XPS. The film thickness as a function of PFOM concentration is shown in fig. 4.3a. Run 1 was made in a prototype coating tank using a developmental procedure. Run 2 was made with the coating tank and... 

Three metrics were employed to compare the performance of low-surface-energy coatings on sliders in the subambient pressure frictional hysteresis loop test (1) frictional hysteresis, (2) lubricant accumulation on the slider during the hysteresis test, and (3) disk scratches. The typical friction force on the slider during loop tests, each carried out with a separate slider, is shown in fig. 4.7. Four test runs were done, each... 

FIGURE 4.7 Results of subambient pressure frictional hysteresis loop tests on low surface energy slider coatings (a) uncoated, (b) PFOM coated, (c) ZNa coated, and (d) FCOC coated. 

Overall, the tribological tests provide a ranking for the performance of the low-surface-energy slider coatings ... 

None of the low-surface-energy coatings completely prevented disk scratching or lubricant transfer to the slider in the subambient pressure frictional hysteresis loop test. Friction and hysteresis were nnaffected by the presence of the coating. 

The thick-flhn limit of the lubricant dispersion surface energy is yf = 13 mJ/m [22]. The dispersion component of the surface energy of the slider is Yi. For the uncoated slider, yf = 43 mJ / m, and the coated slider values are given in table 4.10. The adhesion stress is listed in table 4.13. Further discussion of adhesion-controlled friction is given in the literature [23]. 

The surface energy and tribological performance of poly (lH,lH-pentadeca-fluorooctyl methacrylate) fluorohydrocarbon surfactant were compared with several other types of slider coatings. The surface energy of the fluorinated acrylate polymer was the lowest, and it provides the best compromise for reduction of both lubricant transfer and scratches. The improvement is consistent with a reduction in the adhesion stress by the low-surface-energy coatings on the slider. 

Depending on the complexity of the part, the molds can have a large number of sliders. In Figure 1.136 showing the mold for a harvester roof, eight sliders are necessary in the front area where the deep undercut in the area of the fourth slider needs a very stiff construction. The surface (of the lamp area) located above Slider 4 is etched, and the black-dyed PUR system does not need another coating. 

These improvement possibilities do not only apply to injection molds. In addition to mold cavities for thermoplastics, thermoset and elastomer processing, also extrusion dies, sliders and jaws, ejector systems, melt control systems, no return valves, and cooling channels are treated with success. Also with regard to the treatable mold materials the limits have been further extended in recent years. In addition to typical mold steels, nonferrous metals such as aluminum or various copper alloys can also be optimized by surface and coating technologies. 

The term "stacking the detonators referred to the practice of holding the detonator in place by means of metal prongs raised from the surface of the slider. These prongs sometimes abraded the delicate mechanism and caused a tough surface subject to corrosion. Cemented detonators, on the other hand, left the slider smooth and the cement coating itself was a protection against corrosion. 

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