Mechanical polishing surface roughness

The CPE model has been used152,154,270-274 and it has been found that for electrochemically polished surfaces, the surface roughness is very small compared with mechanically polished surfaces. 

Fig. 2 Before electropolishing the mechanically polished surface of stainless steel appears rough as viewed under lOOOx magnification on scanning electron microscope.

The CPE model has been used to study PC Au, Cd, Ag, Bi, Sb and it has been found that for electrochemically polished electrodes the surface roughness is very small compared with mechanically polished surfaces [5,15,16, 22, 35, 36] (see also Chap. 8 in Vol. 3). 

In the case of the mechanically polished surface, the amplitude of roughness was several atomic diameters of Cu (Fig. 2.29c, d), whereas the mechanically and electrochemically polished stuface exhibited smoothness on the atomic level (Fig. 2.29e, f). The increase in the specular reflection of 20-25 % is due to this fact. It is interesting to note (Fig. 2.29g) that the structure of the bright surface was not oriented. This is in accordance with the assumption that the dissolution process under polishing conditions is a random process. 

Electropohshing decreases the surface area available for adsorphon and reduces the contamination retention of the surface. The electropolished surface generally exhibits a lower coefficient of friction than a mechanically polished surface. The various surface treatments can alter the outgassing properties of the stainless steel surface. The chemical composihon of and defect distribution in electropolished surfaces can be specihed for crihcal applicahons. This includes the chromium-to-iron raho with depth in the oxide layer (AES), the metallic and oxide states (XPS), surface roughness (AFM), and surface defects (SEM). 

At (j> the penetration depth approaches a minimum, particularly for reflective surfaces such as chemi-mechanically polished Si. Total reflection disappears on rough surfaces (Fig. 4.3). Below rj> the penetration depth is in the range of a few nanometers (Fig. 4.4). 

A direct relationship is found between the hardness of a material and its ability to withstand mechanical wear, and as a rule the harder the material, the greater is its wear resistance. A related factor is that harder materials usually take a better polish and, as a result, the wear due to surface roughness mentioned above can be minimized. Choosing material combinations with a low coefficient of friction is also an important factor in reducing mechanical wear. 

Hoogvliet et al. [9] have proposed a pulsed-potential pretreatment procedure, which allows one to decrease, in a reproducible manner, surface roughness of mechanically polished polycrystalline gold electrodes by a factor of 2. 

Generally, smooth surfaces are more easily obtained with monocrystals. The same average roughness Ra can be obtained by mechanical polishing of polycrystals but this operation often leads to an accidental roughness on this type... 

Other SERS-active substrate techniques include mechanical polishing polycristalline silver (Vo-Dinh et al., 1988) or ion bombardment in vacuo (Wood and Zwemer, 1981 Davies et al., 1986). A chemical procedure to prepare silver island films using Tollen s reagent was developed by Ni and Cotton (1986) which turned out to be simple, rapid and highly reproducible. In addition, the surface roughness and hence the enhancement... 

The surface quality of the polished Cu substrate is shown in Fig. 7.22. The polished copper surface has an average surface roughness of 6 A without any signs of corrosion or pitting. This is consistent with the fact that the slurry is well balanced between the chemical and mechanical strengths. This is... 

Finally, before the deposition of the SiO 4.5 wt.% P film, the surface of an Al substrate was intentionally scratched by mechanical polishing. The scratches were about 1.5 pm wide, 1 pm deep, and were oriented 45° with respect to the longitudinal axis of the sample. This system (denoted as D), permits analysis of the effect of an interfacial roughness. 

A number of researchers have indicated the importance of pad surface roughness in determining polish rate and planari- (8,16,25) Pqj. example, Renteln and Coniff have demonstrated that polish rate increases with pad roughness. In addition, they argue that because of the increased porosity at the pad surface, the surface will exhibit a modulus lower than the bulk modulus. Mechanical behavior of the pad may then be modeled by considering the pad as two separate layers whose moduli add in parallel. 

Surface roughness of the metal may be degraded by either scratching from the abrasive or by chemical attack. The optimized slurry formulation must maintain a balance between the chemical component and the mechanical component. A polish that is too... 

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