Substrate surface roughness

Spray pyrolysis has been utilized to produce both powders of SOFC materials [19] and also SOFC component layers [118-121], Thin (1 pm) coatings have been fabricated by spray pyrolysis [121], with zero gas permeability achieved for some conditions of substrate surface roughness and temperature during deposition, but... 

Gardos showed that there was some degree of correlation between coating thickness and the optimum substrate surface roughness. Coatings thicker than about 8,000A had a longer life on surfaces of 0.28 //m CLA, while thinner films performed better on surfaces polished to 0,063 to 0.11//m CLA. 

The average layer thickness of the first coating (layer 2) on the tube structures shown in Fig. 6.6 must be at least 30 to 40 gm to cover the substrate completely, i.e. to ensure the absence of substrate surface roughness effects on the defect... 

The usual industrial process requires purification of the intermediate glucose because the enzymatic hydrolysis does not reach completion. A recently commercialized process combines hydrolysis and hydrogenation by using Ru-loaded H-USY (3 wt % Ru) as a dualfunction catalyst [58]. The outer zeolite surface provides the Bronsted acidity required for the hydrolysis of the polymeric substrate. Surface roughness and crystal size are expected to be important factors. Pressure accelerates hydrolysis as was recently found in the hydrolysis of inulin over H-Beta [59]. The Ru hydrogenation component of the catalyst can exert its action at the inner as well as at the outer surface of the zeolite as the Y pore system is accessible to glucose. 

A small zero knob is located on the side of the instrument to permit external calibration. To take readings, it is necessary to depress a small button. This gauge is very sensitive to residual magnetism in the substrate, surface roughness, edge effect, and tilt of head. Blind hole measurements cannot be made with this gauge. 

The substrate surface roughness has tendency to diminish the values of 0 when this one is lower than 90° and to increase its values for 0 > 90°. 

Mechanical adhesion is defined as when the adhesive flows around the substrate surface roughness. An interlocking action takes place, like the pieces of a puzzle. 

Cermets. Resistor films of this type are usually either mixtures of precious metals (e.g., Ag or Au) and glass frit or mixtures of PdO and glass frit. Cermet resistive inks are made by mixing a cermet powder with an organic vehicle of suitable viscosity. This mixture can be screened onto a substrate and cured by firing. Resistor films are typically 0.25 to 2.0 mils thick, and usually they do not require an overglaze for protection. Cermet films are sufficiently hard and abrasion resistant to be used as slide resistors in potentiometers. Since thick cermet films are not very sensitive to substrate surface roughness, special surface preparation usually are not necessary. 

There are many direct and indirect techniques for measuring the thickness of a deposited thin Im [32,33] general problem in measuring film thickness is the definition of the surface , since surfaces generally have peaks and valleys. Since films have a low thickness, substrate surface roughness may play a major role in thickness measurement. Film and coating thickness may be defined in three ways ... 

The discussion in this section has focussed entirely on perfectly flat solid substrates. Surface roughness, curvature, crevices, or impurities can significantly promote or inhibit heterogeneous nucleation in real systems. 

The second system is the thin liquid films (45-90A) of a nearly spherical, nonpolar molecule, tetrakis(2-ethylhexoxy) silane. The XR analysis demonstrated direct monitoring of internal layering in the thin liquid films. Model-independent fitting to the XR data found that there are three electron density oscillations near the solid-liquid interface, with a period of 10A (consistent with the molecular dimensions). The oscillation amplimde has a strong inverse dependence on the substrate surface roughness. 

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