Coating mass uniformity

Coating Mass Uniformity and Distribution. Basically, there have been two approaches to model the accumulation of mass (coating material) on the surface of bed particles (i) the use of population balances and (ii) the probabilistic modelling of the spray-particle interaction. We will look at each of these approaches and see how it may be possible to combine these methods to give a fuller picture of coating performance. 

The dimensionless variable tD/L -, which appears in the solution, is the Fourier number for mass transport and provides a convenient way of presenting the results of mass transport. This treatment assumes a homogeneous coating, with uniform properties. A theoretical analysis for the case of multilayered coatings can also be found in the literature [48]. 

Electrodeposition Suitable for most articles Gives uniform film even on rough surfaces. With suitable plant will completely coat interior surfaces, sharp edges, etc. but generally only economic on mass production... 

The use of polymeric coatings in catalysis is mainly restricted to the physical and sometimes chemical immobilization of molecular catalysts into the bulk polymer [166, 167]. The catalytic efficiency is often impaired by the local reorganization of polymer attached catalytic sites or the swelling/shrinking of the entire polymer matrix. This results in problems of restricted mass transport and consequently low efficiency of the polymer-supported catalysts. An alternative could be a defined polymer coating on a solid substrate with equally accessible catalytic sites attached to the polymer (side chain) and uniform behavior of the polymer layer upon changes in the environment, such as polymer brushes. 

In the previous section we considered the situation where there was a film of catalyst on the wall of the tube, so that the surface area was the geometric area of the tube wall. Another common situation is where a porous catalyst film is coated on the walls of the tube as shown in Figure 7-20. Finally we consider the case where the gas-phase concentration is uniform across the cross section of the tube and mass transfer rates are large, but C4 falls within the layer of porous catalyst on the wall. The thickness of the film is f, and the surface area of the catalyst per unit volume of catalyst is Sgpc- If we assume that is much less than the tube diameter, then... 

For gelatin-type Cheddites, the nitro-compds(see under manuf of non-gelatinized types) are mixed with NC NG and heated to ca 40° until the mass becomes uniform. Then a finely powdered chlorate is added and coating is conducted with stirring, but without raising the temp(Ref 23)... 

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