Coefficient adhesion efficiency

From this we can determine A-fl" and hence the coefficient of adhesion efficiency a. 

A successful coating process requires that the encapsulation substance adheres sufficiently to the surface of the fluidized-bed material. Of course, the adhesion also affects the collection efficiency. In literature [4,8,9], the impact of adhesion to the coating process is taken into consideration by introduction of the adhesion coefficient X. Thus effective single particle collection efficiency cp may be formulated ... 

Herein, / is the single particle collection efficiency. According to literature [9] for liquids or very soft substances the adhesion coefficient has a value near to one. Another study indicates that for solid aerosols having a diameter in the range of 0.7 pm the adhesion coefficient may vary from 0.001 to 0.01 [4]. 

Fillers are often useful in epoxy-polyamide adhesives (41). Fillers aid flow control—particularly at elevated temperatures. Other properties contributed by fillers are exhibited in the cured system. For example, they can increase the modulus of elasticity, modify the coefficient of thermal expansion, increase heat resistance, and even affect bond strength. Of course, the excellent wetting properties of polyamides Increase the dispersion efficiency of these fillers. The type of filler selected and the amount used also have a pronounced effect on adhesive quality. A few of these effects are illustrated in Tables VI and VII (37). (See also Table VIII.)... 

Vapour degreasing is an excellent way to obtain highly clean surfaces. The efficiency of cleaning can be checked by determining the coefficient of friction, in addition to dark-field-inspection, contact-angle and thin-film-adhesion measurements methods. High values are typical for clean surfaces [7]. 

The efficiency of particle removal can be expressed by means of the removal coefficient or the adhesion number yp [23]... 

From this discussion, it can be seen that the efficiency of removal of adherent particles from different surfaces may be characterized not only by the adhesion number, but also by the coefficient of removal, which is a function of the probability of detachment and removal of the adherent particles. If we know the relationship between the average force of adhesion and the particle size, i.e., Fav - fid), and if the detachment force F et =/( ) is fixed, the method we have just examined can be used to determine the probability of particle detachment over a range of sizes from to c/max ... 

All of the studies discussed above have shown that some silane SAMs are efficient in reducing the coefficient of friction, the work of adhesion, and stiction properties however, their wear resistance is not sufficient to provide high durability to the MEMS components [42]. One possible reason for the low wear durability of SAMs is the lack of a mobile portion in the lubricant. Hence, there is no replenishment in these layers as molecules are continuously removed from the contact area during the wear process. Moreover, the worn particles generated as a result of material removal act as a third body and further accelerate the wear of the film. Therefore, we proposed a lubrication concept of overcoating SAMs (bonded) with an ultrathin layer of per-fiuoropolyether (PFPE) (bound + mobile) to improve the wear durability of SAMs and hence that of the Si substrate (fig. 6.1) [43, 44]. The mobile PFPE is expected to lubricate and replenish the worn regions and hence enhance the wear durability. 

Interphase adhesion can be achieved by several mechanisms. A common and efficient method is through the use of a block or graft copolymer of two homopolymers involved that can act as an emulsifying agent and lower the interfacial tension coefficient, as discussed above. Addition (or production by i.e. plasma) of suitable agents that may not necessarily be copolymeric in nature but contain similar groups as parent homopolymers... 

Direct adhesion of particles to fibres can be explained with Deijaguin—Landau— Verwey—Overbeek (DLVO)" " theory for soft cell particles,and the adhesion of cell particles to the fibres may be quantified by using the attachment rate coefficient, att which is related to the collision efficiency, rj, and the sticking efficiency, , as follows... 

Effect of the Methods of Dust Deposition and the Properties of the Surface on the Detachment of Particles. It is well known that there are other ways in which plates become dusty as well as by free settling. Dust particles may occur in drops of rain and settle on surfaces at the same time as these. When the drops dry in the air, the adhesion of such particles becomes much stronger (see 26). The following represents some experimental data relating to the efficiency with which particles are removed by a flow of water (i.e., the variation in the coefficient K ) as a function of the method by which the particles are deposited on the surface ... 

The third process is a continuous self-cleaning reactor process [5,8-10], In the self-cleaning reactor, low adhesion powders can be easily obtained under low SPS conversions. The heat transfer coefficient in the self-cleaning reactor is relatively high. Multiple reactors are necessary to achieve efficiency in the production scale. 

This effort demonstrates the feasibility of upscaling these complex devices, but the Krebs et al. stress that more resources should be guided toward the development of inks specifically formulated to facilitate the roll-to-roll processing. These inks should be formulated by taking into account, on top of electrical and optical performance, viscosity, shelf life, thermal expansion coefficients, high elasticity and surface adhesion of all the layers. Furthermore, efficient sequential processing requires that each layer be dried in an oven before the next one is deposited and this happens commonly around 80 to 100 °C, which limits the choice of materials to use. 

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