**2.3 Manufacture of coatings**

162 Corrosion Resistance

 **100 µm** 

Fig. 2. SEM micrograph of reinforcement fibers: A. Graphite, B. Silicon nitride and

 **100 µm** 

**C** 

**A B**

finishing the pigment dispersion (1.0% w/w on coating).

Clay modified with amines in gel form was chosen, which was added to the system after

 **100 µm** 

The physical and mechanical properties of the film and its protective capacity depend on the shape and size of the zinc particles and in addition of the PVC. The critical value (CPVC) is

In this study, PVC values ranged from 57.5 to 70.0%; the variation of two consecutive PVC values was 2.5% in all cases. Preliminary laboratory tests (salt spraying chamber), with values of PVC from 10 to 70% for all formulations, helped to define the range of PVC more

strongly influenced by the ability of binder for wetting the pigment particles.

C. Quartz.

**2.1.4 Rheological agent** 

**2.2 Pigment volume concentration** 

convenient to study (Sonawane et al., 2010).

In this paper, the manufacture of hybrid coatings was made by ultrasonic dispersion in the vehicle. The efficiency of the fiber dispersion in the polymeric matrix was rheological monitored (viscosity of the system, measured at 10-3 sec-1, decreased during the sonification process until reaching a stationary value); the SEM observation corroborated both the efficiency of fiber dispersion and its stability after 3 months in can.

Finally, it should also be mentioned that this type of compositions is provided in two packages with the purpose of avoiding the reaction of metallic zinc with any vestige of moisture in some of the components, which would lead to the formation of gaseous hydrogen. In addition, the system could form a gel because of the reaction between silicic acids and zinc cations. Accordingly, prior to the primer application, the metallic zinc was dispersed for 180 seconds at 1400 rpm in high-speed disperser.
