Rain Erosions

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

Protective Coating, Integral Fuel Tank Coating, Polyurethane, Rain, Erosion Resistant Resin-Acid Metal Pretreatment Compound for Aircraft Cement Rubber... 

Degradable Polystyrenes. The Ecolyte "Fast" polystyrene foam has a higher concentration of photosensitive vinyl ketone comonomer than the Ecolyte "Slow" foam and as a result has a shorter irradiation time to embrittlement as listed in Table I. The "Fast" foam was brittle after one month outdoor exposure or 275 hr xenon arc irradiation. The outdoor exposure was facilitated by wind and rain erosion. Turning the sample over after 35 hr xenon irradiation lowered the embrittlement time to a remarkably short period of 70 hr considering the thickness and opacity of the foam. Similarly the "Slow" foam had its xenon embrittlement time reduced from 21+00 hr to only 600 hr by turning the foam over after each 2l+ hr irradiation period. To obtain a better idea of the rate of... 

Laboratory Penetration Tests. Bench-scale laboratory penetration tests were performed to evaluate the possibility of applying molten sulfur directly to soil test specimens consisting of fine construction sand to stabilize them from wind and rain erosion. The emphasis was on penetration of the sulfur or chemically modified sulfur into the test specimen directly, thus avoiding the necessity of applying external heat to promote penetration. 

Chemical modification of sulfur with 6-7% dicyclopentadiene and 1% dipentene at 160 °C was the most suitable mixture tested for spraying a coating on tailings to prevent wind and rain erosion. 

Callen MS, de la Cruz MT, Lopez JM, Murillo R, Navarro MV, Mastral AM (2008) Some inferences on the mechanism of atmospheric gas/particle partitioning of polycyclic aromatic hydrocarbons (PAH) at Zaragoza (Spain). Chemosphere 73 1357-1365 Cerro C, Bech J, Codina B, Lorente J (1998) Modeling rain erosivity using disdrometric techniques. Soil Sci Soc Am J 62 731-735... 

Natural weathering such as wind and rain erosion can eventually lead to failure of protective coatings of composites including paints, and the underlying fiber -resin material, if left exposed, is then vulnerable to continued weathering [29]. Water penetration and UV radiation are other factors damaging composites. 

Figure 6.39 Example of an RP radome with a rain erosion coated surface that is located on the front of the airplane...

PEEK is not chemically attacked by water. It has excellent long-term resistance to water at both ambient and elevated temperatures. It also has excellent rain erosion resistance. Because PEEK is not hydrolyzed by water at elevated temperatures in a continuous cycle environment, the material may be steam sterilized using conventional sterilization equipment. 

Current understanding of the erosion of polymer laminates has come chiefly from rain erosion studies of composite aircraft materials. Analogies have been drawn between cavitation and liquid impingement processes on metallic materials both involve extensive structural damage early in the incubation period as a result of short-term shock pulses. Furthermore, the deformed surfaces of materials which are subjected to both processes are very similar, and so are the methods used to improve their performance [99]. Attempts have been made to prioritize the factors affecting erosion of FRP by liquid impingement, with more or less predictable results [100] in respect of resin composition, fiber volume fraction and orientation, porosity and thermal conductivity. All these factors were found to affect performance. 

Barschdorff, D., "Droplet formation, influence of shock waves and instationary flow patterns by condensation phenomena at supersonic speeds", Proc. 3rd Int. Conf. on "Rain Erosion and Associate Phenomena", R.A.E., Famborough, 1970, pp.691-705. 

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