Wetting Whisker

Fig. 50. TG curve showing the formation of alumina whiskers during oxidation of iron-aluminum alloy in wet hydrogen (2%)/argon mixture (isothermal at 1555 °C). Sample weight 1000 mg...

Surface treatments of carbon fibers can in general be classified into oxidative and non-oxidative treatments. Oxidative treatments are further divided into dry oxidation in the presence of gases, plasma etching and wet oxidation the last of which is carried out chemically or electrolytically. Deposition of more active forms of carbon, such as the highly effective whiskerization, plasma polymerization and grafting of polymers are among the non-oxidative treatments of carbon fiber surfaces. 

Figure 6.32 shows a schematic of the process. When the above reaction is over, the residue is heated to 800°C to remove any free C. Generally, both particles and whiskers are produced together with some excess free carbon. A wet process is used to separate the particles and the whiskers. Typically, the average aspect ratio of the as-produced whiskers is 75. 

Figure 18.5 Surface water NO2 + NO3 concentrations measured at stations located in the oligo-haline (A), mesohaline (B), and polyhaline (C) regions of Chesapeake Bay. The box and whisker plots contain all values for each month in the 20 year data set (1985-2004). Dark squares and circles represent NO2 + NO3 concentrations during all wet and dry years, respectively, in this 20 year data set. Data were from the Chesapeake Bay Water Quality Monitoring Program (2004).

C. Youtsey, L. T. Romano, and I. Adesida, Gallium nitride whiskers formed by selective photoenhanced wet etching of dislocations, Appl. Phys. Lett. 73, 797-799 (1998). 

Figure 4.12. (a) TG curve showing formation of alumina whiskers in wet H2 20<,)/Ar atmosphere (72). (f>) schematic representation of reactions occurring during whisker formation (72). 

Following the 50-hour polyacrylic acid run, the evaporator tube was opened for examination while still wet, and showed an apparently clean bright surface over practically the whole length of the tube. Almost immediately, thin flakes or whiskers of a translucent blue film appeared, detaching from the tube to leave a highly polished copper surface. The flakes appeared to be formed by air drying of a plastic film coating the surface. 

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