Friction Effect Nitrogen

Investigation into the effect has been mainly devoted to reactions with red fuming nitric acid . It seems that in red fuming nitric acid a preliminary reaction results in the formation of a surface deposit of finely divided metallic titanium ignition or pyrophoricity can then be initiated by any slight impact or friction. The tendency to pyrophoricity increases as the nitrogen dioxide content of the nitric acid rises from zero to maximum solubility at about 20%, but decreases as the water content rises, the effect being nearly completely stifled at about 2% water. 

Action of alkalies on diazonium solutions, or of acids on alkali diazoates to give a final pH of 5-6, causes these compounds ( diazoanhydrides ) to separate as oils or solids. Many of these are violently explosive (some exceeding nitrogen trichloride in effect), sensitive to friction and heat or contact with aromatic hydrocarbons [1,2], Individually indexed compounds are ... 

The basic Brophy and Ingraham technique was studied by several other authors. Bayer and Trivedi " found that the effectiveness of the technique depended more on the nature of the coating than on its thickness, and that retained moisture in the electroplate was essential for effective conversion. They recommended a current density of 21.5 A/m for 5 minutes to produce a coating thickness of 1.25 to 2.5 tjm. Nishimura and co-workers found that the presence of air or water or both in the conversion gas improved the wear life. Table 9.5 compares the properties of the in situ films with those of burnished and sputtered films, and shows superior wear life for the in situ films. Their friction results were curious, in that they found that the initial films which were formed gave low friction in air or nitrogen but not in vacuum. Low friction in vacuum was obtained when the initial product was heated in vacuum to 400°C. 

Of the series of additives copper chromate, copper chloride, nickel oxide, iron(lll) oxide or magnesium oxide, the earlier members have the greatest effect in increasing the sensitivity of the explosive salt towards heat, impact or friction. See other PERCHLORATE salts of nitrogenous bases... 

Figure 19-13. Effect of vapors on the friction of graphite. 1 Nitrogen. 2 Hydrogen. 3 Water. 4 Dry air. 5 Ethanol. 6 n-Heptane. 7 Oxygen. From data by G. W. Rowe [54].

Num] Numakura, H., Mima, M., Matsumoto, H., Koiwa, M., Nitrogen Trapping to Chromium in a Iron Studied by Internal Friction and Magnetic After-Effect Techniques , ISIJ Int., 36(3), 290-299 (1996) (Crys. Structme, Experimental, Magn. Prop., 40)... 

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