ISSN:
1573-2711
Keywords:
chloroform
;
extreme-pressure lubrication
;
additives
;
surface chemistry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Carbon tetrachloride is an extremely good extreme-pressure (EP) lubricant additive at low concentrations (〈3 wt% chlorine) since it can react to form a high-melting-point Fe3C antiseizure layer. In contrast, small hydrogen-containing additive molecules (CH2Cl2, CHCl3) decompose to form FeCl2 which melts at ~940 K and limits the maximum seizure load to ~3500 N as measured hi a pin and v-block apparatus. However, both thermodynamic calculations and results of a Mössbauer analysis of an iron foil heated in CHCl3 at 830 K indicate that iron carbide can be formed from chloroform. In addition, it is also found in that case that a plot of seizure load versus concentration, after initially forming a plateau, once again increases with higher additive concentrations (〉4 wt% chlorine) in accord with the idea that a higher melting point carbide film can be formed. It has been shown previously that asymptotes in the plot of removal rate versus applied load correspond to melting of the interfacial anti-seizure film. When using 9.0 wt% chlorine from chloroform as the additive, a drastic increase in removal rate is found at an interfacial temperature of ~940 K corresponding to the melting of FeCl2 and an additional asymptote is evident at ~1500 K due to the melting of Fe3C in accord with the thermodynamic and Mössbauer results.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00157974
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