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Base Oils
Published in Wilfried J. Bartz, Engine Oils and Automotive Lubrication, 2019
The second step in the manufacture of PAO is hydrogenation. This is necessary to obtain a chemically inert product, especially towards oxidation. Hydrogenation has a very minimal effect on the product performance properties. CxnH2xn+H2→CxnH2xn+2
Cutting And Wear Applications
Published in Mark A. Prelas, Galina Popovici, Louis K. Bigelow, Handbook of Industrial Diamonds and Diamond Films, 2018
Several outstanding properties of diamond render it an ideal cutting tool material. Three of these properties are diamond’s high hardness, it’s high thermal conductivity, and it’s low coefficient of friction. Diamond is also one of the most chemically inert substances. However, it cannot be used to machine ferrous metals, nickel-based, or titanium-based alloys because of its chemical reactivity with these materials at the high contact pressures and temperatures generated during the machining process. There is, however, an application where these aforementioned limitations do not exist. This use is in the honing of cylinders in cast iron engine blocks. In that application diamond performs well because the heat generated is very low because the speed is very low, the contact pressures are very low, and the surface is flooded with oil.
Nanoparticles Filled Polymer Nanocomposites: A Technological Review
Published in Cogent Engineering, 2021
Anupama Hiremath, Amar A Murthy, Sridhar Thipperudrappa, Bharath K N
An NP is a scientific term coined to classify such small particles which cannot be deciphered through naked eyes and are known to possess at least one dimension which is less than 100 nm. A more stringent definition defines NPs as such particles whose properties are dependent directly on their size [57]. This definition restricts the size of the NP to be smaller than 10–20 nm. As stated in the aforesaid paragraphs, the size and dispersion of the NPs play a significant role in determining the final properties of the PNCs. This is because of the pronounced increment in surface properties with the reduction in particle size. As the particle size reduces, the surface-to-volume ratio increases. This implies that whenever a material is composed of nano-scaled particles, the surface area of such material increases and such nano-sized materials have a greater number of surface particles. This can be explained through the consideration of a typical case, wherein a 10 nm particle possesses nearly 20% of its particles at its surface as opposed to a 3 nm particle, which has almost 50% of its particles at the surface. This property of the nanomaterials renders them highly reactive. Most of the materials, which are chemically inert in their bulk form, are often found to be severely reactive when they are brought down to nanoscale form. When nanomaterials are incorporated in polymeric matrices, such surface properties largely influence the interfacial properties between the matrix and the reinforcing NPs, tendency of the formation of aggregates/agglomeration of NPs within the matrix and finally leads to the enhancement or reduction in the material property of the PNC. It is found that the high surface area of the NPs results in setting up of an intense Vander Waal’s forces of attraction between the particles which result in agglomeration of NPs (Zare, 2016). Such agglomeration has a negative impact on the mechanical properties of the PNCs as the material is devoid of active interphases due to lack of interfacial area (Chen et al., 2015; Shin et al., 2015).