Effect of cyanide content on the tribological performance of nitrile butadiene rubber

Nitrile butadiene rubber (NBR) has received a lot of attention as a sealing material, and its tribological performance is a crucial factor in determining the efficiency with which it will operate under various operating situations. In this study, NBR specimens with varying degrees of cyanide content, namely low cyanide (DN401), medium cyanide (DN2850), medium-high cyanide (DN3380), and high cyanide (DN4050), were selected to investigate their tribological behavior when subjected to NO.10 aviation oil. To emulate their frictional responses during startup and shutdown operations, all four types of NBR were assessed under dry conditions. As the cyanide content increased, the coefficient of friction (COF) dropped from 1.381 to 0.810 and wear rate dropped from 2.38 × 10⁻³ mm³/(N m) to 1.88 × 10⁻⁴ mm³/(N m). When employed in conjunction with NO.10 aviation oil, DN401 and DN3380 exhibited COFs of 0.0963 and a slightly higher value of 0.127, respectively. Following aging treatment at 80°C in NO.10 aviation oil, stress reduction reached 65.8%, indicating the poorest performance among the four variants of NBR. Considering the COF, wear rate, and aging performance, DN3380 emerges as the most favorable choice for practical applications, thereby offering valuable insights into the selection of nitrile rubber for sealing materials.