Tribofilm formation of a boric acid fuel additive – Material characterization; challenges and insights

In field tests of cars and diesel generators, a boric acid-based fuel additive has shown capacity to reduce the fuel consumption with 6% and 10%, respectively. The mechanisms behind this are unknown. Work towards understanding has included lab tests mimicking the piston ring/cylinder contact, including friction measurements and characterization of tribofilms. The aim here is to investigate tribofilms formed in lab tests, to learn how to best analyze and characterize field-tested engine surfaces. The tests were conducted at room temperature and 100 °C. The formation of the boric acid tribofilms varied with temperature, as found by analyzing with SEM, TEM, EDS and Raman spectroscopy. Since detecting and analyzing the films proved very challenging, insights and suitable techniques are suggested.