The Effects of ZDDP and Ashless Antiwear Additives on the Friction and Wear Characteristics of Tribological Coatings on Steel

Abstract

Over the years, advanced surface coatings e.g. diamond-like carbon, chromium nitride, and titanium nitride were developed to protect substrates from wear and corrosion. Meanwhile, there is a growing trend towards ``greener?? lubricant additives. Zinc dialkyl dithiophosphates (ZDDP) have been extensively used in lubricants as antiwear agents but the pressure to reduce sulphated ash, phosphorus and sulfur content in engine oils is increasing due to their detrimental effect on exhaust after-treatment devices. Also, zinc?containing lubricants, being potentially hazardous to human health, are considered unsafe for the food and agricultural industries. Therefore, it is important to find a more environmentally friendly substitute. In addition, there is a need to review which materials and lubricants are used in partnership, to capitalize on synergies, and also identify compatibility issues to avoid counterproductive results. Investigations on the impact of ZDDP and an ashless antiwear additive on advanced surface coatings were conducted in this project.