Innovation in Nanoparticle Additives for Water-Based Lubricants

The use of mechanical systems and machinery is one of the cornerstones of a modern industrialized economy. Maintaining a long operation life with minimal wear and loss of performance is a crucial concern for any industry. Along with designing more efficient machines and mechanisms, lubrication is a core approach to addressing this concern. It is part of a field of research and industry of its own – tribology. By applying a lubricating agent, reduced wear and extended operation life can be achieved by minimizing friction forces on contact surfaces, and, as a result, reducing mechanical stresses on machine components and increasing operation efficiency [1]. From engine oils to drilling fluids, lubrication agents like oils and greases remain a vital component of industrial processes with an estimated industry worth of $164.3 billion as of 2019. Experts project that by 2024, the lubricant industry, pushed by innovation and growing demand in the transportation industry and other industrial sectors, will  grow to $188 billion [2].
One of the fundamental drivers for innovation within the lubricant industry in what could be considered as the “Third Industrial Revolution” and includes broad technological developments, such as the rise of electric vehicles, automation, and 3D printing, is the expanding application of nanotechnology [3]. The nanotechnology market has grown from $26 billion in 2014 to $48.9 billion in 2017 and has applications in a variety of major industries ranging from pharmaceuticals to semiconductors to the lubricant industry [4,5]. Following the latest market trends of cost optimization, environmental friendliness, as well as higher reliability and performance, end-users expect improved tribological properties (anti-wear, anti-friction, extreme pressure protection, etc.) from modern lubricants. Today, nanotechnology is a leading method for achieving the desired properties in the form of nano-additives [3].
Nano-additives are designed to enhance the tribological performance of the lubricant by reducing friction (or the CoF, to be precise) and forming a protective layer(s) on the contacting surfaces. Such layers are called tribofilms; they are formed by chemical modification when friction forces arise during mechanical operation after physical and/or chemical adsorption of the tribologically active compounds onto the component surface [6]. Protective layers of molybdenum disulfide (MoS 2 ) are commonly sought after due to this material’s capacity of reducing CoF and is traditionally achieved through additives containing MoS 2 or molybdenum complexes containing sulfur compounds such as dithiocarbamate and phosphorodithioate [6,7]. Most of these compounds are difficult to synthesize and their production process involves toxic chemicals. It is a concern, especially when the market is leaning more towards eco-friendlier, sustainable, and scalable products. For example, the use of phosphorodithioates in motor oil...