Sliding friction across a thin soft lubricant film typically occurs by stick-slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick-slip unclear and unknown; its possible vanishing is imp...

We investigate the role of defects and disorder in a 2D-model lubricant interposed between two sliding substrates. Specifically, we consider localized defects (vacancies) and extended defects (grain boundaries) in the lubricant confined between two perfect rigid chains. This work verifies in particular when the perfect ”quantized” dynamical sliding regime identified in previous work [1, 2] is p...

current world conditions require compressors to be both efficient and economical to manufacture. one means of improving efficiency in a rotary vane (or any) compressor is to use the lubricant as a heat transfer agent. A rotary vane refrigerator compressor was modified and instrumented for calorimeter testing so that the performance improvement could be identified. The changes and testing were c...

We review some of the key tribological issues of relevance to motorsport applications. Tribology is the science of friction and wear, and in a high performance engine, friction and wear are controlled by good component design (e.g. the engine and the transmission) and also by the use of high performance lubricants with the correct physical (and chemical) properties, matched to the machine they ...

The synovial fluid (SF) of joints normally functions as a biological lubricant, providing low-friction and low-wear properties to articulating cartilage surfaces through the putative contributions of proteoglycan 4 (PRG4), hyaluronic acid (HA), and surface active phospholipids (SAPL). These lubricants are secreted by chondrocytes in articular cartilage and synoviocytes in synovium, and concentr...

The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant on binary direct compression mixtures. Magnesium stearate (MGST), stearic acid (STAC), glyceryl behenate (COMP) and hexagonal boron nitride (HBN) were tested. The binary mixtures were 1:1 combinations of spray dried lactose (FlowLac 100), dicalcium phosphate dihydrate (Emcom...

We construct a computer code to solve the (Nosé Hoover) finite-temperature classical dynamics of a Lennard-Jones solid lubricant slab between two rigid solid substrates. The code is based on a standard periodically repeated supercell scheme, which imposes relative substrates/lubricant densities. We investigate the possible occurrence of Moiré patterns due to incommensurability, and for the drag...

Corn starch particles are used as a surgical glove lubricant. At present there is no better alternative for this lubricant. Implantation of corn starch particles into the peritoneal cavity can induce foreign body reactions, starch peritonitis and starch granulomata, and may cause adhesions and intestinal obstruction. Starch peritonitis should be treated conservatively.

Using molecular dynamics based on Langevin equations with a coordinate- and velocity-dependent damping coefficient, we study the frictional properties of a thin layer of "soft" lubricant (where the interaction within the lubricant is weaker than the lubricant-substrate interaction) confined between two solids. At low driving velocities the system demonstrates stick-slip motion. The lubricant ma...

Diesel particulate filters (DPF) are an effective means for meeting increasingly stringent emissions regulations that limit particulate matter. Over time, ash primarily derived from metallic additives in the engine oil accumulates in DPFs. Lubricant-derived ash increases pressure drop and reduces fuel economy. After long time periods, the accumulation of ash may lead to irreversible plugging in...