IIT Jodhpur’s Prof. Rakesh K Sharma’s research group have developed Rajasthani clay based solid lubricant for industrial applications.

The success of industries or large machinery or human exploration on Moon and Mars, is critically dependent on the reliable operation of mechanical assemblies and tribological components of lubricants used. The performance of these lubricants alters with environmental conditions such as temperature, humidity, radiation and presence chemical components. The low coefficient of friction and long wear life is key in this respect. Presently the most successful solid lubricant, graphite and MoS2 suffer with decompositionn and sulphur toxicity at temperature above 400 deg as well as cost. It is essential, therefore, to develop a high performing lubricant for various mechanical and tribological application.

IIT Jodhpur’s Prof Rakesh K Sharma’s research group have developed Rajasthani clay based solid lubricant for industrial applications. The lubricant made up of layered Rajasthani clay with spherical metal nanoparticles between the layers that has low friction. The friction coefficient of clay material was found to be from 0.001-0.4 over a wide range of environmental and temperatures conditions. The clay based lubricant works very well from -50 to 1100 degree temperature with very long wear life. The work has been patented and shortly publishing in Friction.

The clay based lubricant occurs via macroscopic friction between clay layers originate from interatomic electrostatic forces. Usually, the frictional forces between the clay layers are very low. This property is thought to be a cause of clay ooze while holding in hand and landslides and various nature avalanches. “Our research group has been involved in development of clay based efficient low cost technology from last one decades and serious efforts are made to develop friction-reducing solid lubricants for variable temperature applications for aviation, space, steel, cement and automobiles industries. The friction between clay layers are bonding forces, not able to explored by any research group across the globe because of their complex stimuli of electrostatic and intermolecular forces, crystallographic alignment, layer roughness and mineral impurities. Our team have been working on Rajasthani clay, an abundant material that was modified by our patented process for solid lubricant purpose by inserting nickel oxide nano-spheres between layers,” says Prof Sharma.

The studies were carried out at atomic level and measured friction force at different sliding positions followed by investigation of wear particles due to worn surface. It has been observed that in presence of nickel oxide nano-spheres, the effect is nullified due to appropriate orientation and favourable electrostatic forces. This is first and most significant discovery in the area of solid lubricants based on natural clay. “Currently we are working on improvement the clay lubricant for space application that can work between -160 to 1000 degree temperature and with friction coefficient close to 0.001,” Prof Sharma sums up.