What is vegetable and animal oil
Vegetable and animal oils are glycerides of higher fatty acids. These oils are extracted by hot pressing of oil-bearing seeds and steam distillation of animal fats tissues examples of vegetable oils olive oil, palm oil, cottonseed oil
Molybdenum disulfide
Structure of molybdenum disulfide Molybdenum disulfide has sandwich-like structure The layer of molybdenum atoms lies between two layers of sulfur atoms. The two layers of S atoms are 6.26A apart the room each whereas the distance between
Why are greases called thixotropic gels?
Thyrotrophic gels are those or fluids that are viscous under normal condition become thin or less viscous over time when agitated (shaken) or otherwise stressed. Similarly, greases on agitation or on being stressed become fluid or less
What are semi solid lubricants?
Semi-solid lubricants are a gel-like substance which reduced friction between two moving surfaces. E.g.; greases, Vaseline, waxes semi-solid lubricants (Greases) Preparation Greases are semi-solid lubricants obtained by thickening of lubricating oil by the addition of metallic soaps.
What are liquid lubricants?
Liquid lubricants are liquids that separate and reduce friction between two moving surfaces and decrease wear and tear. The properties of good liquid lubricants are as follows Properties of oiliness. Appropriate viscosity and should not change appreciably
What are greases?
Greases are defined as semi-conductor lubricants containing soap or mixture of soaps and fillers dispersed in lubricating oils (petroleum oils) making it suitable for lubrication under high load and slow speed. A grease is made up of
Which operational are greases preferred as lubricant?
Greases are preferred as lubricants when – Operating pressure is high. Operating temperature is high (800C) The machine operates at high load, slow speed with intermittent jerks where oil film cannot be maintained. Machine parts are to
Function of various constituents in greases
Soap It acts as a thickener. Presence of soap allows it to stick to the metal surfaces firmly and provides consistency. The nature of soap decides the temperature to which the greases can be used. It provides
How are the greases prepared?
The greases are obtained by mechanical dispersion of soap in petroleum oil. Soap is obtained when fat alkali used soaps are classified as sodium soap (prepared using NaOH), calcium soap (using Ca(OH2), lithium soap (LiOH) etc. The
How are liquid lubricants classified?
Liquid lubricants are classified on basis of original origin as Vegetable oil: these are obtained from plants. E.g. olive oil, palm oil, cottonseed oil etc Animal oil: these are obtained from animals like fishes etc. Mineral oil: