Material Science1

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MATERIAL SCIENCEASSIGNMENT NO-3

TOPIC: LUBRICANTS AND AUXILIARIES

BY:-

PRERNA AGRAWAL


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LUBRICANTS AND AUXILLARIES

CONTENTS:

What are lubricants? Uses and properties of lubricants Types of lubricants Auxiliaries


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WHAT ARE LUBRICANTS?

A lubricant is a substance (often a liquid) introduced between two moving surfaces to reducethe friction between them, improving efficiency and reducing wear. They may also have the

function of dissolving or transporting foreign particles and of distributing heat.

One of the single largest applications for lubricants, in the form ofmotor oil, is to protect the

internal combustion engines in motor vehicles and powered equipment.

Typically lubricants contain 90% base oil (most oftenpetroleum fractions, called mineral

oils) and less than 10% additives. Vegetable oils or synthetic liquids such as hydrogenated

polyolefin, esters, silicones, fluorocarbons and many others are sometimes used as base oils.

Additives deliver reduced friction and wear, increased viscosity, improved viscosity index,

resistance to corrosion and oxidation, aging or contamination, etc.

Lubricants such as 2-cycle oil are also added to some fuels. Sulphur impurities in fuels also

provide some lubrication properties, which has to be taken in account when switching to a

low-sulphur diesel; biodiesel is a popular diesel fuel additive providing additional lubricity.

Non-liquid lubricants include grease, powders (dry graphite, PTFE, Molybdenum disulfide,

tungsten disulfide, etc.), Teflon tape used in plumbing, air cushion and others. Dry lubricants

such as graphite, molybdenum disulfide and tungsten disulfide also offer lubrication at

temperatures (up to 350 C) higher than liquid and oil-based lubricants are able to operate.

Limited interest has been shown in low friction properties ofcompacted oxide glaze layersformed at several hundred degrees Celsius in metallic sliding systems, however, practical use

is still many years away due to their physically unstable nature.

INDUSTRIAL LUBRICANTS

Industrial lubricants are basically defined as compounds like fluids, greases and oils. They

are used in order to lessen wear and tear of materials while reducing binding and friction. In

some extreme cases, they may also prevent or lessen electrical resistivity while it increases

thermal conduction. Of course, they are also favored because they can prevent corrosion in

both the inner and outer surfaces where they are applied.

There are various types of industrial lubricants including low and high viscosity oils,

lubricant powders, waxes and high temperature silicates. With lubricating oils, other forms

are also seen such as natural and synthetic oils. At times, they may also be combined with

waxes or dispersions of solid lubricants. There are still other forms of lubricants used in

several industries.

Dielectric greases and insulating fluids.

Just like the main objective of an industrial lubricant, dielectric greases and insulating fluids

are capable of reducing friction, wear and binding of materials. They are often used in
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capacitors, electric discharge machining, transformers and other electrical devices. It is also

applicable in lubricating, sealing and coating.

Among all the uses of dielectric greases and insulating fluids, they are commendable because

they have the capacity to provide heat stability and they do not breakdown even at the highest

temperature ranges. They are also utilized in dispersing heat from electrical componentswhile they lubricate slide and relay contact switches.

Heat transfer fluids and thermal oils

These are forms of industrial lubricants utilized in order to carry thermal energy for various

applications such as metal working, machine cooling and process heating. It includes other

products to provide machine cooling such as chiller fluids, refrigerants and circulating

coolants. For heating purposes, products such as hot or heater oils are found.

Hydraulic oil and transmission fluids

With the name alone, one will be able to say that these lubricants are made specifically for

power transmission and hydraulic equipment. Power is transmitted from the fluid through the

aid of hydraulic lines before they are transferred to a cylinder. Transmission fluids on the

other hand are useful in applications like gearbox assemblies. Most hydraulic and

transmission fluids include synthetic lubricants, oil-water emulsions and petroleum ormineral oils. They are specifically used in aerospace, automotive, military and marine

applications.

USES AND PROPERTIES OF LUBRICANTS

Lubricants are substances that minimize the resistance between two interacting surfaces. To

use a lubricant, you simply apply it to the area impeded by friction. As soon as the lubricant

hits the surface of the solid, it starts to absorb the rough molecules it comes into contact with,

helping to create a smoother, less resistant surface.

When a lubricant is applied to a rough surface, it undergoes a chemical reaction with the

abrasive dirt and other surface molecules on the solid.

During this reaction, the lubricant absorbs abrasive molecules off the surface of the object towhich it is applied to make the surface smoother. As a result, while lubricants do cut down

the friction between two surfaces, they also typically serve as good cleansers.

Other reasons people generally use types of lubricants can include to:

Help parts continue to move in the appropriate manner (i.e. locks, switches, etc.) make a surface water-resistant prevent wear and tear from damaging a surface transfer power (namely hydrostatic power) from one surface to another transmit heat from one surface to another.


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PURPOSE

Lubricants perform the following key functions.

Keep moving parts apart

Reduce friction Transfer heat Carry away contaminants & debris Transmit power Protect against wear Prevent corrosion Seal for gasses Stop the risk of smoke and fire of objects

Keep moving parts apart

Lubricants are typically used to separate moving parts in a system. This has the benefit of

reducing friction and surface fatigue together with reduced heat generation, operating noise

and vibrations. Lubricants achieve this by several ways. The most common is by forming a

physical barrier i.e. a thin layer of lubricant separates the moving parts. This is termed

hydrodynamic lubrication. In cases of high surface pressures or temperatures the fluid film is

much thinner and some of the forces are transmitted between the surfaces through the

lubricant. This is termed elasto-hydrodynamic lubrication.

Reduce friction

Typically the lubricant-to-surface friction is much less than surface-to-surface friction in a

system without any lubrication. Thus use of a lubricant reduces the overall system friction.

Reduced friction has the benefit of reducing heat generation and reduced formation of wear

particles as well as improved efficiency. Lubricants may contain additives known as friction

modifiers that chemically bind to metal surfaces to reduce surface friction even when there is

insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve

train in a car engine at startup.

Transfer heat

Both gas and liquid lubricants can transfer heat. However, liquid lubricants are much more

effective on account of their high specific heat capacity. Typically the liquid lubricant is

constantly circulated to and from a cooler part of the system, although lubricants may be used

to warm as well as to cool when a regulated temperature is required. This circulating flow

also determines the amount of heat that is carried away in any given unit of time. High flow

systems can carry away a lot of heat and have the additional benefit of reducing the thermal

stress on the lubricant. Thus lower cost liquid lubricants may be used. The primary drawback

is that high flows typically require larger sumps and bigger cooling units. A secondary

drawback is that a high flow system that relies on the flow rate to protect the lubricant from

thermal stress is susceptible to catastrophic failure during sudden system shut downs. An

automotive oil-cooled turbocharger is a typical example. Turbochargers get red hot duringoperation and the oil that is cooling them only survives as its residence time in the system is
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very short i.e. high flow rate. If the system is shut down suddenly (pulling into a service area

after a high speed drive and stopping the engine) the oil that is in the turbo charger

immediately oxidizes and will clog the oil ways with deposits. Over time these deposits can

completely block the oil ways, reducing the cooling with the result that the turbo charger

experiences total failure typically with seized bearings. Non-flowing lubricants such as

greases & pastes are not effective at heat transfer although they do contribute by reducing thegeneration of heat in the first place.

Carry away contaminants and debris

Lubricant circulation systems have the benefit of carrying away internally generated debris

and external contaminants that get introduced into the system to a filter where they can be

removed. Lubricants for machines that regularly generate debris or contaminants such as

automotive engines typically contain detergent and dispersant additives to assist in debris and

contaminant transport to the filter and removal. Over time the filter will get clogged and

require cleaning or replacement, hence the recommendation to change a car's oil filter at thesame time as changing the oil. In closed systems such as gear boxes the filter may be

supplemented by a magnet to attract any iron fines that get created.

It is apparent that in a circulatory system the oil will only be as clean as the filter can make it,

thus it is unfortunate that there are no industry standards by which consumers can readily

assess the filtering ability of various automotive filters. Poor filtration significantly reduces

the life of the machine (engine) as well as making the system inefficient.

Transmit power

Pascal's law is at the heart of hydrostatic power transmission. Hydraulic fluids comprise alarge portion of all lubricants produced in the world.

Protect against wear

Lubricants prevent wear by keeping the moving parts apart. Lubricants may also contain anti-

wear or extreme pressure additives to boost their performance against wear and fatigue.

Prevent corrosion

Good quality lubricants are typically formulated with additives that form chemical bondswith surfaces to prevent corrosion and rust.

Seal for gasses

Lubricants will occupy the clearance between moving parts through the capillary force, thus

sealing the clearance. This effect can be used to seal pistons and shafts.

Industrial and Automotive Lubricants

When people think of lubricants, they tend to picture those used for industrial and automotive

purposes. For the most part, these types of lubricants are meant to reduce friction, rid a
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system of contaminants and preserve the quality of machine and/or car parts. Depending on

their precise use, industrial and automotive lubricants can come in the form of:

greases or powders, as with dry graphite liquids, as with motor oils and fuel additives solids, as with ball bearings or Teflon.

Because some of these lubricants can be used for the same purposes, for many industrial or

automotive projects, the nature of the environment in which you use the lubricant will

determine which type of lubricant will be most effective.

For example, temperature can be a key determinant when choosing between different types of

lubricants. In hotter environments or in situations that will generate a lot of heat, solid

lubricants work best, as some will still operate effectively at temperatures as high as 350C.

However, because solid lubricants also tend to corrode easily, they need to be replaced

frequently and, therefore, aren't used much outside of extremely hot situations.

Lubricant TermsThe terms that describe and differentiate various types of

lubricants can be confusing, as they aren't necessarily

commonly used. Here is a small list of some lubricant-

related terms that will help you understand the unique

features of different types of lubricants:

Abrasive refers to lubricants that are particularharsh. These typically require careful handling and

special disposal. Additives are ingredients that generally make up less

than 10 percent of the lubricant's composition.

Different combinations of additives give various

lubricants their defining properties.

Synthetic refers to lubricants primarily composed ofman-made ingredients, as opposed to natural,

organic ingredients, such as mineral or vegetable

oils.

Viscousdescribes lubricants that are particularlythick and harder to poor. Less viscous lubricants

tend to be more watery in nature.

Medical Applications for Lubricants

Along with its industrial and automotive uses, lubricants also have some important medical

purposes. Doctors and/or nurses may use gel, liquid and jelly lubricants to:

aid the function (and reduce the resistance) of prosthetic organs or body parts cleanse bacteria and other harmful substances from the body facilitate ultrasounds and other imaging tests make certain exams, such as a pelvic exam, more comfortable


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prevent tissue damage when medical instruments need to be inserted in patients protect their expensive equipment from daily wear and tear.

As researchers continue studying new compounds and applications, more medical

applications for lubricants are sure to arise.

Performance:The lubricant marketer claims benefits for the customer based on the superior performance of

the lubricant. Such marketing is supported by glamorous advertising, sponsorships of

typically sporting events and endorsements. Unfortunately broad performance claims are

common in the consumer marketplace, which are difficult or impossible for a typical

consumer to verify. In the B2B market place the marketer is normally expected to show data

that supports the claims, hence reducing the use of broad claims. Increasing performance,

reducing wear and fuel consumption is also aim of the later API, ACEA and car manufacturer

oil specifications, so lubricant marketers can back their claims by doing extensive (and

expensive) testing.

Longevity:The marketer claims that their lubricant maintains its performance over a longer period of

time. For example in the consumer market, a typical motor oil change interval is around the30006000 miles (750015000 km). The lubricant marketer may offer a lubricant that lasts

for 12000 (30000 km) miles or more to convince a user to pay a premium. Typically, the

consumer would need to check or balance the longer life and any warranties offered by the

lubricant manufacturer with the possible loss of equipment manufacturer warranties by not

following its schedule. Many car and engine manufacturers support extended drain intervals,but request extended drain interval certified oil used in that case; and sometimes a special oil

filter. Example: In older Mercedes-Benz engines and in truck engines one can use engine oil

MB 228.1 for basic drain interval. Engine oils conforming with higher specification MB

228.3 may be used twice as long, oil of MB 228.5 specification 3x longer. Note that the oil

drain interval is valid for new engine with fuel conforming car manufacturer specification.

When using lower grade fuel, or worn engine the oil change interval has to shorten

accordingly. In general oils approved for extended use are of higher specification and reduce

wear. In the industrial market place the longevity is generally measured in time units and the

lubricant marketer can suffer large financial penalties if their claims are not substantiated.

Efficiency:The lubricant marketer claims improved equipment efficiency when compared to rival

products or technologies, the claim is usually valid when comparing lubricant of higher

specification with previous grade. Typically the efficiency is proved by showing a reduction

in energy costs to operate the system. Guaranteeing improved efficiency is the goal of some

oil test specifications such asAPI CI-4 Plus for diesel engines. Some car/engine

manufacturers also specifically request certain higher efficiency level for lubricants for

extended drain intervals.

Operational tolerance:
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The lubricant is claimed to cope with specific operational environment needs. Some common

environments include dry, wet, cold, hot, fire risk, high load, high or low speed, chemical

compatibility, atmospheric compatibility, pressure or vacuum and various combinations. The

usual thermal characteristics is outlined with SAE viscosity given for 100C, like SAE 30,

SAE 40. For low temperature viscosity the SAE xxW mark is used. Both markings can be

combined together to form a SAE 0W-60 for example. Viscosity index (VI) marks viscositychange with temperature, with higher VI numbers being more temperature stable.

Economy:The marketer offers a lubricant at a lower cost than rivals either in the same grade or a similar

one that will fill the purpose for lesser price. (Stationary installations with short drain

intervals.) Alternative may be offering a more expensive lubricant and promise return in

lower wear, specific fuel consumption or longer drain intervals. (Expensive machinery, un-

affordable downtimes.)

Environment friendly:The lubricant is said to be environmentally friendly. Typically this is supported by qualifying

statements or conformance to generally accepted approvals. Several organizations, typically

government sponsored, exist globally to qualify and approve such lubricants by evaluating

their potential for environmental harm. Typically, the lubricant manufacturer is allowed to

indicate such approval by showing some special mark. Examples include the German Blue

Angel, European Daisy Eco label, Global Eco-Label GEN mark, Nordic, White

Swan, Japanese Earth friendly mark; USA Green Seal, Canadian Environmental

Choice, Chinese Huan, Singapore Green Label and the French NF Environment mark.

Composition:The marketer claims novel composition of the lubricant which improves some tangible

performance over its rivals. Typically the technology is protected via formal patents or other

intellectual property protection mechanism to prevent rivals from copying. Lot of claims in

this area are simple marketing buzzwords, since most of them are related to a manufacturer

specific process naming (which achieves similar results than other ones) but the competition

is prohibited from using a trademark.

Quality:The marketer claims broad superior quality of its lubricant with no factual evidence. The

quality is proven by references to famous brand, sporting figure, racing team, some

professional endorsement or some similar subjective claim. All motor oil labels wear mark

similar to "of outstanding quality" or "quality additives," the actual comparative evidence is

always lacking.
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TYPES OF LUBRICANTS

Gas Liquid (including emulsions and suspensions) Solid Greases Adhesive

Gaseous lubricants

Gaseous lubricants have a much lower viscosity and higher compressibility compared to

liquid lubricants, but the fluid-film principles apply analogeous to gases. Some examples for

gaseous lubricants are air (used in fluid bearings), technical gases, steam or liquid-metal

vapours.

Liquid lubricants

Liquid lubricants refer to any lube that has a liquid base. The primary ingredient, which

makes up about 60 percent to 90 percent of these types of lubricants, is always some base oil

or other liquid. The remainder of the ingredients for liquid lubricants, usually referred to as

"additives," changes from manufacturer to manufacturer. Often times, the unique

combination of additives is responsible for the nuanced, special features of different types of

liquid lubricants.

For example, while special additives can make one type of liquid lubricant water-resistant, adifferent combination of additives can make another lube especially thick, or more

"viscous."The word viscous is commonly used to describe lubricants: The less viscous a

liquid lubricant is, the more watery it is and, therefore, easier to pour.

Liquid lubricants may be characterized in many different ways. One of the most common

ways is by the type of base oil used. Following are the most common types.

Lanolin (wool grease, natural water repellant) Water Mineral oils Vegetable (natural oil) Synthetic oils Other liquids

Note: although generally lubricants are based on one type of base oil or another, it is quite

possible to use mixtures of the base oils to meet performance requirements.

Lanolin

A natural water repellent, lanolin is derived from sheep wool grease, and is an alternative to

the more common petro-chemical based lubricants. This lubricant is also a corrosioninhibitor, protecting against rust, salts, and acids.
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Water

Water can be used on its own, or as a major component in combination with one of the other

base oils. Commonly used in engineering processes, such as milling and lathe turning.

Mineral oil

This term is used to encompass lubricating base oil derived from crude oil. The American

Petroleum Institute (API) designates several types of lubricant base oil. The main constituent

of such lubricant product is called the base oil, base stock. While it is advantageous to have a

high-grade base oil in a lubricant, proper selection of the lubricant additives is equally as

important.

Vegetable (natural) oils

These are primarily triglyceride esters derived from plants and animals. For lubricant base oiluse the vegetable derived materials are preferred. Common ones include high oleic canola oil,

castor oil, palm oil, sunflower seed oil and rapeseed oil from vegetable, and Tall oil from

animal sources. Many vegetable oils are often hydrolyzed to yield the acids which are

subsequently combined selectively to form specialist synthetic esters.

Synthetic oils

Polyalpha-olefin (PAO) Synthetic esters Polyalkylene glycols (PAG) Phosphate esters Alkylated naphthalenes (AN) Silicate esters Ionic fluids

Solid lubricants

While solid lubricants are not used nearly as often as their liquid counterparts, you can find

them among some household items you use daily. In fact, the Teflon that lines your pans to

prevent food from sticking as you cook is one of the most common types of solid lubricantsthat people regularly come across.

Technically known as Polytetrafluoroethene (PTFE), Teflon is often used to coat the

surface of cookware, as well as pipework, due to the fact that it almost never reacts with

foreign substances. In practical terms, this means that food, chemicals and even waste

products won't stick to or wear down Teflon surfaces.

Mineral solid lubricants are another type of solid lube. While these lubricants can be useful in

extremely hot conditions when others fail, they do rust quickly. As a result, they aren't widely

used because they tend to be too costly. More research needs to be done before minerals can

be used as efficient solid lubricants.
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Teflon or PTFE

Teflon or PTFE is typically used as a coating layer on, for example, cooking utensils to

provide a non-stick surface. Its usable temperature range up to 350C and chemical inertness

make it a useful additive in special greases. Under extreme pressures, teflon powder or solids

is of little value as it is soft and flows away from the area of contact. Ceramic or metal or

alloy lubricants must be used then.

Non-metals

Graphite, hexagonal boron nitride, molybdenum disulfide and tungsten disulfide are

examples of materials that can be used as solid lubricants, often to very high temperature.

The use of some such materials is sometimes restricted by their poor resistance to oxidation

(e.g., molybdenum disulfide can only be used up to 350C in air, but 1100C in reducingenvironments).

Metal/alloy

Metal alloys, composites and pure metals can be used as grease additives or the sole

constituents of sliding surfaces and bearings. Cadmium and Gold are used for plating surfaces

which gives them good corrosion resistance and sliding properties, Lead, Tin, Zinc alloys and

various Bronze alloys are used as sliding bearings, or their powder can be used to lubricate

sliding surfaces alone, or as additives to greases.

Semi-solid:

Greases and petroleum end-products are usually used as semi-solid lubricants. They are

preferred over other lubricants because they have high viscosity, high heat capacity, can

withstand heavy loads and do not flow easily. Moreover they take a long time to get

replenished, so they are used for a longer time.

AUXILIARIES

A chemical or formulated chemical product which enables a processing operation in

preparation, dyeing, printing or finishing to be carried out more effectively, or which isessential if a given effect is to be achieved.
http://en.wikipedia.org/wiki/Polytetrafluoroethylenehttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Boron_nitridehttp://en.wikipedia.org/wiki/Molybdenum_disulfidehttp://en.wikipedia.org/wiki/Tungsten_disulfidehttp://en.wikipedia.org/wiki/Solid_lubricanthttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Bronzehttp://en.wikipedia.org/wiki/Bronzehttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Solid_lubricanthttp://en.wikipedia.org/wiki/Tungsten_disulfidehttp://en.wikipedia.org/wiki/Molybdenum_disulfidehttp://en.wikipedia.org/wiki/Boron_nitridehttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Polytetrafluoroethylene


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NECCESSITY OF AUXILIARIES IN TEXTILE DYEING:

1) To prepare or improve the substrate before colouration by wetting2) To modify the adsorption characteristics or colourants by acceleration orretardation, providing sites for adsorption, creating block or resisting, imp-

roving or resisting the migration of dyes.

3) To stabalize the application medium by dye solubility, forming emulsioninhibiting or promoting foam formation stabilizing a dispersion.

4) To improve the fastness of dyeing5) To enhance the properties of laundering formulations6) To protect or modify the substrate by lubricating the substrate, creating or

resisting the ability of the dye.

Documents

Material Science1