High TechnologyMaterials

introduction

Carbon

Graphite

Filled ptfe Silicon Carbide

Morgan Advanced Materials, a member company ofthe Morgan Crucible Group, is best known as aworld leader in the manufacture of what have becomeknown as ‘mechanical carbon’ components for theengineering industries -- a business in which it hasbeen engaged for the past 80 years. Morgan AdvancedMaterials manufacturing programme includes suchcomplementary high technology engineering materialsas silicon carbide, filled ptfe, and graphites.

The high technology materials of the Morgan AdvancedMaterials range are categorised by the followingprefixes:

Whilst the emphasis of this brochure centres onmechanical carbon, it contains information on thecomplete range of Morgan Advanced Materials,high technology engineering materials.

CY. . . . . . . . . . . . . . . . . . . . amorphous carbon-graphiteEY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .electrographitesMY . . . . . . . . . . . . . . . . . . . . . . . . . . . . metallised carbonHY . . . . . . filled p.t.f.e. and resin bonded compositesP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . silicon carbides

carbon

sealing rings

bearings

Morgan Advanced Materials is the first choice of manymanufacturers for applicationsranging from the mechanicalseal in a washing machine or carcoolant pump to that in a pumpoperating in the hostile environ-ment of a North Sea oil rig, in thestern shaft or in the main shaftseal of an aircraft gas turbine.

Morgan Advanced Materialsseal rings are machined to closetolerances from blank materialor pressed-to-shape when the

The ‘rubbing pair’ is the heart ofany mechanical seal and in themajority of designs one memberof this pair will be carbon, whereits unique properties are fullyexploited.

demand is for large quantities. All are impregnated with either resin or metal to ensureimpermeability and are lapped, when necessary, to within three helium light bands offlatness.

Morgan Advanced Materials seal rings are compatible with a wide range of metallicand ceramic counterfaces including silicon carbide.

Morgan Advanced Materials haveprogressively developed carbonbearings over the past 50 years and currently these are used in awide variety of applications wherethe operating conditions precludethe use of more conventional

Some typical applications are:

Morgan Advanced Materials bearings are usually press, shrinkfitted or bonded directly into theirhousings. They are additionallyavailable as sub-assemblies fittedinto metal shrouds or as conveyorhanger bearings in self-aligningassemblies.

materials.

gland rings

rotary pump vanes

Carbon gland rings are widely used asshaft seals in fans, and water and steamturbines. They are fabricated in segmentswhich form a complete ring whene n c i r c l e d b y a g a r t e r s p r i n g .Extremely fine tolerances are observed intheir manufacture and a feature ofs e g m e n t s m a n u f a c t u r e d b y Morgan Advanced Materials is theirinterchangeability with rings of like design.

The segments of a traditional fan or steamturbine gland are butt-jointed and, ifconditions warrant, several rings are usedin tandem. This design provides anefficient seal under stable runningconditions.

Carbon is ideally suited for vanes used inrotary pumps and compressors forhandling non-lubricating liquids and gasesand where an oil-free delivery is essential.In these applications the self-lubricatingproperties of Morgan Advanced Materialsare critical and, as no odour or taste isimparted to the fluids with which it is incontact, is ideal for food processing plants.

M o r g a n A d v a n c e d M a t e r i a l s i sdimensionally stable both through a widetemperature range and in a variety of fluids.Very fine vane-to-rotor slot clearances may,therefore, be set and maintained, thusensuring maximum efficiency.

Labyrinth designs incorporating graphite improve sealing efficiency in both steam and gasturbines. Rubbing contact between the shaft fins and graphite rings cause no damage. Verysmall radical clearances may, therefore, be tolerated resulting in a significantly reducedleakage rate. A special grade of graphite has been developed which is able to withstand boththe high temperatures and pressures which are obtained in this application and is sufficiently softt o p e r m i t t h e r o t a t i n g s h a f t f i n s t o c u t i n t o t h e s t a t i o n a r y g l a n d r i n g .Carbon glands manufactured by Morgan Advanced Materials are also supplied for waterturbines in hydro-electrical installations. The wedge-type ring is a typical Morgan designwhich, because of its improved efficiency, has been adopted as standard by manymanufacturers in preference to the tenon-jointed ring. The ends of the segments of a wedgering are bevelled and the wedge pieces which are interposed between the segments, moveoutwards to accommodate wear.

Morgan Advanced Materials vanes areused in many applications including:

A variety of counterface materials,pressures, fluids, speeds andtemperatures are accommodatedby the versatility of the Morganrange of Carbon Seals. Theapplications range from dish-washer seals to stern shaft seals forn u c l e a r s u b m a r i n e s .

Pumping equipment fitted withMorgan Advanced Materials SealFaces is capable of handling a widevariety of materials including:

Everybody involved with seals, fromdesigners to users, can beneifit fromthe excellent friction properties andhigh chemical resistance affordedby Morgan materials.

PETROCHEMICALS

ACIDS

ALKALIES

SOLVENTS

FOODSTUFFS

WATER

REFRIGERANTS

For generations designers and engineers have usedMorgan expertise and materials to solve their tribologicalproblems. Many of the materials have been tested andapproved by major companies in the Aerospace, Nuclear,Sealing and Pumping Industries.

This experience, backed by on-going research anddevelopment programmes together with first class technicalfacilities, make Morgan Advanced Materials the ProblemSolvers for Industry.

The company is ISO9001 2000 Registered.

CARBONSEALINGRINGS

CARBONBEARINGS

1 INTRODUCTION

2 MATERIALSCarbon grades

Dry-running

PV CURVES - for continuous dry operation and steady loads.

Shaft materials:

3 OPERATING LIMITS

Morgan Advanced Materials’ bearings are capable ofsustaining Pv’s (kg/cm² X m/s) of 1.5 at temperaturesof 500°C in an oxidising atmosphere and well above350 PV in non-lubricating liquids.

(NB: Morgan Grade Data Sheets giving completephysical properties are available on these and othermaterials).

The shaft to run against a Morgan Advanced Materialsbearing should be hard and corrosion-resistant such asaustenitic iron, hardened stainless steel, thick chromeplate or stellite. Non-ferrous metals and mid steel should

A shaft surface finish of between 0.25-0.50 microns Rais recommended although for lighter loaded applications,2 microns Ra may be accepted.

Carbon and Graphite, manufactured by Morgan Advanced Materials is self lubricating, chemically inert, dimensionallystable, non hygroscopic and is highly wear resistant, which makes it ideal for use in hostile enviroments whereconventional bearings cannot be used.Typical of these are where:

1 oil contamination cannot be tolerated2 temperatures exceed the limits of normal lubricants3 operation is in a non-lubricating fluid

The selection of the appropriate Morgan grade of carbon is dependent upon the bearing operating conditions and isusually from one of the following four categories:

1 Cy2 Cy10

2 CY2C CY10C

3 MY3A MY10A

4 EY9106

The PV curves shown below provide a guide for the continuous operation of Morgan Advanced Materials bearings.

For short periods or interrupted operations, these recom-mendations may be exceeded by a generous margin.

amorphous carbon/graphitemaximum temperature 300°C

amorphous carbon/graphite,resin impregnatedmaximum temperature 270°C

amorphous carbon/graphite,copper impregnatedmaximum temperature 300°C

electrographite maximum temperature500°C oxidising atmosphere3000°C non-oxidising atmosphere

be avoided.

4 DESIGN

Morgan Advanced Materials bearings running in liquidsof high lubricity are capable of achieving performancesapproximating to those of conventional metal bearings.In more mobile liquids such as water, petrol and kerosenethe special characteristics of Morgan Advanced Materials,allied to careful design, permit operations at Pv’s of350 kg/cm² m/s and above.

1 Flanged bearings are not recommended, axial loadsshould be carried on the end of a plain bearing or as e p a r a t e t h r u s t w a s h e r p r o v i d e d .2 No oil, grease or abrasive dust should contaminatet h e r u b b i n g s u r f a c e s o f a d r y b e a r i n g .3 An adequate flow of liquid must be maintained at therubbing surfaces of a lubricated bearing and any groovesprovided to facilitate this must not interrupt the develop-ment of a hydrodynamic liquid film.

Morgan Advanced Materials bearings are available witha maximum length of 100mm and 250mm outside diameter.The curve indicates recommended wall thickness.

Well proven practices should be followed when designinga Morgan Advanced Materials bearing. It should be assimple as possible and unnecessarily close tolerancesavoided. The bearing must be fully supported in its housingand must not be retained by grub screws, pins or similardevices. In addition:

Morgan Advanced Materials bearings should always befully supported. It is desirable, therefore, that they be eitherp ress - o r sh r ink - f i t ted in to meta l hous ings .Press-fitting may only be employed for small bearingswhere the interference will not exceed 0.15mm.The coefficient of thermal expansion of carbon isabout a quarter that of steel. In consequence shrink-fitting is essential for high temperature operations which,by pre-stressing the carbon, provides the added benefitof ensuring approximately constant running clearance.In those applications where shrink-fitting into a housingis impracticable, Morgan Advanced Materials bearingsshould be shrunk into a separate sleeve which in turn maybe located in the main housing by conventional means.

The recommended running clearances for MorganAdvanced Materials bearings are indicated in the curve below.

The coefficient of friction is not a physical property of amaterial and depends on the nature and operatingconditions of a rubbing pair. It will vary with theenvironment, load, speed, surface f inish etc.In dry operations a Morgan Advanced Materials bearingrunning against a hard well finished shaft may be expectedto show a coefficient of friction varying between 0.10 underl i g h t a n d 0 . 2 5 u n d e r h e a v y l o a d s .The characteristics of the liquid will determine thecoefficient of friction in a fully lubricated application whilstunder boundary layer conditions it will probably be withinthe range of 0.01 to 0.10.

Wet running

General

Dimensions

WALL THICKNESS CHART

Friction

Fitting

Running clearances

NORMAL RUNNING CLEARANCE AFTER ASSEMBLY

CARBONGLANDRINGS

1 INTRODUCTION

2 APPLICATIONS

3 CARBON GRADES

SPECIALCARBONVANES

1 INTRODUCTION

3 CHEMICALLY INERT AND NON-TOXIC

5 HIGH MECHANICAL STRENGTH

7 ROTOR 8 APPLICATIONS

6 CYLINDER

4 UNAFFECTED BY MOST ACIDS, ALKALIES, PETROLS OR AQUEOUS SOLUTION

2 SELF-LUBRICATINGMorgan Advanced Materials vanes are made in a range ofcarbon materials (carbon-graphite, metal impregnatedcarbon-graphite and resin bonded graphite) to meetmany different application requirements. All MorganAdvanced Materials grades retain the basic properties whichmake carbon unique as an engineering material, and part-icularly suited for vanes which may operate in conditionsbeyond the limits of other materials.

One of the most important requirements for vane materialsis high mechanical strength. Varbon vanes meet thisrequirement. Their strength is indicated by the pressuresregualrly handled which rane from 3.2 kgf/cm² (45lbf/in² downto high vacuum conditions, with peripheral speeds up to19.5m/sec (3838.5 ft/min).

FOUR CARBONSLIDING VANES

TYPICAL ROTARY PUMP

CARBON END PLATE

9 PHYSICAL PROPERTIESThe figures quoted are for the grades most commonlyused in the manufacture of vanes. These are typical valuesand allowance must be made for the variability attainablebetween individual batches and measurements.

The choice of the correct Morgan Advanced Materials gradedepends on the operating conditions involved: whether liquidor gas is handled, the peripheral speed, the differential pressure, the type of rotor employed and the disposition ofthe slots (whether radial or inclined), maximum permissiblevane thickness and general design of the vanes. Our highlyskilled engineers are available to give advice on the correctchoice of material.

GRADE DATA

NOTES

Additional Products Manufactured byMorgan Advanced Materials

• Graphite bursting discs.

Molten metal pumps•

Continuous casting dies•

Moulds and crucibles•

Degassing tubes•

Distribution rings•

Graphite anodes•

Sintering products•

Carbon and Graphite heating elements•

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