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Int. J. Mech. Eng. & Rob. Res. 2014 Simran Dutt Sharma and Sreedhar Madhana, 2014

ISSN 2278 – 0149 www.ijmerr.com

Vol. 3, No. 3, July, 2014

© 2014 IJMERR. All Rights Reserved

Review Article

A REVIEW OF PROPERTIES, APPLICATIONS AND

PRESENTLY STUDY DONE ON CERAMIC BEARINGS

Simran Dutt Sharma1* and Sreedhar Madhana2

*Corresponding Author: Simran Dutt Sharma � simranduttsharma@gmail.com

Severe and precise operating conditions have led to the study and invention of antifriction,negligible lubricant and long life bearing materials. Ceramic and Hybrid Ceramics are one ofsuch bearing materials. The low tendency of adhesion between steel and ceramic componentsand even less between ceramic parts among themselves provides significant advantage in dryrun and under lubricated run. The Technology of hybrid ceramics and ceramic bearings alongwith their applications and wear rate behavior of different ceramics will be discussed in thispaper.

Keywords: Ceramic bearing, Hybrid bearing, Friction, Silicon nitride

INTRODUCTION

Bearing is a machine element used inmachines to reduce friction and wear whiletransmitting motion and power. Bearingsupports both linear and rotary motion basedon which type of bearing is being employed.Bearings can be classified on basis of

• Type of motion to be allowed, i.e. axialrotation e.g. shaft rotation, linear motione.g. drawer, spherical rotation e.g. balland socket joint, hinge motion e.g. door,elbow, knee.

• Type of loading conditions, i.e. axial,radial and radial-thrust bearings.

1 A Student in Mechanical Department at Lovely Professional University, Jalandhar, Punjab, India.2 Assistant Professor in Mechanical Department at Lovely Professional University, Jalandhar, Punjab, India.

• Type of lubrication system, i.e.boundary, mixed and hydrodynamiclubrication system.

Factors affecting life of bearing are: loadingconditions, lubricant supplied, speed, mate-rial to be used.Reducing friction in bearingsis often important for efficiency, to reducewear and to facilitate extended use at highspeeds and to avoid overheating andpremature failure of the bearing. Essentially,a bearing can reduce friction by:

• By shape, roller, spherical and flexuralbearings are mainly preferred.

• By material, exploits the nature of thebearing material used. (An example

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Int. J. Mech. Eng. & Rob. Res. 2014 Simran Dutt Sharma and Sreedhar Madhana, 2014

would be using plastics that have lowsurface friction.)

• By fluid, it avoids surface to surfacecontact and reduces wear.

• By fields, exploits electromagneticfields, such as magnetic fields, to keepsolid parts from touching.

Combinations of these can even beemployed within the same bearing. Anexample of this is where the cage is made ofplastic, and it separates the rollers/balls,which reduce friction by their shape andfinish.

The life and effectiveness of bearingextensively depends upon the bearingmaterial. Ceramics, chrome steels, stainlesssteel and plastics are most common bearingmaterials being used in industries for makingvarious components of bearings. Everymaterial impart different strength to use ofbearing under different operating conditions.

Such as chrome steel - SAE 52100 is usedfor making components like inner and outerrings, balls and rollers of bearings having(Popp M and Sternagel R, 1999) highstrength to resist cracking and a hard surfaceto resist subsurface rolling contact fatigue.

Stainless steels materials (Popp M andSternagel R, 1999) are used to make bearingcomponents because it is more resistant tosurface corrosion due to the higher contentof chromium (~18%) with the addition ofnickel. The chromium reacts with oxygen toform a layer of chromium oxide on thesurface, creating a passive film.

Carbon alloy steel (Popp M and SternagelR, 1999) materials are used to producevarious components of bearings and havetwo basic types, Medium versus Low CarbonAlloy Steel.

Plastics and non-metallic materials aresometimes used for bearing cages. The mostcommon is molded nylon plastic but moldedacetal (POM) is also used.

Bearings made of ceramic materials fallinto a profitable segment in the bearingindustry. The most common arrangement isa hybrid bearing, usually with stainless steelrings and ceramic balls.

A NEW DIMENSION IN

BEARING TECHNOLOGY

Far more increased wear resistance in dryrun have the all ceramic bearings, which aremanufactured completely from ceramic. Fora long time it was extremely difficult toproduce these bearings as the techniques formachining of the ceramics were not available.The high hardness allows only grinding withdiamond tools. Initially ceramic bearings weremanufactured as ball bearings, angularcontact and deep groove type, with ballsmade from ceramic. The manufacturingprocess of silicon nitride balls is easier toconduct as that of rollers or rings and thusthe hybridbearing was the first step.Additionally, the fact that the ball productionis characterized by a mass productiontechnology encouraged the earlier intro-duction of hybrid bearings. Things becamecompletely different with cylindrical rollers andcomplete bearing rings, which pose particularrequirements:

• Only grinding with diamond tools isapplicable for machining of SiliconNitride ceramic.

• Bearing components have to bemanufactured with advanced qualityrequirements (dimensional andform) as

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a consequence to the high Youngsmodulus of Silicon Nitride.

• 100% quality assurance from powderto the readymade component becauseof costly blank material and productionprocess.

• New clamping and grinding tools

• High flexibility of production linesbecause of small lot sizes.

• High reproducibility because of limitedopportunities for dimensional sorting.

Ceramic bearings are mostly made usingceramic silicon nitride (Si3N4), Alumina Oxide(Al2O3), Zirconia Oxide (ZrO2), Silicon Carbide(SiC) which are both lighter and harder thantraditional steel bearings. (Mazen Al-Hajjaret al., 2013).

ADVANTAGES OF CERAMIC

BEARINGS OVER STEEL

BEARINGS

Ceramic bearings have the normal steel ballsreplaced by white ceramic balls. The ceramicballs are made of solid silicon nitride. Ceramicsilicon nitride balls are called ceramic buthave nothing in common with household dishceramics.

The following is a list of benefits of theceramic silicon nitride ball bearing:

• Lighter: The ceramic ball is lighter thanthe steel ball. By light in weight it exertsless force on outer ring which results inless friction and less wear.

• Harder: The ceramic ball is harder thanthe steel ball. Which results in appx. 10times more life than steel balls.

• Smoother: The ceramic ball hassmoother surface properties than thesteel balls. This means less frictionbetween the ball and bearing racesgiving you a faster spinning bearing.

• Thermal: The ceramic ball has betterthermal properties than the steel ball.The ceramic ball will not heat up like asteel ball.

• Lubrication: The ceramic balls are lessreactive and require no lubrication.

APPLICATIONS OF THE ALL

CERAMIC BEARINGS

• Coating facilities for semiconductorindustry

• Hot dip galvanizing lines for sheet metal

• In-process measurement in foodpacking machinery

• Steam fans for pharmaceuticalproduction

• Furnaces for plastic foil treatment

• Motor engines running under-lubricated

• Vacuum pumps and turbo fans runningdry

Figure 1: Silicon Nitride Bearing

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Int. J. Mech. Eng. & Rob. Res. 2014 Simran Dutt Sharma and Sreedhar Madhana, 2014

• Compressors running with waterinjection

• Fans for process gas in Laser plants

LITERATURE REVIEW

Popp M et al. (2010), studied properties ofdifferent ceramic materials used formanufacturing of bearings and applicationsof hybrid ceramic bearings in space usage.CEROBEAR the world largest ceramic ballbearing manufacturers are working oninventing new ceramics having more preciseproperties. In the past various ceramicmaterials have been developed that aresuitable for rolling bearings. HIPed and gaspressure sintered Silicon Nitride with Al2O3,Y2O3 and MgO additions today are standardmaterials available with high mechanicalstrength and good corrosion behaviour. Withincreased understanding of wear and fatiguebehaviour of ceramic rolling bearings thereis growing demand for improved materials forspecific tribological strains.

Hybrid bearings eliminate almost alllimitations (like usage in vacuum conditions,low frictionmomentum, dry run or underlubrications, accuracy, stiffness, variation ofload conditions) of conventional bearingsbeing used in space. New ceramic bearingsare being invented to further minimize the

friction in non-lubricated rolling contactsallowing to improve load capacity and lifetimeof the bearings.

Ervin V Zretsky et al. (2013), studied aboutproperties of ceramic bearings by conductingendurance test and other experiments. Thispaper gives an idea about where ceramicbearings are most applicable for gas turbines.In view of experiments conducted, it wasconcluded that Silicon nitride produceslongest life as compared to steel rollingbearings. Ceramic bearing withstands hightemperatures of range 644K. They have goodfatigue properties.

Mazen Al-Hajjar et al. (2013), have studiedlatest developments in ceramic materials,which have involved mixing alumina andzirconia to produce two new materialcomposites (ATZ and ZTA), have been shownto be more wear resistant under clinicallyrelevant adverse simulator conditions thanpure alumina. Finally, the wear performanceof alumina-on-alumina, ATZ-on-ATZ and ZTA-on-ZTA bearings have been shown to besuperior to other hip replacement bearingmaterials. And these materials can beeffectively used for hip replacement bearings.

CONCLUSION

From above study done it has been clear thatdue to low friction and usage in dry run andunder lubricated run and comparatively longlife ceramic bearings are one of niche factorfor bearing industries today. Ceramicbearings overcome certain limitations ofconventional steel bearings like corrosionresistance, withstanding high temperatures,

Table 1: Material of BearingComponents in Advanced Hybrid

Ceramic Bearings are Listed Below

Components

Balls/ roller

Rings

Cage

Materials

Silicon Nitride (Si3N4)

X102 CrMo 17, X30 CrMo V 15 2, X40CrMoVN 16.2, HSS 6-5-2, Alloy 718

PEEK, PTFE, PI, CrNi Steel, Monel

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Int. J. Mech. Eng. & Rob. Res. 2014 Simran Dutt Sharma and Sreedhar Madhana, 2014

wear resistance, load bearing capabilities,etc. Till now most of the work has been doneon rolling ceramic and hybrid bearings butdue to its low friction and more surface finishceramics can be used for manufacturing ofsliding contact bearings also.

REFERENCES

1. Ervin V Zretsky (2013), “Ceramic Bearingfor Use in Gas Turbine Engines”, Journalof Materials Engineering andPerformance, 2830, Vol. 22, No. 10.

2. h t tp : / /www.bear ingk ine t ics .com/index.php

3. h t t p : / / w w w. d a i l y p e l o t o n . c o m /displayarticle.asp?pk=19501

4. http://www.astbearings.com/bearing-materials.html1

5. Mazen Al-Hajjar, Louise M Jennings,Sabine Begand, Thomas Oberbach,Daniel Delfosse and John Fisher (2013),“Wear of Novel Ceramic-on-ceramicBearings Under Adverse and ClinicallyRelevant Hip Simulator Conditions”,Society for Biomaterials, 101B: pp. 1456-1462.

6. Popp M and Sternagel R (1999), “HybridCeramic and all Ceramic Anti FrictionBearings”, Proceedings of the 8 th

European Space Mechanisms andTridology Symposiam, France.

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