Comparison of the mechanical__ properties between tantalum

多孔材料 镍合金 铌 钛和钛合金

JournalofAlloysandCompounds439(2007)

67–73

Comparisonofthemechanicalpropertiesbetweentantalum

andnickel–titaniumfoamsimplantmaterials

forboneingrowthapplications

P.Sevilla,C.Aparicio,J.A.Planell,F.J.Gil

CREBDpto.CienciadelosMaterialeseIngenier´ aMetal´urgica,ETSEIB,UniversidadPolit´ecnicadeCatalu na,

Diagonal647,08028Barcelona,Spain

Received24November2005;receivedinrevisedform19August2006;accepted21August2006

Availableonline12October2006

Abstract

Metallicporousmaterialsaredesignedtoallowtheingrowthoflivingtissueinsidetheporesandtoimprovethemechanicalanchorageoftheimplant.Inthepresentwork,tantalumandnickel–titaniumporousmaterialshavebeencharacterized.Thetantalumfoamswereproducedbyvapourchemicaldeposition(CVD/CVI)andtheNiTifoamsbyself-propagatinghightemperaturesynthesis(SHS).Theformerexhibitedanopenporosityrangingbetween65and73%andforthelatteritrangedbetween63and68%.Theporesizeswerebetween370and440 mfortantalumandbetween350and370 mfornickel–titanium.TheYoung’smodulusincompressionofthefoamsstudied,especiallyfortantalum,wereverysimilartothoseofcancellousbone.Thissimilitudemayberelevantinordertominimizethestressshieldingeffectintheloadtransferfromtheimplanttobone.ThestrengthvaluesforNiTifoamarehigherthanfortantalum,especiallyofthestraintofracturewhichisabout23%forNiTiandonly8%fortantalum.Thefatigueendurancelimitsetat108cyclesisabout7.5MPaforNiTiand13.2MPafortantalum.Thefailuremechanismshavebeenstudiedbyscanningelectronmicroscopy.©2006ElsevierB.V.Allrightsreserved.

Keywords:Metalsandalloys;Mechanicalproperties;Shapememory

1.Introduction

Sincethemid-1980savarietyofporoussurfacesandmate-rialshavebeeninvestigatedandusedinordertoachieveboneingrowthandimprovethe xationoftotalhipandkneeprosthe-ses.Bioresorbablepolymers,ceramicsandcementshavebeenusedforthispurpose.Clinicalresultsaswellashistologicalevi-dencefromretrievedimplantshaveclearlyshownthatporoussurfacesenhancetissueingrowthorongrowthwhichisbasicforagoodbiological xationthatprovidesstabilitytotheimplant[1–5].

Tantalumandnickel–titaniumaregoodcandidatesforhighload-bearingapplicationsinskeletalimplantssincetheyshowbettercorrosionresistanceandmechanicalpropertiesandsimi-larbiocompatibilityinrelationwithallothermetalsandalloyscurrentlyusedforthesamepurposes.Thestrengthofcancellous

bonegraft,somebioresorbablepolymersandceramiccementsissuf cientformostnon-load-bearingapplicationsintheshortterm,buttheirmechanicalpropertiesandtheirpredictabilityinvivodecreasewithtime[6–9].Tantalumandnickel–titaniumfoamscanbeananswerfor llingbonydefectswithagoodmechanicalresponse.Theycanbeusedasbulkstructuralmate-rialsinimplants,forboneaugmentationandassubstitutesofbonegraft[10–13].

Inthepresentpaper,poroustantalumandnickel–titaniummeanttobeusedasascaffoldforboneingrowthhavebeenproducedandtheirmechanicalpropertieshavebeenstudied.Foamsofbothmaterialsandwithsimilarporosity(inpercentageandinsize)havebeencharacterizedincompression,three-pointbendingandcompressionfatigue.

2.Materialsandmethods2.1.Samplepreparation

Correspondingauthor.Tel.:+34934016708;fax:+34934016706.E-mailaddress:francesc.xavier.gil@upc.edu(F.J.Gil).

TheporoustantalummaterialswereprovidedbyZimmer®andtheNiTiporousmaterialswereprovidedbyActipore®.

0925-8388/$–seefrontmatter©2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.jallcom.2006.08.069

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