Research On Microstructure And Performance Of RF Magnetron Sputtered Ta-HfN Coatings

Although medical 316L stainless steelis known for its good mechanical properties,but its wear and corrosion resistance,as well as its biocompatibility,proved to be relatively low in the long-term clinical application.In the paper,HfN and Ta-HfN coatings are prepared on AISI316L stainless steel by RF magnetron sputtering technology in order to improve the corrosion resistance,mechanical property and blood compatibility of 316L stainless steel substrate.The effects of negative bias and Ta content on microstructure and properties of HfN coatings and Ta-HfN coatings were studied.The microstructure,composition,morphology,mechanical properties,corrosion resistance and blood compatibility of the coatings were analyzed by XRD,XPS,AFM,SEM,nano indentation experiment,scratch experiment,friction experiment,electrochemical experiment and platelet adhesion experiment.The resultsindicated that HfNthe coatings deposited under different substrate bias wereFCC structureHfN phase which form(111)texture above-150V bias.XPS analysis showedthat the chemical bonds in the HfN coatingsweremainly Hf-N.As the bias increased,the grain sizes of the HfN coatingsincreased first and thendecreased,however,surface roughness change was reverse.When the substrate bias was-150V,the hardness and adhesion of the coatingswere the highest,which made the coatings hadthe minimum coefficient of friction.When the bias was-150V,HfN coatingswith high adhesion,lower surface roughness and dense microstructure had the best corrosion resistance.Compared with the 316L stainless steel substrates,HfN coatings could significantly improve its blood compatibility.The bias had a significant effect on the blood compatibility of the coatings.The HfN coatingsdeposited at-150Vhad the best blood compatibility due to its lower?_s~d/?_s~p and lower surface roughness.The resultsof Ta-HfN coatings with different content of Ta showed that the Ta-HfN coatings were substitutional solid solution withFCCstructure.With Ta content increaseing,the grain sizes of Ta-HfN coatingsdecreased first and then increased.XPS analysis showed that chemical bonds of Ta-HfN coatings were Hf-N and Ta-N bonds.Compared with HfN coatings,the mechanical properties of Ta-HfN coatingswere obviously improved,and the Ta content had obvious effect on its mechanical properties.When Ta was 12.67At.%,Ta-HfN coatings had best comprehensive mechanical properties.Corrosion resistance of Ta-HfN coatings was better than that of 316L stainless steel substrates,however ithad no obvious improvementcompared with the Hf N coatings.As described above,HfN coatings and Ta-HfN coatingscould be used for surface modification of 316L stainless steel and they couldimprove corrosion resistance and blood compatibility of the 316L stainless steel,which could further promote the application of316Lstainless steelin the medical fields.