Microstructure And Properties Of Co-alloyed Layers On Stainless Steel Based On ASPN

Austenite stainless steel(ASS)was widely used as biomedical implant in dental correction,orthopedic surgery and vascular stent,due to the advantages of the lower cost,excellent corrosion resistance,good mechanical properties,superior formability and adequate biocompatibilities,However,its lower hardness,severe adhesion and abrasive wear behaviors and inadequate antibacterial properties,limited its applications in medical treatment and food processing industries.It has great significance to improve the hardness,wear resistance and long-lasting antibacterial properties,and maintain the good corrosion resistance of stainless steel.Based on the traditional active screen plasma nitriding(ASPN)technology,in this paper,Ag-N and Cu-N co-colloyed layers were prepared on 316 austenite stainless steel surface by a modified ASPN technique using a silver or copper plate as the lid of the ASS screen.the microstrue,hardness,corrosion resistance,wear resistance and antibacterial properties of the co-alloyed layers were investigated.The main experimental results show as follows.(1)Ag-N and Cu-N co-alloyed layers composed of an Ag or Cu doped Sphase nanostructured deposition layer and a S-phase diffusion layer were prepared on the 316 austenitic stainless steel by the modified ASPN technique.The thickness of the Ag-N and Cu-N co-alloyed layer could be up to 12.0 ?m,The thickness of the deposited layer was 0.6 ?m and 2.0 ?m,respectively.(2)The surface hardness of the Ag-N and Cu-N co-alloyed layers was improved,significantly.The surface hardness of the Ag-N and Cu-N layer was increased to 1259HV0.05 and 1300 HV0.05,respectively,which was 3-4 times higher than that of stainless steel substrate.(3)The wear mechanisms of Ag-N and Cu-N co-alloyed layer and stainless steel substrate are adhesive and abrasive wear under the dry sliding condition.In simulated body fluid(SBF),the wear mechanisms of Ag-N and Cu-N co-alloyed layer and stainless steel substrate are adhesive,abrasive and corrosion wear.By contrast,it could be found that the adhesion resistance of stainless steel can be improved effectively by Ag-N and Cu-N co-alloying.(4)The antibacterial rate of Ag-N co-alloyed layers was entirely up to 100%.After Cu-N co-alloying treatment,the antibacterial rate of the sample S1 and S2 could be up to 98.5% and 99.8%,respectively.Therefore,we can conclude that the Ag-N and Cu-N co-alloyed ASS shows excellent antibacterial property.