Anti-bacterial Properties of Wear Resistant Thermal Diffusion Coatings
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ORIGINAL ARTICLE
Anti-bacterial Properties of Wear Resistant Thermal Diffusion Coatings S. C. Atul1
•
S. Ilaiyavel1 • K. T. Jaishree2
Received: 25 April 2020 / Accepted: 21 September 2020 Ó The Indian Institute of Metals - IIM 2020
Abstract Bacterial sensitivity of thermally diffused stainless steel grade 316L has been studied in this paper. Thermal diffusion heat treatment processes like salt bath nitriding and slurry paste boronizing have been explored for their anti-bacterial properties. SS316L has been chosen as the substrate material due to its acceptance as a general bio-material in the medical industry. The results from the surface hardness and cross section analysis of the treated specimens revealed their characteristic nitride and boride layers confirming the success of the nitriding and boronizing processes. Surface roughness, prior- and postheat treatment were studied through tactile profilometer. Bacterial sensitivity tests were conducted on the treated and unprocessed specimens with Bacillus subtilis bacteria in nutrient agar. Upon incubating for 24 h, the tests displayed a distinct zone of inhibition adjacent to the treated specimens. Both the nitrided and borided SS316L specimens exhibited anti-bacterial behaviour in response to B. subtilis bacteria. These anti-bacterial surfaces can potentially prevent the formation of infectious biofilm on medical implants and devices. Keywords Bacterial adhesion Stainless steel 316L Nitriding Boronizing Surface hardness Anti-bacterial
& S. C. Atul [email protected] 1
Sri Venkateswara College of Engineering, Sriperumbudur, Tamil Nadu, India
2
Tamil Nadu Government Dental College and Hospital, Chennai, Tamil Nadu, India
1 Introduction Stainless steel is one of the most commonly used materials to produce medical-grade equipment like implants, surgical tools, etc. due to its mechanical properties and corrosion resistance [1]. Medical implants like load-bearing joints and surgical tools like a scalpel or medical shears are expected to have a high degree of wear resistance [2–5]. Though stainless steel provides relatively lesser wear loss when compared to titanium, the wear resistance of stainless steel is considered to be poor and many methods to improve the wear resistance have been explored [6–12]. Further, there are a large number of cases where implant failure is caused by an adverse reaction to metallic debris produce in situ [3, 13]. Medical devices can be exposed to bacteria in many places including the operation theatre due to poor hygiene practices [14, 15]. Medical implants associated infections can impair the host immune system and cause chronic infection, tissue death and significantly reduce the implant service life [16, 17]. Often implantrelated infections are antibiotic-resistant and implants need to be extracted due to uncontrollable infection and adverse host mechanisms [18–20]. In this study, thermal diffusion heat treatments like molten salt bath nitriding and slurry paste boronizing, both conventional forms of diffusio
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