Metal-Containing DLC: Toward a Smart Coating on Smart Materials

Abstract

NiTi shape memory alloys (NiTi-SMA or Nitinol) have successful application thanksto their excellent and unique material properties. However, considering the practical applicationto human body, elution from the toxic Ni ions into human body should be taken into account.Many researchers have dealt with the issue and already proposed various surface treatmenttechniques including the surface oxidation and ion implantation.Our focus is to enhance thefunctionality of Nitinol. We have been developing the smart sensor utilizing metal-containingDiamond-like Carbon (Me-DLC) thin coating. Emphasis can be made on the unique propertiesof Me-DLC deposited on the Nitinol. Strong adhesive strength has been obtained in Me-DLCand Nitinol system. In this paper, we propose a novel Me-DLC coating with multifunctionalityof the suppression of the toxic Ni ions. The paper includes deposition technique, performanceof the coating concerning adhesive strength and suppression of the toxic Ni ions, and finallymultilayered structure aiming at multifunctionality.