Corrosion resistance, surface mechanical properties, and cytocompatibility of plasma immersion ion implantation–treated nickel‐titanium shape memory alloys

Abstract

Nickel-titanium shape memory alloys are promising materials in orthopedic applications because of their unique properties. However, for prolonged use in a human body, deterioration of the corrosion resistance of the materials becomes a critical issue because of the increasing possibility of deleterious ions released from the substrate to living tissues. We have investigated the use of nitrogen, acetylene, and oxygen plasma immersion ion implantation (PIII) to improve the corrosion resistance and mechanical properties of the materials. Our results reveal that the corrosion resistance and mechanical properties such as hardness and elastic modulus are significantly enhanced after surface treatment. The release of nickel is drastically reduced as compared with the untreated control. In addition, our in vitro tests show that the plasma-treated surfaces are well tolerated by osteoblasts. Among the three types of samples, the best biological effects are observed on the nitrogen PIII samples.

Corrosion behavior of ion implanted nickel-titanium orthodontic wire in fluoride mouth rinse solutions

“…However, the corrosion resistance of nickel-titanium orthodontic wire should be improved for safer clinical use because nickel is known to trigger more allergic reactions than other metals such as cobalt and chromium 25,26) . The PIII technique, which incorporates carbon, oxygen or nitrogen into titanium alloys, has been commonly used for the surface modification of biomaterials to improve their mechanical and corrosion properties [9][10][11] . PIII with nitrogen formed a TiN layer on the surface, which produced higher corrosion resistance and mechanical properties 10,11) .…”

“…Recently, a plasma immersion ion implantation (PIII) technique has become quite common in the surface-coating industry to improve the mechanical properties and corrosion resistance of titanium alloys [9][10][11] . About 10 years ago, ion implanted nickel-titanium wire (Neo Sentally Ionguard, GAC International, Islandia, NY, USA) and beta-titanium wire (Low Friction TMA, Ormco, Glendora, CA, USA) were introduced.…”

Application of Plasma Immersion Ion Implantation for Surface Modification of Nickel-titanium Rotary Instruments

“…In addition, minor oxygen species in the ionic or free radical state are recognized as highly reactive species, and the composition of reactive species in non-oxygen plasma may have an effect on the surface properties of a thin PIII-treated layer 25) . As for nitrogen, it is the most common atom in NiTi alloys and stainless steel to enhance their mechanical properties and corrosion resistance 26,27) . The N 1s peak at 396.9 eV for PIII-treated specimens agreed with published data for pure TiN 23) .…”

“…The N 1s peak at 396.9 eV for PIII-treated specimens agreed with published data for pure TiN 23) . With the presence of this TiN layer, the wear 11,27) and corrosion resistance 26,27) properties would likely be improved.…”

TEM study of the mechanism of Ni ion release from Nitinol wires with original oxides

“…This possibility is becoming a reality when the Nitinol surface is not prepared appropriately. A growing number of evidences of systemic allergic responses to Nitinol implants [1][2][3][4][5] in Ni sensitive patients is alarming. This implies that, at present, our knowledge on Ni sources in the alloy product as well as the mechanism of Ni release into the body is not satisfactory.…”