TiN/Ti 및 ZrN/Ti 다층막 코팅된 Ni-Ti합금 파일의 전기화학적 특성

Abstract

본 연구에서는 치과용 Ni-Ti 합금 파일의 내마모성, 내식성, 및 생체안정성을 부여할 목적으로 파일의 표면에 TiN/Ti 및 ZrN/Ti 다층막을 코팅하여 전기화학적 평가를 행한 결과 다음과 같은 결론을 얻었다.

1. Ni-Ti파일표면에 TiN/Ti 및 ZrN/Ti 다층막의 코팅은 단층으로 코팅한 경우나 코팅하지 않은 시편에 비하여 매끄러운 표면형상을 보였으며 코팅의 결과 표면에 존재한 결함이 제거되었다.

2. Ni-Ti파일표면에 TiN/Ti 및 ZrN/Ti 다층막 코팅한 경우가 단층으로 코팅한 경우나 코팅하지 않은 것(-1084 mV, 4.47 X 10-6 A/cm2)에 비하여 부식전위(-732 mV)가 높고 전류밀도(6.16 X 10-8 A/cm2)가 낮았다.

3. Ni-Ti파일표면에 TiN/Ti(5,080,585 Ω㎠) 및 ZrN/Ti(6,750,688 Ω㎠) 다층막 코팅한 경우가 단층으로 코팅한 경우나 코팅하지 않은 것(3,033,490 Ω㎠)에 비하여 분극저항이 높았다.

4. Ni-Ti파일표면에 TiN/Ti 및 ZrN/Ti 다층막 코팅한 경우가 단층으로 코팅한 경우나 코팅하지 않은 것에 비하여 pit의 발생이 없었으며 단층으로 코팅한 경우는 무수히 많은 pit가 형성되었다.

이상의 결과로 부터 Ni-Ti파일의 피로파절수명과 내마모성을 개선하기 위하여 파일에 다층막으로 코팅을 행하면 스크래치와 같은 기계적인 결함과 단층막 코팅으로 해결할 수 없는 코팅층의 결함을 감소시켜 전해액 내에서 이온용출을 억제함으로써 생체안정성을 개선할 수 있을 것으로 생각된다.|Ni-Ti file demands on instruments used to clean and shape the root canals. The clinical Ni-Ti file is required the longest fatigue fracture life and wear resistance with small metallic ion dissolution in root canal space. The purpose of this study was to investigate the electrochemical characteristics of TiN/Ti and ZrN/Ti multilayer coated Ni-Ti alloy files , ProTaperⓇ(Maillfer, Dentsply, Ballaigues, Switzerland) were used, respectively, for experiment. In order to observe the coating film and mechanical manufacturing defects of Ni-Ti file before coating and after coating, surfaces of specimens were observed by field emission scanning electron microscope(FE-SEM). TiN/Ti and ZrN/Ti multilayer coating was carried out on the Ni-Ti file surface using pure Ti and Zr target materials with nitrogen gas at 25℃. The electrochemical tests of TiN/Ti and ZrN/Ti multilayer coated Ni-Ti file surface were performed by using potentiodynamic and AC impedance test in 0.9% NaCl solution at 36.5 ± 1℃. After anodic polarization test, corrosion morphology was observed by FE-SEM and energy dispersive X-ray spectroscopy(EDS).

The results were as follows:

1. The surface of TiN/Ti and ZrN/Ti multilayer coated Ni-Ti files showed the smooth surface without mechanical defects like a scratch formed by manufacturing process compared to non-coated and monolayer coated Ni-Ti files.

2. The corrosion potentials of TiN/Ti and ZrN/Ti(-732 mV) multilayer coated Ni-Ti files were higher than those of non-coated(-1084 mV) and monolayer coated Ni-Ti files, whereas current density of TiN/Ti and ZrN/Ti(6.16 X 10-8 A/cm2) multilayer coated Ni-Ti files was lower than those of non-coated(4.47 X 10-6 A/cm2) and monolayer coated Ni-Ti files.

3. Polarization resistance(Rp) of TiN/Ti(5,080,585 Ω㎠) and ZrN/Ti(6,750,688 Ω㎠) multilayer coated Ni-Ti files were higher than those of non-coated(3,033,490 Ω㎠) and monolayer coated Ni-Ti files

4. The corrosion morphology of non-coated and monolayer coated Ni-Ti files showed the many pit on the surface compared to TiN/Ti and ZrN/Ti multilayer coated Ni-Ti files.

It is confirmed that TiN/Ti and ZrN/Ti multilayer coating on the Ni-Ti files can be improved the bio-stability, wear resistance and fatigue fracture resistance of Ni-Ti file due to delete the mechanical manufacturing defects.