TiNi形狀記憶合金及AZ91鎂合金沉積HMDSZ薄膜表面改質之研究

Abstract

Ti50Ni50與Ti50Ni40Cu10形狀記憶合金在500℃氧化30~60分鐘後可得表面Ni元素濃度較低、表面較平坦以及含有Ni-free region的氧化保護層，因而能夠提升其抗腐蝕性並具有良好之生物相容性。在此氧化膜上利用脈衝式電漿輔助化學氣相沉積法(DC-Pulsed PECVD)沉積六甲基二矽胺(HMDSZ)薄膜並活化表面以產生自由基，接著以UV光誘導接枝聚合丙烯醯胺(AAm)，再以碳化二亞胺(EDAC)為促進劑，使薄膜上之胺基與肝素的羧基縮合形成共價鍵，由FTIR光譜結果證明AAm接枝與肝素固定之成功。經肝素固定後進行抗凝血試驗，由SEM可觀察到的確能夠抑制血纖維蛋白網狀構造之形成，而具有抗凝血之效果。本研究同時對AZ91鎂合金進行電漿表面改質，利用DC-Pulsed PECVD於AZ91上沉積HMDSZ-SiO2薄膜。此層薄膜可使水接觸角由85°下降至70°左右，其表面粗糙度也由原本之12nm降至6~8nm，而薄膜之硬度為163.1Hv。在氧氣流量為1sccm、腔體壓力為220mtorr及沉積時間30分鐘下可以得到最快之薄膜沉積速率，且其FTIR光譜之Si-O特徵峰強度最大，在3.5 wt%鹽水中之抗腐蝕性表現也最好，可降低其腐蝕電流密度達3個數量級。

Ti50Ni50 and Ti50Ni40Cu10 Shape Memory Alloys (SMAs) are oxidized in air at 400-600℃. Experimental results indicate that Ti50Ni50 SMA oxidized at 500℃ for 1 hour can obtain a smooth protective oxide layer with a Ni-free region and the best oxidation condition for Ti50Ni40Cu10 SMA is at 500℃ for 30 minutes. The corrosion resistance of oxidized Ti50Ni50 and Ti50Ni40Cu10 SMAs in Hanks’ solution can be improved and oxidized layers on Ti50Ni50 and Ti50Ni40Cu10 SMAs both have good biocompatibility. Thereafter, HMDSZ thin film deposited on these oxidized layers by DC-pulsed PECVD, the AAm thin film coated by grafting polymerization and heparin immobilized on it. These coatings are proved successfully by FTIR. After heparin immobilization, the surface water contact angle decreases from 66° to 37° and the formation of fibrin network can be reduced to achieve the anti-coagulation. In this study, HMDSZ-SiO2 thin films are also deposited on AZ91 Mg alloy by DC-pulsed PECVD of HMDSZ, O2 and Ar mixture. After this thin film deposited at 1sccm O2 flow rate and 220mtorr for 30 minutes, its Si-O intensity is high and the corrosion current density of AZ91 in 3.5 wt% NaCl solution can be reduced up to 3 orders.