| 摘要: | 在近二十年來，金屬材料被快速地發展於醫療器具上的使用，是因為發現鈦金屬對人體 擁有良好的生物相容性，而目前最普遍的使用是在於手術外科的骨骼植入材，例如CP Ti、 Ti64 和Ti6Al7Nb。近年來研發出新型材料-鈦基金屬玻璃，它有相當優越於一般結晶材料的 生物相容特性，因為它沒有結晶構造上的缺陷，例如差排、晶界和雙晶，所以材料所呈現的是 均勻的化學組成、高強度、低楊氏係數和良好的抗腐蝕能力，雖然從生物醫療的觀點來看，鈦 基金屬玻璃是優秀於一般的結晶材料，但以上兩種材料在長時間使用的狀態下仍存在著一些 疑慮，而主要問題點在於(1)不匹配的楊氏係數(皮質骨10~30 GPa，Ti64 110~120 GPa，鈦基 金屬玻璃 80~90 GPa)，當植入材受到彈性的彎曲變形時，容易造成骨頭無法均勻將負載分散 在植入材料上造成所謂的遮蔽效應，這會引起人體組織的受損，以及增加恢復的時間，(2)經 化學腐蝕或是磨耗釋出有毒金屬離子或顆粒的可能性，在鈦基金屬材料中往往為了增加機械 性質或是玻璃形成能力，而添加對人體不友善的元素，例如Ti64 中的Al 和V，鈦基金屬玻 璃的Ni 和Cu。本研究將設計出具有高玻璃形成能力、寬廣過冷液相區間、高強度、良好的 抗腐蝕能力的無毒性元素添加鈦基金屬玻璃(Ti-Zr-(Ta, Nb)-(Sn, Co)-(Si, B, P))，並且利用過冷 液相區的超塑性質熱壓成多孔材料，來製作出與人骨相似的楊氏係數、高強度和提供骨細胞 生長空間的金屬基仿生植入材。 第一年將設計及改良具有高速冷卻銅輪的薄帶製造設備，來設計製作無毒性元素添加之 鈦基金屬玻璃，並探討其微結構、機械性質、玻璃形成能力與熱性質。第二年將聚焦於無毒性 鈦基金屬玻璃的粉體製作和熱塑成型能力(黏度，流變應力等)之研究，探討熱壓成形後顯微結 構的變化和最佳實驗參數的建立。第三年將依據前一年所獲得之過冷液相温度區間的熱成形 條件，依不同孔隙率評估成品表面形貌，機械性質和抗腐蝕能力，並選擇適當的孔隙率和孔 隙大小來調配出仿生的金屬基植入骨材，期望能將多孔鈦基金屬玻璃材料推廣至商業生醫植入材。 ;In this decade, metallic materials have been rapidly developed for the biomedical purpose after the discovery of good biocompatibility on the Ti metal. The most popular applications of the Ti alloys (e.g. pure (cp) Ti, Ti-6Al-4V and Ti-6Al-7Nb) as biomedical implant materials is in the field of trauma and orthopedic surgery. Recently, several novel Ti-based metallic glasses (Ti-MGs) with superior biomedical properties compared to its crystalline material counterpart has also been developed. These Ti-MGs have no crystal structural defects (such as dislocations, grain boundaries or twins), homogenous chemical composition, higher strength, lower Young’s modulus, and much better corrosion resistance. Although the Ti-MGs present better biomedical properties than the crystalline Ti alloys. However, based on the long-term durability and health concerns, two serious problems still exist in the above-mentioned two kinds of Ti-based materials. The problems are (1) The mismatch of the Young’s modulus (E) between the bone (E=10~30 GPa for cortical bone) and the implant (E=110~120 GPa for Ti-6Al-4V alloys, 80~90 GPa for Ti-MG). Large modulus mismatch will cause stress-shielding on the bone nearby the implant and induced tissue loss and increasing recovery time. (2) The release of toxic metallic ions and/or particles through corrosion and wear processes. Some harmful elements are frequently added in the Ti alloy systems in order to improve mechanical properties and glass-form ability (GFA) (Al, V for Ti-6Al-4V alloys, Ni, Cu for Ti-MG). Accordingly, in this study, we are going to design a series of toxic-element-free Ti-Zr-(Ta, Nb)-(Sn, Co)-(Si, B, P) metallic glasses possess high GFA, wide supercooled temperature (SCL), high strength, and superior corrosion resistance. Then the Ti-MGs will be fabricated into a bulk metallic glass foam (BMGF) by hot pressing within its SCL region, and to fit the requirement of human bone on the strength, Young’s modulus, and the pore size for bone cell growth. In the 1st year, one set of arc-melting and water-cooled melt-spinning equipment will be established and set up to design the high GFA of toxic-element-free Ti-Zr-(Ta, Nb)-(Sn, Co)-(Si, B, P) metallic glasses, and characterize their microstructure, mechanical properties, GFA, and thermal properties. In the 2nd year, the major work will focus on the process study of MG powder manufacturing and thermoplastic forming. The microstructure change of hot-pressed Ti-based BMGF will be investigated and working window of thermoplastic forming process will be established. For the 3rd year, based on the experimental results of 2nd year study on the thermoplastic forming process. The BMGFs with different porosity ratio (30~60 vol.%) will be produced by hot-pressing method. The surface morphology, mechanical properties, corrosion resistance ability will be evaluated. A selected BMGF with suitable pore size, mechanical properties, and Young’s modulus comparable to the human bone will be fabricated for the experiment of bone cell growth by in-vitro test. Hopefully, the Ti-based BMGFs could be applied into the biomedical implant in the future. |
