| Abstract: | 近年來積層製造之技術廣泛應用於骨科植入物的製作，可以替代、支撐、固定或修復受損組織。其中鈦合金作為骨科植入物材料選擇之一，主要鈦合金具備著生物相容性及耐腐蝕性等特性符合骨科植入物需求，然而鈦合金在加工處理時，容易因為高溫與氣體產生反應，使鈦合金在傳統製造中被列為最難加工的金屬之一。積層製造製程沒有傳統製造加工的外型設計約束，當中以選擇性雷射熔融最常用於鈦合金的積層製造，主要其在加工時，產生的高溫能使鈦合金完全熔融，進而增加成品之機械性質。但該製程反覆高溫熔融使的成品不斷經歷加熱及冷卻的過程，冷卻溫度下降速率過大，使內部產生殘留應力，從而導致製造不精確或變型。一般為了降低殘留應力熱處理是最常見的方法。會用氣氛或真空熱處理爐來防止鈦合金與氧進行反應，不過熱處理爐及耗材相當昂貴，導致在積層製造之後熱處理所需成本增加。
本研究之目的為建構出積層製造之低成本熱處理用無氣氛或真空高溫爐之方式，來達到降低內應力所導致的變型翹曲。主要概念將熱理件以碳化矽顆粒包覆，並將其半密封於容器中，達到減少空氣流通性，避免在高溫狀態氧氣與鈦進行反應形成氧化鈦。本論文研究不同熱處理參數對於試片之機械性質之影響，經由實驗結果顯示，金屬積層製造之製備熱處理兩端夾持側長度20mm之翹曲從400μm降低至76μm，減少了五倍以上之翹曲量，並且其降伏應力大於氣氛熱處理之降伏應力。最後在製備型熱處理設計及流程提出改善方式，以便後續進行改進之目標。
;In recent years, the technology of laminated manufacturing has been widely applied to the production of orthopedic implants, which can replace, support, fix or repair damaged tissues. Titanium alloy is one of the materials of choice for orthopedic implants. The main characteristics of titanium alloy, such as biocompatibility and corrosion resistance, meet the needs of orthopedic implants; however, titanium alloy is susceptible to reactive reactions due to high temperatures and gases during the processing of titanium alloys, making titanium alloys one of the most difficult metals to process in conventional manufacturing. The laminated manufacturing process does not have the constraints of conventional manufacturing, and selective laser melting is most commonly used in the laminated manufacturing of titanium alloys. The main reason is that the high temperatures generated during the process can completely melt the titanium alloy, which in turn increases the mechanical properties of the finished product. However, the repeated high-temperature melting in this process makes the finished products go through the process of heating and cooling continuously, and the rate of cooling temperature dropping is too large, which generates residual stress inside and leads to inaccuracy or deformation of the manufacturing. In order to reduce the residual stress, heat treatment is the most common method. Atmospheric or vacuum heat treatment furnaces are used to prevent the titanium alloy from reacting with oxygen. However, heat treatment furnaces and consumables are quite expensive, resulting in increased costs for heat treatment after the laminate has been manufactured.
The purpose of this study is to develop a method to reduce the warpage caused by internal stress and to reduce the cost of heat treatment by using an atmosphere-free or vacuum high-temperature furnace for the heat treatment of laminated fabrication. In this study, silicon carbide is used to prevent oxygen penetration and sealed in a container to reduce the air circulation and avoid the reaction between oxygen and titanium to form titanium oxide at high temperature, and to study the effect of different heat treatment parameters on the mechanical properties of the specimens. The experimental results show that the warpage of 20mm at both ends of the clamping side of the fabricated heat treatment for metal lamination is reduced from 400μm to 76μm, which is more than five times of the warpage, and the yielding stress is larger than that of the atmosphere heat treatment. Finally, the design and process of heat treatment in the preparation type are proposed to be improved in order to achieve the goal of subsequent improvement. |
