Design and manufacturing of graded high-purity magnesium-calcium-zinc-material by fractional crystallization for the application as biodegradable implant material

本研究项目的目标是开发一种替代真空蒸馏的创新制造工艺，以生产用于实现可生物降解植入材料的高纯镁。由于这种方法是基于分步结晶的，这种生产高纯镁及镁合金的方法将减少设备投资，同时提高生产速度和资源效率。利用“条纹”现象，合金元素(如钙和锌)将随着横截面上浓度的增加而集成到基材中，但在一个加工步骤内，并且不需要目前所需的重熔步骤。随着分级镁材料的生产，目前无法实现的在文献中定义为最佳地在增加降解率之前缓慢启动的降解性设计可以实现。关于降解过程的研究将确认除定向降解设计外，分离结晶在制造方面的适用性，同时表征发生在分级材料中的腐蚀机制。为了实现这一点，需要高纯度的镁，因为众所周知，杂质会与微观结构和腐蚀过程产生协同效应。通过这个项目，可以为可植入镁的制造和开发做出必要的、根本性的贡献。

The objective of this research project is to develop an innovativealternative manufacturing process to vacuum distillation in order tomanufacture high-purity magnesium for implementation asbiodegradable implant material. As this proposed method is based on fractional crystallization, this production method of high-purity magnesium and magnesium alloys will reduce equipment Investments while simultaneously increasing production speed and resource efficiency. Utilizing the “striation” phenomena, alloying elements (e.g. calcium and zinc) will be integrated into the substrate material with increasing concentrations over the cross-section, but within one processing step and without the currently required re-melting step. With the production of graded magnesium materials, the currently unattainable degradation design defined in the literature as optimally initiating slowly before increasing degradation rate, can be realized. Investigations regarding the degradation processes will confirm the suitability of fractional crystallization with regards to the manufacturing aspects in addition to the targeted degradation design while simultaneously characterizing the corrosion mechanisms which occur in graded materials. In order to accomplish this, high-purity magnesium is required as impurities are known to cause synergistic effects with both the microstructure and corrosion processes. Through this project, an essential, fundamentally-based contribution to the manufacturing and development of implantable magnesium can be achieved.