医用镁合金激光微喷丸的表面完整性及生物腐蚀性能研究.doc

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摘要 镁合金拥有密度低、比强度和比刚度高、易被人体吸收、弹性模量与人骨相似等特点, 成为现今最具发展潜力的医用金属材料。但镁合金的降解速率过快、抗腐蚀性较差，使其应用受限，所以需要进行表面改性。激光微喷丸技术作为新型的表面改性技术在提高效率、改善加工可达性等方面具有其独特的优势。然而，目前对采用激光微喷丸通过调整医用镁合金表面完整性的办法来改善其生物腐蚀性能的研究仍缺乏系统性，尤其是激光微喷丸对表面完整性以及表面完整性对生物腐蚀性能的影响。本课题对AZ31B镁合金经过激光微喷丸后的表面完整性和生物腐蚀性能等作了若干基础性研究，主要工作如下：

（1）基于镁合金在生理环境中腐蚀机理的基本理论，从宏微观角度分析了激光微喷丸对AZ31B镁合金材料微观组织及表面完整性等的影响机理。同时讨论了激光微喷丸对材料在生理环境中腐蚀行为的影响机制。

（2）进行AZ31B镁合金激光微喷丸实验，测试试样在不同参数下的表面完整性，利用形貌识别技术比较多组参数，最终确定最优工艺参数，为后续实验提供良好试样保障。

（3）使用CS2350双单元电化学工作站对激光微喷丸试样和未喷丸试样进行电化学腐蚀实验，通过比较自腐蚀电流和自腐蚀电位的变化，研究不同激光能量、微凹坑间距下激光微喷丸AZ31B镁合金试样在Hank’s模拟体液中的腐蚀性能，并对比分析不同激光微喷丸参数下试样腐蚀性能差异。

关键词：激光微喷丸；AZ31B镁合金；表面完整性；生物腐蚀性能

 

Abstract Magnesium alloys has become today's most potential medical metallic materials due to its low density, high specific strength and specific stiffness , modulus of elasticity close to the human bone and can be absorbed by the body and so on. But owing to the rapid degradation rate and poor corrosion resistance , magnesium alloys can not be widely used, so it need surface modification. Laser micro-peening technology as a new surface modification technology has its unique advantages to improve the processing of accessibility, improve processing efficiency and so on. However, researchs on improving biological corrosion of medical magnesium alloy by laser micro-peening by adjusting its surface integrity are still lack of systematic, especially the effects on surface integrity and bio-corrision performance by laser micro-peening and surface integrity , respectively .In this paper, several basic research on surface integrity and biological corrosion of AZ31B magnesium alloy treated by laser micro-peening. The main works in this thesis are as follows:

(1) Based on the basic theroy of corrosion mechanism of magnesium alloy in physiological environment，the impact of microstructure and surface integrity of AZ31B magnesium alloy induced by laser micro-peening from the point of view of macro and micro is analyzed. And the impact of corrosion mechanism of materials in physiological environment induced by laser micro-peening is also discussed.

(2) The process tests were carried out of AZ31B magnesium treated with laser micro-peening and the surface integrity of specimens under different parameters were tested. By combining multiple sets of parameters between recognition morphology, the preferred process parameters are finalized and providing a good protection for the subsequent test specimens.

(3) The electrochemical corrosion tests of laser mic-peened and unpeened specimens were processed on the CS2350 two-unit electrochemical workstation, by comparing the changes of corrosion potential and corrosion current, the corrosion performance of AZ31B magnesium alloy in Hank’s by laser micro-peening under different laser energy and spot spacing is analyzed. And the difference between the corrosion mechanism under different laser micro-peening parameters is contrasted and analyzed.

Key words Laser micro-peening    AZ31B magnesium alloy    Surface integrity 

              Biological corrosion performance

 

引     言

镁合金不仅具有金属材料所拥有的优异机械性能，而且还有高分子材料所具有的良好生物相容性和可降解性，所以作为医用植入材料的镁合金具有非常大的临床应用前景。但是，镁合金在人体生理环境中容易发生腐蚀，而且在腐蚀过程中所产生的气体会对植入体周围组织和细胞产生严重影响。目前国内外学者主要通过开发新型镁合金和表面处理解决上述问题，但是并没有取得突破性进展，并且对镁合金腐蚀性为的研究不够系统。因此，对镁合金作为生物医用材料在人体生理环境中的腐蚀过程进行深入研究，可以促进生物医用镁合金材料在临床上的广泛应用，为以后更全面深入地研究镁合金生物应用材料奠定坚实的基础。

针对上述问题，本文利用激光技术通过调整镁合金的表面完整性对其表面进行微喷丸处理，以提高生物医用镁合金的耐腐蚀性能。本课题的研究扩展了激光表面处理技术在生物医用材料中的应用，为生物医用镁合金激光表面微喷丸的参数选择提供了新的参考依据。