氧化参数对工业纯钛及Ti68Zr32氧化膜结构及阻氢性能的影响

IMR OpenIR

	氧化参数对工业纯钛及Ti68Zr32氧化膜结构及阻氢性能的影响
	刘玉
学位类型	硕士
导师	陈德敏 ; 杨柯
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	工业纯钛 Ti68zr32 氧化层阻氢性能 Cp Titanium Ti68zr32 Oxide Layer Hydrogen Insulation Performance
摘要	" 工业纯钛因具有较高的比强度、良好的耐蚀性能以及较好的生物相容性而被广泛应用于航空航天、化工、生物医学等领域。Ti68Zr32作为零基合金被广泛应用于中子散射用样品室材料。由于钛和Ti68Zr32均为吸氢材料，在含氢环境下极易发生氢脆。本文通过控制氧化参数，研究其对工业纯钛及Ti68Zr32氧化层阻氢性能的影响，以期获得具有较高阻氢性能的致密氧化层。对工业纯钛在500~700℃纯氧中氧化后形成的氧化层进行了XRD物相分析，结果表明，其氧化层主要由TiO2组成。TiO2衍射峰强度随氧化温度的升高逐渐增强。通过SEM对工业纯钛氧化层表面及截面厚度进行了分析。结果表明，工业纯钛表层氧化物的厚度及氧化物晶粒随氧化温度的升高而逐渐增加。低于500℃氧化时，氧化物晶粒较为细小，氧化层厚度较薄；当氧化温度高于600℃时，氧化物晶粒较为粗大，氧化层较厚。通过对氧化层阻氢性能分析表明，氧化层阻氢性能由氧化层厚度及致密度共同控制。低于500℃氧化时，氧化层阻氢性能随氧化温度的升高而升高；高于500℃氧化时，因氧化层致密度降低，其阻氢性能随氧化温度的升高而降低。在500℃，4~16h的时间区间内，氧化时间对氧化层表面形貌及其阻氢性能影响较小。对Ti68Zr32在纯氧中氧化后形成的的氧化层的XRD物相分析表明，Ti68Zr32在400~450℃氧化后，其氧化层主要由一种未知氧化物相组成，根据已有信息，推测该物质可能为Ti1.99Zr0.94O5。当氧化温度升高至500℃以上时，其氧化层开始出现Zr0.33Ti0.67O2。通过SEM对Ti68Zr32氧化层表面形貌及截面厚度进行了分析，结果表明，Ti68Zr32在400~550℃氧化动力学符合抛物线规律。当氧化温度高于500℃时，其氧化层表面开始出现裂纹，裂纹数量随氧化温度的升高及氧化时间的延长而逐渐增加。氧分压对氧化层表面形貌及厚度的影响较小。通过对Ti68Zr32氧化层阻氢性能分析表明，低于500℃氧化时，Ti68Zr32氧化层阻氢性能随氧化温度的升高而逐渐增强。当氧化温度高于500℃时，因氧化层致密度降低，氧化层阻氢性能随氧化温度的升高逐渐减弱。氧化时间及氧分压对Ti68Zr32氧化层阻氢性能影响较小。通过降低Ti68Zr32氧化后的冷却速率可以防止氧化层中裂纹的产生，从而提高了氧化层的阻氢性能。
其他摘要	"Because of its high strength-to-weight ratio, excellent corrosion insulation performance and good biocompatibility, commercially pure titanium (CP titanium) is widely used in astronautics, chemical industry, biomedical field and so on. As a null-matrix Ti-Zr alloy, Ti68Zr32 is used to fabricate pressure cells for neutron scattering measurement. As Ti and Ti68Zr32 are well known to be subjected to hydrogen embrittlement when exposed in hydrogen environment, this dissertation was devoted to investigate the effect of oxidation parameters on the hydrogen insulation performance of oxide layers on surfaces of CP titanium and Ti68Zr32 in order to obtain an oxide layer with high hydrogen insulation performance. The XRD analysis of oxide layer on CP titanium surface after oxidation at 500~700℃ for 12h demonstrated that the oxide layer was mainly composed of rutile, and the diffraction peak intensity of the oxide layer was enhanced with the increase of oxidation temperature. The SEM observation on the surface and cross-section morphologies of oxide layers indicated that the grain size and the thickness of the oxide layer increased with the increase of oxidation temperature. When the oxidation temperature was below 500℃，a thin layer of oxide was formed with fine grain size. While the temperature was over 600℃, the grain size was bulky and the layer was thick. The hydrogen insulation of oxide layer was co-controlled by both the thickness and the density of the oxide layer. When the oxidation was conducted below 500℃, with the increase of the oxidation temperature, the hydrogen insulation performance of the oxide layer was enhanced. When the oxidation temperature was above 600℃, the hydrogen insulation performance was deteriorated with the increase of the oxidation temperature. By analyzing the phase of the oxide layer on Ti68Zr32 surface after oxidation at different temperature, it can be concluded that the oxide layer was mainly composed of an unknown phase, which could be predicted by the present information might be Ti1.99Zr0.94O5. When the oxidation temperature was above 500℃, another phase Zr0.33Ti0.67O2 appeared in the oxide layer. The SEM observation of the surface and cross-section morphologies of the oxide layer showed that the oxidation kinetics of Ti68Zr32 between 400~450℃ corresponded to a parabolic-type law. When the temperature was above 500℃, cracks began to appeared on the surface of the oxide layer, and the size & number of the cracks increased with both the increase of the oxidation temperature and the extension of the oxidation time. The oxygen pressure had little effect on the surface and cross-sectional morphologies of the oxide layer. It was shown that the hydrogen insulation performance of the oxide layer was enhanced with the increase of oxidation temperature when the temperature was below 500℃, and when the oxidation temperature was increased above 500℃, the hydrogen insulation performance was deteriorated with the increase of oxidation temperature because of the decrease of the oxide layer density. The oxidation time and oxygen pressure had little effect on the hydrogen insulation performance of the oxide layer. By reducing the cooling rate of Ti68Zr32 after oxidation, the cracks of the oxide layer could be reduced, and therefore, its hydrogen insulation performance was enhanced correspondently."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64523
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	刘玉. 氧化参数对工业纯钛及Ti68Zr32氧化膜结构及阻氢性能的影响[D]. 北京. 中国科学院金属研究所,2012.