【作者】 胡欣；

【导师】 张连云；

【作者基本信息】 天津医科大学 ， 生物医学工程， 2011， 博士

【摘要】 目的：本文针对钛及钛合金在临床应用上存在的问题研制新型口腔修复用钛合金,通过显微组织及力学性能优化合金成分,并对优化合金的摩擦磨损特性、腐蚀特性、生物学性能和铸造性能进行研究。方法：1、合金设计、优化及制备：应用d-电子合金设计理论,将合金设计为Ti-xZr-yNb-2.5Sn (x=2.5,10,12.5,15, y=0,1,2,3,4,5,10,15,20),通过不同配比合金的组织结构和力学性能筛选合金的最佳配比。按Ti-12.5Zr-3Nb-2.5Sn (wt%)比例称取原料配制合金,测定合金差热分析曲线,设定不同时间和温度对合金进行热处理。2、机械性能评价：试样经850℃吲溶1.5h,500℃时效3h后,测试力学性能；观察分析合金显微组织,断口形貌,物相结构,确定合金金相组织中各相的组成结构及种类。3、摩擦磨损性能评价：使用MMV-1立式万能摩擦磨损实验机,进行二体摩擦磨损实验,以纯钛(TA2)为对照组。观察试样表面磨损形貌,分析磨屑成分,测试表面硬度及体积损失量。4、耐腐蚀性能评价：观察合金和对照纯钛(TA2)及Ti6A14V在人工唾液中的电化学行为,比较极化曲线及极化阻力；检测合金和Ti6A14V合金在人工唾液中1、2、3、5、7、15 d的离子释出情况。5、生物学性能评价。采用细胞毒性实验、急性全身毒性实验、口腔粘膜刺激实验、致敏性实验等体内及体外实验,评价其生物学性能。6、铸造性能评价。采用国产LZ5型离心铸钛机铸造试样,测试合金的铸流率铸造反应层和线收缩率。结果：1、Ti-xZr-yNb-2.5Sn合金,在Zr含量为12.5%,Nb含量为3%时,与其他配比合金相比较,具有较高的抗拉强度、延伸率、弹性模量,机械性能较佳。2、合金相变点在769.9～841.1℃之间。合金在200℃,350℃时组织比较混乱,晶界不明显,而在500。C,3h时合金组织清楚,为等轴晶粒,晶粒大小合适,700℃时晶粒十分粗大。3、Ti-12.5Zr-3Nb-2.5Sn合金抗拉强度为652±34.5MPa,屈服强度为590±29.8MPa,延伸率为28.3±2.4%,弹性模量为93.8±7.9Gpa。试样断口处可见明显颈缩现象,呈典型的微孔聚合型断裂方式。金相结构中晶粒组织均匀,呈现针状α分布于粗大的β晶粒中。XRD显示合金为近α相。透射电镜衍射花样标定表明试样的品体结构为密排六方的α相结构。4、Ti-Zr-Nb-Sn合金的磨损量随载荷的增加而增大。载荷不同,合金表现为不同的磨损机制。Ti-Zr-Nb-Sn合金、天然牙釉质的磨损体积量<纯钛(P<0.05)。Ti-Zr-Nb-Sn合金磨损机制主要为磨粒磨损。磨屑成分分析Ti-Zr-Nb-Sn合金磨屑元素成分为Ti、Zr、Sn元素,未见Nb元素；纯钛磨损后磨屑成分主要为Ti元素。5、Ti-6A1-4V的击穿电位(Eb,0.8 V)低于Ti-Zr-Nb-Sn合金(>2.5 V)；Ti-Zr-Nb-Sn合金的维钝电流密度(icon)低于Ti6A14V。合金极化阻力高于Ti-6A1-4V。随浸泡时间增加,两种钛合金的离子溶出量均有不同程度增加,且各个时间点Ti-6A1-4V的离子溶出量均高于Ti-Zr-Nb-Sn合金。6、合金的细胞毒性反应为0级,全身毒性实验中未见急性毒性反应,对口腔粘膜无刺激性,无皮肤致敏反应。7、400℃时铸造,合金铸流率为100%,铸造线收缩率,表面反应层满足修复支架的铸造要求。结论：1、合金的优化配比为Ti-12.5Zr-3Nb-2.5Sn。热处理方式为850℃固溶处理1.5小时,水淬,500℃时效处理3h。2、Ti-12.5Zr-3Nb-2.5Sn合金经热处理后,机械性能较纯钛明显提高。3、摩擦磨损实验表明,载荷增加可增大合金的的磨损量,导致磨损机制改变。Ti-12.5Zr-3Nb-2.5S合金较纯钛(TA2)具有更好耐磨损性能。4、耐腐蚀研究结果表明,合金的耐腐蚀性与纯钛相近,二者均优于Ti-6A1-4V。5、合金具有良好的生物相容性。6、合金铸造时表面反应层和铸造线收缩率能够满足口腔修复支架的精度要求。更多还原

【Abstract】 Objective:A new titanium alloy (Ti-12.5Zr-3Nb-2.5Sn) was developed to meet the needs of clinical requirements for medical titanium alloys and improve the properties of existing titanium alloys.The microstructures, mechanical properties of Ti-Zr-Nb-Sn alloys were investigated to optimizes the alloying constituent.The compatibility wear resistance,corrosion resistance and casting characteristic of selected Ti-12.5Zr-3Nb-2.5Sn alloy that has the excellent properties have been studied.Methods:1. Design, optimize and preparation of alloy:Ti, Zr, Nb, Sn were selected as alloy elements. According to DV-Xa cluster method,design of alloy composition as Ti-xZr-yNb-2.5Sn (x=2.5,10,12.5,15, y=0,1,2,3,4,5,10,15,20) The microstructures, mechanical properties of Ti-Zr-Nb-Sn alloys were investigated to optimize the alloying constituent. Ti, Zr, Nb, Sn were selected as alloy elements. According to proportion of Ti-12.5Zr-3Nb-2.5Sn (wt%), the differential thermal analysis curve were investing. In order to optimize mechanical property, the samples were further aged at different conditions in vacuum resistance furnace and cooled in the furnace.2. Evaluation of mechanical properties:The mechanical properties was tested by universal tensile test machine after quenching process at 850℃for 1.5 hours and aging treatment at 850℃for 3 hours; the microstructure and the fracture morphology were scanned and observed; the alloy microstructure was analyzed with X-ray diffraction phase.3. Evaluation of wear resistance properties:A loading wear test was done by MMV-1 Vertical universal friction and wear testing machine. Ti-Zr-Nb-Sn alloy were two-body wear tested in vitro while the Pure Ti was used as control.Wear resistance was analyzed through measuring the volume wear loss, Wear surface morphology was observed with electron microscope, Debris element analysis was carried out.4. Evaluation of corrosion resistance:In simulated oral environment, the electrochemical behavior of Ti-Zr-Nb-Sn alloy for dental restoration was investigated together with that of Ti-6A1-4V and TA2 as control groups. The anodic polarization curve and polarization resistance of these alloys were analyzed and the element release of Ti-12.5Zr-3Nb-2.5Sn and Ti-6A1-4V alloy after immersion in artificial saliva forld,2d,3d,5d,7d,15dwere measured.5. Evaluation of biological performance:The cell toxicity test, toxicity test, oral mucosa stimulate experiment and sensitization experiments was made to study the biological safety of the new titanium alloys and evaluate its biological properties.6. Evaluation of casting performance:Samples were casted by LZ5-centrifugal casting machine, to study casting temperature of the titanium alloy and to test the alloy casting flow rate, evaluation of alloy casting reaction layer and linear shrinkage.Results:1. The Ti-xZr-yNb-2.5Sn alloy, when the Zr content was the 12.5%, Nb content was 3%, compared with other allocated proportion alloy, had the high tensile strength and elongation ratio, the elasticity coefficient. The mechanical property was good.2. The transition point of alloy was between 769.9 and 841.1℃. The organization was quite chaotic and the crystal boundary was not obvious when the aged temperature was 200℃and 350℃. When the aged temperature was 500℃the organization was quite clear and equiaxed grain was sizeable. But grain was very coarse at 700℃.3. Organizational structure and mechanical properties. The tensile strength, yield strength, elongation and elastic modulus hardness of alloy were 652±34.5MPa,of 590±29.8MPa,93.8±7.9GPa,28.3±2.4% respectively. It clearly showed necking phenomenon. Specimen fracture electron microscopy revealed the formation of organizations in the expansion area. In the metallographic structure, it was showed that the distribution of needle-like a in the thick of (3 grains. XRD display alloy was nearly a-Ti.4. As loads increased, the wear loss of Ti-Zr-Nb-Sn alloy increased.Under 20,50 and 100 N loads, the dominant wear form was different. Volume wear loss and rigidity value of Ti-Zr-Nb-Sn alloy, natural enamel were higher than that of TA2(P< 0.05). The main wear mechanism of Ti-Zr-Nb-Sn alloy was abrasive wear, and enamel and TA2 were adhesion and abrasive wear. Debris element analysis demonstrated that the major component of Ti-Zr-Nb-Sn alloy was Ti, Zr, and Sn, but no Nb; while, the major component of pure TA2 was Ti.5. Polarization curve indicated that Ti-6Al-4V alloy had lower breakdown potential (Eb 0.8V) than Ti-12.5Zr-3Nb-2.5Sn alloy did (> 2.5V). Ti-6Al-4V alloy showed higher passivation current density than Ti-12.5Zr-3Nb-2.5Sn alloy did. The polarization resistance volume Ti-12.5Zr-3Nb-2.5Sn alloy was higher than TA2. With the increasing of dipping time in artificial saliva, the ion release of Ti-12.5Zr-3Nb-2.5Sn alloy and Ti-6Al-4V alloy increased to different degrees. Ti-6Al-4V alloy always showed more ion release than Ti-12.5Zr-3Nb-2.5Sn alloy did in the experiment.6. Biology experiment showed that the alloy cytotoxicity reaction level was 0; no acute toxic reactions, irritation to the oral mucosa, or skin sensitization.7. Casting properties. The casting flow rate was 100% when the alloy were casted at 400℃. Linear shrinkage and the surface reaction layer met the demand.Conclusions:1. The optimized composition of alloy was Ti-12.5Zr-3Nb-2.5Sn. Heat treating regime was quenching process at 850℃for 1.5 hours and aging treatment at 850℃for 3 hours.The mechanical properties were surprior to Titanium obviously, after quenching process and aging treatment.2. The increase of loads enlarges the wear loss of Ti-12.5Zr-3Nb-2.5Sn alloy and changes its dominant wear form. The Ti-12.5Zr-3Nb-2.5Sn alloy had good surface wear resistance than pure Ti and were suitable for dental restoration application.3. Ti-12.5Zr-3Nb-2.5Sn alloy, as well as pure Ti, were superior to Ti-6Al-4V in corrosion resistance.4. Biology experiment showed that the alloy had the good Biological compatibility.5. The surface reaction layer and linear shrinkage met the accuracy requirements of dental demands.更多还原