【作者】 朱娟芳；

【导师】 莫三心；

【作者基本信息】 郑州大学 ， 口腔临床医学， 2004， 硕士

【摘要】 [背景和目的] 钛及钛合金在口腔临床的应用越来越广泛，作为一种经济的生物材料，钛及钛合金有取代可摘局部义齿和固定义齿常用合金的趋势。由于钛及钛合金具有弹性模量低、热导性低、延展性好、密度小、硬度适当等优良的机械性能和卓越的生物相容性、耐腐蚀性以及低廉的价格，因此，使钛及钛合金更适合于牙科修复。近年来，在口腔修复领域，钛及钛合金主要用于可摘局部义齿支架、全口义齿、种植义齿、固定冠桥修复。随着钛在多单位固定桥中应用的增多，需要一种方法将一个修复体中的两个或多个单位连接起来，以减少铸造过程中产生的收缩和变形。钛及钛合金化学性质活泼，在高温下易于和氧、氢、氮发生化学反应，从而导致其成分和机械性能的改变。激光焊接是目前焊钛最好的也是最常用的方法。因此，研究激光焊接对钛性能的影响具有重要的临床意义。 [方法] 本试验主要通过如下实验方法一三点弯曲实验、拉伸实验、显微硬度测量、电子扫描电镜分析、金相学分析、X衍射能谱分析等方法，研究了激光焊接技术对钛性能和低温瓷与钛的结合强度的影响。实验分为3个部分：第一部分是研究激光焊接时不同焊接间距对钛铸件性能的影响；第二部分是研究激光焊接技术对钛铸件的耐应力腐蚀性能的影响；第三部分是研究激光焊接对钛铸件和钛专用瓷结合强度的影响。 [结果] 1 焊接间距分别为0mm、0.25mm、0.5mm、1mm时，各组焊件的抗张强度(677.92郑州大学20()4届硕士研究生毕业论文钦激光焊接的临床应用基础研究士79.78 MPa、605.00士68.23 MPa、619.65士44.35 MPa、632.95士87 MPa)与母材(593.19士42.52 MPa)相比无差别(P>0.05)。断口扫描电镜观察显示断口有一定的塑性，未发现气孔和焊接缺陷。金相分析显示焊区和母材之间分界明显，无明显的热影响区，激光焊接区为细小的针状马氏体结构。各组的显微硬度值变化一致:试件焊缝中央的显微硬度值最大，向两侧逐渐降低，显微硬度增加的范围大约为lmm。 2应力腐蚀试验以后，激光焊接钦试件表面无变色，扫描电镜观察无腐蚀裂纹及腐蚀产物，实验组抗张强度(657.06士54.04 MPa)与对照组(609.81士37.24 MPa)相比无明显区别(P>0.05)。 3断口扫描电镜观察显示激光焊接钦一瓷结合面(实验组)和对照组均有不规则的突起，金属表面表现良好的润湿性，瓷层内没有发现裂纹。X衍射能谱分析发现在界面区可见Ti元素从钦金属向瓷层内扩散，Si、K、Na、Al、Sn等元素从瓷中向钦金属扩散。扩散带宽度大约为10.6腼。激光焊接钦一瓷的结合强度(46.33士O.97MPa、)与对照组的结合强度(40.71士0.93 MPa)无差别(P>0.05)。[结论〕 1不同的焊接间距不影响激光焊接钦试样的性能。临床上应用激光焊接制作修复体，焊接间距小于lmm时，不同的焊接间距不影响焊件的机械性能。焊接间距大于0.smm时，临床操作难度增大。 2激光焊接钦试件具有良好的耐应力腐蚀性能。 3激光焊接不影响钦铸件与瓷的结合强度，结合方式也没有发生改变。更多还原

【Abstract】 Background and purposeTitanium and titanium alloys are being used more frequently in dentistry.A growingtrend involves the use of titanium as an economical and biocompatible replacement for exising alloys.Titanium and titanium alloys have biocompatibility,corrosion resistance,low cost and desirable physical and mechanical properties,such as low modulus,low thermal conductivity,high ductility,low density,and favorable microhardness,which make titanium and titanium alloys more attractive for dental prosthesis.In recent years,titanium and its alloys have been used as a metal for removable partial denture frame works,complete denture bases, implant denture,fixed bridge and crown in dental prosthesis.The increasing use of Ti for multiple-unit fixed prosthesis require a method to join two and more unites in a restorative prosthesis to reduce the contraction and distortion in casting process.Forthermore, titanium and its alloys have a high reactivity with oxygen,nitrogen,and hydrogen.especially with increasing temperature ,which leads to alterations in their composition and mechanical properties.When using titanium,laser welding is the best method and the one most used.So investigation of the influence of laser welding on titanium has great clinical significance. MethodsThese method were used in the study: scanning electron microgram,metallographicexamination, EDAX,tension test, three-bending test,measuer of Vickers microhardness values at welding area,etc.The aim of the study is to determine if laser welding technique will influence the properties of titanium and the bond strength of low-fusing porcelain to laser welded Ti.The experiments are divided into three sections:The first one is to investigate the quality of laser welded Ti by different gap distance .The second one is to investigate the corrosion properties of laser welded Ti,The third one is to investigate the bond strength of low-fusing porcelain to laser welded Ti. Results1 Tensile loads of laser welded titanium by different gaps(0.0mm:677.92 79.78MPa;0.25mm:605.00 68.23MPa;0.5mm:619.65 44.35MPa;1.0mm:632.95 + 87MPa)made no statistic difference from those of the original materials(593.19 42.52MPa).SEM showed no pores and other defects and some ductility at laser welding area. Metallographic examination showed a localized fusion and a heat-affected zone.these zones were limited to the surface region in the joined areas. Fine-grained acicular crystals could be seen at the fusion zone.High hardness values were measured near the fusion zone and tapered off outside the heat-affected zone throughout all the tested samples for laser welded cast titanium. With the welded area taken as the center,the range of increasing hardness was approximately 1mm.2 After stress-corrosion test ,there was no discoloration in the weld zone of the laser welded cast samples. SEM showed no microcrack on any sample’ s surface at the fusion zone.The ultimate tensile strength (UTS) had no significant difference between the stress-corrosion group(657.06 54.04MPa) and the controlled group(609.81 37.24MPa).3 The SEM examination showed that the interfaces of the laser-welded groups and the controlled ones presented similar irregularities with a predominance .All specimens showed good wetting to the metal surface.No fracture lines in the porcelain layers were found in any speciments.The EDAX analyses revealed that titanium diffuses from titanium to porcelain,and silicon,potassium ,natrium,aluminium,and stannum diffused from porcelain to titanium in the interface.The thickness of elemental diffusion layer was approximate 10.6Hm.No significant difference of the bond strength was found between laser-weldedsamples(46.33 0.97MPa) and the controlled samples(40.71 0.93MPa). Conclusion1 the laser welding technique does not affect the mechanical properties by different gap distances,when gap distance is above 0.5mm,it is more difficult to operate in clinic appliance.2 the laser- welded Titanium shows superior corrosion-resistance pro更多还原