Fig。 2。 Micrograph of the Ag– Pd– Au – Cu alloy weld cord。
ing only one charge transfer process。 In the low frequencies areas, the spectrum is controlled by the occurrence of a straight line, and a new Rp and CPEp composition was used to represent the for- mation of a permeable nature interface since this dispersion, observed during the frequency variation, may have been originated from the formation of pits on the surface, thus confirmed by the optic micro- scopy analysis after the corrosion essays (not showed) and by the significant decrease on the polarization resistance number from around 10 kV cm2 to 100 V cm2 (Table 2)。 According to the correspondent impedance diagrams obtained with the Bode format, fair concordance between the experimental and calculated numbers is observed。
Fig。 4。 Potentiodynamic polarization curves to the Ag– Pd– Au – Cu alloy, in 0。9% NaCl airy solution: (a) base metal; (b) laser。
M。L。 Santos et al。 / Materials Letters 57 (2003) 1888–1893 1891
Fig。 5。 Impedance plots for Ag – Pd – Au – Cu, base metal, in 0。9% NaCl at open circuit potential and equivalent electrical circuit for fitting of impedance spectra: (a) complex plane and (b) Bode format。
The use of one CPE to substitute the double electrical layer is due to a correction of the dis- tortions caused by the uniformity in the current distribution caused by the geometry of the electro- dic surface [11 – 13]。 A diffusion process represented
Table 2Fitting of impedance spectra for AgPdCuAu alloy, base metal
by a straight line on the complex plane and by the distortion degree, a c 0。5 (Table 2), is observed at low frequencies。摘要:激光焊接方法被引进牙科领域是在上世纪八十年代末期,其应用更廉价和体积更小的设备,使用更简单的技术,对该领域起到了极大的推动作用。使它能有如此广泛应用,是在于它将焊接过程从热源转换为高能量的光束,使得牙齿修补过程的变形降低到最小。Ag–Pd–Au–Cu合金应用在牙齿修补上的理论在很早之前就提出来了,但是具体的应用是在激光焊出现之后。显微结构分析是使用了光学显微镜,而抗腐蚀性是学习了传统的电气化学技术,在传统电化学的基础上,在口腔中模拟周围的环境。
在焊接区发现一个结构的变化:呈现一个源自高速冷却的微细构造。焊接母材在离开焊接区域处呈现了粗晶的微细构造。电气化学实验显示了在焊缝和母材区域中出现动电位偏极化行为,在焊缝区呈现较高的抗腐蚀性。阻抗频谱分析显示成分和组织被扭曲的特点,呈现低频区域。
D 2002 Elsevier 科学 B。V。 版权所有。
关键字: Ag – Pd – Au – Cu; 激光; 腐蚀; 牙齿的合金
1、引言
对替代合金中搜索符合牙医的金属,在这个过程中, 一些研究员已经应用Ag-Pd 使替换贵重金属的合金, 尝试减少费用和改善机械的性能,并且提高抗腐性能。激光单色性、相干性、方向性极好,亮度极高。激光焊接技术采用聚焦的激光束,把很强的能量集中于一点,加热焊缝,使局部的金属融化,然后冷却,凝固结合在一起。它具有以下的优点:焊接热源为光束,无需与焊接区直接接触,可以论文网
透过玻璃窗进行焊接; 热影响区小,可以获得精确的焊接接头,在靠近烤瓷或树脂贴面的部位和义齿鞍基处可以直接焊接;激光束不受磁场的影响;无需包埋.省时、快速,而且可以减少包埋过程产生的误差;激光焊接的所有参数,如频率、能量级等都行预先设置并自动操作,因此初学者容易掌握;污染小 。 激光焊接方法英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_87359.html