Beta-钛与镍钛、不锈钢正畸弓丝合金成分、表面形貌以及力学性能的对比研究

目的:比较Beta-钛丝与正畸临床常用的超弹性镍钛丝及不锈钢丝的合金成分、表面形貌以及力学性能,为临床应用提供参考。方法:选取Beta-钛丝、超弹性镍钛丝及不锈钢丝,弓丝尺寸均为0.43 mm×0.64 mm。选用EDAX X-射线能谱分析仪联合SUPRATM55热场发射扫描电子显微镜分析弓丝的合金成分,观察其表面形貌。使用Nano Indenter XP纳米压痕测试机测定弓丝弹性模量及硬度,使用Instron 5848微力材料试验机,三点弯曲测定弓丝的负荷-形变曲线。结果:Beta-钛丝合金成分中含有Ti、Zr、Mo、Sn 4种元素,不锈钢丝含有Fe、Mn、Cr、Si,超弹性镍钛丝含有Ni、Ti 2种元素。不锈钢丝表面比Beta-钛丝及镍钛丝光滑。Beta-钛丝的弹性模量及硬度明显小于不锈钢丝,略大于超弹性镍钛丝。当形变3 mm的负荷完全去除时,Beta-钛丝及不锈钢丝均有残余形变,超弹性镍钛丝形变完全恢复。结论:Beta-钛丝、超弹性镍钛丝及不锈钢丝依据其性能适用于正畸治疗的不同阶段。     

The effect of high fiber fraction on some mechanical properties of unidirectional glass fiber-reinforced composite

Objectives

This study was designed to evaluate the effect of an increase of fiber-density on some mechanical properties of higher volume fiber-reinforced composite (FRC).

Methods

Five groups of FRC with increased fiber-density were fabricated and two additional groups were prepared by adding silanated barium-silicate glass fillers (0.7 μm) to the FRC. The unidirectional E-glass fiber rovings were impregnated with light-polymerizable bisGMA-TEGDMA (50-50%) resin. The fibers were pulled through a cylindrical mold with an opening diameter of 4.2 mm, light cured for 40 s and post-cured at elevated temperature. The cylindrical specimens (n = 12) were conditioned at room temperature for 2 days before testing with the three-point bending test (Lloyd Instruments Ltd.) adapted to ISO 10477. Fiber-density was analyzed by combustion and gravimetric analyzes.

Results

ANOVA analysis revealed that by increasing the vol.% fraction of E-glass fibers from 51.7% to 61.7% there was a change of 27% (p < 0.05) in the modulus of elasticity, 34% (p < 0.05) in the toughness, and 15% (p < 0.05) in the load bearing capacity, while there was only 8% (p < 0.05) increase in the flexural strength although it was statistically insignificant. The addition of particulate fillers did not improve the mechanical properties.

Significance

This study showed that the properties of FRC could be improved by increasing fibervolume fraction. Modulus of elasticity, toughness, and load bearing capacity seem to follow the law of ratio of quantity of fibers and volume of the polymer matrix more precisely than flexural strength when high fiber-density is used.     

牙用低弹性模量钛铌锆锡合金的机械性能研究

目的:检测钛铌锆锡(Ti-24Nb-4Zr-7.6Sn)合金铸件的机械性能,评价其作为口腔修复材料的可行性。方法:对钛铌锆锡合金铸件的机械性能、显微硬度进行检测,对剖面组织金相显微结构和断口形貌进行观察。结果:钛铌锆锡合金抗拉强度为681.7 MPa,屈服强度为410 MPa,延伸率为6%,弹性模量为42.1 GPa,维氏硬度为453 Hv;合金金相组织表现为细化的晶粒结构,合金断口呈典型的微孔聚合型断裂形貌。结论:钛铌锆锡合金机械性能能够满足制作口腔修复体的要求。     

配色颜料加入量对MDX-4-4210硅橡胶机械性能的影响

目的:探讨颜面赝复体配色颜料的适合加入量。方法:以MDX-4-4210硅橡胶为基质,按照国家标准要求,以未添加颜料的MDX-4-4210硅橡胶为对照,在相同条件下,对添加镉黄颜料浓度分别为0.1、0.15、0.2、0.25和0.3wt%的MDX-4-4210硅橡胶进行拉伸性能、撕裂性能和硬度等机械性能测定,采用SPSS10.0软件包对结果进行统计学分析。结果:随着颜料添加量的增多,MDX-4-4210硅橡胶扯断强度、扯断伸长率、撕裂强度和硬度均下降,各组之间有显著性差异;而永久变形率(3min后)几乎不发生改变,各组之间的差别无显著性,即硅橡胶的弹性性能相对稳定。结论:配色颜料加入量能够改变硅橡胶的机械性能。当颜料浓度大于或等于0.2wt%时,其机械性能发生显著变化。     

自制焊丝与商品焊丝对激光焊件机械性能的影响

目的:通过宏观及微观分析焊丝对焊件机械强度的影响,为临床选择焊丝提供依据。方法:采用不同焊丝(自制和商业成品焊丝)对钴铬合金、镍铬合金进行焊接,测定焊件的最大抗拉及抗弯强度,对数据进行单因素方差分析;并通过微观断口扫描电镜观察和熔合区金相分析,探讨焊丝对焊件机械强度的影响。结果:钴铬合金自制焊丝组和商品焊丝组的最大抗拉强度分别为(606.40±82.53)MPa和(693.61±47.68)MPa,最大抗弯强度分别为(997.95±88.89)MPa和(1160.76±91.59)MPa,2组焊件的最大抗拉及抗弯强度均有显著差异(P<0.05);镍铬合金自制焊丝组和商品焊丝组的最大抗拉强度分别为(558.14±46.75)MPa和(582.32±35.43)MPa,最大抗弯强度分别为(1084.75±46.02)MPa和(1078.29±36.25)MPa,2组焊件的最大抗拉及抗弯强度均无显著差异(P>0.05)。断口扫描电镜及熔合区金相分析显示:自制焊丝组焊件的裂纹明显多于商品焊丝组。结论:对力学性能要求较高部位的焊接,应采用商业焊丝。     

Effect of titania content and biomimetic coating on the mechanical properties of the Y-TZP/TiO2 composite

Objective

To investigate the effect of titania addition (0, 10 and 30 mol%) on the microstructure, relative density, Young’s modulus (E), Poisson’s ratio (υ), mechanical properties (flexural strength, σ_f, and Weibull modulus, m) of a Y-TZP/TiO₂ composite. The effect of the presence of a biomimetic coating on the microstructure and mechanical properties was also evaluated.

螺旋弹簧与橡皮链远牵尖牙力学性能比较分析

目的比较分析螺旋弹簧与橡皮链远牵尖牙的力学性能,以助提高临床疗效。方法,第一部分为体外模拟实验,应用ＣＨ－０－１型齿科正畸测量仪对５ｍｍ长的螺旋弹簧及三个圈长的橡皮链进行拉伸实验至于１５０克,比较再会得在人工唾液中不同时期不同位移时力值衰减程度的力学性能。第二部分为临床应用研究。结果在模拟口腔环境及尖牙移动的相同实验条件下,螺旋弹簧在２８天内力值衰减明显低于橡皮链,前者衰减２．９％,后者衰减４２．８％,在１５０克初始正畸力作用下,螺旋弹簧远牵尖牙的速率快于橡皮链。结论螺旋弹簧的力学性能优于橡皮链,力值越持续,越适宜牙齿移动,力的持续时间是决定牙齿移动速率的重要因素。     

Effect of titania addition and sintering temperature on the microstructure,optical, mechanical and biological properties of the Y-TZP/TiO2 composite

ObjectiveThe aims of this study were: 1) to evaluate the effect of sintering temperature on microstructure, density and flexural strength of a 3Y-TZP/TiO₂ composite containing 12.5 wt% of TiO₂ compared to 3Y-TZP specimens (control); 2) to compare 3Y-TZP with the experimental 3Y-TZP/TiO₂ composite, both sintered at 1400 °C, with respect to the following parameters: optical properties, characteristic strength, Weibull modulus, fatigue behavior, induction of osteoblasts proliferation and differentiation (mineralization nodules formation).MethodsThe 3Y-TZP and 3Y-TZP/TiO₂ powders were uniaxially pressed and sintered at 1200 °C, 1300 °C, 1400 °C or 1500 °C for one hour in a furnace. The microstructural analysis consisted of X-ray diffraction and scanning electron microscopy. The density was measured by the Archimedes' principle and the flexural strength was obtained by the biaxial flexure test. The optical properties were measured using a spectrophotometer operating in the visible light wavelength range. The step-stress accelerated life testing was performed by the pneumatic mechanical cycler and the biological behavior achieved by using osteoblast-like cells (Osteo-1 cell line).ResultsTetragonal zirconia was identified in all groups and cubic zirconia was identified only at 3Y-TZP group. The addition of TiO₂ decreased the values of density and flexural strength of the composite 3Y-TZP/TiO₂ in relation to 3Y-TZP regardless of the sintering temperature. The color difference between the two materials was not significant regarding L*a*b* parameters. The composite showed higher probability of failure, and induced higher proliferation and differentiation than control.SignificanceThe composite developed have good aesthetic and biologics properties. However, its microstructure and mechanical properties need to be improved for future dental implant applications.     

激光功率对钴铬合金及镍铬合金焊件机械性能的影响

目的:探讨不同激光功率对钴铬合金、镍铬合金焊件机械性能的影响。方法:采用临床上最常用的的2种合金进行不同功率的激光焊接,通过测定焊件的机械强度,并进行断口扫描电镜观察、熔合区金相分析和显微硬度测试,研究激光功率与焊件强度的关系。结果:钴铬合金焊件随着激光功率的增大,最大抗拉强度增大,抗弯强度则有下降的趋势;镍铬合金4组试件的最大抗拉、抗弯强度无显著差异;微观显示随着功率的增大,裂纹和气孔有增多的趋势;熔合区的显微硬度比母材高,随着功率的增大,显微硬度增大的区域增宽。结论:合适的激光功率是取得理想激光焊接接头的关键。