Microtensile bond strength of composite-to-composite repair with different surface treatments and adhesive systems

Objectives: The purpose was to investigate the effect of different surface treatments and bonding agents on the repair bond strength of different resin-based restorative materials by microtensile bond strength (μTBS) testing protocol. Materials and Methods: 24 Grandio SO(VOCO) and 24 Filtek Z250(3?M) resin composite blocks were prepared. Half of the samples (N?=?12) were diamond bur-roughened and the other half (N?=?12) were sandblasted by 50?μm aluminum oxide particles. They were further divided into four sub-groups (n?=?3) and received the following: Sub-Group1: Adper Single Bond2 (Etch&Rinse) (3?M); Sub-Group2: Clearfil SE (Self-etch) (Kuraray); Sub-Group3: Beauty Bond (HEMA-free all-in-one) (Shofu); Sub-Group4: All Bond3 (HEMA-free, hydrophobic, etch&rinse) (Bisco). The samples were repaired by Filtek Z250 to form a block. All of the resultant sub-groups combinations consisted of one of the composite type, surface treatment type, and adhesive systems. A total of 18 groups were prepared including 2 homogeneous blocks. They were thermocycled and μTBS measurements were performed. Data were statistically analyzed with Kruskall–Wallis and Mann–Whitney U tests. Results: The experimental regroups’ μTBS reached to 34.67–66.36% and 43.44–95.52% of the cohesive bond strength for Grandio SO and Z250, respectively. The pre-existing composite type is found to be statistically important. When the surface is bur-finished Grandio performed better; when air-abrasion is considered Z250 showed higher bond strength. All-in-one adhesive system produced the weakest bond strength at all parameters. Conclusion: It may be suggested that when the pre-existing composite is unknown, air-abrasion may be performed with etch&rinse or two-step self-etch adhesives.     

喷砂表面处理控制滑动摩擦尖叫噪声

采用球—平面接触方式,对喷砂处理的制动盘蠕墨铸铁试样进行了滑动摩擦噪声试验,并与光滑表面样品试验对比。在对摩擦噪声特性和摩擦磨损特性进行综合分析的基础上,探讨控制滑动摩擦尖叫噪声触发和演变规律的关键界面因素,研究了喷砂表面对滑动摩擦尖叫噪声的影响及其机理。结果表明:喷砂处理表面能明显的抑制界面摩擦尖叫噪声的产生,且表面粗糙度越大,抑制尖叫噪声效果越明显,界面微凸体的分布和磨损情况对摩擦尖叫噪声的产生及演变具有关键的影响。该试验条件下摩擦尖叫噪声的产生主要归因于磨屑堆积、粘着剥落和犁沟等界面因素引起界面摩擦力剧烈波动,诱发了摩擦系统的自激振动。相比光滑表面,喷砂处理表面的微凸体接触磨损"平台"表面的磨屑堆积、粘着剥落和犁沟等现象较轻,引起摩擦力波动的能量较弱,产生的尖叫噪声强度较低。     

喷砂和退火对DD483合金表面再结晶的影响

研究了DD483合金在服役温度附近经喷砂处理和退火后的组织演变和表面再结晶行为。将DD483合金试样在0.4~0.7 MPa的压力范围内进行喷砂处理,再于1100 ℃退火4和16 h。结果表明,在预定的爆破压力范围内,喷砂能有效地清理合金表面,并将压应力引入表面。喷砂样品退火4和16 h后,Ti和Al元素析出到表面并转化为氧化物,退火后亚表层出现胞状再结晶结构。拓扑密堆积（TCP）相和TiN分别在再结晶区和原始基体近再结晶区析出。此外,再结晶区的厚度随退火时间和实际应力的增加而增加。     

牙种植体表面喷砂酸蚀工艺的优化

对钛表面喷砂酸蚀工艺进行优化研究,以用于牙种植体表面改性。采用喷砂酸蚀法对钛片表面进行粗化处理,以粗化的钛片表面中0.5~2 μm孔洞所占比例和表面平均接触角作为正交试验的参考指标,对喷砂酸蚀工艺进行优化。在试验范围内,表面处理的最优参数为：喷砂材料TiO2,酸蚀温度100 ℃,酸蚀时间20 min,混酸 60%H2SO4、10%HCl和去离子水的体积比1∶1∶2。将得到的最优参数应用于钛片和牙种植体,利用扫描电镜、接触角测量仪及能谱仪对其形貌、接触角、成骨细胞粘附及成分进行分析。结果表明：优化工艺处理后,钛片表面平均接触角达67°,且均匀性较好,利于细胞吸附生长;钛片和牙种植体表面都获得了均匀的微米级孔洞结构,但种植体螺纹不同部分的表面形貌不一样。