Cell Adhesion and in Vivo Osseointegration of Sandblasted/Acid Etched/Anodized Dental Implants

The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20% ± 10.89%) was much greater than those of machined (33.58% ± 8.63%), SLA (58.47% ± 12.89), or ANO Ti (59.62% ± 18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant.     

含泄漏层的井下水力增压器增压特性研究

为了进一步提高水力喷砂射孔技术的射流压力,摆脱传统的地面增压方式因压力传输困难、能耗高等原因对深层地层岩石压裂难的困境,基于实际射孔工艺要求,设计了井下水力增压器。根据井下水力增压器的结构和工作原理,考虑活塞与活塞筒之间的泄漏层对增压效果的影响,建立了增压缸流体域模型,利用动网格技术对增压缸的增压特性进行数值模拟研究。研究结果表明:增压过程中,增压腔压力和流体出射速度均随时间先增大后逐渐呈现出高频周期性波动的规律;增压腔压力和流体出射速度随输入压力和低压腔与增压腔流体的有效作用面积比的增大而增大,且增压腔压力近似等于输入压力和有效作用面积比的乘积;泄漏层厚度对增压腔压力和流体出射速度的波动性影响很大。该研究结果为后期增压器结构设计和参数优选提供了参考。     

280 简易快速的表面超疏水涂层制备及其性能

目的 低成本简易快速地制备出耐腐蚀超疏水涂层,并研究表面喷砂对超疏水涂层的影响。方法 利用喷砂和抛光这2种表面处理方式和喷涂工艺在5050铝合金板基体表面构建出具有多级结构的超疏水表面。通过润湿性、电化学腐蚀、耐磨性、浸泡耐久性和自清洁测试等试验,分别评价制备样品表面的润湿性、耐海水腐蚀、耐磨性、耐长时间浸泡性能和自清洁性能,并通过扫描电子显微镜和能谱仪对表面形貌和元素成分进行分析。结果 制备的样品表面具有优异的超疏水性能。在30次喷涂次数下,喷砂基底的涂层表面的水滴静态接触角为(153.9±1)°,动态滚动角为(2.99±0.5)°。电化学腐蚀测试结果表明,喷涂氟硅树脂/SiO2涂层可以有效增强铝合金表面的耐腐蚀性能。试验中,样品在25次砂纸摩擦后,抛光基底的涂层表面的接触角为(97±1)°,喷砂基底的涂层表面的接触角为(102.4±1)°。样品在NaCl溶液浸泡10 d后,抛光基底的涂层表面的接触角为(69.4±1)°,喷砂基底的涂层表面的接触角为(113.7±1)°。结论 所制备的喷砂和抛光基体在经过不同次数的喷涂氟硅树脂/SiO2复合涂料后具备超疏水性能,且喷砂基底的涂层表面具有更低的滚动角。涂层修饰的表面在NaCl溶液中的耐腐蚀性能随着喷涂次数的提升而增强。在相同的喷涂条件下,喷砂处理基体能提高超疏水表面的耐腐蚀性、耐磨性和耐久性。     

火车车轮喷砂机自动夹持器圆柱凸轮有限元模态分析

圆柱凸轮是火车车轮喷砂机自动夹持器的重要零部件之一,建立圆柱齿轮的动力学控制方程,利用有限元软件对凸轮进行静力学和模态分析,得出应力云图及固有频率和振型等参数,为后续进行谐响应分析或者瞬态动力学分析提供理论参考。     

环氧树脂灌封器件电镀前处理工艺改进

针对环氧灌封器件表面镀层结合力差的问题,在镀前对环氧树脂灌封体进行喷砂,并将铬酸酐?硫酸体系化学粗化改为等离子粗化.采用改进的前处理工艺后,环氧树脂灌封体表面的镀层厚度、结合力及可靠性均满足宇航型号产品的使用要求.     

离心式空气压缩机组安装过程中应注意的问题

将离心式空气压缩机组土建基础施工中遇到的一些问题及管道安装过程中制定的施工方案进行了总结,提出了机组配套辅机出厂时的防锈处理方法。     

基于离散相模型的水力喷砂射孔器优化设计

针对常用水力喷砂射孔器冲蚀磨损严重、使用寿命短的问题,运用数值模拟软件的离散相模型,分析了常用水力喷砂射孔器的冲蚀磨损规律,提出了工具结构和喷嘴结构的优化设计方案;并对新型水力喷砂射孔器的射流性能和耐冲蚀性能进行验证。研究结果表明：常用水力喷砂射孔器的冲蚀磨损主要集中在工具内腔喷嘴入口处、喷嘴内流道和工具外壁喷嘴出口处,且射孔器结构、射孔液运动特性、管柱振动和工作环境是造成冲蚀磨损的4个主要原因;相同条件下,相比于常用水力喷砂射孔器,所提出的新型水力喷砂射孔器的射流速度更大,上下层喷嘴间的速度差更小,耐冲蚀性能更佳。     

喷砂表面三维粗糙度参数对涂层结合强度的影响

目的揭示喷砂预处理表面三维粗糙度参数对热喷涂层结合强度的影响规律。方法以喷砂距离和喷砂速度为影响因子,对45#钢试样进行喷砂处理,采用三维光学显微镜测得各工艺参数下喷砂表面的三维形貌及三维粗糙度参数,并利用"粘接-拉伸"测试方法测得涂层的结合强度。利用回归分析方法,建立涂层结合强度与三维粗糙度参数间回归数学模型,并进一步分析三维粗糙度参数的影响机制。结果喷砂预处理表面随机分布着许多不规则形状的凸峰和凹坑,方向各异,没有固定的取向,其整体表面粗糙度S_a平均为4.84μm,涂层结合强度平均为32.8 MPa。涂层结合强度与三维粗糙度参数间存在着非线性相关关系,且S_a、S_(dr)、S_(dq)、S_q对涂层结合强度的影响较为显著。S_a和S_(dr)越大,有利于增大涂层与基体的接触面积;S_(dq)较大时,所形成的凹坑及凸峰较为尖锐,有利于为涂层机械结合提供更多的锚固点;结合界面的S_q较大时,其表面形貌以较深的凹坑为主,导致凹坑深处易形成残留气孔缺陷,降低涂层与基体间的润湿效果及结合性能。结论 S_a、S_(dr)、S_(dq)、S_q为涂层结合强度的主要影响因素,且存在非线性回归关系,各三维粗糙度参数对涂层结合强度的影响机制及趋势与回归数学模型一致。     

The effect of surface treatments on the microroughness of laser-sintered and vacuum-cast base metal alloys for dental prosthetic frameworks

This study aimed to evaluate the effect of four chemomechanical surface treatments on the surface average microroughness and profile of laser‐sintered and vacuum‐cast dental prosthetic structures. Square‐shaped blocks (10 mm × 10 mm × 1.5 mm) were prepared as follows: (1) laser‐sintered Co? Cr (L) (ST2724G); (2) cast Co? Cr (C) (Gemium‐cn); and (3) cast Ni? Cr? Ti (T) (Tilite). Specimens of each alloy group were randomly divided into five subgroups (n = 10 each), depending on the conditioning method used: (1) no treatment (control); (2) sandblasting (125 μm Al₂O₃‐particles); (3) silica coating (50 μm silica‐modified Al₂O₃‐particles); (4) oxidation; and (5) oxidation plus opacification. Subgroups 2 and 3 represent “inner” pretreatments proposed for ceramometal restorations to improve the metal surface area available for luting cements. Subgroups 4 and 5 are the “outer” pretreatments required for bonding the aesthetic veneering ceramics to the underlying metal frameworks. Average surface roughness (Ra/μm) was determined using a surface profilometer. Data were analyzed by two‐way ANOVA and Student–Newman–Keuls tests (α = 0.05). Metal surface topography was SEM‐analyzed. Despite the inner pretreatment applied, L samples resulted in the highest microroughness (P < 0.001), whereas sandblasting produced a surface‐smoothing effect in cast specimens. After oxidation, a significant increase in surface roughness occurred in all groups compared with controls, L specimens being the roughest (P < 0.001). Opacification caused a flattening effect of all oxidized structures; all opacified groups resulting in similar microroughness. Laser sintering of Co? Cr enhances the roughness of metal structures, which may improve the frameworks' microretention of the cements, and of the opaquer before the copings are veneered with the aesthetic ceramics. Microsc. Res. Tech. 75:1206–1212, 2012. © 2012 Wiley Periodicals, Inc.     

A novel effect of sandblasting on titanium surface: static charge generation

Recent advances in biomaterials’ research suggest that electrical charges on a dental implant surface significantly improve its osseointegration to living bone, as a result of selective osteoblast activation and fibroblast inhibition. This study aims at investigating the possibility of using sandblasting to modify the electrical charges on the surface of titanium materials. Our experiments used Al₂O₃ grits to blast on CP2 titanium plates, for durations between 3 and 30?s. After sandblasting, Ti surfaces were measured for their electrostatic voltage. The results indicate a novel finding, i.e. negative static charges are generated on the titanium surface, which may stimulate osteoblast activity to promote osseointegration around dental implant surface. This finding may at least partially explain the good osseointegration results of sandblasted titanium dental implants, in addition to other known reasons, such as topological changes on the implant’s surface. However, the static charges accumulated on the titanium surface during sandblasting decayed to a lower level with time. It remains a challenging task to seek ways to retain these charges after quantification of desired level of negative charges needed to promote osteoblast activity for osseointegration around dental implants.