The Using of Concrete Wash Water from Ready Mixed Concrete Plants in Cement Systems

Concrete plants accumulate large amounts of concrete wash water. This water, which pH is highly alkaline, has a negative impact on the environment. Its reuse in fresh concrete slightly reduces its mechanical properties. The combination of concrete wash water and zeolitic by-product led to an increase of 4.6% in the compressive strength at 7 days hydration and up to 30% at 28 days hydration. The same combination led to the denser microstructure compared to the samples made with concrete wash water. This could be explained by the pozzolanic reaction of the zeolitic by-product. The complex chemical reactions of cement, zeolitic by-product, and fines presented in the concrete wash water occurred. Therefore, it was suggested the reusing method of concrete wash water together with zeolitic by-product in the fresh concrete mixtures by substituting some amount of tap water with concrete wash water. In this way, the consumption of tap water is possible to reduce in cement systems.     

Release of corrosion products from amalgam in phosphate containing solutions

Abstract— The effect of phosphate concentration on corrosion was compared for two types of amalgam: a conventional alloy (ANA 68) and a high-Cu admixed alloy (Dispersalloy). The test specimens were stored for 4 months in electrolytes containing 85 mM NaCl and 85 mM NaCl with 2.5, 10, or 100 mM phosphate buffer respectively. The solutions were renewed each month and analyzed for Cu, Zn, Sn, Hg, and Ag in an atomic absorption spectrophotometer. The surfaces and cross-sections of the specimens were studied in a scanning electron microscope (SEM) with an energy dispersive detector (EDAX). The corrosion products, mainly Sn-compounds, at the surface of the amalgams were less in the solutions containing high concentrations of phosphate. In cross-section subsurface corrosion of the high-Cu amalgam was observed especially in specimens immersed in the NaCl solution without phosphate. The conventional amalgam showed surface corrosion only. The decrease in release of elements with time from the conventional amalgam in all the experimental solutions might indicate passivation. For the high-Cu amalgam the release of elements increased with time, except for Cu and Sn in the solution with 100 mM phosphate, indicating that phosphate inhibits corrosion of the Cu-Sn-phases. Release of corrosion products from the high-Cu amalgam was more dependent on the presence of phosphate than the conventional amalgam.     

Microvasculature of bone

The three dimensional vascular microarchitecture of mercox resin on the lateral surface of parietal bone in Wistar strain adult male rats (b. w. 260–350 g.) was studied in relation to bone formation by SEM observation of corrosion casts. The microarchitecture was a single layer of network composed of precapillary artery, capillary and postcapillary vein, which were serpigious, sometimes joined with the vein from the vascular foramen of bone. The meshes of this network, which were irregular and varied in size, existed apart from the bone surface. According to the report of Iwaku and Ozawa (1986), it was reported that the vascular microarchitecture of the bone surface was very changable during the process of bone remodeling and this network, which was shown on the flat bone surface in this study, was very similar to one in the resting phase and/or the period in which the bone formation further advanced. From these facts and the morphological features of the bone surface observed here by SEM, it is suggested that this vascular network was closely related with the resting stage and/or the period in which bone formation further advanced in bone remodeling.     

医用钛合金在三种不同生理电解液中的耐腐蚀行为研究

利用电化学方法研究医用钛合金在0.9%NaCl生理盐水，模拟人工唾液，模拟人工体液中的腐蚀情况，分析腐蚀电位和腐蚀电流密度，扫面电镜观察腐蚀表面形貌，CA-A型接触角测试仪测试钛合金表面被腐蚀后接触角的变化。实验表明：钛合金在三种生理电解液中的腐蚀情况依次是：模拟人工唾液〉模拟人工体液〉0.9%NaCl生理盐水。扫面电镜观察表明，医用钛合金在0.9% NaCl生理盐水腐蚀后，表面出现了许多腐蚀孔，经模拟人体体液腐蚀后，表面变得粗糙不平整，腐蚀孔数目变化不大，钛合金经人工唾液腐蚀后，腐蚀孔数目增多，部分腐蚀孔孔径明显增大。经三种生理电解液腐蚀后，钛合金表面接触角都减小。结论：医用钛合金在人工唾液中的腐蚀最严重，在临床应用中应给予相应的防范措施。     

防止银器文物变色的唑系复合缓蚀剂Ⅰ. 缓蚀剂成膜处理工艺与防变色性能的评定

:通过按正交法设计的紫外光照曝露等加速大气腐蚀实验 ,研究了用于防止银变色的唑系复合缓蚀剂成膜处理的工艺 ,并评定其对模拟文物银试片的防变色性能。采用极化曲线和交流阻抗Nyquist图 ,讨论了防变色作用的电化学机理。实验结果表明 ,缓蚀剂 PMTA、MBI和 MBO具有较好的协同作用 ,银试片在 5 0°C、p H 3.0、组分 MBO∶ PMTA∶ MBI为 1∶ 1 .7∶ 3(摩尔比 )、复合缓蚀剂浓度为 0 .0 1 89mol/L的溶液中 4h成膜处理后 ,经 48h硫华气氛和 36h紫外光曝露腐蚀实验 ,无色斑出现 ,表明缓蚀膜明显地提高了银试片的抗变色能力     

铜合金上渗硅层的耐磨耐蚀性

介绍了铜合金在渗剂粉末中高效渗硅,获得无孔的渗硅层。对渗硅层的组织、零件的表面形状和保温时间对渗硅层厚度的影响、摩擦学行为、腐蚀电位等进行了测定,并进行了初步的探讨,说明铜合金上的渗硅层在硫酸介质中具有耐蚀、耐磨(耐磨性提高3倍以上)、减摩等良好性能。     

电化学人工龋的电化学腐蚀机制研究

目的 研究电化学人工龋的电化学腐蚀机制。方法 采用循环伏安法研究牙片电极在K2SO4溶液中的氧化还原反应；以失重法并结合SPSS统计软件统计分析，评价牙片在KCl和K2SO4介质中恒电位腐蚀情况，并现场监测电解液氢离子浓度的变化情况。结果 在0.0-2.5V电位范围内，牙片电极与石墨电极具有波形类似的循环伏安曲线；在KCl和K2SO4介质中牙片的腐蚀速度无显著差异；2.0V恒电位腐蚀牙片8h后，阳极池本体溶液pH值由7.0平均下降到3.87，阴极池则由7.0平均升高到10.65。结论 在外电场作用下，牙片的阳极腐蚀与介质无关；水的阳极氧化引起阳极区氢离子浓度升高，致使牙齿发生酸溶是电化学人工龋形成的主要决定因素。     

天然水处理剂单宁的改性及性能研究

对单宁进行了胺甲基化、季铵盐化和磺化3种改性,通过红外光谱分析了改性产物的结构,并采用失重法,极化曲线、静态阻垢和杀菌实验等手术对其进行了性能评价与研究。实验结果表明,不同的改性方法可以在很大程度上改善单宁的缓蚀、阻垢和杀菌等性能,具有良好的开发前景。     

In Vivo Corrosion of Sleeved Ceramic Femoral Heads: A Retrieval Study

BackgroundThe purpose of this study was to evaluate a series of retrieved sleeved ceramic femoral heads used in total hip arthroplasty (THA) and determine qualitative and quantitative damage and corrosion patterns.MethodsAn IRB-approved implant retrieval database was utilized to identify all sleeved ceramic femoral heads collected from 1995 to 2004. There were 16 implants with an average duration of in situ of 70 months (range, 13-241 months). The femoral stem was known in 14 cases and was titanium alloy in each of those cases. None were revised for metal-related complications. Ten implants (63%) were from primary THAs, and 6 (38%) were from revision THAs. Damage and corrosion were qualitatively graded using a modified Goldberg method. A quantitative assessment was performed with a coordinate measurement machine (CMM).ResultsAmong the 16 retrieved implants, 1 (6%) demonstrated severe Grade 4 corrosion, 5 (31%) had moderate Grade 3 corrosion, 5 (31%) had mild Grade 2 corrosion, and 5 (31%) had no visible corrosion at the inner sleeve that interfaces with the stem trunnion. The only case of grade 4 corrosion occurred in the only head-sleeve in the study that was not factory assembled and was mated with a titanium molybdenum zirconium ferrous (TMZF) alloy stem. The mean maximum linear corrosion depth at the taper interface, as measured by the CMM, was 7.7 microns (range, 0.9-32.9 microns).ConclusionThis study is the first to quantify corrosion at the titanium interface of sleeved ceramic femoral heads. Potentially clinically significant damage and corrosion patterns were observed in a few failed retrievals; however, the majority of cases demonstrated minimal or no damage.