Elasticity,hardness, and fracture toughness of sodium aluminoborosilicate glasses

Due to an increasing demand for oxide glasses with a better mechanical performance, there is a need to improve our understanding of the composition-structure-mechanical property relations in these brittle materials. At present, some properties such as Young's modulus can to a large extent be predicted based on the chemical composition, while others—in particular fracture-related properties—are typically optimized based on a trial-and-error approach. In this work, we study the mechanical properties of a series of 20 glasses in the quartenary Na₂O–Al₂O₃–B₂O₃–SiO₂ system with fixed soda content, thus accessing different structural domains. Ultrasonic echography is used to determine the elastic moduli and Poisson's ratio, while Vickers indentation is used to determine hardness. Furthermore, the single-edge precracked beam method is used to estimate the fracture toughness (K_Ic) for some compositions of interest. The compositional evolutions of Vickers hardness and Young's modulus are in good agreement with those predicted from models based on bond constraint density and strength. Although there is a larger deviation, the overall compositional trend in K_Ic can also be predicted by a model based on the strength of the bonds assumed to be involved in the fracture process.     

自流平型环氧地坪涂料的研制

主要研究了自流平型环氧地坪涂料固化剂对涂膜性能的影响。详细研究了多元脂肪胺的类型、混合多元脂肪胺的混合工艺、助剂、环氧树脂、反应时间等对固化剂的粘度及涂膜的光泽度等的影响。所制得固化剂的粘度为 170 0mPa·s,涂膜硬度为 71% ,光泽度为 97% ,耐腐蚀性能好。     

Non-Hall-Petch hardness dependence in ultrafine fibrous MgAl2O4-MgO eutectic ceramics fabricated by the laser-heated floating zone (LFZ) method

MgAl₂O₄-MgO eutectic ceramics were fabricated by the laser-heated floating zone (LFZ) method with various growth rates to assess its possible beneficial effect on microstructural aspects and mechanical properties. It was determined that the growth rate optimizing the microstructure and mechanical properties is 750 mm/h; below this value, coarsening of the fibrous microstructure takes place with a degradation of these properties. In the extreme case of 50 mm/h growth rate, the presence of undesirable transverse cracks was unavoidable. Thanks to the high growth rate of 750 mm/h, ultra-fine fibrous microstructure MgAl₂O₄-MgO eutectic ceramics can thus be fabricated with greater hardness (15.5 GPa from Vickers indentation and 22 GPa from nanoindentation) and flexural strength (?345 MPa). It is reported that hardness scales with the interfiber spacing λ according to a law of the type lnλ/λ, contrary to the assumed Hall-Petch-like dependence. This proposed law can be explained in terms of dislocation hardening induced by the MgO fibers.     

1种新型低硬度循环冷却水阻垢缓蚀剂的应用

针对我国南方低硬度、易腐蚀型水质作为循环冷却水补水对管道和换热器造成的腐蚀问题,复配出一种无重金属、不含无机磷的新型阻垢缓蚀剂WND-408,用碳酸钙沉积法和旋转挂片法检测该阻垢缓蚀剂性能,通过现场使用,观察该药剂的处理效果.结果表明,WND-408阻垢缓蚀剂使用量在60～80 mg/L时,碳钢腐蚀率＜0.075 mm...     

聚氨酯/微米Si_3N_4复合材料的性能研究

对聚氨酯/微米Si3N4复合材料的性能进行了研究,实验表明：聚氨酯/Si3N4复合材料具有优异的性能,聚氨酯/微米Si3N4复合材料,其硬度、力学性能和抗冲蚀磨损性能比纯聚氨酯优异;在微米Si3N4含量为3%时,其硬度、力学性能最佳;在微米SiN含量为5%时,其抗冲蚀磨损性能最佳。     

离心式高压甲铵泵检修总结

介绍尿素装置离心式高压甲铵泵一次事故后比较艰难的修复经过,总结检修中的经验教训和应注意问题,并对事故原因进行分析。     

工业冷却系统近零排放水处理技术的开发和应用

介绍了工业冷却系统节水及废水近零排放水处理技术及复合药剂TS-50921的研制、实验评定和现场应用,在高硬度高含盐量循环水中,钙硬度达到1 000 mg/L、电导率达到4 000 μS/cm的条件下,可保证腐蚀速率和沉积速率符合国标的要求,对循环水高度浓缩后产生的浊度和铁胶体分散性能优异,可以显著降低新鲜水补用量、减少...     

密封件用高硬度丁腈橡胶的混炼工艺探讨

探讨了高硬度丁腈橡胶的混炼工艺,如一段混炼法、两段混炼法和逆炼法.实验证明,高硬度丁腈橡胶中的炭黑等填充剂用量较大时,可采用逆炼法混炼工艺;该工艺混炼效果较好,胶料质量稳定,并降低能源消耗.     

Surface,tribological, and mechanical characterization of synthetic skins for tribological applications in cosmetic science

Synthetic skin as an ideal human‐tissue substitute is needed for the research and assessment of hair‐ and skin‐care products. In this study, a systematic study was carried out of the surface, tribological, and mechanical properties of two synthetic skins and rat skin with and without skin‐cream treatment with scanning electron microscopy, atomic force microscopy, and a nanoindenter. The film thickness, adhesive force, coefficient of friction, surface roughness, and contact angle of the two synthetic skins and rat skin were comparable. The hardness of one synthetic skin was more similar to rat skin. After treatment with skin cream, the trends of the properties of the two synthetic skins and rat skin were similar. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011