RCC-M中的焊接材料评定

对RCC-M中有关焊接材料评定的规定进行了介绍和讨论,认为RCC-M中的焊接材料评定是焊材厂正常产品检验和设备制造厂焊接工艺评定的简单拼凑,对标准焊材没有实际意义,对开发新焊材的控制力度又显得不够,作为法规条文并不恰当。     

Effect of different types of filler and filler loadings on the properties of carboxylated acrylonitrile–butadiene rubber latex films

The effects of different types of fillers and filler loadings on the properties of carboxylated nitrile rubber (XNBR) latex were identified. Silica, mica, carbon black (CB; N330), and calcium carbonate (CaCO₃) were used as fillers with filler loadings of 10, 15, and 20 parts per hundred rubber. Furnace ashing and Fourier transform infrared analysis proved that interaction existed between the fillers and XNBR latex films. The morphology of the filled XNBR films was significantly different for different types of fillers. Mica and CaCO₃ fillers showed uneven distribution within the XNBR film, whereas other fillers, such as silica and CB, showed homogeneous distribution within the films. In the observation, silica and mica fillers also illustrated some degree of agglomeration. The mechanical properties (e.g., tensile and tear strengths) showed different trends with different types of fillers used. For silica and mica fillers, the mechanical properties increased with filler loadings up to a certain loading, and decreased with higher filler loadings. For CB filler, the mechanical properties increased gradually with increasing filler loadings. CaCO₃ fillers did not increase the mechanical properties. The crosslinking density of the XNBR films increased when they were incorporated with fillers because of the presence of elastomer–filler and filler–filler interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of filler surface treatment on mechanical properties and thermal properties of single and hybrid filler–filled PP composites

The influence of two types of surface treatments (aminosilane and Lica‐12) on the mechanical and thermal properties of polypropylene (PP) filled with single and hybrid filler (silica and mica) was studied. An improvement in tensile properties and impact strength was found for both treatments compared to those of untreated composites. However, the filler with silane coupling agent showed better improvement compared to the filler with Lica‐12 coupling agent. This was due to better adhesion between filler and matrix. Thermal analysis indicates that surface treatments increased the nucleating ability of filler, but decreased the coefficient of thermal expansion of PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Acid/Base Properties of Fumed Silica Fillers Used in Silicone Elastomers

Inverse gas chromatography (IGC) and photoacoustic infrared spectroscopy (PAS) were used to investigate the effects of thermal history and silane treatment on the surface energetics of various fumed silica fillers. The specific interaction parameter, I_sp, was a factor of 2.3 (THF probe) lower for a silane treated fumed silica (Degussa R972) relative to an untreated filler (Degussa A200), thus confirming the deactivating effects of silane treatment. Heat treatment of raw fumed silica (Cabot HS-5) at 150°C and 650°C decreased I_sp (THF probe) from 15.3 kJ/mol to 10.5 kJ/mol. This decrease was attributed to the loss of bound water and surface silanols. The dispersive interactions increased with heat treatment as a result of the formation of higher electron density sites such as strained Si-O-Si bonds. Silazane-treated fillers were prepared using heat treated and hydrated feedstocks. I_sp values were a factor of 2-30 lower, depending upon the probe, for silazane-treated fillers made from heat treated feedstock. The dispersive interactions increased from 27.2 mJ/m² to 57.8 mJ/m² as a result of using heat treated feedstock, thus suggesting some of the strained Si-O-Si bonds formed upon drying remained intact even after silazane treatment.     

Synthesis of cobalt coated nickel powders for improving the stability of the resistivity of PPTC materials

Nickel powders coated by cobalt (Co@Ni powders) on the surface have been obtained by reduction in the ethylene glycol. The morphology and composition were characterized by scanning electron microscope and energy dispersive X‐ray spectroscopy. The valence states of cobalt in the sample were determined by X‐ray photoelectron spectroscopy. The Co@Ni powders were used as the electrically conductive fillers in the polymeric positive temperature coefficient (PPTC) materials in which polyethylene was used as the matrix. The stability of the resistivity of PPTC materials has been improved due to the protection and electrical conductivity of the cobalt layers on the surface of Ni powders. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of model fillers on the adhesive strength of pressure-sensitive tapes

—The effect of various model fillers, namely glass beads, 'Spheriglass', and PTFE powder, on the adhesive strength of natural rubber (NR) and poly(n-butyl acrylate) (PBA) tapes has been investigated. Glass fillers treated with alkyl chlorosilane were also used. The adhesive strength was measured over a range of rates and temperatures, and corrections for the thickness of the adhesive and volume fraction of the polymer were introduced into the rate term. It was observed that the adhesive strength of PBA tapes filled with 20% PTFE is comparable to that of the control sample without filler. The strength measured over a range of strain rates increased for both untreated and treated Spheriglass-filled adhesives. Filled NR adhesives showed an enhanced strength only at very high strain rates. With 40% PTFE, this increase was quite apparent. The mechanism of improvement of the strength of adhesion due to the incorporation of a filler is explained. The addition of a filler introduces an additional mechanism of energy dissipation during deformation of the adhesive and a higher energy will be expended due to debonding of the filler and hysteresis.     

增强型生态浮床填料筛选及工况优化

生态浮床作为一种经济、环保的黑臭水体处理工艺得到广泛应用,但其处理能力受制于植物根系深度及表面积。通过悬浮球、生物绳、弹性和组合填料分别与间种的粉绿狐尾藻（Myriophyllum aquaticum）和西伯利亚鸢尾（Iris sibirica）植物构建生态浮床,探究不同填料对生态浮床效能的强化作用及微生物机制;并在优选填料的基础上进一步探究优选填料的最优添加工况及其强化下浮床对污染物去除的动力学模型。填料优选实验结果显示,生物绳填料对COD、氨氮和总磷的去除率最佳,分别为>99%、43.85%和14.03%;高通量测序分析显示,生物绳填料表面生物膜微生物丰富度最高、物种组成分布最均匀、微生物多样性最高,且生物绳填料可定向富集Flavobacterium、Exiguobacterium、Chryseobacterium、Microbacterium、Caulobacter等脱氮除磷相关功能菌。生物绳工况优化结果显示,修复轻度黑臭水体的最佳生物绳填料投加量为12.5 m/m³,其对COD、氨氮和总磷的去除率分别为96.4%、38.5%和56.6%;动力学模型拟合显示,一级动力学模型能更好地拟合生物绳强化生态浮床的氨氮及COD降解规律。     

材料填充对滤波减速器啮合力与润滑特性的影响

为提高滤波减速器寿命,设计在齿上开槽,并在槽内填充紫铜、硬铝合金、尼龙1010、丁晴橡胶的新型结构。建立了滤波减速器在不同位置啮合的有限元模型,计算了不同填充材料齿轮在不同啮合位置的啮合力。在此基础上建立了考虑齿面粗糙度的滤波减速器混合润滑模型,分析了转速对不同填充材料滤波减速器润滑特性的影响。有限元模型计算结果表明：材料填充可以增加滤波减速器轮齿啮合对数,有效减小啮合力,齿面最大接触力随着填充材料弹性模量的减小而减小。润滑计算结果表明,材料填充可以增大齿面间平均油膜厚度,有效提高滤波减速器润滑性能。在转速小于1 500 r/min时,通过材料填充可以降低接触面积比,转速大于1 500 r/min时,材料填充对接触面积比的影响不明显;在啮入啮出点时,转速大于1 500 r/min时,材料填充可以降低滤波减速器齿面最大接触应力,转速小于1 500 r/min时,最大接触应力随填充材料弹性模量的变化规律不明显;节点啮合时,丁晴橡胶和尼龙1010可以显著降低齿面最大接触应力。     

真空低温下螺钉压紧的Cu-Cu界面间接触热阻的实验研究

为满足航天器热控设计的需要,实验测量了真空条件下接触面温度110 K时螺钉压接的Cu-Cu界面间的接触热阻,比较了不同的螺钉预紧力矩以及不同的导热填料对接触热阻的影响。实验数据表明,界面接触热阻随着螺钉预紧力矩增大成一阶指数衰减,导热填料为铟箔时界面热阻显著的减小,接触热阻最低可以达到2.0×10-5K.m2/W。     

直接蒸发冷却空调填料的性能实验与适用性分析

本文搭建了直接蒸发冷却实验台,对蒸发冷却空调填料的换热性能进行实验测试,研究了填料的材质、进风量、压降对填料热质传递性能的影响。实验结果表明：最优工况下植物纤维填料、泡沫陶瓷填料、PVC填料和金属填料的直接蒸发冷却效率分别为82.93%、71.29%、54.85%和55.34%,植物纤维填料的压降最高,金属填料的压降最低,最适合的进风量不一定是填料传热效率最高的状态点,需要考虑由于填料的压降带来的风机能耗问题。预测了直接蒸发冷却的空调系统在西安市通信机房全年适用小时数,采用植物纤维填料时全年运行4 126 h,全年占比47.10%;采用泡沫陶瓷填料时全年运行3 115 h,全年占比35.56%;采用PVC和金属填料时全年运行2 582 h,全年占比29.47%。