激光表面处理对工业级锆基块体非晶合金弯曲变形和缺口韧性的影响

目的 改善块体非晶合金的弯曲力学性能,同时考虑航空结构材料选材的经济性,研究激光表面处理工艺对工业级Zr_49.7Ti₂Cu_37.8Al₁₀Er_0.5块体非晶合金弯曲变形和缺口韧性的影响规律。方法 采用低纯原料和低真空制备条件获得工业级Zr_49.7Ti₂Cu_37.8Al₁₀Er_0.5块体非晶合金试样,考虑到弯曲条件下试样受到拉伸和压缩2种正应力状态,研究不同处理工艺和激光处理表面对试样弯曲变形和缺口韧性的影响。结果 当激光处理表面位于弯曲试样的2个侧表面时,其对试样的塑性变形能力和断裂强度没有明显的影响,但会显著降低试样的缺口韧性,从(56.4±3.4)MPa·m^1/2降低到(26.2±4.8)MPa·m^1/2;激光处理表面位于弯曲试样的受拉侧时,试样的弯曲断裂强度从2 150 MPa降低到1 800 MPa;当激光处理表面位于...     

金属材料实验室加速腐蚀环境谱等效加速关系的确定方法

目的 解决现有实验室加速环境谱等效加速关系确定方法的不足。方法 提出一种针对航空金属材料实验室加速腐蚀环境谱与实际大气间等效关系的“双桥连接式”快速确定方法。结果 该方法以金属材料在腐蚀环境下的质量损失情况作为腐蚀当量,通过基于“环境因素加权浓缩”的方法编制实验室加速环境谱、基于“电量（电流）等效桥”获得实际大气环境长年累积腐蚀电量、基于“质量损失等效桥”确定等效加速关系3个步骤,计算获得了实际大气长年监测数据对应的材料累积腐蚀电荷量和腐蚀质量损失大小。通过将金属材料在实际大气下和实验室加速环境下的腐蚀质量损失速率相比,获得了金属材料的等效加速关系。结论 该方法能够有效克服现有研究中由于缺少实地长时间大气暴晒件,以及当量参数选取不当引入误差,导致无法获取实验室加速腐蚀环境谱和实际大气环境间等效加速关系（或当量加速关系）的不足,为金属材料实验室加速腐蚀试验提供了方法支撑。     

多孔矿物-聚磷酸铵对甲烷爆炸的协同抑制研究

为探究新型多孔矿物(MTS)-聚磷酸铵(APP)复合粉体对甲烷-空气预混气爆炸的抑制效果,采用20 L球形爆炸装置开展多孔矿物、APP及其复合粉体在不同组成、不同添加浓度条件下的甲烷爆炸抑制试验,并使用热分析仪研究其热解行为.研究结果表明:当粉体添加量为0.100 g/L,多孔矿物与APP质量组成比为1∶3时,复合粉体...     

Thermal barrier coated diesel engine running on biodiesel: a review

Thermal barrier coated diesel engine, also known as low heat rejection (LHR) engine have offered the promise of reducing heat rejection to the engine coolant and increase the combustion temperature which results in increase of thermal efficiency, decrease of fuel consumption and emission rate of the engine. Biodiesel derived from the vegetable oils are a promising alternative fuel for diesel fuel. The viscosity of vegetable oil after transestrification is still higher than that of diesel fuel. The various researchers have reported that the energy of the biodiesel could be released more efficiently with the concept of LHR engine. In the case of LHR engine running on different biodiesel blends, almost all experimental studies has predicted improved performance. This paper analyses and discussed the operating conditions under which the experimental studies are carried out and the factors which affect thermal efficiency and exhaust emissions in LHR engine.     

对纳米医学材料安全性问题的思考

笔者在综合国内外研究的基础上,从风险辨识、剂量反应阈值、接触阈值、风险评价、风险管理等5个步骤进行了危害分析和控制,提出了"人体、社会环境以及纳米医学材料"三者所构成系统的安全评价模型,认为其过程可分3步来进行;针对该模型提出建立健全相关法律、法规、质量和安全标准等8项安全对策措施,以降低纳米医学材料带来的风险。     

浅谈汽车内饰材料挥发成雾性测试

汽车内饰材料中所含挥发性物质的释放是造成车内环境污染最直接的也是最主要的原因。对汽车内饰材料进行挥发性物质测试的重要方法之一就是挥发成雾性测试。本文中,笔者将对汽车内饰材料挥发成雾性测试的测试原理、测试设备、当前业界流行的主要测试方法和相关的标准作一些介绍。     

Novel materials for environmental remediation of tailing pond waters containing naphthenic acids

A nanofiltration strategy for tailing pond waters (TPWs) that utilizes cyclodextrin (CD)-based polymeric materials as supramolecular sorbents is proposed. Naphthenic acids (NAs) from the Athabasca TPWs are investigated as the target sorbate molecules.The sorption properties of several supramolecular porous materials were characterized using equilibrium sorption isotherms in aqueous solution wherein electrospray ionization mass spectrometry was used to monitor the concentration of NAs in aqueous solution. The characterization of the supramolecular sorbents was performed using ¹³C NMR and IR spectroscopy, while nitrogen porosimetry was used to estimate their surface area and pore structure properties. Independent estimates of surface area were obtained using a chromophore dye adsorption method in aqueous solution.The sorption results for NAs in solution were compared between a commercially available standard; granular activated carbon (GAC) and three types of synthetic materials. The sorption capacities for GAC ranged from 100 to 160 mg NAs/g of material whereas the polymeric materials ranged from 20 to 30 mg NAs/g of material over the experimental conditions investigated. In general, differences in the sorption properties between GAC and the CD-based sorbents were observed and related to differences in the surface areas of the materials and the chemical nature of the sorbents. The CD-based supramolecular materials displayed sorption capacities ranging from 36.2 to 657 m²/g as compared to that for GAC (795 m²/g).     

Performance evaluation of a water mist system in semiconductor wet bench fires

Wet benches are typically utilized in semiconductor facilities for wafer and parts cleaning. Heaters and some flammable liquids, such as acetone and isopropyl alcohol (IPA), are employed during the cleaning process. Wet bench fires have caused serious losses in the semiconductor industry. To assess the fire protection performance, several field tests were performed using a water mist system installed in the wet bench. In this study, acetone pan fuel was used as fire source. The test parameters were operational pressure, pan size, nozzle location, cylinder obstruction and degree of door closure. An appropriate design for operating pressure and the location of water mist nozzles extinguished wet bench fires effectively in the early fire stages. The nozzles are suggested to be fixed above or on the each side of the pan, ensuring that mist can completely cover a pan surface with sufficient momentum. With this suggested design, fires can be extinguished in the pan and do not spread over the wet bench.     

PAH desorption from river floodplain soils using supercritical fluid extraction

Sequential supercritical fluid extraction (SFE) was performed in order to estimate desorption of PAHs from river floodplain soils which contain coal and coal-derived particles. Original soils, soils' light fractions (ρ < 2 g cm⁻³), and <63 μm fractions were studied for PAHs' desorption kinetics. Desorption data were successfully described using a two-site model. Desorption rate constants were one order of magnitude lower than those of “slow” and “very slow” desorption rates from other studies. This suggests very slow and extremely slow desorption. Estimated time scales releasing 99% of total extractable contaminants ranged from decades for 2-4-ring PAHs and hundreds of years for 5-6-ring PAHs. We demonstrate that, despite high soil PAH concentrations which are due to coal and coal-derived particles, the general environmental risk is reduced by the very slow and extremely slow desorption rates.     

滇池富营养化水体新型除藻材料的试验研究

通过实验室小试 (2 0L)和滇池水体围栏扩大试验 (30 0m2 ) ,研究新型轻质除藻材料对滇池湖水中藻类的除藻及净化作用。小试结果表明 ,该除藻材料放入滇池水样实验 2 6d后 ,水质明显好转 ,藻类去除率可达 98% ,COD、TN及TP的去除率达到 38%～ 62 %。滇池湖边 30 0m2 水面围栏扩大试验结果显示 ,除藻材料放入试验区水体 1 0d后 ,水体中藻类含量明显减少 ,水体透光率从 55 %增加到 80 % ,水质状况也有很大改善。研究表明 ,该除藻材料是一种具有研究和应用价值的新型水体除藻材料。