High-temperature mechanical properties of Inconel-625: role of carbides and delta phase

Based on the temperature sensitivity characteristics, high-temperature tensile tests were performed at different temperatures and after different solid solution treatments to investigate the effect of Cr-rich M₂₃C₆, Nb-rich MC and the delta phase on the mechanical properties of Inconel 625. The experimental results indicated that the Cr-rich M₂₃C₆ carbides and the Nb-rich MC carbides decomposed at 700°C, which could be the reason for resulting tensile strength anomaly that was observed in a narrow temperature range from 650 to 700°C during the tensile tests at different temperatures. For the samples subjected to a prior solid solution treatment, the size of the δ phase was found to increase with the solution treatment temperature, whereas the elongation at fracture decreased.     

基于MC9328MX1的家庭智能控制终端系统中BOOTLOADER设计

BOOTLOADER设计是嵌入式系统开发中一项非常重要的工作，文中阐述了BOOTLOADER程序的功能和用途，给出了BOOTLOADER程序的设计思路，并基于具体的硬件电路设计了一个BOOTLOADER程序。应用结果表明，这种设计方法是可行的。     

熔模铸造条件下K424合金枝晶间缩松及微观偏析研究

结合熔模铸造条件下K424高温合金出现的高温持久性能下降的问题,对所存在的一些缺陷进行了研究,对缺陷的形态、成因以及对高温持久性能的影响进行了阐述。借助扫描电子显微镜、显微硬度计等仪器对K424合金试棒进行了观察和测试。结果表明,试棒的枝晶间存在显微缩松。显微缩松附近有呈规则正八面体的MC碳化物聚集。Cr元素发生了较严重的偏析。显微缩松是相邻枝晶臂搭接,剩余液相被封闭在晶间区域收缩而成。显微缩松在高温持久测试时引起应力集中,作用于薄弱的晶间组织,导致高温持久性能不足。     

Insight of corrosion mitigation performance of SABIC iron in 0.5 M HCl solution by tryptophan and histidine: Experimental and computational approaches

The inhibitory strength of two amino acids namely, tryptophan (Tryp) and histidine (Hist) on the corrosion of SABIC iron (SABIC Fe) in a 0.5 M HCl solution was examined utilizing mass loss (MS), electrochemical (PDP and EIS) and theoretical studies. Density functional theory (DFT) and Monte Carlo (MC) simulation were inspected for Tryp and Hist inhibitors. All the corrosion parameters and theoretical data obtained from these studies confirm the inhibiting impact of the two amino acids. The efficacy of inhibition augment with augmentation the concentration of two amino acids from 100 to 500 ppm and reducing at elevated temperature. The effectiveness of the inhibition depends on the presence of some active centers that accelerate the adsorption process and the molar mass of the inhibitors. The inhibition efficacy of Tryp is greater than that of Hist reaching 92.09% at a concentration of 500 ppm while in the presence of Hist it is 89.37% using PDP measurements. Inhibition was demonstrated by spontaneous adsorption of Hist and Tryp on the surface of SABIC Fe according to the Langmuir adsorption isotherm. PDP curves clarified that the Tryp and Hist compounds acted as mixed type inhibitors. A variety of thermodynamic and kinetics parameters were computed and explained. SEM images demonstrate that the protective layer constructed on the surface of S– Fe in the presence of both amino acids. The results obtained from DFT are in complete agreement with the experimental work. Tryp and Hist compounds are adsorbed horizontally onto the surface of Fe (110).     

Effects of oily contamination and decontamination on the flame resistance of thermal protective textiles

This paper reports an experimental study wherein flame resistance and limiting oxygen index of protective fabrics were determined before and after contamination with oil and after decontamination. Experimental variables were presence of contamination, laundry treatment, number of contamination/decontamination cycles, and fabric type. Although laundering with pre‐wash products alone was the most effective in removing oil, some product residues may have contributed to the increased flammability of some fabrics. Thus, use of that product was truly effective only if combined with detergent. For two fabrics higher flammability was noted after five contamination/decontamination cycles than after one. Of the three fabrics studied, aramid specimens retained the least oil, and although they had the highest flammability both before and after contamination, it increased the least with contamination. The FR cotton/nylon fabric retained the most oil after decontamination, but had better flame resistance than aramid. Much of the oil remained in the interior of cotton fibres making it difficult to remove but also less accessible for vaporization and combustion. For the aramid/FR viscose, energy from combustion of residual oil activated the FR additive, thereby reducing apparent fabric flammability, but this FR transference effect occurred only up to an optimum quantity of oil. Copyright © 2010 John Wiley & Sons, Ltd.     

改性马来酸酐橡胶接枝物增韧尼龙6的制备及表征

为了促进橡胶接枝物与尼龙6(PA6)的相容性并提高增韧效果,利用马来酸酐和对苯二胺合成了一种含酰胺键的二元羧酸,命名为对苯马来二酰胺二酸(改性马来酸酐,MDMA),并将MDMA接枝到三元乙丙橡胶(EPDM)上,制备出不同接枝率的改性马来酸酐橡胶接枝物(EPDM-g-MDMA),以EPDM-g-MDMA与PA6质量比为30∶70,通过共混挤出制备了含不同接枝率接枝物的EPDM-g-MDMA/PA6共混物。通过核磁共振和红外光谱对MDMA进行了测试,表明成功合成了所需要的二元羧酸。对共混物进行了相容性测试、DSC、熔融指数(MI)、SEM、拉伸和冲击力学性能测试。结果表明:随着接枝率的增大,共混物的熔融峰温度略有降低,其熔体黏度不断增大,橡胶接枝物在PA6基体中有良好的分散性,使EPDM-g-MDMA/PA6共混物的冲击强度提高了5.5倍,说明EPDM-g-MDMA对PA6的增韧效果较为明显。     

尼龙66纤维/6061铝合金复合板静电植绒工艺及隔声性能

为研究不同植绒工艺条件下尼龙66纤维/6061铝合金复合板的植绒性能与隔声性能,首先,采用静电植绒工艺将6061铝合金板与尼龙66纤维复合,制成隔音复合板;然后,研究了植绒时间、植绒电压、极板间距以及胶黏剂涂覆量等工艺参数对植绒面密度和植绒纤维耐磨性能的影响;最后,利用混响室-消声室法研究了尼龙66纤维/6061铝合金复合板在不同入射声频下和不同纤维结构参数时的隔声性能。结果表明:在0~40s植绒时间范围内,随着植绒时间的延长,植绒面密度持续增大,而后保持不变;同时,在0~90kV电压范围内,随着电压的增加,植绒面密度连续增大,而后因极板间距不同植绒面密度增大或减小;植绒纤维的耐磨性能随胶黏剂涂覆量的增加而提高,但当涂覆量超过155g/m2后会产生气泡;当植绒时间为40s、植绒电压为90kV、极板间距为11.5cm且胶黏剂涂覆量为155g/m2时,尼龙66纤维/6061铝合金复合板的性能最好。该复合板具有较高的中高频隔声性能,隔声量在500~1 600Hz频率范围内满足6dB/倍频程规律;在2 000Hz后出现吻合效应。提高植绒面密度以及减小尼龙66纤维直径均可增大该尼龙66纤维/6061铝合金复合板的隔声量。研究结论可为建筑用新型隔音复合材料的开发与应用奠定基础。     

基于集成电路的控制力矩陀螺控制系统设计

控制力矩陀螺(CMG)作为姿态控制执行机构,相比于传统控制方法有诸多优势,同样也对机电控制系统有更高的性能要求。提出了一种基于MC33035、L298N和STC12C5A60S2等集成电路的CMG控制系统,介绍了系统构成,分析并设计系统各部分硬件电路及相应软件。通过该系统实现了对CMG的有效控制,并给出测试波形及实验结果。     

锦纶现状及展望

本文简要介绍了我国锦纶纤维发展的现状，着重分析了锦纶工业建设中的主要问题和失误的原因．并对锦纶纤维今后发展的前景和应该采取的对策进行了简单的的阐述。     

β-环糊精磺酰化及改性聚酰胺纤维研究

以对甲苯磺酰氯（β-TsCl）直接在β-环糊精的2号碳仲羟基处进行取代反应，合成了β-环糊精-2-磺酰酯，借助IR、UV以及溶解度的测定对产物进行了表征．探讨了β-环糊精-2-磺酰酯的合成条件及其对聚酰胺纤维的改性应用．结果表明：用β-环糊精-2-磺酰酯对聚酰胺纤维进行改性，将环糊精接到聚酰胺纤维上，可以改善聚酰胺纤维的吸水性、染色性等性能．