火花放电原子发射光谱多功能光谱夹具的研究与应用

为了解决了目前光谱夹具的单一性问题,研究并开发了多功能光谱夹具,并将其用于火花放电原子发射光谱分析中。多功能光谱夹具是融合了传统的立式和卧式夹具的原理改进而成,通过合理的拆卸设计,完成棒、线、管、片材和球状样品的分析测试。根据卧式光谱夹具的原理,可用于外径或宽度在1.0~10mm之间棒、线、管、片材样品分析;另外该夹具根据立式光谱夹具的原理,将圆球形样品借助不锈钢钢管、弹簧及螺栓完成了向棒材样品转换,通过定位板和V型板的定位,可用于外径在2.5~10mm之间钢球样品的测定。     

LA-ICP-MS测定高纯金中铁含量的不确定度评定

对激光剥蚀-电感耦合等离子体质谱法(LA-ICP-MS)测定高纯金中铁含量的不确定度进行了评定,对标准物质、工作曲线和测量重复性的各分量的不确定度进行分析与计算,并计算出扩展不确定度。结果表明,测定高纯金中的铁含量为2.349 mg/kg时,不确定度为0.836 mg/kg,不确定度主要来源于标准物质的不确定度。     

火花放电原子发射光谱法分析钢铁屑状样品的探讨

屑状样品其外观呈无规则状态,并具有一定的流动性。在一般情况下,它不能完全覆盖仪器的激发孔,无法形成一个密闭的氩气气氛,因此不能采用火花放电原子发射光谱法直接检测。为了能采用该法测定屑状样品,试验将钢铁屑状样品进行分类,根据各类金属屑状样品的强度和硬度选择合适的制样方法,将样品制备成规则的块状样品。其中塑性和韧性较好的样品采用冷压法制样,而超高强度、脆性大以及不适合冷压法制样的样品采用熔融法制样。制备好的样品选择合适的校准曲线,采用控样法,对样品进行定量分析。对样品10个不同部位测定的数据进行统计,测定结果的相对标准偏差(RSD,n=10)均小于2%,符合标准JJG 768—2005中的A级要求。用一级或二级标准物质/样品进行验证,测定值与认定值的差值都在标准物质规定的不确定度范围内。     

Effect of aluminium on the microstructure and mechanical properties of as-cast magnesium–manganese alloys

In this paper, the effect of aluminium on microstructure and mechanical properties of as-cast magnesium–manganese alloy has been investigated by means of X-ray diffraction, optical microscopy and scanning electron microscopy. The results reveal that various Al–Mn intermetallic compounds form with an increase of Al content. As a result, microstructure of AM11 alloy has been effectively refined due to the formation of Al₈Mn₅ phase along the grain boundary, while Al addition is explained as the main reason on refining the microstructure of AM91 alloy due to its higher grain growth restriction factor value of ～4.32. The tensile yield strength (TYS) has been improved steadily from 27.4 to 122.9?MPa with increasing Al content, because of the combined effects of grain boundary strengthening, solid solution strengthening and precipitation hardening behaviours.     

基于C8051F130和MAX038的信号源发生器

以Cygnal单片机C8051F130和波形产生器MAX038为核心,辅以高性能D/A转换器AD7533和AD7303及数字电位器X9C103等外围电路设计了1种信号源发生器.给出了详细的硬件设计方案和软件设计方案.经实际测试,该信号源发生器能输出频率小于15 MHz,幅度200 mV～20 V(VPP)连续可调,占空...     

预应力混凝土用钢绞线应力松弛试验结果不确定度的评定和分析

采用GB／T10120—1996标准规定的方法对预应力混凝土用钢绞线进行了应力松弛试验,根据JJF1059-1999《测量不确定度评定与表示》对试验结果的不确定度进行了评定和分析,提供了评定同类试验结果不确定度的参考依据。     

嵌套模型在航道整治工程中的应用

采用2-D浅水方程建立了嵌套模型。以乌江郭母子滩航道整治工程为例,模型研究了整治河段的水动力学特点以及对上、下游水流条件的影响。结果表明:该方法解决了整治河段近区难以直接获取边界条件的困难,能获得足够的计算精度,还能为工程提供全面的水动力信息,是预测和评估工程的有力工具。     

Tensile creep behavior of notched two-dimensional-C/SiC composite

Tensile creep tests of two-dimensional-C/SiC specimens with double-edge arc notches have been carried out at 1100, 1300 and 1500 °C in vacuum. The matrix cracks on the surface and resonance frequency were examined at different creeping times. At 1100 °C, the creep strains of both smooth and notched specimens were concentrated at the transient stage and the steady creep rates were nearly zero, whereas steady creep rates of notched specimens and smooth specimens were similar at 1500 °C. It has been observed that the creep damage mainly concentrated at the area near the notches. Micro-cracks appeared in the area near the notches and on the cross-points of the woven fiber bundles, and the longitudinal fibers near the notches fractured easily. Both types of curves, namely quantity of micro-cracks vs. time and micro-crack width vs. time, were extremely similar as for the creep curves. In general, micro-cracks developed fast during the first 10 h. It has been noticed that within the first 2 h, the micro-cracks near the notches grow faster than those far from the notches, whereas the growth rate of micro-cracks far from notches was faster than those near the notches after 2 h. This phenomenon indicates the stress redistribution during creep. Damage curves at 1300 and 1500 °C have similar trend, though the damage and the quantity of micro-cracks at 1500 °C are higher than those at 1300 °C.     

Numerical modeling of a microwave plasma CVD reactor

This paper presents the results of numerical simulation of a microwave CVD reactor operating in CW and pulsed regimes. Dependencies of discharge parameters on the hydrogen pressure and microwave power have been studied. The possibility to use the pulse–periodic regime of discharge for deposition of diamond films has been analyzed. It is shown that a pulsed discharge may be used to improve the quality and increase the growth rate of the films.     

载Ag改性桑枝韧皮纤维素/聚乙烯醇复合膜的制备及表征

采用流延法制备了载Ag改性桑枝韧皮纤维素/聚乙烯醇（Ag-T-CMC/PVA）复合膜,并利用XRD、SEM、DSC等分析测试方法研究了该复合膜的结构和性能。结果表明:随着Ag-T-CMC含量增加,Ag-T-CMC/PVA复合膜的力学性能、耐水性及抗菌性能均有提高。当Ag-T-CMC与PVA质量比为2%时,力学性能达到最佳,拉伸强度提高了3.4%。SEM分析表明:Ag-T-CMC均匀分散于Ag-T-CMC/PVA复合膜中,表现出良好的相容性;随着Ag-T-CMC含量的增加,断层逐渐变得光滑平面,在Ag-T-CMC与PVA质量比为2%时,断层最光滑。吸水性能测试表明:Ag-T-CMC能明显降低Ag-T-CMC/PVA复合膜的吸水性。抑菌性能测试表明:Ag-T-CMC/PVA复合膜对大肠杆菌和金黄色葡萄球菌有一定的抑菌效果,且随着Ag-T-CMC含量的增大,抑菌圈直径变大,抑菌效果增强。