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51.
52.
为研究石油套管钢(34Mn6)中夹杂物的演变规律,对钙处理效果进行精准化控制,进行全流程取样分析,通过采用SEM-EDS分析夹杂物形貌和成分,同时结合Aspex夹杂物自动分析仪统计夹杂物的数量、成分和尺寸分布。研究结果表明,LF精炼具有较好的脱硫与脱氧能力;钙处理前,由于渣钢反应的进行,夹杂物数量明显减少,夹杂物成分中SiO2含量增加;经过钙处理后,夹杂物成分发生显著变化,由MgO-Al2O3系转变为MgO-Al2O3-CaO系和SiO2-Al2O3-CaO系,夹杂物形貌由尖角夹杂向球状夹杂过渡。在铸坯中,夹杂物数量减少,其成分已偏离液相区,向富CaO区域移动。对钙处理进行优化,通过利用热力学软件FactSage进行计算,得出钢液中钙的质量分数稳定在0.001 3%时对夹杂物的改性效果最佳,钢液中的夹杂物控制较好。 相似文献
53.
H.B. Li G. C. Yao Z.Q. Guo Y.H. Liu H.J. Yu H.B. Ji 《金属学报(英文版)》2006,19(5):355-361
Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys ormalin. while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength (UTS) and yield strength (YS) of the alloy with lwt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3phase worsens the elongation. 相似文献
54.
以一种简便的方法制备了环氧基保留完好的高纯度环氧脂肪酸钙/锌,并对其热稳定性进行了研究。研究表明,环氧脂肪酸钙/锌对聚氯乙烯(PVC)的热稳定作用类似于硬脂酸钙/锌,但其热稳定效能明显优于后者,环氧脂肪酸钙比硬脂酸钙具有较好的初期着色性,环氧脂肪酸锌较硬脂酸锌具有较长的“锌烧”时间。 相似文献
55.
介绍了以山西运城南风自产芒硝为原料生产精制元明粉的几种工艺,以及国内外精制元明粉的市场及生产状况.精制工艺包括化学除杂法、原料优选法、重结晶法.结果表明,精制元明粉的生产过程实质是一个除杂、提纯过程:对于钙离子含量高的原料,可采用化学除杂法;对于氯离子含量高的原料,可采用氯离子富集法、冷冻法或洗涤法;镁离子较难去除,可采用水硝洗涤、冷冻法. 相似文献
56.
Soil incubation studies were undertaken in controlled environment cabinets at 15°C to investigate the effect of increasing application rates of calcium ammonium nitrate (CAN) on net nitrification in two grassland soils. Granular CAN was applied to the surface of freshly collected, moist soil, at a rate equivalent to 0, 100, 200, 400, 800 and 1600µg NH
4
+
-N and NO
3
-
-N per gram of oven dry soil. In half the treatments finely ground CaCO3 was incorporated into the moist soil to raise the starting pH. Changes in soil mineral N and pH were measured at weekly intervals up to six-weeks. The most probable number (MPN) technique was used to enumerate the NH
4
+
-N and NO
2
-
-N oxidizers at the beginning and end of the incubation.At low rates of CAN application there was considerable NH
4
+
-N oxidation to NO
3
-
-N during the incubation of both soils. Lime stimulated this N transformation. At high application rates (i.e. 800 and 1600 ppm) there was little change in NH
4
+
-N or NO
3
-
-N on either soil during the 6 week incubation, in the presence or absence of lime. The rate of NO
3
-
-N produced peaked at 5.6 and 3.8 mg NO
3
-
-N kg–1 d–1 on soil 1 and 2 respectively, in the presence of lime. Above a level of 400 ppm CAN (equivalent to 38 kg N ha–1) the rate of NO
3
-
-N produced decreased. The higher rate of net nitrification in soil 1 compared with soil 2 was probably due to a higher number of nitrifying bacteria. Although high rates of CAN decreased the nitrifying activity of both soils there was little difference between treatments in the actual numbers of NH
4
+
-N and NO
2
-
-N oxidizers determined by the MPN technique.The results showed that the rate of granular CAN applied to the soil surface can influence the local activity of nitrifying bacteria and subsequent N transformations. At application rates of CAN generally used agriculturally for grass production, it is likely that net nitrification of the NH
4
+
-N in the fertilizer granule will be inhibited. 相似文献
57.
介绍了纳米碳酸钙原位聚合聚氯乙烯的结构和性能,同时对该树脂进行了有关的应用试验,并对其发展前景作了科学展望。 相似文献
58.
系统地研究了用空气——乙炔火焰原子吸收光谱分析法测定高纯石英粉中钙的最佳条件,建立了14%的乙醇作为增感剂,在2%盐酸介质中,0.4% LaCl3溶液作为释放剂,用塞曼火焰原子吸收法测定的可行性方案,探讨了共存元素对钙的干扰及其消除。方法操作简便快速,干扰少,方法相对标准偏差小于3%,适用于日常分析石英粉中的杂质。 相似文献
59.
稀土复合热稳定剂对聚氯乙烯性能影响研究 总被引:7,自引:0,他引:7
主要以有机锡热稳定剂为对比物,研究了稀土热稳定剂对聚氯乙烯(PVC)的热稳定性及其他性能的影响。稀土热稳定剂对PVC的力学性能、加工性能都有不同程度的提高,稀土热稳定剂的热稳定性能符合PVC的加工条件要求,并研究了抗冲改性剂ACR(丙烯酸酯共聚物)对体系的影响。 相似文献
60.
Nucleation and crystallization of polypropylene by mineral fillers: relationship to impact strength 总被引:3,自引:0,他引:3
P.M. McGenity J.J. Hooper C.D. Paynter A.M. Riley C. Nutbeem N.J. Elton J.M. Adams 《Polymer》1992,33(24):5215-5224
The mechanical properties of mineral-filled polypropylene (PP) are determined not only by the size, shape and modulus of the filler particles, but also by microstructure. For example, poor impact strength is correlated with a high capacity for nucleation of crystallization. In the present study, optical microscopy has been used to measure the growth rate of spherulites in PP. In tandem with this, isothermal d.s.c. measurements have been made of the crystallization of the PP filled with talc, calcium carbonate and stearate-coated carbonate at different loading levels. Computer simulation of spherulite growth has been used to derive the number of nucleating sites per unit volume of polymer and, using surface area measurements, the number of sites per unit area of mineral surface was obtained. Values for talc were, as expected, considerably higher than those for carbonate (and especially coated carbonate) fillers. The presence of filler affects not only the nucleation and kinetics of the crystallization process but also the crystallinity and orientation indices and the proportion of β-phase crystallites present. The connection between these factors and impact strength is discussed. It is concluded that impact properties are determined by inter alia crack pinning and blocking by filler particles, stress concentrations at the edges of the filler particles, and the nucleating ability of the filler. 相似文献