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排序方式: 共有1599条查询结果,搜索用时 15 毫秒
1.
Nicolas Larché Benoit Emo Audrey Allion Elisabeth Johansson Dominique Thierry 《工业材料与腐蚀》2021,72(8):1338-1349
With lower alloying cost and higher mechanical properties, lean duplex stainless steels can be an alternative to the more commonly used austenitic stainless steels. However, these alloys are still not the preferred choice, probably due to a lack of field experience. A study was thus initiated in view of defining the limits of use of selected (lean) duplexes for urban wastewater treatment units. The present paper shows the localized corrosion performance of selected lean duplexes in chloride contaminated solutions. The results are compared with austenitic S30403 and S31603 and with the more standard duplexes S82441 and S32205. The effect of welding was also investigated. Exposures in field municipal wastewater plants were conducted for 1 year in low and high chloride content units. The results show that lean duplexes S32101 and S32202 can be used as alternatives to S30403 and S31603 in low chloride electrolytes. At 500 ppm of chloride content, duplex stainless steel S32304 showed better corrosion resistance than S30403 and S31603. For higher chloride contents (1000 ppm and above) the standard duplexes S82441 and S32205 shall be preferred. 相似文献
2.
The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions. 相似文献
3.
分析了建筑陶瓷企业实施精益生产的条件和当前推行精益生产的主要障碍,对应用中存在的问题进行了分析并提出了相关建议。 相似文献
4.
5.
深入阐述了牙膏增稠的流变学理论,同时,介绍了用于生产牙膏的儿种主要增稠剂的性能及其在牙膏配方中的应用。流变学理论和黏合剂化学技术的有机结合直接导致了新型牙膏配方产品的诞生。 相似文献
6.
The reduction of NO
x
with propene or propane in the presence of 1 or 4% O2 was studied at low conversions over a 7.4 wt% Cu-ZrO2 and a 3.2 wt% Cu-ZSM-5 catalyst. The rates of N2 production were compared in experiments using only NO or a mixture of NO and NO2 in the feed. They were also compared with the rates of NO2 reduction to NO under the same conditions, and of NO oxidation to NO2 in the absence of hydrocarbon. It was found that the reduction of NO2 to NO was very fast, consistent with literature data. The data were best explained by a reaction scheme in which the hydrocarbon was activated primarily by reaction with adsorbed NO2 to form an adsorbed oxidized N-containing hydrocarbon intermediate, the reaction of which with NO was the principal route to produce N2 under lean NO
x
conditions.On leave from State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China. 相似文献
7.
The dissolution rate coefficients of Cr‐substituted (0‐20 at.% Cr) iron oxides viz. hematite and magnetite were determined by using an inverse cubic rate (ICR) law applicable for spherical particles as well as by a general kinetic equation (GKE) applicable for polydispersed particles. An attempt is made to compare both the treatments for different kinds of dissolution profiles obtained by employing oxides with narrow particle size distribution in V(II)‐EDTA and citric acid‐EDTA‐ascorbic acid formulations at 353±5K. The dissolution profiles could be classified into three types based on the nature of oxide and formulations. It is observed that both ICR and GKE treat the dissolution course as a function of decrease in fraction of undissolved mass, m/m0. The dissolution rate coefficients determined by ICR and GKE have shown the similar trend of decrease with increasing Cr content of the oxides and was ascribed to lattice stabilization. 相似文献
8.
The flotation of pure and natural carbonaceous iron ore samples in the oleate flotation system was investigated. Starch can
depress hematite effectively in a wide pH range, but cannot depress siderite efficiently in neutral conditions. The flotation
recovery of pure hematite, siderite, and quartz in the oleate-starch-CaCl2 system is significantly different when the slurry pH varies from 4 to 12. A novel two-step flotation process was developed
for the separation of iron concentrate from Donganshan carbonaceous iron ore through which the siderite concentrate is first
recovered and the high quality hematite concentrates with relative high iron recovery can be obtained in the second step flotation.
The siderite concentrate may be utilized directly or undergo further concentration steps to increase iron grade. 相似文献
9.
贫瘦煤替代瘦煤制备优质焦炭性能研究 总被引:1,自引:0,他引:1
根据瘦煤和贫瘦煤结焦机理、成焦显微结构和粒度变化特征,对贫瘦煤替代瘦煤的结焦显微结构、焦炭性能进行了研究。结果表明,瘦煤与贫瘦煤可以互相替代,并且在合理配比的情况下可改善焦炭质量;通过合理的粒度调整和配煤,在提高贫瘦煤或瘦煤比率的同时亦可得到优质焦炭。 相似文献
10.
The H2/NO/O2 reaction under lean-burn conditions has been studied by means of in situ DRIFTS, reactor measurements and temperature-programmed desorption with the aim of understanding the very different behavior of Pd/TiO2 and Pd/Al2O3 catalysts. The former deliver very high NO
x
conversions (70-80%) with good N2 selectivity whereas the latter show very low activity. In addition, PdTiO2 exhibits two distinct NO
x
reduction pathways, thus greatly extending the useful temperature range. It is shown that the PdTiO2 low-temperature channel involves adsorption and subsequent dissociation of NO on reduced (Pd0) metal sites. The low activity of PdAl2O3 is a consequence of palladium remaining in an oxidized state under reaction conditions. The high-temperature NO reduction channel found with PdTiO2 is associated with the generation and subsequent reaction of NH
x
species. 相似文献