共查询到19条相似文献,搜索用时 93 毫秒
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氨法沉镁是盐湖镁资源综合利用的基本途径,而溶液中少量杂质锂对产品性质的影响一直被忽略。从含锂氯化镁溶液中离子间作用的角度阐述杂质锂对氨法沉镁产物性质影响机制。采用XRD、SEM、FTIR、TGA和激光粒度分析等研究锂杂质对氨法制备氢氧化镁过程及其产物性质的影响规律;在6-311G/B3LYP基组水平对Mg(H2O)2+6和Li(H2O)+4体系进行量子化学计算,解析镁锂离子间的作用机制。结果表明:锂的存在对氨沉产物的晶相、形貌和红外吸收影响较小,但在含锂杂质条件下制备的氢氧化镁产物,(001)弱极性晶面的相对强度有所下降,产物的比表面积明显变小,热失重率随制备过程中锂添加量的变化发生了较为显著的改变。在含锂氯化镁水溶液中,当溶液中Mg2+和Li+间距离小于10时作用能较大;当Mg2+-Li+间距离在7~10时,溶剂化趋势远大于稀溶液,氨沉时OH-更易定向夺氢;首次用电子空间范围计算结果模拟了1 mol/L溶液中离子间作用模型,发现锂离子的存在会使溶剂化自由能的ΔG(solv)绝对值大幅减小。 相似文献
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《稀有金属材料与工程》2001,18(3):43-45
分析了钛及钛合金中特殊污染层的产生原因,详细介绍了用氟化氢氨溶液腐蚀金相法观察检测特殊污染层的方法和步骤。结果表明,氟化氢氨溶液腐蚀金相法观察钛及钛合金的特殊污染层是一种有效、直观、经济和值得推广的方法。 相似文献
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分析了海绵钛残留氯化镁对钛及钛合金熔铸的影响。在钛及钛合金铸锭生产过程中,由于氯化镁吸湿现象导致压制的电极块出现白色析出物、一次锭表面有潮湿的黑斑以及真空系统内沉积物水化等现象。残留氯化镁对真空熔炼及设备的危害主要有:①增大发气量,降低熔炼真空度;②使铸锭气体杂质含量偏高,气孔增加;③使铸锭中残留的高熔点颗粒增加;④腐蚀真空系统,降低设备寿命。最后对出现的问题,提出了相应的预防措施。 相似文献
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现行的Kroll法生产海绵钛存在的问题是镁电解的投资较高,以及氯的环境污染控制要求较高。基于此,本工作提出了将还原蒸馏产生的熔融态氯化镁直接氧化热解得到高纯氧化镁及氯气,氧化镁经热还原法炼镁,实现海绵钛过程新的镁钛联合。本工作对新的镁钛联合关键环节熔融态氯化镁氧化热解过程进行了研究,通过绘制Mg-O-Cl体系优势区图,获得Mg O相稳定存在的条件;确定了适宜的反应条件:反应温度1200℃、输入氧分压0.1 MPa,反应时间为50 min,该条件下,氯化镁的热解率可达99.9%,产物中氯含量为0.00262%;XRD和SEM分析表明:氧化镁结晶度高,颗粒粒度分布均匀,分散性较好,为不规则的六面体,氧化镁颗粒的平均粒度在1μm左右。 相似文献
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盐湖卤水硼镁分离工艺及高纯氧化镁的制备 总被引:1,自引:0,他引:1
以富含硼、镁、锂的盐湖卤水为原料,采用硫酸和离子交换法联合提硼,实现硼与镁、锂分离;采用氨法沉淀镁实现镁与锂的分离。分别用静态法和动态法研究卤水pH值、吸附温度、吸附时间、树脂用量、卤水流速、交换柱高径比对硼提取率的影响,确定提硼最佳工艺条件,硼提取率达95%以上。研究卤水硼浓度对氢氧化镁中硼含量的影响。结果表明:当卤水中的硼浓度由4.54 mg/L增加到1 200 mg/L时,氢氧化镁中硼含量由0.04 mg/g增加到8.82 mg/g。对硼浓度4.54 mg/L的卤水用氨法沉淀制备氢氧化镁,在1 500℃下煅烧得到氧化镁,其纯度为99.8%。 相似文献
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《稀有金属材料与工程》2000,17(6):37-39
钛作为一种重要的稀有金属,具有质量轻、耐腐蚀、耐磨损的特点,广泛用于航空、航海、化工、石油等工业部门。在工业化生产海绵钛的工艺中,镁还原-真空蒸馏是最有竞争力的工艺,在海绵钛生产中占主导地位。随着设备的大型化和自动化程度的提高,镁法生产海绵钛的成本已接近民用的范围,产品质量亦逐渐提高。因此钛的应用具有广阔的前景。镁法生产海绵钛是在高温和惰性气体保护下,在密闭的反应器中用镁还原四氯化钛,得到钛和氯化镁,最后用真空蒸馏或浸出的方法除去钛坨中残留的镁和氯化镁杂质,得到纯净的海绵钛。还原过程中被镁从四氯… 相似文献
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以纯钛为原料,经等通道转角大应变加工处理得到超细晶纯钛,采用微弧氧化法对纯钛和超细晶纯钛表面进行了改性处理,研究了改性处理对样品的表面形貌、润湿性和耐腐蚀性等的影响。实验发现微弧氧化处理后,虽纯钛及超细晶纯钛表面均形成多孔氧化膜层、接触角减小、表面粗糙度和表面能提高,但与纯钛相比,超细晶纯钛腐蚀速率与电流密度较纯钛的更小。因此,经微弧氧化法改性后,超细晶纯钛比纯钛更适合应用于医用植入物领域。 相似文献
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The magnesium ingots from factory A, B and C were remelted. The microstructure and property of un-remelted and remelted magnesium ingots were investigated. The results indicate that the microstructure and property of the remelted magnesium alloy take on a hereditary transmission similar or resembling to those of feed materials. The characteristics of the short range order structure atomic group in alloy is the same as or resembles to that of feed materials during the melting process. The hereditary transmission of magnesium alloy can be explained by atomic conglobation theory. 相似文献
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Preparation and properties of superfine Mg(OH)2 flame retardant 总被引:12,自引:0,他引:12
1 Introduction With the fast development of the macromolecule industry,the macromolecule synthetic materials such as plastic, synthetic rubber and synthetic fibre are used in a wide range of fields of building materials, household appliances, plane and au… 相似文献
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Magnesium phosphate conversion coating (MPCC) was fabricated on AZ31 magnesium alloy for corrosion protection by immersion treatment in a simple MPCC solution containing Mg2+ and PO3?4 ions. The MPCC on AZ31 Mg alloy showed micro-cracks structure and a uniform thickness with the thickness of about 2.5 µm after 20 min of phosphating treatment. The composition analyzed by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy revealed that the coating consisted of magnesium phosphate and magnesium hydroxide/oxide compounds. The MPCC showed a significant protective effect on AZ31 Mg alloy. The corrosion current of MPCC was reduced to about 3% of that of the uncoated surface and the time for the deterioration process during immersion in 0.5 mol/L NaCl solution improved from about 10 min to about 24 h. 相似文献
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Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique. It was found that the mass gain increased rapidly at the beginning of exposure and then slowly with time. The corrosion morphologies were observed and the results showed that NaCl deposition resulted in the occurrence of localized corrosion. The composition of corrosion product was analyzed using X-ray photo electron spectroscopy. It was suggested that the corrosion product was a mixture of oxide and hydroxide of magnesium and aluminum. 相似文献
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Corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition was investigated.The results show that corrosion potential shifts positively and the corrosion current density decreases at low wet-dry cyclic time.Further increase of the cyclic time results in the negative movement of corrosion potential and the increase of current density.SEM observation indicates that corrosion occurs only inαphase,βphase is inert in corrosive medium,and the corrosion of AZ91 magnesium a... 相似文献