一种适用于稀土萃取车间的高精度超声波流量计的设计

基于时差法原理和高精度的设计思想,针对稀土萃取生产车间强酸强碱的特殊环境、多电机运转的特殊场合以及不能够改装原有管道的特殊条件等问题,分析了时差法的测量原理,研究了抗电磁干扰的设计方法,提出了一种基于STM32单片机和TDC-GP22高精度时间测量芯片的超声波流量计系统设计,在保证其精度的同时,大大简化了硬件外围电路的设计,有效地防止了电磁干扰的问题,改善了稀土萃取车间管道流量的监测问题,增加了企业效益。     

反应条件对氢氧化钇及氧化钇形貌的影响

以氨水和硝酸钇为原料制备氧化钇前驱体,考察表面活性剂及其用量对晶粒形貌和尺寸的影响;并在水热条件下研究体系pH、温度及时间对沉淀重整效果的影响.用XRD,SEM技术检测样品的晶型、尺寸和形貌.结果显示,阴离子型表面活性剂的浓度对一级晶粒的尺寸有较明显的影响,而阳离子型表面活性剂和非离子型表面活性剂的浓度对一级晶粒的尺寸的影响不明显.水热条件下对沉淀进行重整,可制备氢氧化钇纳米棒,溶液的碱浓度、温度及时间影响纳米棒的直径和长度.样品经600 ℃焙烧2 h,可制得立方晶相氧化钇,一级晶粒7～20 nm;氢氧化钇纳米棒焙烧后形成的氧化钇仍具有棒状结构.     

水对皂化P507萃取稀土的影响

研究了P507和皂化P507对水的萃取行为,并针对氯化镧的萃取,研究了皂化P507萃取稀土过程中水在有机相中的分布。结果表明:盐酸的存在会抑制水进入P507中,NH~+_4的存在会促进水进入P507中;氨皂化后的P507更易萃取水;萃取时提高相比(V_O∶V_A)有利于缩短皂化P507萃取稀土的分相时间,避免乳化现象发生。     

皂化P507对Fe~(3+)和Fe~(2+)的萃取行为

研究了皂化P507对Fe~(3+)和Fe~(2+)的萃取行为,考察了萃取相比、料液pH、Fe~(3+)质量浓度等因素对萃取的影响。结果表明:氨皂化后的P507对Fe~(3+)有很强的萃取能力;在相比Vo∶Va=3∶1、料液pH为0~2、Fe~(3+)质量浓度0.7g/L条件下,Fe~(3+)萃取率接近100%;但在料液pH≥1.5条件下,部分皂化P507进入下层水相形成水包油型乳化物,导致乳化现象发生;部分Fe~(3+)水解后被皂化P507萃取;皂化P507对Fe~(2+)的萃取过程没有出现乳化现象,Fe~(2+)萃取率随料液pH降低及Fe~(2+)质量浓度升高而降低;P507对Fe~(3+)的萃取能力大于对Fe~(2+)的萃取能力。     

钕铁硼永磁材料腐蚀机理及表面防护技术现状

综合论述钕铁硼永磁材料的物相组成、腐蚀机理以及表面防护工作,阐述了钕铁硼永磁材料高温氧化、湿热吸氢和电化学腐蚀的腐蚀特性以及电镀、化学镀该领域应用现状以及这些技术的基本原理、技术特点、研究现状及发展趋势。     

Effect of mechanical attrition on microstructure and properties of electro-deposition coatings on NdFeB

Surface mechanical attrition treatment （SMAT） was developed to synthesize nanostructure coatings on alloy surface. The SMAT action was applied in the process of Ni and Cu electroplating coatings on NdFeB substrates in this paper. The role of mechanical attrition during barrel plating on the microstructure, mechanical and corrosion resistant properties of the coatings was exam- ined. The scanning electron microscopy （SEM） observation showed that the mechanical attrition could refine grain size, markedly smooth the coating surface and obviously decrease the number of pore in the coatings. The continuous collisions of glass balls onto the NdFeB samples could induce more beneficial nucleation defects on the coating, which was helpful for increasing nucleation sites and the nucleation rate. The mechanical attrition could also restrain the heterogeneous growth of the coating grain tips due to the abra- sive action of stainless steel balls. The Tafel polarization curve experimental results indicated that SMAT process could enhance the corrosion resistance of coatings on NdFeB. The scratching test revealed that the binding force between coating and NdFeB substrate could be improved dramatically with SMAT process.