一种电磁振动雾化-速凝制造NdFeB合金粉的方法

本文介绍了一种新发明的电磁振动雾化-速凝制金属粉方法,研制了电磁振动雾化-速凝制备金属粉炉,并用该装置制造了NdFeB合金粉,讨论了电磁振动雾化频率、激振力等参数对制粉的影响因素.     

稀土元素镱对木质化学镀镍-磷电磁屏蔽材料的影响

采用在传统的化学镀镀液中添加稀土元素镱的方法制备了木质化学镀Ni-P电磁屏蔽材料.考察了稀土氧化物Yb2O3质量浓度对化学镀镀速、镀液稳定性、Ni-P镀层质量及其电磁屏蔽性能的影响.结果表明,与传统的化学镀方法相比,添加质量浓度为40 mg/L的Yb2O3可分别使Ni-P平均镀速、镀液稳定性和电磁屏蔽性能提高12.6%、36.4%和8.0%,并使Ni-P镀层更加致密、平整和光亮.     

流化床法制备硅化镁的工艺研究

在一定的温度,高纯氢气氛围下,以硅粉、镁粉为原料,于流化床反应器中制备硅化镁.考察了硅粉与镁粉粒度、反应温度、反应时间、不同原料配比以及载气流量对反应的影响.实验结果表明,实验最佳条件是镁粉与硅粉摩尔比为2.05∶1、镁粉和硅粉的粒度在100～160目且粒度相差20目以内、反应温度570℃、反应时间2.0h、载气流量为3.0～5.0 L/min.在此实验条件下,硅化镁的质量含量≥98.3％.     

纳米钛酸镁陶瓷粉体的制备研究进展

钛酸镁粉体是一种非常重要的微波介质陶瓷材料,具有很高的品质因素(Q值)和较低的介电常数,得到了广泛应用。介绍了纳米钛酸镁粉体的主要制备技术,包括沉淀法、溶胶-凝胶法、机械力化学法等,分析了各种制备方法的发展现状、优势及不足。最后,指出了纳米钛酸镁粉体的发展方向。     

超声波振动制备有机改性蒙脱土

采用傅立叶变换红外光谱(FTIR)仪、热重分析仪和X射线衍射仪等手段研究了超声波振动与磁力加热搅拌两种不同方式制备的有机改性蒙脱土(OMMT),通过设计正交实验验证了改性剂的用量、pH值、超声波振动时间和超声波振动功率4个因素对OMMT的层间距的影响,同时,还验证了不同种类的OMMT对聚丙烯(PP)雾化性能的影响。结果表明,相比磁力加热搅拌法,超声波振动制备的OMMT不需加热和搅拌、反应速度快、制备的OMMT层间距更大;通过正交实验得出的最佳方案为选用十六烷基三甲基溴化铵的用量为1.5 g,pH值为7.0或6.5、超声波振动60 min,超声波功率为80%;按照最佳方案采用超声波技术制备的OMMT,对于改善PP的雾化有较好的效果。     

ZnO和金属单质催化尿素醇解法制备碳酸二甲酯的研究

使用不同方法制备ZnO催化剂并对其催化活性进行了比较,选出了高催化活性的催化剂,找到了合成碳酸二甲酯(DMC)的最佳工艺条件并且对催化剂进行了XRD和SEM表征.同时对3种金属单质进行了活性比较,得到镁粉有高的催化活性,并提出了镁粉催化反应的机理.同时,本实验还优化了通气方式.     

超声法合成对二溴苯双格氏试剂

以对二溴苯为原料,采用超声法制备苯基双格氏试剂,用正交实验法考察了反应时间、反应温度、镁粉用量等因素对双格氏试剂和单格氏试剂收率的影响.最佳反应条件是反应温度45 ℃、反应时间45 min、镁粉用量为三倍对二溴苯摩尔数.双格氏试剂收率99%以上,单格氏试剂收率小于0.1%.     

影响可再分散聚合物乳胶粉性能的因素分析

采用喷雾干燥法制备可再分散聚合物乳胶粉。探讨了干燥室进口温度、喷雾液黏度、雾化轮转速及喷雾液进料速率对制备可再分散乳胶粉及其性能的影响,并用扫描电镜对乳胶粉进行表征。结果表明:进口温度为120～140℃、喷雾液黏度在15～20 s、雾化盘转速24 000 r/min、进料泵转速为30～35 r/min时,制备的乳胶粉流动性好、无结块,再分散性优良,满足制备乳胶粉的性能要求。     

电磁振动给料机在配料称量系统中的应用分析

根据粉料自动配料称量系统对喂料设备的要求,简述了电磁振动给料机的结构、工作原理及设计计算方法,提出了电磁振动给料机在设计和安装过程中需要注意的问题,并分析了在调试电磁振动给料机时易出现的问题及解决措施,为电磁振动给料机在粉料自动配料称量系统中的正确应用提高了保证.     

碳微晶结构对球磨制备镁基储氢材料的影响

以杏壳活性炭和煤基碳作为镁粉的助磨剂,用氢气反应球磨法制备了镁基储氢材料,对比研究了这两种不同微晶结构的碳在制备镁基储氢材料时作用的差异。结果表明,杏壳活性炭和煤基碳都是镁粉的有效助磨剂,能防止镁粉发生"冷焊"及粘附现象,得到分散的纳米级镁基储氢材料。杏壳活性炭对镁粉的分散性优于煤基碳,但用煤基碳作助磨剂所制得粉体的粒度更小,储氢密度更大,放氢温度更低。     

A new pulverized biomass utilization technology

Pulverized wood biomass utilization technologies, such as gasification and liquefaction, were discussed. Firstly, pulverization technique of wood biomass by a vibration mill was introduced, and pulverized wood biomass characteristics were evaluated. The wood powder pulverized by the vibration mill had a round shape, and the wood fibers were completely broken. Therefore, the diameter of wood powder was fine and the crystallinity of cellulose was very low. By using this pulverized wood biomass, high temperature gasification experiment and liquefaction experiment were conducted. Gasification experiment was conducted in an entrained down flow gasifire. Since fine wood powder had a high reactivity, the gasification experiment showed the high gasification performance without a tar generation. Liquefaction experiment of wood biomass was conducted in a hot compressed water to produce saccharine. Pulverized wood biomass was also used as a raw material in the liquefaction experiment. By using very fine wood powder, productivity of saccharine increased dramatically.     

EFFECT OF DRYING ON POWDER COATING EFFICIENCY AND AGGLOMERATION IN VIBRO-FLUIDIZED BED

Glass beads of 43 μm were coated in a vibro-fluidized bed by atomizing a fine silica powder together with polyvinyl alcohol aqueous solution. The coating efficiency and weight fraction of the agglomerated particles were measured under various experimental conditions, and their dependencies on the frequency and the direction of vibration were investigated. The coating efficiency and the degree of the agglomeration among core particles correlated well with an index R. The index R was introduced to evaluate quantitatively the drying conditions in a fluidized bed.

Application of vertical vibration on the fluidized bed lowered the coating efficiency somewhat, while it prevented agglomeration. From the experimental results it was confirmed that coating with high quality and high efficiency, where few agglomerates were produced and silica powder was utilized efficiently, was possible in a vibro-fluidized bed with adequate vibration frequency and orientation of the vibration vector.     

EFFECT OF DRYING ON POWDER COATING EFFICIENCY AND AGGLOMERATION IN VIBRO-FLUIDIZED BED

Glass beads of 43 μm were coated in a vibro-fluidized bed by atomizing a fine silica powder together with polyvinyl alcohol aqueous solution. The coating efficiency and weight fraction of the agglomerated particles were measured under various experimental conditions, and their dependencies on the frequency and the direction of vibration were investigated. The coating efficiency and the degree of the agglomeration among core particles correlated well with an index R. The index R was introduced to evaluate quantitatively the drying conditions in a fluidized bed.

Application of vertical vibration on the fluidized bed lowered the coating efficiency somewhat, while it prevented agglomeration. From the experimental results it was confirmed that coating with high quality and high efficiency, where few agglomerates were produced and silica powder was utilized efficiently, was possible in a vibro-fluidized bed with adequate vibration frequency and orientation of the vibration vector.     

氮气雾化微细球形铝粉的生产工艺

介绍了氮气雾化微细球形铝粉的生产工艺,铝锭熔化,雾化制粉、铝粉分级和包装都是在氮气保护中进行,气体雾化器和铝液喷嘴紧密耦合并用高温高压氮气雾化,生产的铝粉颗粒为球形,流动性好,氧含量低,细粉收率高.     

水热法生长Mg（OH）_2晶体研究

以MgCl2.6H2O、NH3.H2O为原料,水作为水热介质,乙二醇作为表面活性剂,研究了在不同温度条件及表面活性剂用量对水热法生长Mg（OH）2晶体的影响。利用X-射线衍射仪（XRD）和扫描电子显微镜（SEM）对所制得氢氧化镁颗粒的晶相和形貌进行了表征。实验结果表明,增加乙二醇的用量,有助于获得结晶性和分散性较好的Mg（OH）2晶体。同时,随着生长温度的升高,Mg（OH）2晶体形貌从球状外形的片状晶体向分散的小晶粒过渡。     

粘合衬用热熔胶全细粉的制备及性能研究

采用“溶涨”粉化法对聚酰胺热熔胶进行制粉 ,通过优化粉化条件 ,制得细粉 (通过 2 0 0目 )达 90 %以上。同深冷粉碎法相比 ,细粉收率高 ,胶粉的应用性能与其相当     

Influence of process parameters on SAC305 lead-free solder powder produced by centrifugal atomization

In the present work, a centrifugal atomizer was constructed in order to study the effects of operating parameters: rotating speed, melt feed rate, shape and size of atomizer, and oxygen content in the atomizer chamber, on the characters of SAC305 powder. It was evidenced from the experimental results that the median size of the atomized powders became smaller with increasing rotating speed, decreasing melt feed rate, and the use of larger atomizer. At same operating conditions, a cup shaped atomizer was able to give approx. 11% finer powder compared to that from a flat-disk shaped one. Median particle size appeared to be smaller with decreasing oxygen content in the chamber. SEM micrographs revealed that SAC305 particles atomized under atmospheric condition were found to form various shapes: ligament, teardrop, flake, and irregular. The shape of powder particles tends to be rounder with decreasing oxygen content in the chamber. Fine particles of SAC305 powder (− 45 μm) containing oxygen less than 100 ppm could be synthesized by purging nitrogen gas into the atomizing chamber. Production yield of the SAC305 powder increased with increasing atomizer's rotating speed, lower melt feed rate, and larger atomizer.     

在配料称量系统中使用的喂料设备

根据粉料自动配料称量系统对喂料设备的要求,简述了电磁振动给料机的结构、工作原理及设计计算方法,提出了电磁振动给料机在设计和安装过程中需要注意的问题,并指出了在调试电磁振动给料机时易出现的问题及其解决措施,为电磁振动给料机在粉料自动配料称量系统中的正确应用提供了保证。     

B位离子共沉-煅烧法制备Ba(Mg1/3Ta2/3)O3微波陶瓷材料

采用钽镁共沉淀法制备ＭｇＴａ２Ｏ６粉体,然后与ＢａＣＯ粉体混合制备Ｂａ（Ｍｇ１／３Ｔａ２／３）Ｏ３（简称ＢＭＴ）微波陶瓷材料,成功地解决了ＴａＣｌ３溶解问题。对钽镁共沉条件和粉体热分解工艺与粉体的平均粒径和钽镁比例关系;ＢＭＴ陶瓷制备工艺与材料的微观结构和微波性能关系进行了研究,制备的ＭｇＴａ２Ｏ６晶相粉体平均粒径为０．３μｍ,最大与最小粒径比为５。制备的ＢＭＴ陶瓷的几乎不含ＢａＴａ２Ｏ６等杂相,     

The influence of bioactive hydroxyapatite shape and size on the mechanical and biodegradation behaviour of magnesium based composite

Reinforcement of hydroxyapatite in magnesium-based composites stands out due to their inherent properties, like, corrosion resistance, osteoconduction, and osteoinduction, apart from the compositional similarity with human bones. This study highlights the shape and size effect of bioactive HA ceramics on microstructural, mechanical, and biodegradation properties of the biocompatible Mg–3Zn based composites, fabricated via spark plasma sintering. Reinforcement of smaller size cylindrical HA (15 wt%) in Mg–3Zn matrix reduced the interparticle spacing. It generated comparatively higher constraint to the matrix deformation, which enhanced the hardness and elastic modulus by 23 and 16%, respectively, as compared to round HA. Qualitative behaviour of the plastically deformed indents was analysed via SPM imaging. Ultimate compressive strength of cylindrical HA reinforced composite enhanced by ~22 and 40%, when compared to round HA and Mg–3Zn composites, respectively, due to Hall-Petch strengthening. Reduction in the grain size of cylindrical HA reinforced composites increased the grain boundary area per unit volume, which facilitated the apatite precipitation sites in the physiological environment. Consequently, the corrosion resistance was enhanced by 63 and 27%, as compared to Mg–3Zn and round HA reinforced composite. The fabricated composite possesses superior biomechanical and biodegradation behaviour, rendering them potentially useful for temporary orthopaedic implants.