共查询到20条相似文献,搜索用时 140 毫秒
1.
采用超音速气流粉碎法进行硅酸钙的超细粉碎 ,借助激光粒度仪和TEM进行超细粒子粒径和形貌表征。得到了平均粒径 1 1μm、粒径分布 0 4~ 3μm、粒子大小形状基本一致的超细硅酸钙样品。研究表明 ,气流粉碎后的超细粒子易于形成软团聚 ,但在应用时容易分散 相似文献
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气流粉碎法制备超细硅酸钙粒子的研究 总被引:7,自引:0,他引:7
采用超音速气流粉碎法进行硅酸钙的超细粉碎,借助激光粒度仪和TEM进行超细粒子粒径和形貌表征。得到了平均粒径1.1μm、粒径分布0.4-3μm、粒子大小形状基本一致的超细硅酸钙样品。研究表明,气流粉碎后的超细粒子易于形成软团聚,但在应用时容易分散。 相似文献
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B4C超细粉末的制备及烧结 总被引:10,自引:0,他引:10
采用气流粉碎对B4C粗粉(比表面积0.52m^2/g,中位粒径20.4μm)进行了一系列粉碎实验,研究了气流粉碎次数,成形压力和烧结温度对烧结密度的影响。结果表明,当粉碎次数达到3次后,可获得<1μm的B4C超细粉末。经过4次气流粉碎的B4C超细粉末的比表面积为2.53m^2/g,中位粒径为0.56μm;该粉末分别于2200和2250℃无压烧结1h,其烧结密度分别达到理论密度的78.6% 82.5%,平均晶粒尺寸分别为28和50μm,抗压强度分别为390和555MPa。 相似文献
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叶菁 《高分子材料科学与工程》2005,21(4):236-239
对PVC树脂进行低温冷脆处理,可以有效地实现PVC树脂的超细粉碎。利用PVC树脂低温超细气流粉碎系统通过液氮致冷降低粉碎温度。使PVC超细粉碎效率得到提高。并在每千克PVC粉体液氮耗量为131mL~167mL的范围内。每小时获得8.23kg~11.65kg、平均粒径为6.45μm~9.02μm的超细PVC粉体。 相似文献
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采用LNJST-120HT型闭路循环氮气保护气流粉碎分级系统对磷酸铁锂粉进行超细加工、干燥;对粉碎、分级、收集、输送和包装系统的操作参数、设备结构及系统运行过程中出现的流动性、水分增加等问题进行分析探讨,并优化改进;通过加工超细磷酸铁锂粉的工业试验,对改进后的超音速气流磨进行测试。结果表明,控制螺杆加料机和分级机转速分别为62和1 072 r/min,气源压力和温度分别为0.5 MPa和120℃,包装房露点温度控制在-20℃以下,磷酸铁锂粉成品水分含量维持在0.35‰~0.55‰,成品粒径d_(50)=0.8~1.2μm、d_(100)<8μm,产量为200~230 kg/h。 相似文献
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B4C超细粉末的制备及烧结 总被引:4,自引:1,他引:3
采用气流粉碎对B4C粗粉(比表面积0.52m2/g,中位粒径20.4μm)进行了一系列粉碎实验,研究了气流粉碎次数、成形压力和烧结温度对烧结密度的影响.结果表明,当粉碎次数达到3次后,可获得<1μm的B4C超细粉末.经过4次气流粉碎的B4C超细粉末的比表面积为2.53m2/g,中位粒径为0.56μm;粉末分别于2200和2250℃压烧结1h,其烧结密度分别达到理论密度的78.6%和82.5%,平均晶粒尺寸分别为28和50μm抗压强度分别为390和555MPa. 相似文献
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采用球磨、气流粉碎和喷雾干燥等物理方法对麦草碱木质素分别进行预处理,制备不同结构特征的木质素颗粒。结果表明,气流粉碎木质素的平均粒径最小,为3.01μm,其次为球磨木质素和喷雾干燥木质素,平均粒径分别为16.02μm和27.23μm。气流粉碎木质素的比表面积最大,达到21.87 m2/g,球磨和喷雾干燥木质素的比表面积分别为2.61 m2/g和1.90m2/g。将3种预处理方法制备的木质素颗粒分别与低密度聚乙烯(LDPE)熔融共混制备木质素/LDPE复合材料,结果表明,在木质素质量分数相同时,采用喷雾干燥木质素制备的复合材料的拉伸强度比气流粉碎木质素大0.4MPa,比球磨木质素大1.5MPa。微观结构分析表明,喷雾干燥木质素在LDPE中分散最均匀,与LDPE相之间的结合力较好。 相似文献
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Rui Li Mingli Qin Chengcheng Liu Zheng Chen Xuanli Wang Xuanhui Qu 《Advanced Powder Technology》2017,28(6):1603-1610
Fine grinding process of different particle size tungsten powders was carried out by fluidized bed jet milling. The results showed that the jet milling treatment caused deagglomeration of tungsten powders, which led to particles sufficient dispersion and narrow particle size distribution. Grinding gas pressure of 0.70 Mpa made the particles achieve high speed which promoted the particles collision contributing to particle dispersion and shape modification. For tungsten powder with particle size of 3 μm FSSS, a higher packing density with 5.54 g/cm3 was obtained, compared with the 3.71 g/cm3 of the original powder. For tungsten powder with particle size of 1 μm FSSS, the big agglomerates disappeared and the particle size distribution become narrower, while small aggregates about 2–3 μm still exist after the jet milling process. For tungsten powder with particle size of 5 μm and 10 μm FSSS, different medium diameter particle size and narrow particle size distribution of monodisperse tungsten powders can be produced by the optimized jet milling parameters. More important, the effective dispersion, favorable shape modification and precise classification have been achieved in the simple process. 相似文献
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为了研究操作参数对双蜗壳式旋风分离器分离性能的影响,本文采用试验方法测量了液滴粒径、液滴浓度不同时旋风管的分离效率。结果表明:旋风管对小粒径液滴的分离效率较低,当入口液滴的中位粒径从19.02μm升高到37.28μm,旋风管的分离效率升高了接近20%。喷雾液滴的浓度升高时,旋风管的分离效率也随之升高,但影响程度较粒度较小。 相似文献
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A. Molinari I. Lonardelli K. Demetrio C. Menapace 《Journal of Materials Science》2010,45(24):6739-6746
A nanostructured aluminum powder was obtained using cryogenic mechanical milling. The powder produced after 25 h of milling
showed a broad particle size distribution, ranging between a few microns up to about 150 μm. Five different granulometric
classes were selected and for each of these, structural and microstructural features, as well as the thermal stability were
investigated using ex situ X-ray diffraction and transmission electron microscopy. There is a direct correlation between particle
size and crystallite size. Grain growth tendency was found strongly dependent to the initial grain size with noticeable changes
on the thermal stability for the five granulometric classes considered. Particularly the quantity of nitrogen content measured
(after degassing) in each of the five granulometric classes increases with decreasing the particles size. This might justify
why the calculated drag stress exerted by segregated impurities, second-phase particles and pores is effectively higher for
small particles. This approach can give a methodology to modulate the microstructure of bulk nanostructured/ultrafine metals
just selecting different combination in terms of particle size. 相似文献
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This work examined the effects of milling using a gravity ball mill on the reactivity of natural zeolites used as supplementary cementitious materials (SCMs). Six different particle size distributions of zeolites, created by milling the as-received zeolite in a ball mill for a specified amount of time, were characterized using x-ray fluorescence, quantitative x-ray diffraction, particle size analysis, pore size distribution and surface area analysis. Following material characterization, the pozzolanic reactivity of the zeolites was determined by measuring the quantity of calcium hydroxide in paste after 28 or 90 days and by tracking the compressive strength of zeolite-cement mortars. Results showed that a critical milling time exists, corresponding to a d50 of 7–9 μm, after which reductions in particle size can no longer be achieved and zeolite performance can no longer be improved through ball milling. 相似文献
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Rui Li Mingli Qin Hua Huang Chengcheng Liu Zheng Chen Min Huang Lin Zhang Xuanhui Qu 《Advanced Powder Technology》2017,28(12):3158-3163
Fine-grained spherical tungsten powder with particle size from 6 μm to 11 μm has been fabricated by a well-designed method with two simple steps. A pretreatment of tungsten powder was carried out in the first step. Complete dispersion, effective classification and favorable shape modification have been achieved by jet milling process. Accordingly, monodisperse tungsten powders with narrow particle size distribution were obtained. On the basis of the existing calculation and simulation results, plasma spheroidization parameters have been optimized. Thus, fine-grained spherical tungsten powder with narrow particle size distribution has been prepared by subsequent radio frequency (RF) inductively coupled plasma spheroidization. Furthermore, the presented method can be useful in fabricating spherical tungsten powder of different particle size with narrow particle size distribution as well as for process control in large-scale continuous production. 相似文献
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Linli Gan Zhiheng Xiao Heng Pan Weilin Xu Yunli Wang Xungai Wang 《Advanced Powder Technology》2021,32(2):630-636
Polyester has the highest share of world fibre market, which also leads to a large volume of polyester waste. In this study, a compact process combining alkali treatment and stone milling was used to recycle waste polyester fibre into ultrafine powder efficiently. The morphology of the original polyester fibre, alkali modified fibre and milled polyester powder were observed by Scanning electronic microscopy (SEM) and atomic force microscope (AFM). The particle size, crystallinity and strength loss were also studied. It was found that the alkali treatment greatly reduced fibre strength and the crystallinity of the fibre largely decreased after stone milling. The waste polyester fibre was converted into micron powders easily and efficiently. About 700 g dry ultrafine powders with particle size of around 60 µm were achieved in 2 h. This method shows a great potential for industrial application of waste polyester in the future. 相似文献
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通过比较三七超微粉体、细粉(三七常规饮片)以及不同目数范围粉体(三七细粉经多次筛分得到的粉体)在粒度分布、显微形貌特征方面的差异,探讨了超微粉碎技术应用于中药三七加工的优势。应用激光粒度分析仪对三七超微粉体与细粉、不同目数范围粉体的粒度及其分布进行表征,观察其显微形貌特征。粒度分布测试和显微形貌观察的结果表明,超微粉粒度分布在0.30~24μm,大部分粉体达到了10μm以下,呈对称的单峰分布,引起团聚的作用力为各种表面力,说明超微粉体均匀度高质量易控。三七细粉及不同目数范围的粉体粒度分布范围在2~190μm,分布不对称,引起团聚的作用力为重力的等质量力,说明其均匀度差,质量难以控制。 相似文献
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It has been proposed that the breakage behavior of particulate materials can be described by two material parameters fmat and Wmin. fmat describes the resistance of the material to fracture in impact pulverization and Wmin characterizes the specific energy which a particle can absorb without fracture. It is shown in this study that this concept can be used to quantify breakage behavior of bronze and cast iron chips in jet milling process and also to predict particle size of the jet milled product. Different tin bronze and cast iron chips with varying initial size were pulverized in a target plate jet mill with different velocity. fmat was found to be in the range of 0.06–0.09 and 0.18–0.25 for bronze and cast iron alloys, respectively. For the cast iron alloys fmat increased with increasing content of carbon and silicon. Similarly, for the bronze alloys, fmat increased with increasing tin content. An equation was developed to predict mean particle size of the jet milled chips as a function of the kinetic energy, initial chip size and material parameters. The experimental results of various alloys confirmed that the mean particle size after single and multiple impacts were accurately predicted. 相似文献