片状铝粉的制备及其活性?

采用立式球磨机,在乙酸乙酯溶剂中对平均粒径14μm的球形铝粉进行球磨,制备了具有高活性的片状铝粉。采用激光粒度仪和扫描电子显微镜(SEM)对铝粉球磨前、后的粒度及形貌进行了分析。用X射线粉末衍射(XRD)对铝粉球磨前、后晶型进行了表征,发现球磨2 h后,得到的粒径大小为1μm的片状铝粉,其晶形与原料铝粉晶形一致。通过氧化还原滴定法测试了球磨前、后铝粉中活性铝的质量分数,分别为90.41%和98.42%。采用TG-DSC法对球磨前、后的铝粉进行了热反应特性研究,发现片状铝粉在480~980℃时,氧化增重84.8%,氧化反应活性明显高于原料铝粉。因此,铝粉片状化能够提高推进剂以及火炸药体系的能量。     

铝粉/聚四氟乙烯机械活化含能材料的制备及其微观性能研究

为了研究铝粉/聚四氟乙烯机械活化含能材料的微观性能,利用自制高能球磨机制备了不同球磨时间的机械活化含能材料,利用场发射扫描电镜分析了机械活化含能材料的微观形貌及表面元素分布,利用X射线衍射仪和红外光谱仪表征了材料的物相结构和化学结构。进一步利用分子动力学手段研究了铝粉的不同晶面与聚四氟乙烯的相互作用。结果表明,在长时间的强机械能作用下,聚四氟乙烯和铝粉紧密接触在一起,形成直径为100μm左右的薄片状复合物;球磨20min以后,铝粉和聚四氟乙烯分散得较为均匀,但离完全均匀分散还有一定差距;高能球磨仅能引起铝粉/聚四氟乙烯复合材料微观物理结构的变化;分子动力学计算显示,铝粉的不同晶面与聚四氟乙烯相互作用的过程中,范德华力占主导地位。     

片状锌粉表面复合改性剂的研究

利用干式高能球磨法制备片状锌粉,采用正交实验法研究不同球磨助剂配方对球磨锌粉中位粒径d50、松装密度和水面遮盖率的影响,确定最佳复合助剂配方。结果表明,在加入硬脂酸、棕榈酸、硬脂酸锌、聚乙二醇的最佳质量分数分别为2.5%、0.3%、0.3%、0.1%的最优复合助剂配方条件下,制得片状锌粉颗粒的中位粒径d50为13.12μm,松装密度为0.934 8 g/cm3,水面遮盖率为2 280.2 cm2/g;过程中没有新相产生,锌粉颗粒得到有效包覆。     

片状铝粉制备过程中助磨剂的研究

片状铝粉具有特殊的二维平面结构和较大的径厚比,在应用于涂料、颜料、汽车等工业中表现出很好的优良性能.简要介绍了片状铝粉制备过程中添加剂对产品的影响以及不同助磨剂在球磨过程中产生的不同效应.对进一步研究铝粉的制备具有一定的参考价值.     

加气混凝土用铝粉的应用与制备

用干式球磨法生产加气混凝土用铝粉。根据加气混凝土的生产工艺,确定其对铝粉的性能要求。在加气混凝土用铝粉的生产工艺中,通过调整原料铝粉的粒度、助磨剂加入量和磨内滞留时间的工艺参数来控制铝粉的性能。通过实践及数据分析,确定最佳工艺参数:原料铝粉粒度d97=630￣280μm;助磨剂加入量在3.0%;铝粉磨内滞留时间为16.6￣19h。     

金色闪光铝粉颜料的制备研究

本文采用乳液聚合法将聚甲基丙烯酸甲酯(PMMA)包覆在片状闪光铝粉颜料表面,得到了具有金色闪光效果的铝粉颜料.通过扫描电镜(SEM)照片表明在铝粉颗粒表面可形成厚度均匀的PMMA包覆干涉层;通过差热分析(TG)、光电子能谱(XPS)对片状铝粉表面结构进行分析,得出铝粉颗粒表面确实存在PMMA的包覆层且PMMA与铝粉颗粒是以化学键作用相结合.     

机械化学法一步合成表面改性氧化锌纳米粉体

以醋酸锌、氢氧化钠、硬脂酸为原料,采用机械化学法,一步制备出具有表面亲油性能的氧化锌粉体。借助XRD、FTIR、TEM、纳米粒度测试等方法对粉体进行了表征,研究了硬脂酸对氧化锌粉体表面改性的机理。结果表明,硬脂酸中的羧基与氧化锌颗粒表面的羟基发生了酯化反应,并在表面形成有机膜,氧化锌粉末由亲水性转化为亲油性。当球磨时间为50 min、硬脂酸加入量为氧化锌质量的4.5%时,可以得到平均粒度为90 nm的亲油性氧化锌粉体。     

球磨法制备高活性铝粉

为提高含铝炸药爆热性能,探索高活性金属铝粉的制备方法,采用立式球磨机对球形铝粉进行处理,研究球磨机的搅拌转速、球磨时间、助磨剂的配比对活性铝粉粒径、形貌、热性能的影响;利用扫描电子显微镜、激光粒度测试仪和同步热分析仪检测活性铝粉形貌、粒径及热分解特性;采用热分析参数法测定活性铝含量。结果表明:制备活性铝粉的最佳条件为搅拌转速1 100 r/min,研磨时间4 h,助磨剂占铝粉质量比4%;制备的活性铝粉粒径d_(50)为1.108μm,片状,活性铝质量分数由90.42%增加到98.42%;用于含铝炸药中,爆热值由6 805 kJ/kg增加到7 642 kJ/kg。     

反应条件对SiO_2包覆片状铝粉表面形貌的影响

以硅酸钠(Na2SiO3.9H2O)和片状铝粉为原料,在缓冲溶液中制备SiO2包覆片状铝粉,研究不同pH值、温度、包覆量等对铝粉表面SiO2包覆层形貌的影响;用场发射扫描电镜表征包覆层的形貌,并测定粉体中SiO2的含量。结果表明:溶液pH、温度对包覆层的形貌有较大影响;在反应温度为85℃、pH=9.5的条件下,铝粉表面形成致密、表面平滑的SiO2包覆层。     

高速湿法球磨对羰基铁粉微结构及吸波性能的影响

采用高速球磨法快速制备片状羰基铁粉。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、矢量网络分析仪(VNA)对材料的微观形貌、物相、吸波性能进行了表征与分析。结果表明：球磨0～60 min时,羰基铁粉的厚度随球磨时间延长逐渐减小,形成片状结构,直径厚度比最大可达80∶1;球磨90 min时,羰基铁粉由大片状破碎成小片状,部分片状羰基铁粉经球磨珠撞击后重叠堆积,材料的厚度逐渐增加,比表面积下降;球磨120～180 min时,多数羰基铁粉的片状结构被粉碎破坏,形状回归为类球形,少数羰基铁粉进一步堆叠成块状。球磨前后羰基铁粉的晶体结构未发生实质性改变,羰基铁粉的综合吸波性能随着球磨时间的延长呈现先上升后下降趋势,并在球磨90 min时达到最优的吸波效果：反射损耗最小值为-54.94 dB (12.64 GHz),匹配厚度为2.17 mm,有效吸波带宽达到了8.48 GHz。     

湿法机械球磨制备片状镍粉研究

以类球形镍粉为原料,进行了湿法机械球磨制备片状镍粉的试验,考察了乙醇体积、球料比、球磨转速、球磨时间及助剂用量等因素对镍粉形貌的影响,采用XRD、SEM等对镍粉结构形貌进行了表征分析,确定了最佳工艺条件:乙醇体积60mL、球料比30:1、球磨转速450r/min、球磨时间3.5h、助剂A用量2%。在该条件下,得到的片状镍粉径厚比89,表面光滑平整,碎片粘附少,具有良好的金属光泽;其微观结构表明,球磨过程中,镍粉的微观内应力逐渐增加,晶粒不断细化;而且产品的片状化程度与<200>择优取向度有关。     

Application of mechano-chemical synthesis for protective coating on steel grinding media prior to ball milling of copper

One of the major sources of contamination during mechanical milling/alloying is from the surface erosion of the container and the grinding medium. This can either be prevented by using grinding medium and container of same material of the milled material or by adding a coating of the milled material on them. The paper describes the observations made during a mechano-chemical reaction, being used for coating the balls and vials in a planetary ball mill. Visual observation, XRD, optical micrography and EDS analysis were used to understand the progress of the reaction. Copper was successfully coated on the steel balls and vials. The method can easily be adopted in daily production purposes, prior to mechanical milling of a Cu-based powder for prevention of Fe contamination.     

Preparation of hot-pressed silicon-germanium ingots: Part II - Reduction of chill cast material

Nine different reduction techniques were evaluated for reducing Si-Ge chill cast alloys. Planetary ball milling with agate vessels and balls proved best for producing large quantities of high purity Si-Ge alloy powders. With the planetary ball mill Si-rich alloys were more difficult to reduce than Ge-rich alloys and the addition of dopant (boron or phosphorus) decreased the grinding time necessary for comparable particle size distributions.     

Microstructural Evaluation of NiTi-powder,Steatite, and Steel Balls After Different Milling Conditions

The present research deals with the investigation of morphological characteristics after mechanical alloying of Ni–50 at. %Ti in a high-energy planetary ball mill at various milling times (i.e., 4, 8, 30, 40, 50, and 60 h). Crystallite size was observed to be decreased with the increase of milling time, entire titanium fused in the nickel trellis, and results of intermetallic NiTi. The shape of particle also changed from lamella to globular. Steatite-ceramic and hardened balls were separately used for the ball milling. The observations of morphologies revealed that steatite balls are more durable and wear resistant as compared to steel ball. This research shows that ball milling with steatite-ceramic balls is a cost-effective, high purity, and productive step toward the formation of NiTi intermetallic compound with homogeneous composition and desired particle size.     

卧式行星球磨机最佳参数的数值模拟

采用颗粒离散元法模拟得到卧式行星磨磨筒内钢球平均接触力大小以及随填球率、钢球直径、磨筒半径和公转半径的变化规律,并与实验结果进行了比较分析。结果表明:行星磨的粉磨速率可以由平均接触力大小来确定,粉磨速率的对数是平均接触力线性函数,斜率为0.087。磨筒填球率的增加,导致钢球的平均接触力减小;随着钢球直径、磨筒半径、公转半径的增大,平均接触力呈线性增长,斜率分别为2.5,0.14,0.03,其中钢球直径对平均接触力的影响最大。     

Scale-up methodology for tumbling ball mill based on impact energy of grinding balls using discrete element analysis

This paper provides a method to scale-up horizontal tumbling ball mills, i.e. to determine the dimensions of the rotating drum and the drum rotational speed. In order to develop the scale-up methodology, the motion of grinding balls in tumbling ball mills with different drum diameters was calculated using the discrete element method (DEM). The impact energy of grinding balls was numerically analyzed, and the influence of drum dimensions and drum rotational speed on the impact energy was investigated. It was found that scale-up of the rotating drum should be carried out based on the mechanical energy instantaneously applied to the powder and its cumulative amount. The former was evaluated in terms of the frequency distribution of the impact energy and the latter its cumulative amount over the elapsed milling time, which could be controlled by the drum rotational speed and the milling time, respectively. Validity of the proposed scale-up methodology was evaluated through dry grinding experiments of aluminum hydroxide powder, and the experimental results supported its usefulness in practical applications.     

Analysis of abrasion mechanism of grinding media in a planetary mill with DEM simulation

In order to investigate the abrasion phenomena in a planetary ball mill, we conducted the grinding operation without a powder and sought a correlation between the ball abrasion and the ball impact energy estimated by a Discrete Element Method (DEM) simulation. Experimental results showed that the mass of abraded balls increased in proportion to the grinding time in the early stage of grinding up to 75 min. The abrasion rate increases quadratically with the mill rotation speed. It decreases with an increase in ball diameter up to 12.7 mm and then slightly increases when the diameter is 15.8 mm. It also increases with an increase in the ball-filling ratio of the mill up to 50%. Similar tendencies are found in the impact energy calculated from the balls motion simulated by DEM. Therefore, it is said that the abrasion rate has a strong correlation to the impact energy of balls under any milling conditions.     

机械球磨法制备Ti3SiC2 / Al 纳米复合材料

研究了用微米级Ti₃SiC₂ 陶瓷颗粒与Al 粉复合球磨制备纳米复合材料的工艺过程。结果表明, 在其他实验参数相同的条件下, 不同材质的磨球对陶瓷颗粒的细化作用差异很大。采用氧化锆磨球可以使Ti₃SiC₂ 的颗粒更好地细化且均匀分散在Al 基体中, 而用钢球和玛瑙球则易产生混合粉的团聚。用氧化锆球进行球磨后的复合粉在550 ℃的温度及20 MPa 的压力下成功地制备了组织成分均匀的大块纳米复合材料。与同成分的非纳米材料相比, Ti₃SiC₂ / Al 纳米复合材料的硬度从HV60 提高到HV80 , 强度则从110 MPa 提高到150 MPa 。      

高能球磨法制备Fe_3Si合金粉末

采用高能球磨法研究了原子配比Fe75Si25的混合粉末在不同的球磨条件下的机械合金化,用X射线衍射(XRD)仪、扫描电子显微镜(SEM)表征样品的物相、晶体结构、晶粒尺寸和点阵常数,分析了Fe75Si25粉末的机械合金化机理。研究表明,球磨时间、球料比和球磨机转速对机械合金化(MA)进程有重要影响。MA 55h后可达到完全合金化,Si溶入Fe中形成α-Fe(Si)饱和固溶体,晶粒尺寸减小至7～8nm。