直流电弧等离子体蒸发法制备超细锌粉

采用自行研制的高真空三枪直流电弧等离子体蒸发金属纳米粉体连续制备设备,通过控制阴极电流大小制备不同粒径的超细锌粉。利用X射线衍射(XRD)、X射线荧光分析(XRF)、透射电子显微镜(TEM)和相应的选区电子衍射(SAED)以及Simple PCI软件等测试手段对样品的晶体结构、成分、形貌和粒径分布进行表征。结果表明:等离子体法制备的超细锌粉纯度(质量分数)高达99.945%,粒径分布窄,分散性好,颗粒以球状为主,夹杂少量六方形态;超细锌粉的晶体结构与块体材料相同,为六方结构,晶格常数略有收缩;当其他参数恒定,工作电流从150 A增加到300 A时,超细锌粉的平均粒径从165 nm增加到596 nm,产率从2 258.55 g/h提高到7 027.20 g/h。     

直流氢电弧等离子体蒸发法制备纳米锡粉

采用高纯锡,通过自行设计的直流电弧等离子体蒸发设备制备了纯净的纳米锡粉。利用X射线衍射（XRD）、透射电子显微镜（TEM）和选区电子衍射（ED）以及Simple PCI软件对样品的成分、形貌、晶体结构和粒径分布进行了分析。结果表明：在本文制备工艺参数条件下,该设备可以成功制备平均粒径为26至49nm的纳米锡粉;粉体的产率和粒径随充气压力升高而增大。所制备的纳米锡粉颗粒细小,纯净,为多晶结构;通过分析不同腔体内的粉体粒径,发现距离钨电极越远,所形成的颗粒尺寸越大。     

制备方法对块体纳米晶镍组织性能的影响

以高能球磨法和等离子体蒸发法制备的纳米晶镍粉为原料,采用预压烧结法制备了块体纳米晶镍.采用XRD、SEM和自动压汞仪对试样的微观组织结构及孔隙率进行检测,对其硬度、压缩强度进行测试.结果表明:由于等离子体蒸发法制备的纳米晶镍粉为均匀、细小的球状晶粒,具有较小的微观应变,从而比球磨试样更易于成型,块体的致密度更高,热稳定性更好.等离子体蒸发试样的硬度较高,压缩屈服强度达310～410 MPa,表现出较低的加工硬化和良好的塑性压缩形变能力,断口为沿晶断裂,晶界滑移在变形中起到重要作用.     

气体雾化法制备锌粉及其性能研究

探讨了锌粉雾化的基本原理,以及雾化喷嘴结构、喷射顶角、锌液温度和气体压力等对锌粉粒度的影响,并运用激光粒度分析仪、比表面积测试仪和蔡司显微镜等对制备的雾化锌粉的粒度分布、比表面积大小及锌粉形貌进行分析。研究的锌液温度为(620±10)℃,雾化压力为1.6 MPa;结果表明:适当提高锌液温度及提高喷枪入口的气流速度或压力均有利于锌粉的细化;雾化法制得的锌粉呈近球形,锌粉的D_(50)≤20μm;随锌粉的平均粒径减小,比表面积呈逐渐增大的趋势,锌粉粒径为-100~-325目时,比表面积从0.1367 m~2/g增大到0.2233 m~2/g。     

直流氢电弧等离子体蒸发法制备纳米Cu粉

采用99.99%的高纯Cu,通过自行设计的直流电弧等离子体蒸发设备实现了高产率纳米Cu粉的制备.系统研究了电流、氢氩比、充气压力3个工艺参数对纳米Cu粉产率及粒度的影响.利用X射线衍射（XRD）、透射电子显微镜（TEM）和选区电子衍射（ED）以及Simple PCI软件对试样的成分、形貌、晶体结构和粒径分布进行了分析.结果表明,电流和氢氩比（H2/Ar）分别是对粉体产率和平均粒径影响的显著性因素;所制备的纳米铜粉为多晶结构,平均粒径在29～116 nm范围内;在试验参数相近的情况下,产率比同类研究结果提高了26.65倍.     

气相氧化法制备氧化锌的结晶形貌

研究了锌蒸气高温气相氧化条件对氧化锌结晶形貌的影响结果.结果表明:气相氧化法制备的氧化锌有无定形、颗粒状、单针状、四针状、多针状等5种典型的结晶形貌;这些结晶形貌与原料锌粉的粒度及表面状态没有直接联系,但都强烈地依赖于锌蒸气氧化时的物理化学环境;在不同的氧分压下,锌蒸气具有不同的氧化行为,由此导致了不同形貌的氧化锌结晶;通过改变制备条件可以有效地调控氧化锌的结晶形貌.     

低碳钢表面锌-铝复合涂层的研究

以锌粉、纳米铝粉和马来酸酐一丙烯酸共聚物为原料,通过实验探索,研制了一种水性涂料,并采用SEM和XPS对该涂料制备的锌铝复合层的形貌和组成进行了分析.结果表明:在铝粉与锌粉质量比为4:6,马丙共聚物质量分数为60%,固化时间50 min,固化温度100℃的条件下,可以形成均匀致密的锌一铝复合涂层,涂层的抗冲击性能和耐盐...     

机械镀锌和锌铝镀层的形貌及耐蚀性

用球状锌粉、片状锌粉和片状锌铝合金粉分别制备出3种机械镀锌层,借助扫描电镜（SEM）比较了各种镀层的表面及断口形貌,并对镀层表面进行了钝化处理及耐腐蚀性能测试.结果表明,片状锌粉形成的机械镀层的综合性能好于传统的球状锌粉形成的机械镀层,且片状锌-铝（10wt%）合金粉形成的机械镀层的综合性能最好.     

不同粒度金属粉形成机械镀层形貌及耐腐蚀性能研究

分别采用200、325、500、800锌粉和325目锌、铝粉混合球磨成的片状锌-铝粉,经SnSO4活化,进行机械镀.用扫描电镜观察,锌粉多为较规则的球形,片状锌-铝粉多为不规则的片状结构.镀层表面球形颗粒状锌粉变形较大,镀层内部球形颗粒变形较小,多为椭球形.随着粒度的变小,镀层的致密程度增加.片状锌-铝粉形成的镀层的致密、平滑程度不如800、500目锌粉形成的镀层.但镀层的色泽明显改观,亮度增大.采用片状锌-铝粉形成的镀层受损后有自愈性.通过盐雾试验、极化曲线试验,验证了随着粒度的变小,耐腐蚀性显著增加,间接证明镀层致密性增加;片状锌-铝粉形成的镀层的耐腐蚀性能与800目球状锌粉形成的镀层相当.     

直流电弧等离子体法制备铋纳米粉体

采用自行研制的高真空三枪直流电弧金属纳米粉体连续制备设备,通过控制充气压力制备不同粒径的纳米铋粉.利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应的选区电子衍射(SAED)以及Simple PCI软件等测试手段对样品的成分、晶体结构、形貌和粒径分布进行表征.结果表明:等离子体法制备的纳米铋粉纯度高,粒径分布窄,分散性好,颗粒呈链球状均匀分布;纳米粉体的晶体结构与块体材料相同,为六方结构、空间群R-3m,晶格常数略有增大;当电流恒定为250 A、充气压力从5 kPa增加到60 kPa时,纳米铋粉的平均粒径从35 nm增加到143 nm.     

高能球磨法制备纳米晶Ni粉的研究

采用高能球磨法制备出了纳米晶镍粉,并利用X射线衍射仪（XRD）、扫描电镜（SEM）、透射电镜（TEM）等分析检测手段,研究了该纳米晶镍粉末的结构、形貌和相的变化。结果表明,镍粉末平均粒度和晶粒度随球磨时间增加不断减小,而应变随球磨时间增加不断增大;当高能球磨54h后,球磨产物为FCC结构的鳞片状多晶体,晶粒度为17nm左右,应变为0.48%,颗粒尺寸为150～200nm;球磨时间增加至98h,产物中出现非晶相,但仍以多晶为主,晶粒尺寸为7nm,应变为1.24%,粉末团聚严重。     

Preparation and characterization of amorphous boron powder with high activity

The amorphous boron powders with high activity were prepared by the high-energy ball milling–combustion synthesis method. The effects of the milling rate and milling time on the crystallinity, microscopic morphology and reactivity of amorphous boron powder were studied. The results show that the crystallinity of amorphous nano-boron powder is only 22.5%, and its purity reaches 92.86%. The high-energy ball milling can significantly refine boron powder particle sizes, whose average particle sizes are smaller than 50 nm, and specific surface areas are of up to 70.03 m²/g. When the transmission electron beam irradiates the samples, they rapidly melt. It can be seen that the monomer amorphous boron size is less than 30 nm from the specimen melting traces, which indicates that the samples have high reactivity.     

Surface characteristics of rapidly solidified nickel-based superalloy pow-ders prepared by PREP

The surface microstructure and the surface segregation of FGH95 nickel-based superalloy powders prepared through plasma rotating electrode processing (PREP) have been investigated by using SEM and AES. The results indicate that the surface microstructure of powders changes from dendrite into cellular structure as the particle size of powders de-crease, and the predominant precipitates solidified on the particle surfaces were identified as MC' type carbides enriched with Nb and Ti. It was also indicated that along with the depth of particle surfaces, the segregation layer of S, C and O ele-ments are thick, and that of Ti, Cr elements are thin for large size powders while they are in reverse for median size parti-cles.     

两种3D打印用雾化Ti-6Al-4V粉末的对比研究

本研究分别利用水冷铜坩埚真空感应熔炼气雾化(VIGA-CC)和等离子旋转电极(PREP)两种技术制备出球形Ti-6Al-4V合金粉末,作者利用SEM、同步辐射CT扫描-三维重建和氩气含量测试等分析手段对不同粒径的Ti-6Al-4V合金粉末的孔洞缺陷和氩气含量、硬度值进行了表征。实验结果表明, VIGA-CC粉末粒度分布宽,细粉收得率较多,粉末粒度分布在40~180 μm之间, PREP粉末的粒度分布较窄,主要集中在110~180 μm之间；金属粉末内部的孔隙率、气体含量和孔尺寸随着粉末粒度的增大而增大,且同一粒径范围内VIGA-CC粉末的气孔概率多于PREP粉末；随着粉末粒径减小,粉末截面组织逐渐细化,其硬度值逐渐升高,整体上VIGA-CC粉末硬度值高于PREP粉末。     

Characterization of thermal sprayed hydroxyapatite powders and coatings

Calcium phosphate materials such as hydroxyapatite (HA) have biocompatible properties that can promote osteogenesis or new bone formation. Thermal spraying is an economical and effective process for coating the hydroxyapatite onto metal. It has been reported that plasma spraying changes the degree of crystallinity as well as the phase composition of the HA. This article reports the preparation and characterization of HA powders and coatings by two thermal spray processes (plasma and combustion flame) and suggests that the state of the starting powder adversely affects the coating characteristics. The raw HA powders are synthesized through a chemical reaction involving calcium hydroxide and orthophosphoric acid. Phase analysis using an X- ray diffractometer revealed that the synthesized powder consists of predominantly the HA phase. Calcined and crushed HA powders of various size ranges were fed into the plasma jet to produce HA coatings on metallic substrates. In addition, some HA powders were sprayed into distilled water by plasma spraying and combustion flame spraying to study powder melting characteristics. Other samples were plasma sprayed onto a solid rotating target to study atomization and impact behavior. The morphology of the rapidly solidified powders and thermal sprayed coatings were examined by scanning electron microscopy (SEM). An X- ray sedimentation particle size analyzer, laser diffraction particle size analyzer, and image analyzer performed the particle size analysis. Preliminary results indicate that particle cohesion, size range, and thermal treatment in the plasma affect the phase and structure of the as- sprayed coating, and some post- spray treatment may be necessary to produce a dense and adherent coating with the desired biocompatible properties.     

Preparation of doping titania antibacterial powder by ultrasonic spray pyrolysis

Doping titania powders were synthesized by ultrasonic spray pyrolysis method from an aqueous solution containing H2TiF6 and AgNO3. The effects of the processing parameters on particle size distribution, structure, and morphology of doping particles were investigated. The results show that aggregation-free spherical particles with average diameter of 200-600 nm are obtained and the particle size of the powder can be controlled by adjusting the concentration of solution. The experimental approach indicates that the size and the value of standard deviation of particle size increase from 210 nm to 450 nm and from 0.46 to 0.73 respectively with the increase of the titanic ion concentration from 0.05 to 0.4 mol/L. Composite TiOF2 is obtained when the pyrolysis temperature is set to be 400 ℃. With increasing pyrolysis temperature from 400 ℃ to 800 ℃, the crystal size of titania powders increases from 14.1 to 26.5 nm and TiOF2 content of powder decreases dramatically. The property of ion released from powder is affected significantly by the pyrolysis temperature, and the amount of fluorine ion and silver ion released from powder decrease with increasing pyrolysis temperature. The optical property of doping titania powders is not affected by pyrolysis temperature. Antibacterial test results show that composite powders containing more fluorine ions exhibit stronger antibacterial activity against E.coli.     

W-20%Cu纳米复合粉的制备

采用雾化干燥结合氢还原工艺制备W-20％Cu(质量分数)纳米复合粉，分别用XRD，SEM，TEM等手段表征了制备过程中各步骤的产物及最终复合粉，结果表明该复合粉的粒子平均尺寸为240nm，粒子中弥散均匀分布的钨晶粒平均尺寸约为16nm。     

Effect of the feeding rate on microstructure and properties of plasma spheroidized GH4169 powder

The growing interest in additive manufacturing of GH4169 alloy was accompanied by the demand on spherical GH4169 powders with high performance.The powder particles were treated by radio frequency plasma with the different feeding rates.The microstructure and morphology,the particle size distribution of as-treated powders were studied by scanning electron microscopy and laser particle size analysis.It was demonstrated that GH4169 powders with extremely fine followability were obtained by radio frequency plasma spheroidization technology.With the same plasma parameters,the spheroidization efficiency of the particles varied with the feeding rates.When the rate of the powder feeding rates was too small,the excessive absorption of the heating by the powders caused vaporization,then the collection decreased.When the feeding rates was too large,the powder particles were insufficiently absorbed,resulting in defects in the powders.The microstructure of the as-treated spherical particles was mainly cell crystals,columnar crystals,and even microcrystals.Under the suitable plasma parameters,the resulting powders haved a slightly increased average particle size,excellent spheroidization,surface smoothness,followability,and bulk ratio.     

纯相低氧纳米WC-Co复合粉的制备

以紫钨、四氧化三钴、炭黑为原料,在高真空度条件下利用原位反应合成技术制备出物相纯净、平均粒径约为80 nm的WC-Co复合粉。研究了制备工艺参数对纳米复合粉相组成、粒径、氧含量及最终烧结硬质合金块体材料组织性能的影响。结果表明,纳米复合粉中氧含量较高时,会导致后续烧结过程中发生脱碳反应,使烧结制备的块体材料致密度和力学性能明显下降。将纳米复合粉在800℃下真空热处理2.5 h可有效降低粉末中的氧含量,同时热处理后的粉末颗粒无明显长大,平均粒径为85 nm。向复合粉中加入1.1%TiC与0.9%VC进行SPS烧结,烧结块体平均晶粒尺寸为105 nm,且尺寸分布均匀,致密度达99%以上,硬度(HV30)为21 450 MPa,断裂韧性达到9.81 MPa·m~(1/2)。     

Mechanical alloying of platinum with 5% ZrO2 nanoparticles for glass making tools

Synthesis and characterization of mechanically alloyed Pt–5%ZrO₂ (volume fraction) for structural components in the glass industry were described. Zirconia (ZrO₂) nanoparticles (<100 nm) were produced by the electrical explosion of zirconium (Zr) wires, and blended with platinum (Pt) powders (<44 μm) for 2–72 h in ambient atmosphere. The Pt particle size followed the typical decreasing trend of the normal ball milling process up to 48 h, but particle agglomeration was observed at 72 h. The grain size evolution was similar to that of the particle size, dropping down to around 50 nm at 48 h. The root mean square strain of the Pt crystallites showed the opposite behavior, maximizing at 48 h with a subsequent relaxation process. For the 48 h ball milled powders, spark plasma sintering was carried out to form a bulk disk. The measured mass loss of the sintered bulk sample shows a decent thermal stability despite its relatively low density.