射频等离子体球化SiO2粉体的研究

采用射频等离子体球化颗粒形状不规则的二氧化硅粉体,研究了加料速率、颗粒大小等因素对球化率的影响.用光学显微镜观察球化前后颗粒的形貌;用流动仪测定球化后粉体的松装密度.结果显示,球化后的二氧化硅颗粒球形度高,细颗粒长大,并且随着球化率的增大粉体松装密度增加.初步查明加料速率、原料粒度等参数对球化率的影响.在适当的条件下可以得到球化率高、球形度好的粉体.     

直流电弧等离子体球化U_3Si_2粉体

研制了直流电弧等离子体球化U3 Si2 粉体装置。在Ar+He气氛下对粒度为 10～ 15 0 μm范围内不规则形状的U3 Si2 粉体进行了球化 ,球化率达 90 %。     

直流电弧等离子体球化U3Si2粉体

研制了直流电弧等离子体球化U3Si2粉体装置,因Ar He气氛下对粒度为10－150μm范围内不规则形状的U3Si2粉体进行了球化,球化率达90％。     

冷等离子体中的粉体研究

介绍了在冷等离子体中粉体研究的几个重要成果，分析了粉体在两种反应室结构中的运动、沉降时间及刻蚀状况。理论分析和实验结果表明带振动阴极的反应室在粉体表面刻蚀方面比传统阴极结构的反应室要优越得多。研究表明冷等离子体对硅粉纯化具有应用前景。     

射频等离子体对纯钛表面的氨基化改性

采用射频辉光等离子体技术,以氮气与氨气的混合气体为气体源对纯钛进行处理。采用X射线光电子能谱对改性的样品表面成分进行分析,并讨论氨基化机理;采用表面接触角测试仪研究了处理时间、放置时间及保存方式对材料表面亲水性的影响。结果表明:经过氮气与氨气的混合气体等离子体改性后,材料表面存在氨基和氮钛化合物,处理90 min后,表面氨基含量高;改性后材料表面亲水性增加,但随放置时间的增加亲水性变差,在5 h内,改性钛片保存在氮气气氛中有利于亲水性的保持。     

干法刻蚀中射频等离子体电特性的研究

射频功率为５０－５００Ｗ（１３．５６ＭＨＺ），气压为１．３－１３．３Ｐａ的氩和四氟化碳放电气气氛中，测量了阻抗、直流自偏压和峰－峰电压。测量结果表明，这种放电可以采用容的电阻的串、并联来描述。同时研究了离子轰击两个电极的能量比率，指出过去被广泛假设的离子轰击能量的比率与电极面积比的四次方关系并不相符。     

干法刻蚀中射频等离子体电特性的研究

射频功率为50～500W（1．56MHz）、气压为1．3～13．3Pa的氩和四氟化碳放电气氛中，测量了阻抗、直流自编压和峰－峰电压。测量结果表明，这种放电可以采用电容与电阻的串、并联来描述。同时研究了离子轰击两个电极的能量比率，指出过去被广泛假设的离子轰击能量的比率与电极面积比的四次方关系并不相符。     

射频自偏压在等离子体工艺中的作用

木文讨论了射频自生负偏压的作用，认为自偏压代表了等离子体状态而且也代表了离子对各个表面的轰击能量。     

静电探针测量射频感应耦合等离子体密度

本文介绍了一种可以测量射频感应耦合等离子体密度的静电探针方法,并给出了它的测量原理,实验方法和实验结果。实验结果表明：所测等离子体密度反映了等离子体的特性,并且诊断手段简单、易行,为等离子体诊断提供了一种很好的实验手段。     

常温下采用射频等离子体法合成碳化硅膜

采用射频等离子体增强的气相沉积法，以硅烷和乙烯为原料，在常温下成功的合成了碳化硅薄膜。对于该条件下合成的碳化硅薄膜的结构特征，采用SEM、TEM、XRD、IR等手段进行了分析；分析结果表明我们的样品是以碳硅键为主的薄膜。     

射频ICP离子源设计研究

本文介绍了射频 (RF)感应耦合等离子体 (ICP)离子源的设计研究。对RFICP的结构、离子流的引出以及离子流的均匀性、中性化和射频匹配网络进行了研究。     

Plasma spheroidization of iron powders in a non-transferred DC thermal plasma jet

In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high.     

Characterization of Virgin,Re-used,and Oxygen-reduced Copper Powders processed by the Plasma Spheroidization Process

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and assess oxygen reduction of the powder lots given their initial oxygen contents. Also, to investigate the impact of re-spheroidization on powder properties, the second round of spheroidization was performed on the already used-spheroidized powder. The impact of powder type on powder sphericity and particle size distribution was evaluated using the image analysis of scanning electron microscope (SEM) micrographs and laser diffraction, respectively. The spheroidized powder showed higher sphericity and more uniform particle size distribution overall. Depending on the powder collection bin, second round of spheroidization affected the powder sphericity differently. The possibility of deploying the plasma spheroidization process as an alternative oxygen-reduction technique was also investigated through tracking the powders’ oxygen content using inert gas fusion method before and after the spheroidization. The plasma spheroidized powder showed less oxygen content than the hydrogen-treated powder. The second round of spheroidization caused no change in oxygen content. The correlation between oxygen-reduction and created cracks was discussed and compared between plasma spheroidization and hydrogen-treatment. The plasma spheroidization process created a powder with higher sphericity, uniform particle size, and less oxygen content.     

Spheroidization of metal and ceramic powders in thermal plasma jet

In the present investigation, a theoretical estimation of the percentage of spheroidization of particles has been made from basic fluid dynamic equations. Particles of different sizes were considered at different plasma gas flow rates and temperatures (input power). Particle inflight residence and melting times were calculated and using them, percentage of spheroidization was estimated. Spheroidization was found to be strongly dependent on particle size and plasma jet temperature.     

钛合金表面等离子体电解氮碳共渗的研究

在含有硝酸铵、甘油、乙醇的水溶液中,利用等离子体电解渗入技术在Ti6Al4V钛合金表面制备了氮碳共渗层.利用SEM、XRD、GDS以及显微硬度计分析了渗层的形貌、成分、组织和显微硬度,探讨了渗层形成的机理和过程.结果表明:(1)以300V的电压经45min处理制备的渗层总厚度约为100μm,其中化合物层约为20μm,主要由Ti(C,N)相组成;(2)渗层最高显微硬度超过2000HK0.0025.等离子体电解渗入技术可以较快地在钛合金表面制备出厚度大、硬度高的氮碳共渗层.     

高频等离子体法制备纳米三氧化二锑

以普通三氧化二锑为原料,采用高频等离子体为热源,经高温加热和骤冷工艺,得到纳米三氧化二锑粉,对制备的粉体进行化学成分、比表面积、粒径、物相和形貌等测试。结果表明,采用高频等离子法制备的纳米三氧化二锑为立方晶系,粉体颗粒为球形,平均粒径为30 nm,比表面积为90.9 m2/g。     

等离子合成与雾化制粉技术及其应用

等离子体做为一种极端参数技术在粉体材料的球化处理与合成制备方面的研究和应用日益引起人们的关注。本文概述了等离子技术的主要特点及应用领域,综述了国内外有关射频等离子体对不同金属粉末、陶瓷粉末的球化处理及纳米粉末的合成方面的研究成果;介绍了北京科技大学在射频等离子体粉体处理系统开发、制备球形钨粉和钛粉方面的研究成果,在此基础上对等离子体粉体球化处理技术的应用前景进行了展望。     

射频等离子体放电的宏观参数与PET表面改性的关系

通过射频等离子体放电，采用O2，CF4及CH4／CF4混合气体等离子体对PET表面进行处理。改变射频等离子体放电的宏观参数，如放电时间、放电功率、电极间距离和复合参数，详细地研究了这些参数对PET表面改性的影响。结果表明：碳氟混合气体等离子体在PET表面的沉积速率为正值，在PET表面形成了聚合物；而O2和纯CF4气体的沉积速率为负值，两者在PET表面产生刻蚀效应。增加等离子体放电功率和放电时间，聚合或刻蚀效果更明显；而增加电极间距离和复合参数，聚合或刻蚀效果明显减弱。     

采用连续、脉冲等离子体合成低表面能薄膜

采用连续与脉冲射频等离子体合成低表面能薄膜SiCxOy.通过对薄膜性能的表征,发现等离子体放电模式影响聚合膜的化学结构、表面成份、表面能数值大小,认为采用脉冲射频等离子体更易合成低表面能聚合物.     

射频磁控溅射法制备HfSiON高k薄膜的结构特性

在室温下,采用射频磁控溅射法在p型Si(111)衬底上制备了HfSiON高k栅介质薄膜。用X射线光电子能谱(XPS)分析了HfSiON薄膜的成分,用掠入射X射线衍射(XRD)检测了薄膜的结构,用高分辨率扫描电子显微镜(HRSEM)、原子力显微镜(AFM)观察了薄膜断面和表面形貌。XRD谱显示,HfSiON薄膜经900℃高温退火处理后仍为非晶态。HRSEM断面和AFM形貌像显示所制备的薄膜具有非常平整的表面,表明薄膜具有优良的热稳定性。电学测试表明,HfSiON薄膜具有较好的介电特性,其介电常数较高为18.9,漏电流密度较低在+1.5V为2.5×10-7A/cm2。这些特性表明HfSiON薄膜是一种很有希望替代SiO2的新型高k栅介质材料,同时也表明射频磁控溅射法是一种制备HfSiON新型高k栅介质薄膜的有效方法。