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1.
This paper investigates the influence of particle injection angle on particle in-flight behaviors and characteristics at different
primary and carrier gas flow rates through an integrated modeling and experimental approach. Particle in-flight status such
as temperature, velocity, size and their distribution are analyzed to examine particle’s melting status before impact. Results
from the experiments and numerical simulations both show that, when carrier gas flow rate is fixed, a small injection angle
favors the particle melting and flattening. This behavior is independent of primary and secondary gas flow rates, spray distance
and carrier gas flow rate. When both carrier gas flow and injection angle vary, a high carrier gas flow rate and a small injection
angle are recommended for high particle temperature and velocity. 相似文献
2.
Comparative Study of Plasma Spray Flow Fields and Particle Behavior Near to Flat Inclined Substrates
Numerical models have been developed using computational fluid dynamics (CFD) analysis program FLUENT V6.02© to investigate the effect of the substrate on the behavior of the plasma flow fields and in-flight particles. Simulations are performed for cases where flat substrates are either present or absent, for the former, the substrate is oriented perpendicularly or inclined to the torch axis. It is shown that although the presence of perpendicular or inclined substrate significantly influences the plasma flow fields at the vicinity of the substrate, the particle behavior remain relatively unaffected. The insignificant effect of the substrate on particle behavior is qualitatively verified by experimental observation using SprayWatch© imaging diagnostics equipment. Images captured by the equipment confirm that the particles travel through the plasma plume with high momentum and show no sudden change in theirtrajectories right before impacting the substrate. Both the numerical and experimental findings show that the freestream model is sufficiently detailed for future work of this nature. 相似文献
3.
Heat Generation and Particle Injection in a Thermal Plasma Torch 总被引:1,自引:0,他引:1
Vardelle A. Fauchais P. Dussoubs B. Themelis N. J. 《Plasma Chemistry and Plasma Processing》1998,18(4):551-574
The operation of plasma guns used for plasma spraying involves a continuous movement of the anode arc root. The resulting fluctuations of voltage and thermal energy input introduce an undesirable element in the spray process. This paper deals with the effects of these arc instabilities on the plasma jet, and the behavior of particles injected in the flow. The first part refers to the formation of the plasma jet. Measurements show that the static behavior of the arc depends strongly upon the plasma-forming gas mixture, especially the mass flow rate, of the heavy gas, injection mode, nozzle diameter, and arc current. These parameters control the electric field in the arc column, the arc length, its stability, and the gas velocity and temperature. The dynamic behavior of the arc is examined to determine how the tempeature and velocity of the plasma gas vary with voltage variations. Relationships between the gas velocity at the nozzle exit and the lifetime of the arc roots, and the independent operating parameters of the gun can be established from a dimensional analysis. The second part discusses the interaction between the plasma jet and the particles injected into the flow. The parameters controlling particle injection and trajectory are examined to determine how injection velocity must vary with particle size and density to achieve a given trajectory. The effect of the transverse injection of the powder carrier gas is investigated using a 3-D computational fluid dynamics code. Finally, the effect of the jet fluctuations on particle trajectory is studied under the assumption that the jet velocity follows the voltage variation. The result is a continuous variation of the particle spray jet position in the flow. Experimental observations confirm the model predictions. 相似文献
4.
开发了一种基于雾化室加热的微流动注射进样系统,并用于血清中Pt的测定。该进样系统由微量毛细管雾化器、加热微型雾化室、八通道十六孔多功能旋转阀、蠕动泵和注射泵组成。研究了雾化室尺寸、加热温度和采样环体积对信号强度的影响。当雾化室内径为9 mm、加热段长度为6 cm,雾化室温度90 ℃,采样环体积为5 μL时,195Pt的信号强度提高了2.31倍,同时信号精密度从5.1%降至2.2%,并得到峰形良好的信号峰。该进样系统的试样消耗小、灵敏度和检出限均优于常规进样系统。10次测定10 μg/L的Pt标准溶液和血清样品溶液,峰高的RSD分别为2.9%和3.3%。该进样系统测得10个血清中的Pt含量与常规进样系统的测试结果无显著差异,在样品量稀少的情况下具有良好的应用价值。 相似文献
5.
Phenomena Involved in Suspension Plasma Spraying Part 2: Zirconia Particle Treatment and Coating Formation 总被引:1,自引:0,他引:1
C. Delbos J. Fazilleau V. Rat J. F. Coudert P. Fauchais B. Pateyron 《Plasma Chemistry and Plasma Processing》2006,26(4):393-414
The first part of this paper was devoted to phenomena related to liquid injection in the Suspension Plasma Spraying (SPS) process. This second part emphasizes the solid particles treatment and the coating generation. A simplified theoretical approach is proposed to evaluate the influence of the numerous experimental parameters on heat and momentum transfers from the plasma jet to individual particles. It is shown that small solid particles vanish by vaporization and are very sensitive to plasma arc fluctuations and thermophoresis effect, which makes particles to escape from the jet. This study is completed by experimental investigations concerning, first, in-flight collection of particles and, second, coating elaboration. The importance of the particle size distribution of the injected powder and the parameters for the plasma generation is demonstrated, as their choice can give either porous or dense coatings. 相似文献
6.
电解液,被称为锂电池的血液,对锂离子电池的主要性能起着决定作用。六氟磷酸锂(LiPF6)是生产电解液的核心材料,电解液中的杂质离子会对电池性能造成极大的负面影响。因此,掌握锂离子六氟磷酸锂电解液中杂质元素的检测方法显得格外重要。传统的消解后测试的方法会造成部分元素损失,会引入新的污染,对低含量的元素难以准确定量,标准推荐的稀释剂需要用到电子级碳酸甲乙酯,成本较高。采用30%(V/V)乙醇水溶液稀释六氟磷酸锂电解液后直接进样,搭配电感耦合等离子体发射光谱(ICP-OES)有机进样系统,采用标准曲线法,测定了六氟磷酸锂电解液中的铝、砷、钙、镉、钴、铬、铜、铁、汞、钾、镁、钼、镍、钠、铅、硫、锌共17种杂质元素含量。实验中对ICP-OES最佳工作条件(包括雾化室温度、雾化气流量、雾化器、蠕动泵转速、电源功率、氧气流量)进行了优化,结果表明,雾化室温度在5℃,雾化气流量在0.6 L/min,使用的雾化器为OneNeb雾化器,蠕动泵转速为50 r/min,电源功率为1 150 W,氧气流量为50 mL/min时,各元素的灵敏度、试液的消耗、耗材的磨损能达到最佳效果。结果表明... 相似文献
7.
8.
电荷注入检测器—端视等离子体原子发射光谱中分析动态范围 总被引:2,自引:0,他引:2
实验研究了电荷注入检测器-端视电感耦合等离子体光谱中分析动态范围,测量了AL,B、Be,Cd,Cu,Co,Fe,Li,Sr,V,K,Sr等12个元素的不同光谱级次的44条分析工作曲线。结果表明,分析范围为4-5个数量级,无明显自吸收,Lomakin公式的自吸收系数b=1,说明在CID-AVICP光谱中有较宽的分析动态范围 。 相似文献
9.
A simple and inexpensive laboratory-built vapor generator was used with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of mercury in urine and seawater samples. The applications of vapor generation ICP-MS alleviated the non-spectroscopic interferences and the sensitivity problem of mercury determination encountered when the conventional pneumatic nebulizer was used for sample introduction. The concentration of mercury was determined by isotope dilution method. The isotope ratio of mercury was calculated from the peak areas of each injection peak. The repeatability of the peak areas and isotope ratio determinations of seven consecutive injections of 1 ng mL?1 Hg solution were 2.3% and 2.2%, respectively. This method has a detection limit of 0.07 ng mL?1 for mercury. This method was applied to determine mercury in a CASS-3 nearshore seawater reference sample, NASS-4 open ocean seawater reference sample, NIST SRM 2670 freeze-dried urine reference sample and several urine and seawater samples collected from National Sun Yat-Sen University. The results for the reference samples agreed satisfactorily with the reference values. Results for other samples analyzed by the isotope dilution method and the method of standard additions agreed satisfactorily. Precision was better than 10% for most of the determinations. 相似文献
10.
微流动注射-等离子体质谱直接测定白酒中铅和镉 总被引:1,自引:0,他引:1
研制了多采样体积的微流控芯片, 结合普通的八通阀实现了等离子体质谱(ICP-MS)亚微升级样品的进样. 研究了白酒基体[52%(体积分数)乙醇]引入量对ICP的稳定性和裂解后所产生碳干扰的情况, 考察了进样体积与灵敏度的关系, 并优化了载流流速. 实验结果表明, 当进样量低于0.8 μL时, ICP-MS能长时间正常运行, 未出现积碳现象; 进一步将进样量降到0.3 μL以下, 可消除白酒基体中的碳所引入的质谱干扰. 在此基础上建立了用微流动注射ICP-MS直接测定白酒中Pb和Cd的方法, 每小时可分析45个样品, Pb和Cd的检出限分别为12和42 ng/L. 以水标准溶液直接测定了6个白酒样品中的Cd和Pb含量, 结果与微波消解-常规进样系统ICP-MS的分析结果一致. 相似文献
11.
本文采用1%四甲基氢氧化铵溶液溶解样品,单氦碰撞池模式直接分析特殊医用配方食品中的铬、钼和硒。研究表明:铬、钼和硒在质量浓度2.0~50.0μg/L范围内呈良好的线性关系,铬、钼、硒的检出限分别为0.012、0.009和0.009mg/kg;加标回收率在94%~117%之间,相对标准偏差在1.47%~5.78%之间。本方法对NIST 1849a和FAPAS T07216QC标准物质中铬、钼和硒的测定值与参考值相符。该方法操作简单、快速,适合特殊医用配方食品中铬、钼和硒的同时测定。 相似文献
12.
13.
Decomposition of Benzene in Air in a Plasma Reactor: Effect of Reactor Type and Operating Conditions 总被引:2,自引:0,他引:2
Ogata A. Miyamae K. Mizuno K. Kushiyama S. Tezuka M. 《Plasma Chemistry and Plasma Processing》2002,22(4):537-552
The decomposition of benzene was carried out in two types of plasma reactors packed with BaTiO3 pellets: one reactor had two stainless steel electrodes (SUS reactor), and the other reactor had a glass layer between two concentric electrodes (GL reactor). The decomposition efficiency and the suppression of formation of N2O and NOx were greater in the GL reactor than in the SUS reactor. In contrast, the suppression of O3 formation and the oxidation to COx in the SUS reactor were superior to those in the GL reactor. The effect of wa eform and frequency of applied ac power was in estigated for each reactor. 相似文献
14.
A new reactor and a novel in-situ sampling technique were developed for the study of the synthesis of CeO2 powders produced from dissolved cerium nitrate salts. The conical reactor minimized particle recirculation and provided a
highly symmetrical and undisturbed plasma flow suitable for the analysis of the phenomena affecting the formation of CeO2 powders. Both a calorimetric study of the reactor and a thermodynamic analysis of CeO2 formation were conducted. The sampling probe is described and near-isokinetic sampling was achieved. The sampled particles
were collected using a miniature wet collection system, i.e. a mist atomizer and a custom-made spray chamber. A numerical
simulation of the velocity and temperature fields of the plasma gas in the reactor was done using Fluent. A comprehensive
droplet-to-particle formation mechanism presented elsewhere is revisited and expanded based on calorimetry, thermodynamics
of CeO2 formation, numerical simulations and collected particles. No traces of other oxidation states other than CeO2 were found. 相似文献
15.
A novel reactor design, sampling probe and wet collection system were used to investigate the combined effects of plasma operating
parameters and particle collection mechanisms on the synthesis of CeO2 particles from liquid precursors. The sampling of particles in-flight and the collection of particles at several reactor
regions were used to provide experimental evidence of particle size at different reactor locations at various plasma operating
conditions, i.e., power and plasma gas flow rates. This information provided a picture of how CeO2 particles were formed and how these particles were collected in various locations. The effect of adding water-soluble fuels
(alanine and glycine) to the original cerium nitrate solutions was also investigated. Fuel addition decreased the temperature
of CeO2 formation by acting as a local heat source as a result of fuel auto-ignition. Photographs of the particles in-flight were
taken using a fast speed CCD camera. 相似文献