大功率等离子喷枪研制

简要介绍一种自行研制的大功率等离子喷枪。喷枪采用中间环套螺纹联接、可调电极和气体沿钨极直线向下进 气等方式。经试验论证,该枪在高功率下能够稳定工作,枪体、喷嘴和钨极体的设计可以保证良好的冷却效果。     

等离子喷涂平面工作台的研制

大工件等离子平面喷涂由于其移枪速度、喷涂距离等工艺难以掌握，是热喷涂应用推广的一大障碍。我们针对这一问题，设计了一种采用微机控制的等离子平面工作台，通过实验考核，平面工作台性能稳定、质量良好、工作可靠。     

等离子弧喷涂设备现状及发展趋势

等离于弧喷涂技术是随着现代航空、航天技术的出现而发展起来的,目前已广泛应用于航空、航天、军事、纺织、机械、电力及生物工程等各个领域,是一项应用广泛的热喷涂技术,约占喷涂工艺的40％以上。目前,国内外普遍使用的还是中等功率(喷枪的使用功率在40kW左右),送粉方式     

油漆喷枪的研究现状

随着油漆喷涂技术的不断发展和广泛应用,作为该技术核心装置的油漆喷涂喷枪日益受到关注,改进现有的油漆喷涂装置和研发新装置,对获得高质量的涂层和提高喷涂效率、降低成本十分重要。文章综述了各类油漆喷涂喷枪的原理、特点、结构和现有的几种雾化方式、现有喷枪的优势以及喷枪所存在的一些问题,并列举了关于喷枪喷嘴、寿命和雾化效果方面不断优化的研究实例,并据此提出了现有的油漆喷涂喷枪还应继续优化以满足喷涂技术不断发展需要的建议。     

PLC在等离子喷涂控制中的应用

等离子喷涂作为一种应用广泛的热喷涂工艺，几十年来在我国发展迅速。作为喷涂工艺的保障，等离子喷涂设备也得到了长足的发展。在等离子喷涂设备中，控制系统起的作用至关重要，它起着控制喷涂过程、喷涂参数、遇异常情况保护电源和喷枪不被烧毁等作用。     

等离子喷涂耐磨陶瓷涂层的组织研究

为了满足表面冶金强化零件的各项性能要求,本论文主要研究了等离子喷涂Al2O3-13wt%TiO2复合陶瓷涂层的微观组织结构以及涂层的硬度和摩擦磨损等性能。研究表明:Al2O3-13%TiO2涂层具有良好的致密度,结合强度相对较低;而硬度又较大;涂层中有硬质相或颗粒,虽然宏观硬度并不特别高,但具有很高的耐磨性。     

高炉风口的等离子喷涂工艺

高炉风口是炼铁生产的重要易损件。本文简介绍了风口的使用情况，并较详细地介绍了用等离子喷涂工艺在风口的易损面上喷涂瓷层来提高使用寿命的方法。     

等离子喷涂活塞环工艺的研究

主要论述了９５型活塞环的等离子喷涂工艺参数选择的步骤，原则和方法，为该项工艺的实际应用提供方便。     

Modelling and diagnostics of multiple cathodes plasma torch system for plasma spraying

Usage of a multiple-arcs system has significantly improved process stability and coating properties in air plasma spraying. However, there are still demands on understanding and controlling the physical process to determine process conditions for reproducible coating quality and homogeneity of coating microstructure. The main goal of this work is the application of numerical simulation for the prediction of the temperature profiles at the torch outlet for real process conditions. Behaviour of the gas flow and electric arcs were described in a three-dimensional numerical model. The calculated results showed the characteristic triangular temperature distribution at the torch nozzle outlet caused by three electric arcs. These results were compared with experimentally determined temperature distributions, which were obtained with specially developed computed tomography equipment for reconstructing the emissivity and temperature distribution of the plasma jet close to the torch exit. The calculated results related to temperature values and contours were verified for the most process parameters with experimental ones.     

Fabrication of diamond nanopowder using microwave plasma torch technique

This article presents a manufacturing process for diamond nanopowder by using a microwave plasma torch technique in a laboratory at near atmospheric pressure. The unique technique utilized in the arrangement is the hybrid plasma torch which was patented in 1997 by Dr. Cheng-Ming Wu in Taiwan. It has the advantage of working at near atmospheric pressure and does not require an extreme vacuum system, which is a necessary condition for fabrication of a large amount of nanoparticles. The applied constituents of gas mixtures for synthesizing diamond nanopowder in the process are CH₄ with AR and CH₄ with N₂, where AR and N₂ serve as catalysts. In processing the reaction chamber, it is first pumped to varied pressures from 40–300 Torr to induce plasma; then, the input reactive gas CH₄ is fixed at a constant flow rate of 0.6 l/min and mixed up with varied input flow rate of the catalysts Ar and N₂ from 0.6–1.2 l/min. The particle size of synthesized diamond nanopowder is within about 25--50 nm diameter, which mainly depends on flow rate of CH₄:AR and CH₄:N₂.     

微波消解微波等离子体炬原子发射光谱法测定芦荟中Fe和Pb的含量

用微波等离子体炬(MPT)为激发光源,氩气为等离子体工作气体,用气动雾化进样,采用标准加入法研究微波等离于体炬原于发射光谱法(MPTAES)测定芦荟中Fe和Pb的方法。详细考察溶液硝酸浓度、微波前向功率、载气流量、工作气流量、氧屏蔽气流量等实验参数对测定的影响,还考察共存离子对测定的影响。同时,还通过常规消解方法与微波消解方法相比较,得出微波消解微波等离子体炬原子发射光谱法具有简单、快速、准确、待测元素不受污染等特点。结果表明,微波消解微波等离子体炬原子发射光谱法可以作为研究芦荟中微量元素的含量的一种行之有效的方法。     

细丝半自动CO2气体保护焊焊枪的改进

分析了焊枪的应用原理,针对目前推丝式鹅颈形焊枪存在的一些缺点加以改进,有效地提高了焊枪性能和焊接质量.     

等离子射流与喷涂粒子微观交互作用研究现状

从微观角度看,等离子喷涂层实质上是由大量喷涂粒子在等离子射流中经过一系列复杂的理化变换之后,撞击基体并迅速铺展凝固所形成的,因而熔滴撞击基体前的理化特性对涂层的组织结构、缺陷密度、力学性能等指标具有重要影响。通过对喷涂粒子基本特征参数、射流中的传热机理、传质机理与粒子加速行为四个方面的总结,详细综述等离子射流与喷涂粒子的交互作用过程。总体来说,温度、速度是粒子的基本特征参数,而采用一些综合温度与速度的复合参数（如熔融指数、雷诺数、韦伯数等）对熔滴的理化特性具有更好的表征效果;粒子的加热过程由表及里,受到热导率、比表面积、热容量、飞行路径及射流特性等多种因素影响,部分熔滴容易由于温度过高而发生汽化现象;处于熔融状态的粒子具有较高的活性,因而容易在射流中与气体介质发生反应,包括O₂、N₂、H₂等,同时粉体内部也会发生一定的元素迁移或化学反应;粒子在射流中由于受到气流拖拽力、重力、热泳力及气压梯度力的综合作用而不断加速,同时会由于射流特性及熔化状态的差异而发生不同程度的破碎或细化现象。     

Characterisation of a microwave induced plasma torch for glass surface modification

Microwave induced plasma torches find wide applications in material and chemical analysis. Investigation of a coaxial electrode microwave induced plasma (CE–MIP) torch is conducted in this study, making it available for glass surface modification and polishing. A dedicated nozzle is designed to inject secondary gases into the main plasma jet. This study details the adaptation of a characterisation process for CE–MIP technology. Microwave spectrum analysis is used to create a polar plot of the microwave energy being emitted from the coaxial electrode, where the microwave energy couples with the gas to generate the plasma jet. Optical emission spectroscopy analysis is also employed to create spatial maps of the photonic intensity distribution within the plasma jet when different additional gases are injected into it. The CE–MIP torch is experimentally tested for surface energy modification on glass where it creates a super-hydrophilic surface.     

Performance in Resistance to Surface Fatigue for Cr3C2–25%NiCr Coatings by Plasma Spray and CDS Spray

Three Cr₃C₂–25%NiCr coatings, prepared by Air Plasma Spray (APS)-Ar/H₂, APS-Ar/He and Continuous Detonation Spraying CDS, have been tested on a double-point-contact fatigue-test machine to examine their surface fatigue limit. Results show that the CDS coating exhibits the best performance in resistance to contact fatigue, while the other two coatings tested in our study are unacceptable as fatigue-resistant materials. On the basis of SEM observations, different failure mechanisms for the coatings are suggested. The fatigue limit of the Cr₃C₂–25%NiCr coatings decreases with the reduction of coating thickness, and the causes for the phenomenon have been discussed.     

电感耦合等离子体原子发射光谱炬管积碳成因分析

讨论了电感耦合等离子体原子发射光谱(ICP-AES)测试过程中形成积碳的原因。从泵速快慢、炬管位置高低、炬管第二层管位置不同、等离子体火焰两端样品浓度不同和溶剂体系等不同方面讨论炬管积碳形成的原因及改进措施。     

AZ91D镁合金表面热喷涂陶瓷涂层研究

介绍在AZ91D镁合金表面热喷涂Al2O3+TiO2陶瓷涂层的组织、性能。该涂层和基体结合良好,涂层硬度可达 800HV以上,并有良好的耐短期热冲击能力。     

Numerical simulation of fluid flow and heat transfer in a plasma spray gun

A computational fluid dynamics (CFD) simulation for analyzing fluid flow patterns in a plasma spray gun is presented in this study. It is coupled with a heat transfer simulation of the plasma spray gun. Based on CFD and heat transfer theory, the numerical model of the nozzle in the plasma spray gun is developed, and the coupled simulation of the flow fluid and heat transfer is carried out with the semi-implicit method for pressure-linked equations (SIMPLE) method. Local turbulence, which will lead to appearance of a static-water region, is found at the front corner of the cooling channel in the nozzle. The locations insufficiently cooled are found in the wall near the heat source and in the gasket in the rear of the nozzle. Then, cooling processes with different parameters of cooling water are analyzed. The optimal velocity and direction of cooling water, which efficiently cool the nozzle and improve the service life of the plasma jet, are obtained .