工艺参数对空心阴极真空电弧电子温度影响

为了研究空心阴极真空电弧等离子体特性,通过光谱仪获得了空心阴极真空电弧的发射光谱分布,同时利用相对强度法计算了电子激发温度.结果表明,空心阴极真空电弧等离子体主要由氩离子、氩原子构成;随着放电气压的降低和焊接电流的增加,空心阴极真空电弧的离子浓度逐渐增加;在一定气体流量下,空心阴极真空电弧的电子激发温度随着焊接电流的增加而升高;在低气体流量、大焊接电流时,电子激发温度较高;随着放电气压的升高,空心阴极真空电弧的电子激发温度逐渐降低.当焊接电流较大和气体流量较低时,空心阴极真空电弧的轴线附近的氩离子谱线强度较高,并且其径向分布梯度较大.     

Microstructure and hardness of hollow cathode discharge ion-plated titanium nitride film

Titanium nitride (TiN) films were deposited on 304 stainless steel substrate by hollow cathode discharge (HCD) ion-plating technique. The preferred orientation and microstructure were studied by x-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Microhardness of the TiN film was measured and correlated to the microstructure and preferred orientation. The results of TEM study showed that the microstructure of TiN film contains grains with nanometer scale. As the film thickness increases, the grain size of TiN increases. The x-ray results show that TiN(111) is the major preferred orientation of the film. The hardness of TiN film is primarily contributed from TiN(111) preferred orientation.     

空心阴极真空电弧焊接的引弧机理

空心阴极真空电弧焊接（Hollow Cathode Vacuum Arc Welding,HCVAW)技术是一项新型、独特的技术,在航空,航天等工业部门有着巨大的应用潜力,本文介绍了空心阴极真空电弧焊接技术的特点及其放电机理,讨论了低气压下空心阴极电弧放电与常规电弧和电的不同特点,根据电离气体中性化条件,初步探讨了在低气压下空心阴极电弧放电的引弧过程,分析了影响低气压下空心阴极电弧放电引弧电压的因素。     

Equipment and technology for welding with a thermoemission hollow cathode in vacuum

ABSTRACT

The physical special features and principle of the method of welding with a thermoemission hollow cathode are investigated. The characteristics and applications of the welding method are described in detail and practical recommendations are presented for using the method in welding special engineering components.     

Effect of powder synthesis atmosphere on the characteristics of iron nanopowder in a plasma arc discharge process

To investigate the effect of the powder synthesis atmosphere on the characteristics of iron nano powder in a plasma arc discharge process, the hydrogen volume fraction in the powder synthesis atmosphere was changed from 10 to 50%. The particle size, phase structure, and magnetic property of the synthesized iron powder were studied using FE-TEM, XRD, XPS, and a vibration sample magnetometer at room temperature. The particle size increased simultaneously with the increase in the hydrogen volume fraction, and the particle size ranged from about 20 to 100 nm with the change in the hydrogen volume fraction from 10 to 50%. The synthesized iron powder particles had a two-layered shell-core structure composed of α-Fe in the core, Fe₃O₄ in the inner shell, and FeO(OH) in the outer shell. The thickness of the oxide shells decreased with increasing hydrogen volume fraction in the powder synthesis atmosphere.     

Special features of the excitation of welding arc discharge with a hollow cathode in vacuum

A system of concepts is suggested, which enables a criterial approach to soldered joints designing. New constructional forms of the soldered joints are worked out; these forms expand product mix and favour upgrading soldered constructions due to multicriterion comparative analysis at the design phase.     

Digital visualisation of the process of heating and melting of metal in arc discharge with a non-consumable electrode

Images of an electric arc, burning in argon, were produced using a digital camera in different wavelength ranges of the visible spectrum. The charts of the thermal fields of the heating spot were constructed and the plasma temperature in the anode section of the arc was calculated. It is shown that the digital technology of producing images in the visible range of the wavelength can be used for analysis of the processes taking place directly in the anode region of the arc and for evaluating the dimensions of the arc column.     

Optical emission from plasma discharge in electrochemical systems applied for modification of material surfaces

In this paper, spectral characteristics of optical radiation from a glow discharge with electrolytic cathode and temperature of the gas discharge were studied. Two formation mechanisms for excited species in such discharge are suggested. One of them is associated with electron collisions and another with direct production of excited particles during the non-equilibrium transfer of the solution components to the plasma due to ion bombardment.     

Zirconium vacuum arc operation in a mixture of Ar and O2 gases: Ar effect on the arcing characteristics,deposition rate and coating properties

The effect of oxygen and argon partial pressures (P_O2, P_Ar) in a Zr vacuum arc on plasma ion current density J_p, arc voltage V_arc, deposition rate v_d, and selected coating properties was determined. A d.c. arc current of I_arc = 100 A was initiated between a Zr cathode and a grounded anode. Cathode spots produced a plasma jet, which entered a 1/8 torus macroparticle (MP) filter. The plasma was guided by a d.c. magnetic field through an aperture to a glass substrate or a flat disk probe, mounted on a rotatable holder. J_p was measured with the probe, negatively biased to V_b = − 60 V. Coating thickness was measured using a profilometer, and coating properties were investigated using optical microscopy, energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), nano-indentation and optical analysis.     

高气压环境下脉冲MIG焊频率优化改善电弧稳定性的研究

对比分析不同压力环境下焊缝宏观图及相应焊接过程的电流、电压信号,并在此基础上分析了电流电压波形图、U-I图和概率密度图,探索脉冲频率对高气压环境下焊接电弧稳定性的影响。试验证实,压力环境下通过提高脉冲频率来补偿电弧弧柱区的能量损失,形成良好的焊接质量方法的可行性。试验证明,在0.3 MPa的压力下,脉冲频率提高到220 Hz,在0.5 MPa的压力下,脉冲频率提高到250 Hz,能够明显改善电弧燃烧的稳定性;实现稳定的焊接过程。为高气压环境下焊接工艺的改进提供有效的理论依据。     

渤海凝析油气藏探井转开发井防腐技术研究

目的 探究海上凝析油气藏CO2和H2S共存情况下,深探井转开发井回接生产时套管的腐蚀行为,控制井筒腐蚀风险,指导海上油气田可转开发井的深探井防腐设计和油套管材质优选。方法 基于现场所取储层流体样品的组分分析,确定储层井流物的组分以及其物化性质,然后针对可能选用的不同防腐等级的套管材质试片,采用室内高温高压腐蚀评价釜来进行腐蚀试验,最后根据腐蚀速率以及腐蚀形貌微观形态（SEM）结果,优选海上油气田探井转开发井生产套管的防腐材质。结果 同构造邻井中油气样CO2和H2S共存,所含CO2的物质的量分数为6.57%,H2S质量浓度为46.31 mg/m3,并且储层温度高达171.9 ℃,储层测试时虽不含水,但是探井转生产井后期不排除出水可能,出水后油套管腐蚀风险高。现场工况下,共进行了3Cr不锈钢、13Cr不锈钢及超级13Cr不锈钢材质的腐蚀评价试验,三种套管材质腐蚀速率分别为2.8844、0.0749、0.0182 mm/a。结论 常规3Cr不锈钢套管材质的腐蚀速率超过腐蚀控制线,综合考虑油气井后期开发出水等风险,推荐使用13Cr以上的防腐材质,能够有效降低探井转开发井后期回接生产时的生产套管腐蚀风险,目前已应用于渤海油气田4口探井转开发井的7寸尾管选材中,取得了良好的防腐效果。