离子镀膜中的弧电流对膜层质量的影响

论述了电弧电流对多弧离子镀膜层的硬度，厚度及其外观形貌的影响，并进一步阐述了电弧电流在实际应用中的作用，说明了镀制不同功能的膜层，应选择不同弧电流的重要性。     

双弧脉冲MIG焊耦合电弧特性的数值模拟研究

针对双弧脉冲MIG焊热源稳定性差的问题,本文对双弧脉冲MIG焊耦合电弧进行瞬态数值模拟,分析了不同脉冲电流参数下耦合电弧形态、温度和压力的分布及变化规律。研究表明：耦合电弧呈驼峰状,脉冲电流发生跳变时,耦合电弧伸展或收缩,并逐渐稳定,峰值电流越小,越快达到稳定;增大脉冲电流,耦合电弧温度和电弧压力随之升高;保持总电流不变,减小主弧电流,增大旁弧电流,主弧温度和电弧压力减小,旁弧温度和电弧压力增大,当旁弧电流足够大时,耦合电弧温度和电弧压力呈双峰分布。数值模拟结果与双弧脉冲MIG焊工艺实验结果吻合良好,模拟结果对调控双弧脉冲MIG焊脉冲电流参数,改善其耦合电弧稳定性及工艺性能具有重要意义。     

直流电弧对工业硅埋弧炉内传热过程影响的数值模拟

为优化直流埋弧炉工业硅冶炼过程,建立二维轴对称等离子体电弧的磁流体动力学模型,运用有限元分析软件,计算得到了等离子体电弧的形态特征分布,并与已有的实验测量结果进行了比较。通过计算不同电流、弧长条件下电弧的温度、速度变化以及熔池表平面的热通量组成分布,分析了电弧的形态变化规律和电弧的传热方式,由此计算不同电流值、不同电弧弧长的条件时,电弧向阳极熔池表面传热的效率。结果表明:弧长越长,向熔池表面传热的效率越小;电流越大,向熔池表面传热的效率越高。基于结果分析,工业硅生产应采用长电弧低电流高电压的冶炼模式。     

新型微束等离子弧焊接电源的研制

鉴于高频电弧具有较强的自收缩作用及较好的电弧稳定性的特点 ,研制了调制型脉冲微束等离子弧电源 .本电源可通过对高频电流的低频脉冲调制调节电弧对焊缝的热输入 ,同时具有电弧能量密度大、主弧空载电压低及起始电流递增和熄弧电流递减等功能 ,适用于铜、钛、不锈钢等金属薄件、微细件的焊接 .     

磁过滤真空阴极电弧技术弧电流对四面体非晶碳薄膜性能的影响

研究了磁过滤阴极真空电弧技术中不同弧电流(20~100 A),制备的四面体非晶碳薄膜性能的影响。通过对薄膜厚度、薄膜硬度、表面形貌以及sp3键含量随弧电流的变化结果进行了测试。结果表明,当弧电流从20增大至100 A,表征薄膜sp杂化碳含量的ID/IG从0.212增加到1.18,显示制备薄膜的sp3键含量逐渐减少,同时sp2键在逐渐增加。随着弧电流值上升,薄膜硬度增加,表明其值与弧电流值呈正相关性,高的弧电流使通过磁过滤器的大颗粒等离子体数增加,从而薄膜表面形貌易于沉积大颗粒,导致薄膜表面质量下降。因此,选择合适的弧电流值可优化Ta-C薄膜制备工艺,本文研究内容为工业应用中通过弧电流调整优化膜层综合性能提供参考。     

新型阴极弧电源研制及脉冲增强电子发射(P3e)效应研究

本文研制了新型脉冲阴极弧电源,并实现了脉冲增强电子发射(P3e)以提高真空室内等离子体密度。该电源核心由脉冲发射和维持电流系统构成,由单片机和触摸屏系统协同控制和管理。对P3e电源进行放电特性和脉冲增强电子发射效应进行了研究。结果表明,在相同平均电弧电流条件下,与直流相比,P3e技术能够显著提高工件(基体)脉冲电流与平均电流。在电弧平均电流90 A时,基体脉冲电流由5 A提高到19.6 A,基体平均电流由2.2 A最大提高到4.6 A,表明脉冲增强了电子发射,进而获得高的等离子体密度,这将有助于增加膜层致密性、降低膜层应力。该新型电源对于阴极弧靶中毒抑制、膜层结构改善、膜层颗粒污染控制具有重要的意义。     

工艺参数对阴极电弧离子镀ZrN薄膜表面形貌及结构的影响

本文采用阴极电弧离子镀技术制备了ZrN膜层,研究了工作气压、偏压、弧流等工艺参数对ZrN膜层表面形貌和结构的影响,分别用扫描电镜(SEM)、X射线衍射仪(XRD)分析了膜层的表面形貌及相结构。结果表明:工作气压、偏压、弧电流等工艺参数对ZrN膜层的表面形貌有较大的影响,在本实验内适当提高N2压强、偏压以及在稳弧前提下降低弧流有利于减少大颗粒,改善ZrN膜层表面形貌,提高膜层综合性能;不同工艺参数下制备的ZrN膜层均具有典型的面心立方结构,工作气压和弧电流对ZrN膜层晶体生长方向的影响较小,偏压对晶体生长方向的影响显著,在20 V偏压下,晶体呈(200)面择优取向,继续提高偏压(100 V~300 V),晶体生长呈(111)面择优取向。     

工艺参数对电弧离子镀沉积铜薄膜微结构及性能的影响

采用脉冲偏压电弧离子镀技术在不同工艺参数(弧电流、基体负偏压)水平下制备了一系列铜薄膜。利用金相显微镜、腐蚀失重试验和双向弯曲试验分别研究了弧电流和基体负偏压对铜薄膜组织结构、耐腐蚀性能和结合性能的影响。结果表明,弧电流由40A增加到80A,薄膜表面颗粒含量明显增加,大颗粒尺寸由13.71μm增加到19.36μm,膜层平均腐蚀速率降低;随着弧电流提高,薄膜结合性能先降低后提高,60A时膜层结合性能最理想;随着基体脉冲负偏压升高,薄膜结合性能提高,薄膜表面颗粒含量及其尺寸减小、负偏压达到200V时大颗粒净化效果明显;基体脉冲负偏压由20V升高到180V,膜层平均腐蚀速率先降低后升高,140V时膜层耐腐蚀性能最佳。     

电弧对焊接过程辐射测温的影响分析

针对小电流电弧的辐射特点，对焊接过程近弧区辐射温点的电弧干扰进行了分析，得到了电弧干扰对测温的信噪比公式及影响因素，定量地证明了存在小电流电弧成时辐射测湿法的可行性。     

不同弧源电流TiN薄膜的表面形貌及其摩擦学性能研究

本文使用AIP-01型国产多弧离子镀膜设备,采用不同的弧源电流在不锈钢衬底及Si片上制备了TiN薄膜,对其硬度、表面形貌以及摩擦系数等进行了测试,从电弧沉积的物理机制角度详细分析了弧源电流对TiN薄膜表面熔滴的影响,结果表明:随着弧源电流的增大,薄膜沉积速率增大、硬度提高,但薄膜表面熔滴(MP)数量增多、尺寸变大,表面粗糙,摩擦系数增大,因此控制最佳弧源电流来获得最好的薄膜性能是离子镀TiN薄膜的关键问题之一.     

纳米Ag-Fe合金的真空电弧特性

利用微乳液法制备出纳米复合Ag-Fe合金,在真空条件下,利用高速摄影机观测Ag-Fe系列合金的阴极斑点运动,采用示波仪记录放电电流曲线,并利用扫描电子显微镜观察电极表面烧蚀状况.研究结果表明:Fe纳米粒子的加入使得电弧分散,电孤的寿命增加,截流值降低.     

脉冲偏压电弧离子镀制备C_(1-x-y)N_xZr_y超硬复合薄膜

用脉冲偏压电弧离子镀方法在保持石墨靶弧流恒定的条件下,通过同步改变锆靶弧流与氮流量,在硬质合金基体上制备了一系列不同成分的C1-x-yNxZry复合薄膜.随着锆靶弧流与N流量增加,薄膜中Zr与N含量都呈线性增加,同时C含量快速减少.Raman光谱显示所制备的薄膜具有DLC特征,而XRD结果显示薄膜中还存在有明显的ZrN晶体相,说明本实验所制备的薄膜属于在DLC非晶基体上匹配有ZrN晶体相的碳基复合薄膜.随Zr与N含量增加,薄膜硬度先增大后降低,当x=0.19,y=0.28时薄膜具有最高硬度值,为43.6GPa,达到了超硬薄膜的硬度值.     

Laser-Monitor-Assisted Investigation of the Regions of Closure of Current on the Electrodes of an Atmospheric-Pressure Low-Current Carbon Arc

The results are given of observations of regions of closure of current on the electrodes of an atmospheric-pressure low-current carbon arc, performed using a laser monitor immediately during the time of burning of the arc. It is found that the time of existence of a cathode crater on a graphite cathode is 0.2–0.3 s. An analysis of images of the region of closure of current on a pyrographite cathode reveals evidence of melting of pyrographite. A comparison of images of the region of closure of current on the electrodes of a carbon arc with the available literature data on the conditions of closure of current on the anode and cathode enables one to establish the origins of the various details of images of the region of closure of current on the cathode and anode of a low-current carbon arc. The results of this comparison further lead one to conclude that a low-current electric arc is an arc with liquid cathode and anode spots, and that the melting process is a stabilizing factor as regards the current density in those spots.     

变极性等离子弧穿孔熔池受力及焊缝成形稳定性

通过YB005-01型压力变送器测定相同参数条件下正极性等离子电弧力大于反极性等离子电弧力,并建立了铝合金VPPA焊接穿孔熔池受力模型,分析了在不对称正、反极性等离子电弧力的作用下,穿孔溶池稳定性及其焊缝成形机理.同时进一步分析铝合金VPPA力学特性,掌握了焊接电流和离子气流量等重要焊接参数对其影响.经穿孔焊工艺实验,...     

Robust sensing of arc length

During arc welding, the arc heats and melts the workpiece as heat flux. When the welding current is given, the distribution and the intensity of the heat flux are determined by the length of the are. The measurement and control of the are length are fundamental in robotic and automated welding operations. Length of welding arc determines the distribution of the arc energy and thus the heat input and width of the weld. This work aims at improving the measurement accuracy of arc length using the spectrum of are light at a particular wavelength during gas tungsten arc welding (GTAW) with argon shield. To this end, effects of welding parameters on spectral distributions were studied. To verify the effects of base metal and arc length, the arc column was also sampled horizontally as Layers for spectral analysis. Results show that spectral lines of argon atoms are determined by are length, independent of welding parameters other than the current. Based on these findings, a compact arc light sensor has been designed to measure the arc length with adequate accuracy. A closed-loop arc length control system has been developed with the proposed sensor     

Numerical study on effect of external magnetic field, current profile, arc current and arc column radius on helical instabilities of arcs

This model differs from previous works in that the electrical conductivity (and the current profile) is approximated in a more realistic way (parabolic instead of flat profile). The magnetohydrodynamic equations in an electrostatic approximation serve as the starting point of the theory. The effects of the external axial magnetic field, current profile, arc current and arc column radius on the helical instabilities of arcs were numerically studied. Numerical results show that the short wavelength perturbation can be stabilized by positive direction magnetic field, whereas the long wavelength perturbation can be stabilized by reverse magnetic field when the current profile is the uniform distribution. In the short wavelength perturbation case, the effect of positive direction magnetic field on the arc stability is very small when the current profile has a parabolic distribution. However, its stabilizing effect is enhanced for the long wavelength perturbation. The intermediate and long wavelength perturbation can also be stabilized by reverse magnetic field. The low current is beneficial for stabilizing arcs.     

多弧离子镀用于制备高质量的Ti-N膜

研究了多弧离子镀制备Ｔｉ－Ｎ膜的重要工艺参数（磁场、弧电流、偏压和氮气流量）对膜层质量的影响．详细分析了它们影响膜层特性的原因,实验证明,提高弧电流的同时抑制液滴的产生,是提高膜层质量和生产效率的有效途径。     

Formation of stainless steel layer on mild steel by welding arc cladding

The discrete microstructural characterization and the formation of stainless steel layer on mild steel where produced in cladding deposits, and fusion boundary region were investigated using tungsten inert gas (TIG) arc, high current pulsed arc and constricted plasma arc. The experimental procedure involved making bead-on-plate method for controlled travel speed, employing filler metal by using tungsten inert gas arc, pulsed current gas tungsten arc and transferred plasma arc, with subsequent sectioning and examination of the reaction interface. For TIG arc cladding, using filler metal of small diameter the deposit does not become stainless steel, but on using 3.2 mm diameter filler metal it becomes stainless steel with less than 50% dilution. For pulsed arc cladding, the complete stainless steel is not obtained on account of the existence of an incomplete mixture, particularly at the fusion boundary region. However, on using a large diameter filler metal at a pulse frequency of 500 Hz, the complete stainless steel microstructure has been accomplished. The plasma arc cladding can be achieved in such a way that the conversion into stainless steel on the mild steel surface — which is the microstructures of cellular austenite in cladding deposit and cellular dendritic austenite containing δ or σ-phase in fusion boundary region — is possible irrespective of the melt penetration and the dilution. The following conditions were found to be beneficial for the formation of stainless steel microstructure layer on the mild steel: using large diameter filler metal, below 50% dilution, and further rendering arc localized and constricted.     

Erosion of a Copper Cathode in a Nonstationary Arc Spot. I. Experimental Investigation

A study has been made of the dependence of the erosion of a copper cathode of an electricarc heater on the basic operating parameters: the arc current, the velocity of movement of an arc spot, and the temperature of the electrode surface. The experiments were conducted in a coaxial electricarc heater with a magnetic movement of the arc in an air medium for an arc current of 95–480 A and a magnetic field of 0.005–0.417 T. The duration of the experiment, the axial velocity of a plasmaforming gas, and the flow rate of a cooling water were held constant. It has been shown that there are two different erosion regimes: the microerosion regime characterized by a weak dependence on the current and the macroerosion regime with a strong dependence on the current; the transition from one regime to the other is realized upon the attainment of the critical value of the current, dependent on the magnetic field and the thermal regime of the electrode. The existence of a velocity interval in which the specific erosion is minimum has been shown, which confirms the predictions of the earlier thermal model of erosion of cold electrodes.