Fabrication of in-situ TiC reinforced composite coating via plasma transferred arc process

In this work, the in-situ TiC panicles reinforced composite coating was prepared by plasma transferred arc process on the surface of Q235 steel. Microstructures, phase composition and wear property of the coating were investigated. The results showed that the composite coating consisted mainly of T-Ni, TiC, Cr23C6, Cr7C3, Ni3Si, CrB, Cr5B3 and FeNi3 phases, and was characterized by fine TiC panicles embedded in Ni matrix. The wear resistance of composite coating was significantly improved compared with that of the steel substrate. The wear volume loss of the substrate was 443 mm3, which was about 9 times as that of in-situ TiC particles reinforced composite coating （49 mm3 ）. It is mainly attributed to the presence of chromium carbide particles and in-situ TiC particles and their favorable combination with Ni matrix.

Ni/Al Intermetallics Plasma Transferred Arc Processing

In-situ alloy development during surface processing allows for a limitless materials selection to protect components exposed to severe service conditions. In fact surface alloying offers the possibility to strengthen surface components with alloys that would not be possible to process otherwise. This work used Plasma transferred arc (PTA) hardfacing for surface alloying. Different amounts of aluminium powder, 5-25%, were added to a Ni based superalloy, from Hastealloy C family, in the atomized form. The mixture was homogeneized in a ball mill and PTA deposited on carbon steel substrate. The influence of different processing parameters on the final surface alloy was evaluated as current intensity and depositing velocity were varied. Coatings were characterized by optical and scanning electronic microscopy, X-ray diffraction and Vickers microhardness profiles, under a 500g load. Results showed that PTA hardfacing is an adequate surface alloying. For the conditions tested increasing hardness was obtained by solid solution for the lower amounts of Al added and due to the new intermetallic phases for the richer Al mixture.

Synthetically quantitative evaluation function of characteristic parameters on CO_2 arc welding process

The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis shows that the sensitivity of each characteristic parameter with regard to the variation of the short circuiting transfer process is different. The sensitivity of 4 kinds among these characteristic parameters is more intense than that of the short circuiting transfer frequency. In order to take account of the synthetic influence of these characteristic parameters, by means of the characteristic parameters synthetic value, a quantitative evaluation function is built up to describe and evaluate the short circuiting transfer process of CO 2 arc welding in real time. The testing shows that the evaluation function can give a suitable synthetic valuation for the short circuiting transfer process with a variety of welding variables.

Approximate entropy——a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding.

Keyhole Double-Sided Arc Welding Process

In the proposed method, the current/arc is guided through the keyhole so that the energy of the plasma jet is compensated while it is consumed in heating the workpiece along the keyhole. As a result, deep narrow penetration has been achieved on 12.7 mm (1/2') thick stainless steel plates using 70 A welding current.

Numerical simulation of temperature distribution and heat transfer during solidification of titanium alloy ingots in vacuum arc remelting process

In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium alloy ingots during VAR process.The results show that the temperature fields obtained by the simulation are well validated through the experiment results.The temperature distribution is different during the whole VAR process and the steady-state molten pool forms at 329 s for d100 mm × 180 mm ingots.At the initial stage of remelting,the heat dissipation of crucible bottom plays an important role in the whole heat dissipation system.At the middle of remelting,the crucible wall becomes a major heat dissipation way.The effect of cooling velocity on the solidification structure of ingots was investigated based on the temperature fields and the results can well explain the macrostructure of titanium alloy ingots.

Physical Characteristics of Welding Arc Ignition Process

The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack.The tungsten inert gas（TIG） touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system.The changing phenomenon of main ionized element provided the electrons in the arc ignition is found.The metallic element is the main contributor to provide the electrons at the beginning of the discharging,and then the excitated shielding gas element replaces the function of the metallic element.The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα.Through the discussion with the repeatability in relaxation phenomenon,the statistical regularity in the arc ignition process is analyzed.The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas（MIG） arc ignition experiments.This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

New methods for processing and interpreting marine magnetic anomalies:Application to structure,oil and gas exploration,Kuril forearc,Barents and Caspian seas

New methods are presented for processing and interpretation of shallow marine differential magnetic data, including constructing maps of offshore total magnetic anomalies with an extremely high reso- lution of up to 1-2 nT, mapping weak anomalies of 5-10 nT caused by mineralization effects at the contacts of hydrocarbons with host rocks, estimating depths to upper and lower boundaries of anom- alous magnetic sources, and estimating thickness of magnetic layers and boundaries of tectonic blocks. Horizontal dimensions of tectonic blocks in the so-called ＂seismic gap＂ region in the central Kuril Arc vary from 10 to 100 km, with typical dimensions of 25-30 km. The area of the ＂seismic gap＂ is a zone of intense tectonic activity and recent volcanism. Deep sources causing magnetic anomalies in the area are similar to the ＂magnetic belt＂ near Hokkaido. In the southern and central parts of Barents Sea, tectonic blocks with widths of 30-100 kin, and upper and lower boundaries of magnetic layers ranging from depths of 10 to 5 km and 18 to 30 km are calculated. Models of the magnetic layer underlying the Mezen Basin in an inland part of the White Sea-Barents Sea paleorift indicate depths to the lower boundary of the layer of 12-30 km. Weak local magnetic anomalies of 2-5 nT in the northern and central Caspian Sea were identified using the new methods, and drilling confirms that the anomalies are related to concentrations of hydrocarbon. Two layers causing magnetic anomalies are identified in the northern Caspian Sea from magnetic anomaly spectra. The upper layer lies immediately beneath the sea bottom and the lower layer occurs at depths between 30-40 m and 150-200 m.

Numerical Simulation of Gas Flow During Arcing Process for 252 kV Puffer Circuit Breakers

A numerical simulation model for 252 kV puffer circuit breaker is constructed, by using a proven commercial computational fluid dynamics （CFD） package, PHOENICS. The model takes into account the moving parts in the circuit breaker, turbulence enhanced momentum and energy transport, radiation transport. The arcing process in a SF6 puffer circuit breaker with two hollow contacts is simulated under different conditions, and the simulation results are verified with experimental results. Through simulation, the pressure, temperature and velocity in the arc quenching chamber can be obtained. The simulation model is also capable of predicting the influence of design parameters variations on breaker performance, and can thus help to reduce the number of short-circuit tests during the design stage.

Short-circuit process model in underwater welding using rotating arc sensor

In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments using rotating arc sensor is done. Different radius of rotating arc sensor is used. And the corresponding welding current and voltage is obtained,which is compared with the results of rotating arc sensor short-circuit process simulation model under high-pressure water environment established in this article. The results show that under high-pressure water environment,rotating arc radius should be optimized,otherwise the short-circuit-arcing cycle will transit to a short-circuit-arcing-abruption cycle,making the welding quality poor. At last the critical radius between the short-circuit-arcing cycle and short-circuit-arcing-abruption cycle under high-pressure water environment is obtained.

Processing parameters for Cu nanopowders prepared by anodic arc plasma

Copper nanopowders were successfully prepared by anodic arc discharging plasma method with home-made experimental apparatus.The effects of various processing parameters on the particle size of Cu nanopowders were investigated in the process,and the optimum processing parameters were obtained.In addition,the morphology,crystal structure,particle size distribution of the nanopowders were characterized via X-ray diffraction(XRD),transmission electron microscopy(TEM)and the corresponding selected area electron diffraction(SAED).The experimental results show that the crystal structure of the samples is the same fcc structure as that of the bulk materials.The processing parameters play a major role in controlling the particle size.The particle size increases with the increase of the arc current or gas pressure.

Real-time monitoring of weld penetration quality in robotic arc welding process

It is of great significance to develop an intelligent monitoring system for weld penetration defects such as incomplete penetration and burn-through in real-time during robotic arc welding process. In this paper, robotic gas metal arc welding experiments are carried out on the mild steel test pieces with Vee-type groove. Through-the-arc sensing method is used to capture the transient values of the welding voltage and current. The raw data of the captured welding current and voltage are processed statistically, and the feature vector SIO is extracted to correlate the welding conditions to the weld penetration information. It lays foundation for intelligent monitoring of weld quality in robotic arc welding.

ARC-SPLINE AND ARCLET PROCESSING

This paper presents a new spline called arc spline.It takes two arcsconnecting adjacent points among a sampled series,with known tangental of eachsampled point.The calculation for the parallel.the curve length and the segment-ing point coordinates are simple,thus making map symbol generation simplified.When 'arclet' occurs,some special processing must be taken.

ARC流程联合32点渗漏量表在居家输尿管皮肤造口患者换袋识别中的效果观察

目的探讨ARC流程联合32点渗漏量表在居家输尿管皮肤造口患者换袋识别中的应用效果。方法选取医院2018年1月—2020年5月行根治性膀胱全切+输尿管皮肤造口术后的患者152例,按照组间基本特征具有可比性的原则分为对照组和观察组,每组76例。对照组实施常规护理及换袋流程指导,观察组在对照组的基础上采用ARC流程联合32点渗漏量表客观测量的指导方法,比较两组患者造口周围皮肤(DET)评分、并发症发生率、生活质量评分及换袋识别准确程度。结果两组患者造口周围皮肤变色、侵蚀、组织增生评分及DET总分均随时间呈逐渐先升高再下降的趋势(P时间<0.05);出院后1个月、3个月时均为观察组低于对照组(P组间<0.05),并且随观察时间延长,组间差异逐渐增大(P交互<0.05)。两组患者出院后1个月、3个月,观察组患者并发症发生率均低于对照组,换袋识别准确程度均高于对照组,差异有统计学意义(P<0.05)。观察两组患者生理健康、心理健康、社会健康、精神健康评分比较结果显示,两组三个时点均呈逐渐升高的趋势(P时间<0.05);出院后1个月、3个月时均以观察组高于对照组(P组间<0.05),并且随观察时间延长,组间差异逐渐增大(P交互<0.05)。结论ARC流程联合32点渗漏量表有助于改善输尿管皮肤造口患者周围皮肤情况,降低皮肤并发症发生率,提高患者居家生活质量及换袋识别准确程度。

A modified heat source model for rotating arc welding

A modified mathematical model of heat source for rotating arc welding （RAW） process was developed for investigating the heat and temperature distribution. The characteristics of temperature field based on the complex welding motion trajectory were studied. In this work, a transient three-dimensional （ 3D ） model was established and computed by a finite element analysis computer program MARC as well as its subroutine. In RA＇W process, the temperature changes in the style of stepladder. Moreover in the high temperature zone, there are multiple peak temperature points. These characteristics of temperature distribution are induced by the arc rotating which leads the repetitive heating or fasing during the welding process. In contrast with non-rotating arc （NRAW） process, the width of temperature distribution enlarges, and the peak temperature of weld pool decreases. Good agreement is shown between the computed results and experimental results of thermal cycle in RAW process.

ARC换药流程在结直肠癌术后造口周围皮肤的应用研究

目的探讨ARC换药流程在结直肠癌造口术后患者造口周围皮肤的应用效果。方法选取122例结直肠癌行结肠或回肠造口术后的患者,随机分为观察组和对照组,观察组执行ARC造口换药流程并对患者及家属进行相关宣教;对照组执行常规护理流程和术后宣教。于出院前、出院1个月和3个月时对两组患者周围皮肤情况进行DET评分;每次换药如发生造口周围皮肤并发症则分类记录;比较两组患者出院后再就诊费用的总数。结果观察组的皮肤并发症发生率、出院后2次DET评分、再就诊费用均低于对照组,差异有统计学意义(P<0.05)。结论在结直肠癌造口术后患者中执行ARC造口换药流程能减少造口周围皮肤并发症的发生,改善造口周围皮肤情况,减轻患者再就诊的经济负担,提高造口患者保护造口周围皮肤的意识,进一步为医护人员造口换药操作流程提供参考。

基于ARCS模型的教学软件设计与实践

本文详细阐述了ARCS模型以及基于ARCS模型的教学软件的设计与实现方式。

ARCS动机模式在高职英语写作教学中的应用

本文在比较ARCS动机模式与过程教学法的基础上,探讨师生角色重新定位的重要性及特质,进一步阐述影响学生学习动机的引起动机、相关体验、自信心和满足感四大因素及其在写作教学中的具体应用和注意事项。最后,以学生的大学英语六级考试写作成绩为依据,证明ARCS动机模式在高职英语写作教学中的应用是行之有效的。

Cold Cracking of Flux Cored Arc Welded Armour Grade High Strength Steel Weldments

In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered （Q＆.T） steel welds. Flux cored arc welding （FCAW） process were used making welds using austenitic stainless steel （ASS） and low hydrogen ferritic steel （LHF） consumables. The diffusible hydrogen levels in the weld metal of the ASS and LHF consumables were determined by mercury method. Residual stresses were evaluated using X-ray stress analyzer and implant test was carried out to study the cold cracking of the welds. Results indicate that ASS welds offer a greater resistance to cold cracking of armour grade Q＆T steel welds.

Effects of processing parameters on figuration during the GMAW rapid prototyping process

As a deposition technology, gas metal arc welding （GMAW） has shown new promise for rapid prototyping of metallic parts. During the process of metal forming using the arc of GMA W, low heat input and stable droplet transition are critical to high quality figuration. The effects of various processing parameters on figuration quality were studied in the experiment of GMA W rapid prototyping using the wire of ERSO-6 , including welding voltage, wire feeding rate, welding speed and so on. The optimal parameters for ERSO-6 are obtained. Simultaneously, it is verified that the rapid prototyping parts with favorable structures and quality can be achieved under the conditions of low heat input and stable droplet transition.