A356铝合金双重除气工艺研究

采用水模拟试验研究了两种旋转喷吹转子对气泡的影响,并分别采用透气砖、旋转喷吹和双重除气工艺对铝合金熔体除气,开发出一种双重除气工艺。结果表明,转子形状对铝液除气效果有较大影响,双层转子能够充分破碎气泡,并使气泡更加分散,起到良好的除气效果。旋转喷吹对底部铝液除气效果较差,而透气砖除气效率较低,采用透气砖和旋转喷吹双重除气,能够充分处理底部铝液中的气体,显著提高除气效率。     

铝合金旋转喷吹除气工艺的水模拟实验研究

基于CO2-NaOH体系来模拟实际的铝液净化工艺.首先利用初步正交水模拟试验法确定铝液旋转喷吹净化的最主要影响因素为气流量和旋转头转速;而后得到气流量、喷吹时间以及旋转头转速的二次回归方程,确定了旋转除气净化的最佳工艺参数为转速v=374r/min,气流量q=1.8L/min.     

铝熔体旋转喷吹的除气效果及其对成分的影响

利用旋转喷吹装置对A356合金熔体进行净化处理,研究其除气效果以及净化过程中对合金元素烧损的影响.结果表明,旋转喷吹净化的除气效果优于传统的熔剂除气精炼;在净化过程中会造成Sr、Mg元素的烧损.     

旋转喷吹氩气在Al-Si合金熔体净化中的应用

对ZL101熔体分别采用熔剂处理、旋转喷吹氩气处理,检测处理前后的含氢量。将未净化及采用两种不同工艺处理的ZL101熔体分别浇注砂型、金属型铸件,对比两种处理方法对铸件针孔度的影响。结果表明,旋转喷吹氩气的除气效果明显优于熔剂处理;旋转喷吹氩气后,不论是砂型还是金属型,铸件针孔度都可达到一级。     

铸造镁合金旋转喷吹除气的试验研究

研究了旋转喷吹技术在AZ91镁合金熔体除气净化处理上的应用。采用减压凝固法考察了旋转喷吹的除气净化工艺的净化效果，确定了最佳的除气时间。利用金相显微镜观察了除气前后合金的微观组织。对除气前后的合金，进行了金属型和低压砂型铸造试验浇注，并对其力学性能进行了测试和比较。研究结果表明，经过30min旋转喷吹除气处理后，能快速显著地降低镁合金中的含气量，AZ91合金金属型和低压砂型试样的力学性能都明显地得到提高，特别是合金的伸长率得到大幅度的提高。     

镁合金熔体除气净化现状及未来展望

本文阐述了镁合金熔体中气体对于镁合金的危害,通过除气可以降低合金中的氢含量,从而减少微观组织缩松,提高合金的力学性能以及腐蚀性能.综述了活性气体、惰性气体、稀土除气、真空除气、超声波除气、旋转喷吹除气以及复合除气等各种镁合金除气方法及其应用特点.并对未来镁合金的除气方式进行了展望,复合净化既具有良好的除气效果同时也能去...     

旋转喷吹除气法的影响因素分析及其水模拟实验研究

通过水模拟实验研究了影响旋转喷吹除气法的诸因素.探讨了喷头旋转所引起的漩涡的形态及其对除气效果的不利影响,考察了阻流体的形状和位置对除气效果的影响.分析了喷孔尺寸、气流量、旋转头转速、熔池形状等参数对除气效率的影响.实验表明,喷头的结构和设计参数是影响不同的旋转喷吹设备净化效果的决定性因素,旋转喷头的设计应尽量增加其对气泡的附加紊流切应力和改善除气条件.     

铝合金精炼与变质复合工艺的试验研究

研究了不同精炼处理工艺对铝液精炼效果的影响,分析了精炼工艺对不同变质剂变质效果的影响。结果表明,氩气旋转喷吹技术与盐类精炼复合的精炼工艺,可提高铝液的精炼效果;氩气旋转喷吹精炼与钠盐变质处理同时进行的复合工艺,可降低钠盐变质处理时的吸气倾向;氩气旋转喷吹精炼能减少铝液中锶的烧损,提高Sr的变质效果。     

旋转吹氮铝液精炼方式的改进及效果研究

为了改善铝合金重力铸造中针孔及夹杂缺陷，通过对吹氮净化铝液工艺中的旋转喷头的改进，来细化氮气气泡的体积，增加氮气与铝液的接触面积，从而提高除气除渣的效果，达到铝液净化的目的，最终提高产品的质量。     

国外铸造文摘

91301 惰性气体在铝液中的除气作用(日)/大塚良达等/轻金属4,1990,290～297 本研究为通过新开发的旋转喷嘴在铝液中喷入直径为2～8mm细小的惰性气体进行除气。使用其旋转喷嘴对纯铝及各种铝合金熔液施于氩气冒泡,由此研究其熔液的除氢效果为:(1)经过3分钟左右的氩气冒泡处理后,熔液的氢气浓度急剧下降,而6分钟     

STRUCTURE AND SURFACE CONDITION OF ULTRAFINE AI PARTICLES

The crystal habit,crystalline structure,surface condition and composition of the ultrafine Alparticles prepared by inert gas evaporation method were studied in detail by means of highresolution transmission electron microscope,X-ray diffraction and X-ray photo-electronspectrum.The results indicate that the ultrafine Al particles prepared in high pure inert gasare of clear crystal habits,single crystal in a large majority and fcc crystalline structure witha_0=0.405 nm.It is also found on the surface of the Al particles that there is a layer of amor-phous Al_2O_3 with 2 nm average thickness,which could protect the particles against oxidizingfurther.Therefore,the ultrafine Al particles prepared by the inert gas evaporation method arevery stable in atmosphere.     

Effect of hot dip aluminising on interfacial microstructure and mechanical properties of Ti/Al joint by TIG arc welding brazing

Abstract

The joint of Al 5A06 and aluminised Ti–6Al–4V dissimilar alloys was achieved by means of tungsten inert gas arc welding brazing. The effect of aluminized coating on the spreading behaviour of filler metal on Ti substrate was studied. The spreadability of liquid filler metal on the Ti substrate was enhanced obviously due to the presence of aluminised coating. The interfacial reaction layer was characterised by a uniform lamellar layer of TiAl₃ intermetallic, with a thickness of 1 μm. Sound joints with well appearance were obtained, and the optimised tensile strength of the joint reached 216 MPa. The failure initiated from the interfacial layer at the root face and then propagated within the weld seam at the upper part of the joint. Capable welding parameters were broadened by the presence of aluminised coating for dissimilar metal joining of Ti/Al.     

Al-coated iron particles: Synthesis, characterization and improvement of oxidation resistance

A Fluidized Bed Metal Organic Chemical Vapour Deposition (FB-MOCVD) process has been successfully applied to coat Fe particles with Al. N₂ inert gas was used to transport the organometallic Al precursor (liquid triethylaluminium) inside the fluidized bed reactor whose temperature is 350 °C. XPS analyses and TEM observations have revealed the presence of a thin alumina layer surrounding the Al coating. Oxidation treatments, performed in the temperature range 350-500 °C, demonstrate that this multi-scale coating constitutes an efficient barrier to protect iron particles against oxidation. Such a treatment may be used to perform environmental barrier coatings around magnetic powders.     

惰性气体保护熔炼--国外精铸技术进展述评(8)

惰性气体保护熔炼的基本原理是将低温液态惰性气体滴在熔池表面或直接将惰性气体覆盖在熔池上方，驱赶熔池上方的空气，降低熔池上方气体中的氧含量，从而避免合金液氧化和吸气。使用该技术后，熔炼过程无须熔剂覆盖和脱氧，不仅非金属夹杂物、气体夹渣等铸造缺陷大为减少，而且由于合金液纯净度提高，流动性也有所改善，浇不足、冷隔等缺陷随之减少：     

LSM法制备TiB2/Al复合材料净化的研究

采用X射线衍射仪、图像分析仪和光学显微镜,分析LSM法制备TiB2/Al复合材料的相组成,考察了净化方式对TiB2/Al复合材料的影响.结果表明:熔剂法精炼对TiB2/Al复合材料中TiB2颗粒的分布无明显影响,精炼后TiB2含量基本保持不变,而浮游法精炼则有显著影响,精炼后未检测到TiB2颗粒.普通铝合金的浮游法精炼工艺不适于复合材料的精炼.     

Mechanical properties of welded joints in thin walled aluminium extrusions

Abstract

The present work describes the tensile properties of weldments in thin walled extruded Al–Mg–Si alloys. Tungsten inert gas (TIG), metal inert gas (MIG), and friction stir (FS) welding are considered. Properties of joints welded with different filler metals are presented, both matching and undermatching the parent materials in strength. The weldments were tested in both as welded and post-weld aged conditions. It is shown that silicon rich filler metals (Al–5Si and Al–12Si) were adequate for the welding of 6063 alloy but did not give welds with strength sufficient to match that of 6082 alloy. Tungsten inert gas welding resulted in large heat affected zone (HAZ) widths of 20 mm, compared with HAZ widths of 10 and 8 mm for MIG and FS welding respectively. This relationship was also seen in tensile tests where FS specimens exhibited the highest strength and TIG specimens exhibited the lowest strength. The post-weld aged materials recovered some strength, with increases in tensile strength of 10–15% for 6063 alloy and of 20% for alloy 6082 compared with the strengths of the as welded specimens. Comparisons between experimental data and two design codes, a draft European standard and the British standard BS 8118, show that the European standard is conservative for welds in thin walled material. Standard BS 8118 describes MIG and FS HAZ widths well but underestimates the HAZ width for TIG welds.     

表面阳极化铝型材焊接工艺研究

对表面阳极化铝型材分别在不同母材表面预处理和采用不同填充材料情况下的焊接工艺进行了试验研究.结果表明,采用钨极氩弧焊方法,在两种预处理条件下,用Al-Si焊丝施焊获得的接头组织致密,未发现有气孔、夹杂和微裂纹等缺陷,接头性能明显优于用纯Al焊丝获得的接头.     

金属材料中微量氢和氧的分析

叙述了惰性气氛熔化法测定金属材料中微量氢和氧的条件和方法。着重研究影响分析限的空白因素及降低空白的方法和分析限，制定出了Ｔｉ，Ｚｒ，Ｈｆ，Ｔａ，Ｎｂ，Ｗ，Ｍｏ，Ａｌ，Ｃｕ等及其合金中微量氢和氧的分析方法。     

铜质零件电刷镀多元合金的反应扩散钎焊工艺

介绍了在铜质零件上局部电刷镀多元合金后,把零件放入惰性气体保护炉内,连接处形成过渡液相的接触反应扩散钎焊工艺。     

向金属液中吹氩精炼的研究

介绍了向金属液中吹入惰性气体进行精炼的各种方法,包括中频炉底埋置透气砖吹入法、浇包底置透气砖吹入法及用石墨管向铜液中吹入惰性气体法。例举了吹入惰性气体法的优点：净化金属液,提高金属件品质,降低铸件废品率。