Post-mortem analysis of high alumina brick attacked by vanadium and titanium bearing slag after service in torpedo ladle

Abstract

High alumina brick after service in a torpedo ladle was analysed by means of atomic emission spectroscopy, X-ray diffraction, electron probe microanalysis and themochemical analysis in order to determine the corrosion mechanism during industrial application in a steel works. The results showed that slag containing vanadium and titanium oxide is more corrosive than common silica slags, and that this facilitates corrosion and penetration into the high alumina brick. Mineralogical observation confirmed that V₂O₅, TiO₂, MnO and FeO and MgO in the slag reacted with native phases presented in high alumina brick to form complex spinel, corundum and anorthite solid solution, etc. The dissolved content of V₂O₅ in the spinel decreased from 6·08 to 2·78 wt-% from the working face to the inner area. However, the FeO and MnO content in the spinel varied little with a slight increase in the TiO₂ content. The expansion coefficient mismatch between the penetrated zone and cold face zones, which results in densification spalling and increased porosity, play a key role in the failure of the high alumina brick.     

Copper Anode Furnace: Chemical,Mineralogical and Thermo-Chemical Considerations of Refractory Wear Mechanisms

In copper anode furnaces, the installed refractory lining is exposed to chemical attack caused by slag and copper oxide. This results in infiltration of the brick microstructure and corrosion of the bricks’ inherent components. Increased temperature level changes the temperature and partial pressure during the furnace operation, as well as the copper infiltration into the brick microstructure, leading to further degeneration of the microstructure and decreased lining life. The mechanical load includes the erosion caused by primary movement of the metal bath, slag and charging material, as well as stresses in the brickwork due to improper lining procedures. Thus, chemical and mineralogical investigation carried out on “post-mortem samples”, together with thermochemical calculations by FactSage? software, enables better understanding of refractory wear in the copper anode furnace.     

Status of Basic Refractory Technology

A summary of the most recent developments in the use of high-purity periclase, chrome ore, and chrome-ore agglomerates as raw materials for basic brick manufacture. The mechanisms of deterioration and eventual failure of basic brick are discussed. Areas of possible improvement in basic brick quality are considered.     

航空光电雷达电机换向器激光沉积再制造

航空光电雷达电机换向器部位使用的纯铜材料在服役中容易发生表面损伤,传统红外激光沉积纯铜材料过程中激光吸收率较低。采用蓝光激光器对纯铜电机换向器失效部位进行送粉式激光沉积修复(所用粉末为 Cu-15Sn),研究蓝色激光工艺参数对修复形貌及修复区组织性能的影响。采用光学显微镜、扫描电镜及附带能谱仪、显微硬度计、微型摩擦磨损试验仪表征和测试修复区的微观组织、显微硬度及耐磨性能。结果表明：蓝光激光可以在较宽的工艺参数窗口范围获得良好的修复层。 修复层为典型的枝晶结构,由铜固溶体枝晶和铜锡金属间化合物共晶组成;平均显微硬度为铜基体硬度的 2.24 倍,修复区相对耐磨性为基体的 2.37 倍。修复区相对于基体硬度和耐磨性提升的原因在于快速凝固条件下形成的细小非均匀枝晶结构(固溶体和金属间化合物的混合结构)和固溶强化效应。铜基体和修复区磨损机制均为磨粒磨损、氧化磨损及黏着磨损。其中修复区主要为粘着磨损和氧化磨损,铜基体为粘着磨损和轻微氧化磨损。研究结果能够为电机换向器部位纯铜材料的高效修复提供数据支撑和理论基础,推进蓝色激光沉积再制造技术在有色金属加工领域的应用。     

含钴铜转炉渣的工艺矿物学

研究了铜转炉渣的化学与矿物学特征,用光学显微镜查明了炉渣各主要渣相为铁橄榄石,磁铁矿和无定形玻璃体,铜主要以冰铜相裹夹于渣相中,铜滴的尺度与渣的冷却历史有关。用X射线衍射谱,扫描电子显微镜,X射线能谱和X射线波谱及化学物相分析,对铜和钴的赋存状态及在各相中的分布进行了表征和量化。结果表明,钴主要以类质同象形式取代铁橄榄石和磁铁矿晶格中部分Fe^2 ,作为氧化物富集其中,二者约占钴总量的95％,渣中钴的提取需要以铁橄榄石和磁铁矿的分解为前提,使钴的氧化的游离出来而酸溶。     

金属复合低碳镁碳渣线砖氧化剥落分析

金属Al/Si复合低碳MgO-C砖在冶炼品种钢的210 t钢包渣线试用,取得良好使用效果。采用XRD、SEM、EDS对用后残砖分段带进行了物相和显微结构分析,结果表明:用后残砖可分为原砖带、原砖渐变带和氧化带三个段带;原砖渐变带里Al和Si与C和N2反应,原位生成Al4C3、AlN和SiC,有利于提高高温强度和热震稳定性;氧化带里的AlN和SiC先后逐渐被氧化,并与MgO反应生成镁铝尖晶石和镁橄榄石,结构比较疏松,抗热震稳定性有所减弱。可以认为该砖的损毁原因主要是氧化后的结构剥落。今后改进的方向主要为改善材料氧化后的热震稳定性。     

改进型T23钢的再热裂纹敏感性

利用光学显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)研究了T23钢及4组改进型T23钢CGHAZ的微观组织,采用Gleeble热模拟及高温缓慢拉伸的方法评判T23钢和4组改进型T23钢焊接热影响区粗晶区(CGHAZ)的再热裂纹敏感性。探讨了再热裂纹敏感性的影响因素,分析了改进型T23钢再热裂纹敏感性改善的原因。结果表明,晶粒尺寸、晶界和晶内析出相以及晶内固溶元素均对再热裂纹敏感性有较大的影响。与T23钢相比,成分改进后的T23钢CGHAZ的微观组织得到了优化,晶界晶内强度差减小,再热裂纹敏感性得到改善。     

EFFECTS OF TEMPERATURE ON DISTRIBUTION BEHAVIORS OF MINOR ELEMENTS IN COPPER FLASH SMELTING──COMPUTER SIMULATION

ＥＦＦＥＣＴＳＯＦＴＥＭＰＥＲＡＴＵＲＥＯＮＤＩＳＴＲＩＢＵＴＩＯＮＢＥＨＡＶＩＯＲＳＯＦＭＩＮＯＲＥＬＥＭＥＮＴＳＩＮＣＯＰＰＥＲＦＬＡＳＨＳＭＥＬＴＩＮＧ──ＣＯＭＰＵＴＥＲＳＩＭＵＬＡＴＩＯＮ￥ＴａｎＰｅｎｇｆｕ；ＺｈａｎｇＣｈｕａｎｆｕ（Ｄｅ...     

调温器不锈钢焊接接头开裂分析

在试车过程中,发动机调温器焊接接头靠近SUS430壳体一侧开裂。通过对调温器壳体化学成分分析,焊接接头断口扫描观察、金相组织观察并结合调温器失效前的情况综合分析,确定了调温器不锈钢焊接接头开裂的模式及产生原因。结果表明:调温器壳体一侧焊接接头为晶间腐蚀导致的沿晶开裂;焊接接头热影响细晶区的晶间腐蚀敏感性以及试机采用的自来水提供的腐蚀环境是导致调温器在壳体热影响细晶区腐蚀开裂的主因。针对调温器在焊接接头开裂的原因做出了合理的改进,取得了良好的效果。     

Chemical and mineralogical characterizations of a copper converter slag

A copper converter slag was examined chemically and mineralogically to determine its existing phases,in particular those containing Co and Cu.The slag consists predominantly of fayalite and magnetite,together with some glass,chalcocite,and metallic copper,Copper is entrapped in the slag mostly as chalcocite and metallic copper,as well as trace copper oxide,There was no indication of any independent Co was detected in all the phases of the slag by SEM-EDX(scanning electron microscopy equipped with model EDAX-9100 energy dispersive spectrometer)and WDS(model WDX-2AX-ray wave-length dispersive spectrometer.).     

BNi68CrWB钎焊K24/GH648异种高温合金的界面形成机理

采用BNi68CrWB钎料粉末对K24和GH648异种高温合金进行钎焊连接,分析了接头典型界面组织,提出了钎焊过程反应机理.结果表明,接头由共晶区、等温凝固区和扩散区组成.共晶区由WB,CrB和镍基固溶体组成,等温凝固区为镍基固溶体,GH648侧扩散区由WB,W_xB_y,Cr_xB_y,以及沿晶界析出的镍基固溶体和少量的Cr₂Ni₃相组成,K24侧扩散区与母材差异不明显.钎焊过程由元素富集、母材溶解、等温凝固和共晶凝固四个阶段组成.其中等温凝固阶段是钎焊过程中最关键的阶段,等温凝固不完全时,钎缝中央存在共晶组织,影响接头性能.钎焊温度1 150℃,保温120 min时,等温凝固完全,接头组织均匀,力学性能最优,室温拉剪强度可达323 MPa.     

激光成形修复K418高温合金的显微组织与开裂行为

研究了激光成形修复航空发动机涡轮叶片用K418高温合金的组织特征与开裂行为。研究发现:K418合金激光修复区组织主要由γ-FeCr0.29Ni0.16C0.06固溶体基体、方形γ′相、枝晶间杆状或骨架状初生MC碳化物和骨架状(γ+MC)共晶组成。激光成形修复所用铸件基体中MC碳化物为TiC,呈块状分布在晶内和晶界;而激光修复区中MC碳化物为(NbTi)C,呈骨架状或杆状分布于枝晶间。从基体、热影响区到修复区,γ′相形貌、尺寸和数量呈现不同特征。修复区裂纹为与液膜有关的结晶裂纹,裂纹沿枝晶晶界扩展。通过试验优化,确定了较佳的激光成形修复K418合金的工艺参数,大大降低了其开裂倾向。     

Thermodynamic Database for the Al-Ca-Co-Cr-Fe-Mg-Mn-Ni-Si-O-P-S System and Applications in Ferrous Process Metallurgy

Computerized thermodynamic databases for solid and liquid metals, slag, and solid oxide phases in the Al₂O₃-CaO-CoO-CrO-Cr₂O₃-FeO-Fe₂O₃-MgO-MnO-NiO-SiO₂ system (with dissolved S and P) have been developed by critical evaluation/optimization of various available phase equilibrium and thermodynamic data. The databases contain parameters of models specifically developed for molten slags, liquid steel, and solid oxide solutions such as spinel, pyroxenes, olivine, monoxide (wustite, periclase, lime), corundum, etc. By means of the optimization process, model parameters are found which reproduce various thermodynamic and phase equilibrium data within experimental error limits. Furthermore, the models permit extrapolation into regions of temperature and composition where data are not available. The databases are automatically accessed by user-friendly software that calculates complex equilibria involving slag, metals, refractories, and gases simultaneously, for systems with many components, over wide ranges of temperature, oxygen potential, and pressure. A short review of the available databases is presented. The critical evaluation/optimization procedure is outlined using the Al₂O₃-CaO-FeO-Fe₂O₃-MgO-SiO₂ and Al₂O₃-CaO-MnO-SiO₂ systems as examples. Several applications of the databases to deoxidation, dehydrogenation, and dephosphorization of iron and to inclusion control in steel are discussed.     

热机械加工对2099铝锂合金挤压材组织与抗腐蚀性能的影响

采用金相组织观察、XRD分析、硬度和导电率测试等手段,研究了热机械加工(Thermo-Mechanical Processing, TMP)对2099铝锂合金挤压材组织、硬度、导电率、晶间腐蚀及剥落腐蚀性能的影响。结果表明：与经T83 (540 ℃/2 h固溶、3%预压缩、121 ℃/14 h + 181 ℃/48 h时效)热处理的2099铝锂合金挤压材相比,经TMP(540 ℃/2 h固溶、400 ℃/48 h过时效、约50%大应变变形、540 ℃/2 h再结晶/固溶)+(121 ℃/14 h + 181 ℃/48 h时效)处理的2099铝锂合金挤压材发生了明显的再结晶,硬度（HV）降低(从2006.2 MPa到1865.3 MPa),位错强化亦降低,但导电率和抗晶间腐蚀性能明显提高,同时抗剥落腐蚀性能也有所提高。结果表明,热机械加工是不显著降低2099铝锂合金挤压材硬度,但显著提高其抗晶间腐蚀性能的有效途径     

Oxidation of nickel-manganese alloys in the temperature range 873–1273 K

Ni-Mn alloys containing up to 38% Mn have been oxidized in pure oxygen between 873 and 1273 K and the parabolic rate constants measured. The scale morphologies and oxide compositions are interpreted in terms of modifications to the scale on pure Mn caused by the presence of Ni. The scales are composed predominantly of two layers at all temperatures, giving the sequences of phases alloy/cubic monoxide (Ni, Mn)O/ternary spinel, with the cubic (Ni, Mn)O layer always having the greater thickness. There is limited evidence for a third, very thin, outer layer in the scales on all alloys at 873 K and for Ni-38%Mn at 1073 K, which is tentatively considered to be Mn₂O₃, giving layers in the order alloy/cubic monoxide/ternary spinel/Mn₂O₃, by analogy with the scale formed on pure Mn. The distribution of the alloy components in the scale is discussed in relation to the Ni-Mn-O phase diagram and in terms of recent theoretical treatments of solid solution scale formation on binary alloys, as far as the available diffusion data allow. The occurrence of internal and intergranular oxidation and the formation of a Mn-depleted zone coincident with the band of uniform internal oxide are considered briefly.Deceased.     

Intergranular stress corrosion cracking of copper in nitrite solutions

Semi-hard tubes of deoxidized high phosphorous copper with different levels of tangential residual stresses have been exposed to nitrite solutions in a laboratory heating circuit. After characterization of investigated materials influence of temperature, location of heating, concentration of solution, electrochemical potential, and atmosphere on stress corrosion cracking susceptibility of those copper tubes has been investigated. Threshold stress for crack initiation has been determined. Maximum duration of experiments was 1 month. Breakthrough time of tubes has been measured as criterion for susceptibility to SCC.To vary stress level in a wider range constant load tests on tubes with different degrees of cold working (annealed, semi-hard, hard) were done by mounting them in a steel frame.Stress corrosion cracks were always intergranular. A tenorite layer covered surface of cracked copper tubes. A reaction scheme for ammonia formation is presented. Necessary conditions for formation of stress corrosion are shown and critically discussed.Results show that intergranular cracking takes place at much lower stress levels below yield strength when compared to literature data on transgranular cracking above yield strength. For transgranular cracking cross slipping and cleavage formation as cracking mechanism is confirmed while for intergranular cracking chemical dissolution of grain boundaries plays a more important role.     

MICROSCOPIC STUDY ON SLAGGED HIGH-ALUMINA ARC FURNACE ROOF BRICKS

本文汇集1957年以来某些电炉炉顶使用后高铝砖的显微镜观察工作,砖体主要受MgO,CaO和铁氧化物侵蚀.MgO来源于补炉镁砂和镁质炉墙在高温下的冲蚀和挥发,X射线和显微镜分析证实渣蚀带一些区域内存在粒状和针状方镁石晶体.存在铁氧化物时,基本上吸附在渣蚀带表面,形成有两个尖晶石固溶体〔(MF’)A和(F’M)F〕系列的矿物共生组合,当不存在铁氧化物时,在渣蚀带生成纯MA.其它平衡相有钙镁橄榄石和钙长石.在渣蚀带内层,反应产物为六铝酸钙和钙铝黄长石.     

不同固溶制度对6082铝合金力学性能和腐蚀性能的影响

采用拉伸力学性能试验、电导率性能试验、剥落腐蚀试验、晶间腐蚀试验、光学显微镜、扫描电镜、透射电镜等研究了不同固溶工艺对轨道交通用6082合金板材力学性能和腐蚀性能的影响。结果表明:530~560℃固溶及180℃时效处理后,6082合金板材的屈服强度和抗拉强度随着固溶温度升高而升高,而伸长率几乎保持不变。在530~560℃不同温度固溶处理的时效态6082板材的剥落腐蚀等级均为N级,显示出良好的耐剥落腐蚀性能,最大晶间腐蚀深度随着固溶温度升高而增加。不同温度固溶处理后时效态6082合金板材的晶界处均没有沉淀物析出,晶界附近的无沉淀析出带(PFZ)越宽,最大晶间腐蚀深度越深。     

Direct Production of Copper

The use of commercially pure oxygen in flash smelting a typical chalcopyrite concentrate or a low grade comminuted matte directly to copper produces a large excess of heat. The heat balance is controlled by adjusting the calorific value of the solid feed. A portion of the sulfide material is roasted to produce a calcine which is blended with unroasted material, and the blend is then autogeneously smelted with oxygen and flux directly to copper. Either iron silicate or iron calcareous slags are produced, both being subject to a slag cleaning treatment. Practically all of the sulfur is contained in a continuous stream of SO₂ gas, most of which is strong enough for liquefaction. A particularly attractive feature of these technologies is that no radically new metallurgical equipment needs to be developed. The oxygen smelting can be carried out not only in the Inco type flash furnace but in other suitable smelters such as cyclone furnaces. Another major advantage stems from abolishion of the ever-troublesome converter aisle, which is replaced with continuous roasting of a fraction of the copper sulfide feed.     

紫铜-黄铜搅拌摩擦焊接头的组织与力学性能

研究了紫铜和黄铜搅拌摩擦焊接的可行性,对焊接接头的金相组织进行了分析,并通过拉伸实验、硬度分析、弯曲实验,对接头的性能进行了验证.结果表明:紫铜-黄铜具有良好的搅拌摩擦焊接性能,可获得与母材等强度的搅拌摩擦焊接接头.焊合区在热力偶合作用下获得动态再结晶组织,接头黄铜一侧热影响区沿厚度方向上下不同,下侧可分为再结晶区、不完全再结晶区、动态回复区;上侧出现明显的偏析现象;接头紫铜一侧热影响区出现明显的须状组织,并有晶粒微溶的迹象.