活化焙烧-酸浸法富集中低品位富钛料

采用还原磨选法制得的富钛料TiO2品位低,不适合直接作生产氯化法钛白和海绵钛的原料.热力学分析表明,采取添加Na2CO3进行焙烧处理后,可破坏富钛料中主要矿物组分黑钛石(Me3O5型固溶体,Me=Ti、Fe、Mg、Mn等)的固溶体结构,使固溶于其中的杂质元素铁和镁等转变为易溶于稀盐酸的物质.结果表明,用稀盐酸浸出活化富钛料可使浸出产物TiO2品位提高到90%以上,比直接用稀盐酸浸取未经活化的富钛料浸出产物TiO2的品位提高了近10%.     

锂离子电池负极材料Li_4Ti_5O_(12)的原位水解合成与表征

以TiCl_4水溶液和LiOH·H_2O为原料,采用原位水解与后续热处理相结合的方法制备尖晶石型锂离子电池用负极材料Li_4Ti_5O_(12).结果表明:从TiCl_4水溶液原位水解合成Li_4Ti_5O_(12)经历由TiCl_4→TiO_2→Li_2TiO_3→Li_4Ti_5O_(12) 3个阶段的原位相转变过程;TiCl_4水溶液的浓度及稳定性对合成Li_4Ti_5O_(12)的结构有较大的影响;随着TiCl_4浓度的增加,合成纯Li_4Ti_5O_(12)所需的水解时间延长;以0.5 mol/L TiCl_4水溶液水解1 h、以添加1.0 mol/L LiCl的0.5 mol/L TiCl_4水溶液水解3 h、以1.0 mol/L与1.5 mol/L TiCl_4水溶液水解5 h均可获得纯Li_4Ti_5O_(12);由低浓度TiCl_4水溶液合成的Li_4Ti_5O_(12)循环性能优良.     

低温烧结Bi_6Ti_5TeO_(22)和Bi_2Ti_3TeO_(12)陶瓷及其微波介电性能

采用固相烧结法,研究了不同温度和配方Bi_2O_3-TiO_2-TeO_2体系陶瓷的低温烧结情况,研究了产物物相、微观结构和微波介电性能.研究表明,配方A(Bi_2O_3:TiO_2:TeO_2=1:3:1)在800 ℃以上煅烧可制备出较纯净的Bi_6Ti_5TeO_(22),配方B (Bi_2O_3:TiO_2:TeO_2=1.025:3:1)在700℃以上煅烧可制备纯净的Bi_2Ti_3TeO_(12)粉末.所得Bi_6Ti_5TeO_(22)和Bi_2Ti_3TeO_(12)粉末都能在750～900 ℃度实现低温烧结.配方B在750℃烧结的介电性能较好,ε_r=32.5,介电损失为0.20%(100 MHz).     

Al_2O_3/(Ag_(72)Cu_(28))_(97)Ti_3/Ti-6Al-4V界面结构及性能研究

在1．8ks,1073K－1173K条件下对Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V进行了钎焊试验。通过扫描电镜、波谱、能谱、X射线衍射界面结构进行了分析。小于1123K的界面结构为Al2O3/Cu2Ti4O/Cu4Ti3/Ag-Cu共晶＋富Ag相＋Ti固溶体;1173K的界面结构为Al2O3/Cu3TiO5 CuAl2O4/Cu4Ti3/富Ag相。采用拉剪试验测试了接头剪切强度。在1．8ks,1123K时剪切强度最高达到189MPa,大于或小于1123K接头强度呈下降趋势。     

Al_2O_3/(Ag_(72)Cu_(28))_(97)Ti_3/Ti-6Al-4V界面结构及性能研究

在 1.8 ks,10 73 K～ 1173 K条件下对 Al2 O3/ ( Ag72 Cu2 8) 97Ti3/ Ti- 6Al- 4 V进行了钎焊试验。通过扫描电镜、波谱、能谱、X射线衍射对界面结构进行了分析。小于 112 3 K的界面结构为 Al2 O3/ Cu2 Ti4 O/ Cu4 Ti3/ Ag- Cu共晶 +富 Ag相 + Ti固溶体 ;1173 K的界面结构为 Al2 O3/ Cu3Ti O5+ Cu Al2 O4 / Cu4 Ti3/富 Ag相。采用拉剪试验测试了接头剪切强度。在 1.8ks,112 3 K时剪切强度最高达到 189MPa,大于或小于 112 3 K接头强度呈下降趋势。     

添加玻璃料对BaSm_2Ti_4O_(12)微波介质陶瓷烧结行为和介电性能的影响

利用固相法制备BaSm_2Ti_4O_(12)(BST)微波介质陶瓷.研究了复合添加Li_2CO_3-B_2O_3-SiO_2-CaO-Al_2O_3(LBSCA)和BaO-B_2O_3-SiO_2(BBS) 玻璃料对BaSm_2Ti_4O_(12)微波介质陶瓷的烧结性能、介电性能、相组成和微观结构的影响.研究表明:复合掺杂10% LBSCA和2%～5% BBS可使烧结温度降至900 ℃.XRD分析表明复合掺杂两种玻璃料的BST陶瓷主晶相为BaSm_2Ti_4O_(12)相,玻璃料以玻璃相的形式存在陶瓷晶粒间.复合掺杂10% LBSCA+3%BBS玻璃料的BST陶瓷可在900 ℃、保温2 h条件下烧结致密,微波介电性能为:ε_r =55.63,Q_f = 4266 GHz,τ_f= -13.5×10~(-6)℃~(-1),这种陶瓷材料有望与纯Ag电极共烧,制作各种多层微波频率元器件.     

ACTIVITY OF TiO_2 IN MOLTEN BLAST FURNACE SLAG

Activity of TiO_2 in the molten blast furnace slag containing TiO_2 has been examinedat 1500℃ by means of “molten slag-Sn” chemical equilibrium method,using metallicSn as flux and graphite as deoxidizer,together with phase diagram caIculation.In thepentary slag system CaO-MgO-SiO_2-TiO_2-Al_2O_3,a_(TiO_2)=0.01—0.05 or 0.02—0.10 withpure liquid or solid TiO_2 as standard state,respectively.The activity and activitycoefficient of TiO_2 in relation to concentration of TiO_2 have been discussed.     

RELATIONSHIP BETWEEN REDUCIBILITY AND HIGH TEMPERATURE PROPERTIES OF TITANIA-RICH SLAGS

采用高温显微镜研究了Ti渣还原度与高温性质的关系。随着Ti渣还原度提高及FeO含量降低,其熔化性和流动性温度曲折地上升。在22.21>FeO wt-％>12.68,0FeO wt-％>5.44,0.11相似文献   

陶瓷/AgCuTi/不锈钢钎焊连接界面组织与结构

采用Ag-Cu-Ti钎料对日用陶瓷与1Cr18Ni9Ti不锈钢进行了钎焊连接.用扫描电镜、能谱仪以及X射线衍射仪对接头的微观组织形貌、特征点的成分以及钎焊接头的物相等进行了分析研究.结果表明,接头界面处形成了多种化合物,包括TiO,TiSi_2,Ti_5Si_3和Fe_2Ti.当温度为850℃,保温时间为5 min时,接头界面结构为1Cr18Ni9Ti不锈钢/Fe_2Ti/Ag[s,s]+Cu[s,s]+Fe_2TiO+Ti_5Si_3+TiSi_2/陶瓷.当钎焊温度较高或保温时间较长时,界面反应层厚度增加,界面中基体相Ag[s,s],Cu[s,s]所占比例显著减小.

Abstract：

Domestic ceramics and lCrl8Ni9Ti stainless steel were brazed using Ag-Cu-Ti filler metal. Microstructure, the component of characteristic points and the phases of brazing joints were studied by scanning electronic microscopy ( SEM) , energy distribution spectrometer (EDS) and x-ray diffraction (XRD). The results show that several kinds of intermetallics such as TiO_2, TiO, TiSi_2 , Ti_5 Si_3 and Fe_2 Ti were formed. The interfacial structure of joints is 1Cr18Ni9Ti stainless steel/Fez Ti/Ag[ s, s] + Cu[s,s] + Fe_2Ti/TiO_2 + TiO + Ti_5Si_3 + TiSi_2/ceramics when brazing temperature and time are 850 ℃ and 5min, respectively. The depth of interfacial reactive layer increases and the ratio of matrix phase Ag [ s, s ], Cu [ s, s ] which are in the middle of interface reduces evidently as brazing temperature is very high or holding time is very long.     

Mechanical and corrosion properties of newly developed Mg–Mn–Ca alloys as potential biodegradable implant materials

Calcium and manganese were selected as alloying elements to develop Mg–2Mn–xCa (x?=?0·8, 1·0, 1·2 wt-%) alloys as potential biodegradable implant materials. The mechanical properties and corrosion mechanism of both as cast and solution naturally age (T4) treated Mg–2Mn–xCa alloys were investigated. The results indicated that the distribution of the second phase dominated the corrosion process. T4 treatment could transfer coarse Mg₂Ca and α-Mn phases into dispersed fine precipitated phases, which improve mechanical and corrosion properties. Mg–2Mn–1·0Ca alloy has the best integrated performance among the developed alloys. This research indicated that T4 treated Mg–2Mn–xCa alloys are a promising candidate used as biodegradable implant material.     

Removal of iron from ilmenite by KOH leaching-oxalate leaching method

Oxalic acid was used for the removal of iron from the intermediates of ilmenite leached by KOH liquor. Various parameters, such as pH, temperature, initial oxalate concentration, and illumination were investigated. Meanwhile, it was found that orthorhombic crystal Ti2O2(OH)2(C2O4)·H2O formed as the leaching proceeded. Scanning electronic microscope (SEM) images implied that the formation of Ti2O2(OH)2(C2O4)·H2O with good crystallinity proceeded through three stages. Calcining Ti2O2(OH)2(C2O4)·H2O, anatase (350°C) or rutile (550°C) type TiO2 was obtained, respectively. Element analysis found that the calcined product contained 94.9% TiO2 and 2.5% iron oxide, but only about 1600 ppm dissolvable iron oxide was left, which indicates that oxalic acid was comparatively effective on iron oxide removal from the intermediates. Finally, an improved route was proposed for the upgrading of ilmenite into rutile.     

Structure,phase composition,and strengthening of cast Al–Ca–Mg–Sc alloys

The structure and phase composition of Al–Ca–Mg–Sc alloys containing 0.3 wt % Sc, up to 10 wt % Ca, and up to 10 wt % Mg have been investigated in the cast state and state after heat treatment. It has been shown that only binary phases Al₄Ca, Al₃Sc, and Al₃Mg₂ can be in equilibrium with the aluminum solid solution. It has been found that the maximum strengthening effect caused by the precipitation of Al₃Sc nanoparticles for all investigated alloys is attained after annealing at 300–350°C.     

CRYSTALLIZATION OF THE BORON COMPONENT BEARING MgO-B_2O_3-SiO_2 SLAG

ＣＲＹＳＴＡＬＬＩＺＡＴＩＯＮＯＦＴＨＥＢＯＲＯＮＣＯＭＰＯＮＥＮＴＢＥＡＲＩＮＧＭｇＯ－Ｂ_２Ｏ_３－ＳｉＯ_２ＳＬＡＧＺｈａｎｇＰｅｉｘｉｎ；ＧｕｏＺｈｅｎｚｈｏｎｇ；ＬｉｎＨｏｎｇ；ＳｕｉＺｈｉｔｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＮｏｎｆｅｒｒｏｕ?..     

Ti_3Al及其渗铝涂层的热腐蚀性能

采用电化学方法并结合各种物相分析技术研究了Ti_3Al金属间化合物在熔融(Na,K)_2SO_4-NaCl中的热腐蚀行为及渗铝涂层对其耐蚀性能的影响。结果表明,Ti_3Al耐热腐蚀性能较差。形成了外层为TiO_2,中间层为富铝的TiO_2-Al_2O_3复合层,内层为富铌的Nb_2O_5-TiO_2-Al_2O_3层的三层结构。渗铝涂层能在合金表面形成Al_2O_3氧化膜而明显改善Ti_3Al的耐蚀性能。     

Y_(0.08)Sr_(0.92)TiO_(3+δ)/Gd_(0.2)Ce_(0.8)O_(1.9)双相混合导体合成及在氧传感器中应用

以SrCO_3、TiO_2、Y_2O_3、CeO_2及Gd_2O_3为原料,用传统固相烧结法在不同温度下制备了一系列比例(体积比)的Y_0.08Sr_0.92TiO_(3+δ)/Gd_0.2Ce_0.8O_1.9(CGO)双相复合混合导体材料.用Archimedes法、SEM 、XRD、 EIS等手段对材料的致密度、微观结构、化学相容性及导电性能进行了研究.结果表明,1600 ℃烧结的40% (体积分数, 下同)YST/60% CGO的试样相对体密度达到了99%,未发生相转变,化学相容性较好且电导率较高.以40%YST/60%CGO的粉体作为混合导体制备极限电流传感器,进行O_2敏感性能测试.结果表明:传感器在氧浓度低于0.1%,温度范围在600～700℃内,极限电流随氧浓度增大而增大,二者具有较好的线性关系.实验证明YST/CGO混合导体材料可以作为限流型氧传感器的扩散阻使用.     

高脱渣率烧结焊剂熔渣晶体类型及其成分分布

通过均匀设计方法,以脱渣性为目标,对高碱度MgO-Al₂O₃-CaO渣系进行优化,并试验测定了脱渣率.在此基础上分别采用SEM观察熔渣晶体微观组织形貌及其特征、EDAX测定熔渣不同微区的成分含量、XRD确定熔渣的物相组成.发现脱渣率较高的10号焊剂的熔渣主要由含Zr,Mg,Ca,Al及Si元素的复合岩石相构成,熔渣不同微区的元素含量差别很大,形成了锆型雪花晶、镁型十字晶及钙型树枝晶.锆型和钙型晶体能够阻碍镁型晶体的生长,锆还起到细化镁型晶体的作用.结果表明,通过提高焊剂中大理石及锆英砂的含量使熔渣中镁型晶体微观组织的连续性和方向性发生改变,是改善脱渣性的一种有效途径.     

Preparation of Ti-rich material from titanium slag by activation roasting followed by acid leaching

A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of H₃PO₄ dosage, roasting temperature, and roasting time on TiO₂ grade were investigated. A Ti-rich material containing 88.54% TiO₂, 0.42% (CaO+MgO) was obtained when finely ground titanium slag was roasted with 7.5% H₃PO₄ at 1000 °C for 2 h, followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h. The XRD patterns show that the product is titanium dioxide with a rutile structure. Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process. As a result, titanium components in titanium slag are transformed into TiO₂ (rutile) while impurities are transformed into acid-soluble phosphate and quartz.     

Phase Diagram of Ternary Calcium Acetate—Magnesium Acetate—Water System at 298 K, 313 K and 323 K

The solubility data of the calcium acetate-magnesium acetate-water system at 298, 313, and 323 K were measured using the Schreinemaker’s wet residue method, the corresponding phase diagram for the system were constructed. The solid phase in the system at different temperatures was confirmed by the Schreinemaker’s wet residue method, which correspond to Mg(CH₃COO)₂·4H₂O and Ca(CH₃COO)₂·2H₂O. At the studied temperature, no double salt was formed. The crystalline region of Ca(CH₃COO)₂·2H₂O is larger than that of Mg(CH₃COO)₂·4H₂O. The solubility of Mg(CH₃COO)₂ increases with the increasing of the temperature, while the solubility of Ca(CH₃COO)₂ decreases with the increasing of the temperature.     

Solidification characteristics of Al–9·6Mg alloy solidified under high pressure (4 GPa)

Abstract

The present paper studies influences of high pressure up to 4 GPa at 1273 K on the microstructures and the phases of Al–9·6Mg alloy by means of optical microscopy (OM), X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results showed that fine dendrite with long primary arm formed at 4 GPa in comparison with the coarse discontinuous dendrite under normal pressure. Specially, a new high pressure metastable phase, Al_(63·7)Mg_(36·3), was produced besides a small amount of β-Al₃Mg₂ phases at 4 GPa, which was not found in other solidification conditions. Al_(63·7)Mg_(36·3) phase has bcc structure with the lattice constant a=8·495 Å. Evolution mechanism of microstructures and phases was studied in the present paper. Furthermore, Mg concentration in α-Al phase has increased by 42%. Correspondingly, the lattice constant of α-Al phase has increased by 0·44%. The nanohardness of α-Al phase in the alloy increased under high pressure, whereas that of the elastic modulus decreased.