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。     

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.     

PHASE COMPOSITION OF HIGH Ti-SLAG WITH HIGH Mg AND Ca CONTENTS

高镁、钙的高钛渣经查明有5个相。高钙、镁富集区结晶相化合物为2CaO·TiO_2,玻璃相中富集MgO。黑钛石固溶体含MgO很低,只占渣中MgO总量的11.65％,MgTi_2O_5/Ti_3O_5的分子比为1∶24。导出了渣中黑钛石的分子式为0.15[(Mg_(0.27)Ti_(0.73))0.2TiO_2]·0.85[Ti_2O_3·TiO_2]。     

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。     

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含量对等离子喷涂TiO_2-Al_2O_3陶瓷涂层组织性能的影响

采用大气等离子喷涂方法制备TiO2–Al2O3陶瓷涂层,利用SEM和XRD分析了涂层的显微组织和相结构,并研究了涂层的电阻率随温度变化的规律。研究结果表明:TiO2–Al2O3陶瓷涂层主要由金红石型TiO2、锐钛矿型TiO2、Magneli相、α–Al2O3及γ–Al2O3组成。涂层的显微硬度和电阻率随Al2O3含量的增加而增加,在通电升温条件下涂层的电阻率随温度升高而降低。     

EFFECT OF CoCrAl COATING ON OXIDATION RESISTANCE OF INTERMETALLIC COMPOUND TiA1

Effect of a sputtered Co-30Cr-5Al microcrystalline coating on oxidation resistance ofintermetallic compound TiAl and oxidation behavior of the bare TiAl were investigatedat 900—1000℃ in static air.The oxidation kinetics for the TiAl alloy seems toapproximately follow a linear rate law.Poor oxidation resistance of TiAl is due to theformation of the mixed Al_2O_3+TiO_2 scale which is loosely packed and easily spalledoff.but not of dense and adherent pure Al_2O_3.A sputtered Co-30Cr-5Al coating,30μm thickness,can remarkably improve the oxidation resistance of TiAl owing to theformation of adherent Al_2O_3 protective scale.However,many Kirkendall voids wereformed between coating and substrate.     

等离子喷涂Cr2O3-8TiO2涂层的封孔处理

等离子喷涂技术在工业上得到越来越广泛的应用,但涂层的高孔隙率阻碍了该技术在耐腐蚀产品中的应用。采用环氧树脂和有机硅透明树脂剂两种封孔剂对等离子喷涂Cr_2O_3-8TiO_2涂层进行封孔试验,对环氧树脂采用常规和真空两种封孔工艺。用电化学和盐雾腐蚀试验比较了封孔和未封孔涂层的耐腐蚀性能,用扫描电镜(SEM)光学显微镜(OM)观察了腐蚀前后涂层的截面形貌。结果表明,封孔涂层的耐腐蚀性明显优于未封孔涂层。未封孔涂层在盐雾腐蚀240h后出现裂纹并发生剥落。