TiN粉体粒径大小对SPS烧结过程的影响

采用低温液相还原法,即在液氨中采用金属钠为还原剂,通过还原四氯化钛(TiCl4)成功制备了纳米氮化钛粉体,通过XRD、SEM、TEM分析表明,粉体颗粒尺寸小于20 nm,并且为立方相的纳米氮化钛.以所合成的纳米TiN粉体为初始原料,采用SPS进行快速烧结,同时进行了微米TiN的烧结.结果发现采用SPS烧结技术可以抑制纳米TiN的晶粒快速长大过程,晶粒长大到100 nm～150 nm.但是纳米TiN粉体的烧结温度明显低于微米TiN粉体,并且致密度更高.     

Removal of fluoride from aqueous solution onto Zr-loaded garlic peel （Zr-GP） particles

Garlic peel, as the raw material, was modified by loading with zirconium(IV), exhibiting quite good uptaking behaviour for fluoride anion. The adsorption experiments were carried out in batch shaking vessels, and the process was strongly dependent on the pH value. The adsorption fits Langmuir model well, and the maximum adsorption capacities at equilibrium pH 2 and 6 are evaluated to be 1.10 and 0.89 mol(fluoride)/kg of Zr-loaded garlic peel gel, respectively. The evaluation of effects of coexisting anions such as nitrate, sulfate and phosphate shows that nitrate and sulfate have no negative effect on the adsorption of fluoride, while phosphate has a little effect. Adsorption kinetics of fluoride is well described by pseudo-second-order rate equation, and the corresponding adsorption rate constant is calculated to be 3.25×10⁻³ g/(mg·min).     

高钛渣碳热还原—浮选法提取Ti_2CO

通过高温碳热还原分别将高钛渣中的钛和铁还原至富钛相物质Ti2CO和金属铁,并使其中的熔渣相MOx不被还原,然后选用油酸作为捕收剂对Ti2CO/MOx模拟混合原料开展了浮选研究。结果表明,采用该工艺从还原产物中得到了产率79.88%、Ti2CO回收率87.74%的浮选效果。     

阳极氧化工艺条件对氮化钽烧结体电性能的影响

用纳米氮化钽粉末烧结制备了氮化钽烧结体,分析了烧结体的物相结构,研究了形成液种类、形成液浓度、温度、电流密度以及赋能电压等条件对氮化钽阳极氧化膜电性能的影响。结果表明,该烧结体是由纯氮化钽组成的,氮化钽阳极块体阳极氧化过程的最佳赋能工艺:磷酸溶液浓度0.01%,形成液温度55℃,电流密度40mA/g,形成电压小于16V。     

放电等离子体烧结Si_3N_4-BN复合陶瓷性能研究

以Si3N4和BN粉末为原料,Si3N4-BN复合粉末中BN的体积分数分别选定为10%、20%和30%,采用质量分数为2%的Al2O3和6%的Y2O3作为烧结助剂,分别在1500、1600和1650℃,压力50 MPa,保温5 min的条件下,采用放电等离子体烧结法制备了致密Si3N4-BN复合陶瓷。XRD结果和SEM分析表明:当煅烧温度为1650℃时,复合陶瓷中的α-Si3N4已完全转变为β-Si3N4;BN的加入抑制了复合陶瓷中Si3N4晶粒的生长而使结构细化;复合陶瓷的维氏硬度和断裂韧性随BN含量的增加而逐渐降低。     

利用钠-氨溶液制备纳米金属镍粉末及其表征

利用两步法制备得到纳米金属镍粉末。首先以氯化镍为原料在钠-氨溶液内通过还原-氮化反应制备得到纳米氮化镍粉末,然后通过真空热分解成功制备出纳米尺度的金属镍粉末。研究表明:钠-氨溶液内制备得到的纳米氮化镍粉末为六方结构,其平均晶粒尺度为19 nm;在300℃条件下进行真空热处理后,纳米氮化镍粉末完全分解,获得立方结构的纳米金属镍粉末,其平均晶粒尺度为21.4 nm,比表面积为30.5 m2·g-1;在300~700℃真空热处理过程中,纳米金属镍粉末的平均晶粒尺度增大为36.8 nm,比表面积减小为13.2 m2·g-1。     

Electrochemical co-deposition of magnesium based alloy from molten salts

Magnesium based alloys with aluminum and zinc were obtained through electrochemical co-deposition from LiCl-NaCl-MgCl2 melt. The possibility of electrochemical co-deposition was discussed in detail by electro-analytical methods including cyclic voltametry, square wave voltametry, and chronopotentiometry. The co-deposition happens when the concentration of aluminum and zinc ions is kept at low value and the current density is high enough. The components of alloy elements can be controlled by fixing the components of the feeding salts. A laboratory experiment of the preparation by step-current co-deposition was also performed and certain compositions of the Mg-Al, and Mg-Zn were obtained. The alloys obtained from the co-deposition show a typical as-cast microstructure. The best conditions of electrolysis such as temperature, amount of addition and mode of feeding were discussed in detail.     

LiCl-NaCl熔融盐体系镁铝合金电化学共沉积的实现

采用循环伏安法、电位扫描法和阶跃电流法在973 K的LiCl-NaCl-MgCl_2-AlCl_3熔融盐体系中,对Mg-Al共沉积的可行性进行探讨。结果表明,当Al~(3+)阴极电化学过程为极限扩散控制时,Mg和Al可以在相同的电位下在阴极共同析出,合金理论沉积电压稳定在氯化镁的分解电压附近,随着电解的进行,阴极极化程度逐渐减小,导致槽电压降低。     

钛铁原料选择性还原与冶金新流程探索

以钒钛磁铁精矿、钛精矿和高钛渣为原料,通过碳热还原分别将铁和钛还原至金属铁和碳氧化钛,得到Fe-TiCxOy-MOx复合物。经过湿法分离提纯得到了高纯碳氧化钛。这一选择性碳热还原和湿法分离的方法为高效率利用钒钛磁铁矿等钛、铁资源冶金新流程奠定了基础。     

柠檬酸活化赤泥对亚甲基蓝染料废水的吸附净化作用

采用一种活化赤泥吸附剂用于水溶液中亚甲基蓝的吸附净化.考察吸附剂用量、pH值、亚甲基蓝浓度、吸附温度和吸附时间对活化赤泥吸附性能的影响规律.结果表明:采用稀柠檬酸活化处理可显著提高赤泥对染料分子的吸附效率;吸附率随吸附剂用量增加而增加,随初始亚甲基蓝浓度和温度升高而降低;测得活化赤泥对亚甲基蓝的最大吸附容量为30 mg/g,吸附过程符合Langmuir等温吸附模型;吸附动力学过程可用准二级动力学方程描述,计算出吸附过程的表观活化能为9.88 kJ/mol.对吸附过程焓和熵值的计算结果表明,活化赤泥对水溶液中亚甲基蓝染料的吸附是一个自发的放热过程.