B_4C和Al在高温条件下的化学反应及相组成的研究

采用X射线衍射和差热分析系统研究了B4C和Al在高温条件下的化学反应和相组成.研究结果表明:B4C和Al在0～1 500 ℃温度区间内反应生成相有Al3BC、AlB2、Al4C3和AlB12C2.在该区间内,B4C和Al生成新相的反应分为三个阶段:Al3BC和AlB2相在625～690 ℃温度区间反应生成;Al4C3相在1 150～1 185 ℃温度区间反应生成;AlB12C2相在1 320～1 350 ℃温度区间反应生成.分析了无压浸渗法所制备B4C/Al复合材料的相组成,并测试了其力学性能.     

M—MA—M2S—CMS系镁质耐火材料高温固相组成的计算

本文运用数学分析的方法,建立了M-MA-M_2S-CMS系镁质耐火材料高温固相组成的计算公式。结合具体例子说明了公式的使用方法及其精确程度。     

钒钛磁铁矿高温熔态还原过程中渣相矿物组成变化

不同预还原度的钒钛球团矿在铁浴内高温熔态还原过程中,取熔渣样作矿相观察,并化学分析FeO含量。据此分析讨论了钒钛磁铁矿的高温熔态还原过程及还原速度、时间和铁浴温度及铁矿料预还原度与熔渣矿物组成的变化关系。     

La_2O_3-H_3BO_3-C体系高温烧结过程的相组成研究

采用TG-DTA和XRD等分析手段对La2O3-H3BO3-C体系高温烧结过程中的相组成进行了研究.结果表明:在 82～390 ℃之间,发生了H3BO3的三阶段脱水反应,第一阶段为82～153 ℃,生成了HBO2;第二阶段为153～222 ℃,生成了H2B4O7;第三阶段为287～390 ℃,生成了B2O3.在836～1 400 ℃时,主要是La2O3与B2O3反应生成LaB3O6和 LaBO3.在1 450 ℃的高温下, La2O3、B2O3和C共同作用生成LaBO3和B4C,此时LaBO3相占主要地位,计算得到其晶胞参数为:a=7.955,b=8.160,c=6.499,属于单斜晶系.在1 500 ℃时, LaBO3和B4C反应生成LaB4、B和LaB6; LaB4和B进一步烧结生成LaB6,其生成率随烧结时间延长而增加,计算得到其晶胞参数为:a=4.156,属于立方晶系.     

原位生成TiB2颗粒增韧B4C陶瓷的研究

通过ＴｉＣ与Ｂ４Ｃ的化学反应，在Ｂ４Ｃ基体内原位生成ＴｉＢ２颗粒，获得的ＴｉＢ２颗粒径一般在３μｍ以下。其中加入２０ｖｏｌ％ＴｉＣ（对应的ＴｉＢ２为３５ｖｏｌ％）的复相陶瓷的断裂韧性值Ｋｉｃ达６．３ＭＰａ．ｍ＾１／２。比单体Ｂ４Ｃ提高７５％，加入１０ｖｏｌ％ＴｉＣ（对应的ＴｉＢ２为１４ｖｏｌ％）的复相陶瓷的抗弯强度达到最大值６２０ＭＰａ，比单体Ｂ４Ｃ提高４０％，由Ｂ４Ｃ和ＴｉＢ２颗粒之间热膨胀系数     

CeO2对2024铝合金显微组织和拉伸性能的影响

利用金相组织观察、扫描电镜分析、X射线衍射分析和拉伸性能检测等方法,研究了不同CeO2含量对2024铝合金显微组织及力学性能的影响.结果表明,CeO2能够细化2024铝合金的铸态组织和退火态组织.CeO2与金属Al反应生成的Ce,与基体中的Al和Cu形成新相Al3Ce、CeCu2.添加CeO2能够提高2024铝合金的抗拉强度和屈服强度,而且添加0.25%(质量分数,下同)时能够获得最佳性能,铸态下的抗拉强度和屈服强度分别提高了55%和50%,退火态下的抗拉强度和屈服强度分别提高了30%和17%.但是CeO2的加入量过高,反而使合金的性能降低.当未添加CeO2时,2024铝合金断口表面呈准解理和韧窝状态,表现为脆性与韧性结合的混合断裂特征,而添加一定量的CeO2时,合金呈现出塑性断裂特征.     

添加YAG对ZrB2及ZrB2-Al2O3陶瓷抗高温氧化性的影响

研究了掺杂相对ZrB2-YAG-Al2O3复相陶瓷高温抗氧化性能的影响,以提高高温陶瓷的高温抗氧化性能.结果表明:通过引入YAG制备的陶瓷和纯ZrB2陶瓷相比,在相同氧化条件下得到的氧化增重有所减小,在相同氧化条件下,引入YAG越多的陶瓷氧化增重越小,说明通过引入YAG可以改善ZrB2陶瓷的抗氧化性能.ZrB2-YAG...     

TiH2对TiB2自蔓延高温合成过程的影响

采用纯Ｔｉ粉或氢化钛粉、Ａｌ粉及Ｂ粉混合后进行整体加热，使其发生自蔓延高温反应，合成了ＴｉＢ２粉末。研究了氢化钛粉及合成温度对ＴｉＢ２合成反应过程的影响，探讨了ＴｉＢ２粒子的形成机理。     

几种钼酸铵相组成的研究

采用电镜X—射线衍射分析及差热、热重等测试手段,结合化学分析的结果,研究了三种不同厂家的钼酸铵的形貌及相组成,以便研究钼酸铵作为原料在加热还原制取钼产品过程中的物理化学性质的变化。     

LaMgAl11O19-La2Ce2O7 复合陶瓷的高温相稳定性

La2Ce2O7(LC) 和 LaMgAl11O19(LMA) 是两种新型热障涂层材料。 LC 具有优良的热物理及抗腐蚀性能, 但 其断裂韧性差。 LMA 具有良好的综合性能, 特别是力学性能优良。 基于复合材料设计理念, 为充分利用 LC 和 LMA 的优势, 本文探究了制备 LMA-LC 双相复合陶瓷的可行性。 采用高温固相法合成了 LMA 和 LC 粉末, 重 点研究了 LMA 和 LC 的高温稳定性, 初步研究了 LMA-LC 复合陶瓷块材的力学性能。 结果表明： LMA 和 LC 在 高温下发生了化学反应, 反应程度随温度升高而加剧, 主要反应产物为 LaAlO3, 其在低温下的铁弹性可能是复 合陶瓷在室温下具有良好力学性能的原因。     

In-Situ Wet Chemical Composition of Multicomponent Precursors to Blue Emitting Sr2CeO4 Phosphors

Hybrid precursors were assembled with cerium coordination polymers, polyethyl glycohol (PEG), SrCO3 and other functional components using a modified in-situ chemical polymeric gel technology. The hybrid precursors were calcinated to achieve the Sr2CeO4 phosphors, whose particle sizes were in the range of micrometer by XRD and SEM. The photoluminescence spectra indicate that the phosphors present a strong blue emission.     

Reaction of FeO-V2O5 System at High Temperature

 FeO and V2O5 are two main components of the obtained vanadium steel slag, and the reaction of FeO-V2O5 system determines the physical property of the slag. Through thermodynamic calculation and experimental study, it can be found that within the ranges of steel-making temperature, V2O5 is reduced to VO2. As FeO exists in FeO-V2O5 system, VO2 will be reduced to V2O3 further while FeO is oxidized to Fe2O3. In this multi-system, as the content of FeO and temperature increase, the system will have products in turn such as V3O5, V3O4, FeVO4, Fe2VO4 and Fe3O4. The products are mainly V3O5 and Fe2O3 when the content of FeO is 0.58 mol and the temperature is 1100 K, and as the temperature increases, Fe2O3 starts to react with V2O5 and then generates FeVO4; FeVO4 disappears while the content of FeO and the temperature increase at the same time, and then Fe2VO4 is generated by the reaction of FeO, Fe2O3 and V2O3. Iron oxides are also generated such as Fe3O4 and so on.     

多元多相体系化学平衡组成的计算

本文从用计算机代替人工计算多元多相复杂体系化学平衡问题出发,对应用于计算机的Brinkley法,Vcs法及White法作了讨论和比较。指出White法在计算机上实现解决计算多元多相体系化学平衡问题的优点。并介绍了用White法编制的计算多元多相体系化学反应平衡的计算机应用程序的结构及基本工作原理。列出考题。其计算结果与位于联邦德国阿亨大学的冶金热力学数据库、中国科学院化工冶金研究所的无机热化学数据库的计算结果相一致。     

Phase Constitution in Mixed Gd_2O_3 and B_4C by Sintering at High Temperature

The phase constitution in mixed Gd2O3 and B4C by sintering in graphite tube furnace at the temperature of 100～1489 ℃ in argon atmosphere was studied by means of XRD and TG-DTA. The results show that the impurity C reacts with O in the B4C at the temperature of 367～458 ℃. When the temperature is 800 ℃, Gd2O3 reacts with B4C, and the reaction products include GdB6, GdB4, GdBO3, GdBC and B. GdBC changes into GdB4 at 1200 ℃. When the temperature is 1470 ℃, GdB6 is obtained by the reaction of GdB4 with elemental B. The content of GdB6 is increasing with the prolonging time.     

固相烧结辅助高温球磨合成LiNi_xMn_(2-x)O_4

以氢氧化锂、硝酸镍、二氧化锰为原料,用固相烧结辅助高温球磨方法,合成了具有Ni掺杂的LiMn_2O_4正极材料。研究了Ni在不同掺杂量时对材料的相结构、形貌和充放电性能的影响,并与未掺杂Ni的LiMn_2O_4进行对比。结果表明,掺Ni后材料的放电比容量随着掺杂量的增大逐渐减小,而材料的容量保持率相比未掺杂时略有提高;当掺杂量x=0.05时,所得产物的充放电性能最佳,首次放电容量达到122.9mAh/g,充放电容量保持率在40次循环后为97.48%。     

Influence of Chemical Composition on Phase Transformation Temperature and Thermal Hot Work Expansion Coefficient of Die Steel

On the basis of the uniform design method, six kinds of martensitic hot work die steels were designed. The phase transformation temperatures including Ac1 , Ac3 , and Ms were measured by DIL805A quenching dilatometer. The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis, and three corresponding equations were obtained. These equations, in which the interactions of the elements were considered, showed more effectiveness than the traditional ones. In addition, the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests. The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed; the equations obtained were verified by using several kinds of steels. The predicted values were in accordance with the results of the experiments.     

Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

 On the basis of the uniform design method, six kinds of martensitic hot work die steels were designed. The phase transformation temperatures including Ac1, Ac3, and Ms were measured by DIL805A quenching dilatometer. The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis, and three corresponding equations were obtained. These equations, in which the interactions of the elements were considered, showed more effectiveness than the traditional ones. In addition, the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests. The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed; the equations obtained were verified by using several kinds of steels. The predicted values were in accordance with the results of the experiments.     

7055铝合金的化学成分、物相组成及其性能特点

说明了7055合金中Zn、Cu、Mg、Si、Fe和Zr等元素在该合金中的作用或影响;阐述了该合金的物相组成和-αAl、η（MgZn2）、S（Al2CuMg）、T（Al2Zn3Mg2）以及Al3Zr的作用;讲解了基体沉淀相（MPt）、晶界沉淀相（GBP）和晶间无析出带宽度（PFZ）对该合金性能的影响,介绍了该合金的性能特点进而介绍了该合金晶界腐蚀、应力腐蚀和剥落腐蚀的产生机理。总结了该合金化学成分、物相组成与宏观性能的对应关系。