TiB2—xFe体系SHS合成的热力学计算与实验

对ＳＨＳ法制备了ＴｉＢ２－ｘＦｅ系统复合材料进行热力学力学计算，得到了绝热燃烧温度同金属稀释剂含量，绝热燃烧温度同反应器预热温度等关系，依据热力学计算的结果对ＳＨＳ合成ＴｉＢ２－ｘＦｅ系统的过程机理进行了预测，并运用实验结果以验证。     

（Si—Fe2O3）—（Al—Fe2O3—SiO2）复合体系自蔓延热力学分析

研究了（Ｓｉ－Ｆｅ２Ｏ３）－（Ａｌ－Ｆｅ２Ｏ３－ＳｉＯ２）复合体系的单位质量热效应ΔＨ＾０和绝热燃烧温度Ｔａｄ。指出ΔＨ＾０与Ａｌ－Ｆｅ２Ｏ３－ＳｉＯ２在复合体系中所占质量分数Ｒ呈线性关系。其斜率由ＳｉＯ２在Ａｌ－Ｆｅ２Ｏ３－ＳｉＯ２中的质量分数γ控制,其截距恒定且数值等于Ｓｉ－Ｆｅ２Ｏ３系单位质量热效应。当γ＝γ２＝１７ｗｔ％时,Ａｌ－Ｆｅ２Ｏ３－ＳｉＯ２加入对复合体系Ｔａｄ无影响,当γ〈γ２时     

纤维C—内标技术对TN12M10合金的SHS反应过程

利用特殊的Ｃ－内标技术对ＴＮ１２Ｍ１０合金的ＳＨＳ反应结晶过程进行了实验研究，发现包裹Ｃ－粒的包覆熔体中含有杂质与合金元素，随着温度升高，Ｃａ，Ｓｉ，Ｆｅ，Ｎｉ的含量减少，直至消失，Ｔｉ，Ｍｏ含量则随之增加；ＢＦＴ最后流到就近的Ｔｉ（Ｍｏ）Ｃ晶粒上结晶。因之，作者提出了ＴＮ１２Ｍ１０合金ＳＨＳ反应结晶过程的顺序：（１）Ｃａ，Ｓｉ，Ｎｉ，Ｆｅ，Ｔｉ，Ｍｏ等杂质及合金元素随着加热温度铁升高，依次先后熔     

Sm3（Fe1—x,Tix）29化合物及其氮化物的结构与磁性

用快速急冷方法制备了单相Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９化全物，研究了Ｔｉ元素对Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９成相的影响，通过气固相反应获得了Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９Ｎｙ氮化物。     

Sm_3（Fe_（1－x），Ti_x）_（29）化合物及其氨化物的结构与磁性

用快速急玲方法制备了单相Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９化合物，研究了Ｔｉ元素对Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９成相的影响，通过气团相反应获得了Ｓｍ３（Ｆｅ１－ｘ，Ｔｉｘ）２９Ｎｙ（ｙ＝５）氮化物．     

外加电场作用下自蔓延燃烧规律研究

通过对（１－ ｘ）（ Ｔｉ＋ Ｃ）＋ ｘ（ Ｎｉ＋ Ａｌ）＝ （１－ ｘ） Ｔｉ Ｃ＋ ｘ Ｎｉ Ａｌ反应体系的 Ｓ Ｈ Ｓ实验研究，获得了外加电场对燃烧过程及产物的影响规律： Ｓ Ｈ Ｓ过程中燃烧波速与外加电场电压呈线性关系；外加电场将使燃烧温度升高，升高的比率与预热条件有关；外加电场对燃烧产物颗粒尺寸有显著影响。通过选择合适的外加电压，可以将颗粒尺寸控制在所需范围之内，进而达到控制产品性能的目的。     

FeS-2分子筛的合成及对苯酚羟化的催化性能研究

合成了一系列Ｓｉ／Ｆｅ比不同的ＦｅＳ－２分子筛，用于进行Ｈ＿２Ｏ＿２和苯酚羟化反应合成邻苯二酚对苯二酚。考察了分子筛的Ｓｉ／Ｆｅ摩尔比、反应时间、反应温度、催化剂用量、苯酚／Ｈ＿２Ｏ＿２摩尔比对ＦｅＳ－２分子筛催化活性的影响。结果表明，在最佳反应条件下，以Ｓｉ／Ｆｅ＝８０的ＦｅＳ－２为催化剂，苯酚的转化率为１７．７３％，邻苯二酚的选择性为６４．１９％，对苯二酚的选择性为２９．５％，苯醌的选择性为６．３１％。     

金属间化物（Dy_xSm_（1－x）_2Fe_（17）N_y的自旋重取向研究

制备了金属间化物（ＤｙｘＳｍ１－ｘ）２Ｆｅ１７Ｎｙ（ｘ＝０．２，０．４，０．６，０．８；２＜ｙ＜３）的取向样品，并通过变温穆斯堡尔谱等手段研究金属间化物（ＤｙｘＳｍ１－ｘ）２Ｆｅ１７Ｎｙ（ｘ＝０．４；２＜ｙ＜３）的自旋重取向现象，进而对其中的各向异性产生机制等方面进行了分析。由试验得出以下结论：１）取向样品（ＤｙｘＳｍ１－ｘ）２Ｆｅ１７Ｎｙ（ｘ＝０．４；２＜ｙ＜３）在１００～１５０Ｋ温度之间存在自旋重取向现象，即由易Ｃ轴各向异性变为易锥面各向异性；２）金属间化物（ＤｙｘＳｍ１－ｘ）２Ｆｅ１７Ｎｙ（ｘ＝０．４；２＜ｙ＜３）中Ｄｙ次格子的单轴各向异性较强，导致在较低温度下出现自旋磁结构的相变。     

FeS—2分子筛的合成及对苯酚羟化的催化性能研究

合成了一系列Ｓｉ／Ｆｅ比不同的ＦｅＳ－２分子筛，用于进行Ｈ２Ｏ２和苯酚羟化反应合成邻苯二酚和对苯二酚。考察了分子筛的Ｓｉ／Ｆｅ摩尔比、反应时间、反应温度、催化剂用量、苯酚／Ｈ２Ｏ２摩尔比对ＦｅＳ－２分子筛催化活性的影响。结果表明，在最佳反应条件下，以Ｓｉ／Ｆｅ＝８０的ＦｅＳ－２为催化剂，苯酚的转化率为１７．７３％，邻苯二酚的选择性为６４．１９％，对苯二酚的选择性为２９．５％，苯醌的选择性为６．３１     

钇金属茂与羰基铁茂复合催化甲基丙烯酸甲酯的聚合

报道一种新的复合Ｚｉｅｇｌｅｒ－Ｎａｔｔａ催化剂－「（ＣＯ）２ＦｅＣｐ）」２／「（ＣＨ３）２Ｓｉ（ＣｐＭｅ）２ＹＣｌ」２／Ａｌ（ｉ－Ｂｕ）３催化甲基丙烯酸甲酯聚合的结果。研究了ＭＭＡ／（Ｙ＋Ｆｅ）摩尔比、Ａｌ／（Ｙ＋Ｆｅ）摩尔比及反应温度对聚合的影响。     

Oxygen defects in Fe-substituted Tl-system superconductors

For Fe-doped T1-1223 phase,the excess oxygen defects induced by Fe dopants are studied by means of Hall coefficient,thermogravimetric measurements,Mossbauer spectroscopy,and the model calculation of the effective bond valence.The extra oxygen defects have effects on carrier density and microstructure of the superconductors.In the light doping level of Fe (x=0-0.05),the superconducting transition and carrier density have significant corresponding relation--the zero resistance temperature Tco and carrier densities decrease linearly with Fe dopants increasing.The thermogravimetric measurements show that the Fe3+ ions' substituting for Cu2+ ions can bring the extra oxygen into the lattice to form extra oxygen defects.The calculation of the effective bond valence shows that the decrease of carrier density originates the strongly localized binding of the extra oxygen defects.The distortion of Cu-O layer induced by the extra oxygen defects decreases the superconductive transition temperature.The microstructure     

Dy2FeAl化合物中的R-T交换耦合常数的计算

提出利用分子场近似结合中子衍射或Ｘ射线衍射的实验结果,计算Ｒ２Ｆｅ１７型稀土过 渡族化合物中的稀土磁矩与过渡族磁矩之间的交换耦合常数的方法．计算了 Ｄｙ２Ｆｅ１７－ｘＡｌｘ （ｘ＝２,３,４,５,６,７,８）化合物中的稀土磁矩与过渡族磁矩之间的交换耦合常数－ＪＲＴ／ｋ, 结果分别为７,７７ Ｋ,７．２７ Ｋ,７．３９ Ｋ,８．６２ Ｋ,８．６４Ｋ,９．５２ Ｋ,１０．３４ Ｋ．其中对ｘ＝５,６, ７,８的化合物计算结果与高场测量的实验值８．７７ Ｋ,９．２５ Ｋ,１０．１Ｋ,１０．９Ｋ符合得较好． 说明从分子场理论出发,利用Ｘ射线衍射或中子衍射的结果更细致地考虑一些替代的细 节,计算稀土过渡族化合物中的稀土（Ｒ）磁矩与过渡族（Ｔ）磁矩之间的交换耦合常数是 一种可取的方法．     

TiB_2/SiC陶瓷复合材料制备工艺的研究

以TiO2、B4C和C为原料,基于原位合成法在SiC基体中生成TiB2颗粒,并采用无压烧结法制备出TiB2/SiC复合陶瓷.通过对复合材料制备工艺的研究,发现：高于1 300℃的预烧结能形成TiB2/SiC复合陶瓷坯体.C含量、烧结温度和保温时间对复合材料的相对密度均有影响.当C含量（质量分数）为4%时、在1 400℃×60 min＋2000℃×30 min的烧结工艺下能够制备出致密的TiB2/SiC陶瓷复合材料.微米级TiO2粉比纳米级TiO2粉更有利于形成较致密的烧结复合材料.随着生成TiB2体积分数的增加（5%～20%）,复合材料中TiB2颗粒逐渐粗化,间距逐渐变小.对复合材料的烧结机理还进行了分析.     

图像分析技术分析晶粒对Ti_3AlC_2/TiB_2材料性能的影响

采用DS-5M图像分析仪分析了不同TiB2含量的Ti3AlC2/TiB2复合材料微观晶粒大小和分布情况,分析结果表明,TiB2体积含量为10%的烧结样品晶粒发育较完善,分布也较均匀,随着TiB2含量的增加,层状晶粒的生长受到进一步的抑制,晶粒尺寸明显变小。采用阿基米德常数法测定烧结试样的密度,发现TiB2体积含量为10%的烧结样品相对密度最大,达到99.07%,TiB2体积比含量超过10%,相对密度逐渐减小;SPS烧结过程中TiB2体积含量少于10%时,样品呈现一个很窄的快速致密化阶段,随着TiB2含量的增加,原料发生反应所需温度升高和反应过程所需时间增加,降低了材料的致密化程度。可见图像分析复合材料微观晶粒的情况能很好地呼应材料宏观性能测试结果,提供了一种有效的测试分析手段。     

Combustion Synthesis and Densification of NiAl/TiB_2 Composites

A suitable combustion synthesis and densification process was designed to fabricate dense NiAl/ TiB2 composites from Ni-Al- Ti-B system. Combustion synthesis processing and microstructure characteristics of products were studied in detail. The results show that the amount of TiB2 ceramics has a great influence on the combustion synthesis processing and microstructure; with the increase of the amount of TiB2 ceramics, the combustion temperature and combustion velocity increase rapidly. The volume of synthesized products and the grain size of ceramics particle size are also affected by the amount of TiB2 ceramics. TiB2 ceramics fiber can be produced in this synthesis system. The dense NiAl/ TiB2 composites with residual porosity of no more than 1% are fabricated by the combustion synthesis and hot pressing, the mechanical properties of the dense NiAl/ TiB2 composites increase with increase of the amount of TiB2 ceramics.     

Crystallographic and Low Frequency Conductivity Studies of the Spinel Systems CuFe_2O_4 and Cu_（1-x）Zn_xGa_（0.1）Fe_（1.9）O_4

Spinel solid solutions of CuFe2O4 and Cu1-xZnxGa0.1Fe1.9O4 with (0.0≤x≤0.5) are synthesized. Crystallographic phase transformation from tetragonal-to-cubic occurred at x=0.2. The derived structural parameters manifest that Zn occupies the tetrahedral A-site while Cu and Ga occupy the octahedral B-site and Fe distributes among A- and B-sites. Electrical conductivity measurements of these materials as a function of temperature and frequency revealed semiconducting behavior except CuFe2O4 sample, which has a metallic behavior at low frequency and at high frequency, metallic -to- semiconductor transition occurred as temperature increases. The metallic behavior in this sample is attributed to cation-cation interactions at B-site while, the semiconductor behavior in Cu1-xZnxGa0.1Fe1.9O4 compounds is due to the cation- anion -cation interactions at the same site in the spinel lattice. All compositions exhibit transition with change in the slope of conductivity versus temperature curve. This transition temperature (Tc) decreases linearly with increasing Zn content x. The relation of the universal exponent s with temperature gives evidence that over large polaron OLP and correlated barrier hopping CBH conduction mechanisms are presented in CuFe2O4 and Cu1-xZnxGa0.1Fe1.9O4 compounds respectively.     

Thermodynamic Study on Self-propagating High Temperature Synthesis of TiB_2/Fe Composites

Based on the experimental analysis and theoretical calculation, the self-propagating high temperature synthesis of TiB_2/Fe composite was studied. The experimental results show that the interfacial between TiB_2 and Fe was smooth and clear, and the composite bending strength increased with the addition of Fe, however, the hardness decreased accordingly. The thermodynamics of the composites preparation process was calculated. The calculation results show that the primary chemical reaction was the reaction between Ti and B. The extra B can react with Fe, producing the brittle phase Fe_2 B. By increasing Ti, the production of Fe_2B will decrease and a few of Ti-Fe intermetallic compound will be produced by the reaction between Ti and Fe in the composites. Finally, according to the Merzhanov condition of the adiabatic system, it is concluded that the Fe content must be selected between 16.3% and 54.3% by the thermodynamics temperature of reaction calculation.     

Processing technique and sliding friction and wear behavior of TiB2／ZA27 composite

In-situ TiB2 particles reinforced ZA27 composite was prepared by the stir-casting technique and a twostep method. TiB2/Al composite was produced by incorporating K2 TiF6, KBF4 salts and other agents into Al melt. As a master alloy, TiB2/Al composite was used to manufacture TiB2/ZA27 composite, which results in the generation of well-distributed reinforcing TiB2 phase. The hardness, friction and wear behavior of TiB2/ZA27 composite were investigated. The results show that the hardness of the composite is enhanced with increasing the content of TiB2 particles, the incorporation of TiB2 reduces the wear rate of TiB2/ZA27 composite and improves the friction property under lubricated and dry sliding friction conditions. The worn track width of ZA27 alloy is 1.6 and 2.5 times as long as that of 2.1%TiB2/ZA27 composite at 150 N and 700 N load under lubricated conditions, which indicates that TiB2/ZA27 composite possesses higher bearing ability.     

Structure and Properties of TiB2 Thin Films Deposited at Low Temperatures Using RF Magnetron Sputtering

The TiB2 thin films were deposited on steel substrates using RF magnetron sputtering technique with the low normalized substrate temperature (0.1相似文献   

Effect of TiB_2 content on resistance to sodium penetration of TiB_2/C cathode composites for aluminium electrolysis

1　INTRODUCTIONInrecent years ,therehavebeenincreasingeffortstoimprovetheHall Heroult processintheprimaryaluminiumindustry[1 ] .InordertoovercometheshortagesofHall Heroultprocess ,suchashighconsumptionofelectricalpower ,highconsumptionofcarbonanodeandserious pollutionduetocarbonanodemanufactureandconsumptionetc ,anoveltypeofaluminareducedcellsbasedoninertanodeandwettablecathodesystemwasdevelopedtoreplaceconventionalHall Heroultprocess[2 ,3 ] .Titaniumdiboride(TiB2 )appearstobethebestca…