掺杂对Al_2O_3/TiAl复合材料性能的影响

本研究采用Ti-Al-TiO2-La2O3体系,通过热压烧结工艺原位合成了Al2O3/TiAl复合材料.借助X射线衍射(XRD)、扫描电镜(SEM)等分析研究了材料的物相组成和微观组织结构,同时分别将掺杂La2O3和掺杂Fe2O3对合成Al2O3/TiAl复合材料微观结构和力学性能的影响进行了对比.结果表明:掺杂La2O3合成的Al2O3/TiAl复合材料基体尺寸相对掺杂Fe2O3合成产物较小,分散更加均匀,致密度更高.当La2O3掺杂量为3.93wt%时,Al2O3/TiAl复合材料的抗弯强度和断裂韧性达到最大值,分别为701.95MPa和7.79MPa·m1/2.由于稀土氧化物具有对基体和增强颗粒的净化,细化晶粒等作用,因此提高了TiAl基体与Al2O3增强颗粒结合强度,所以掺杂La2O3合成材料的力学性能相比掺杂Fe2O3合成的产物较高.     

Low temperature sintering and dielectric properties of Ca-Ba-Al-B-Si-O glass/Al2O3 composites for LTCC applications

The effects of various SiO2 contents on both the microstructures and properties of Ca-Ba- A1-B-Si-O glass/Al2O3 cotrtposites were investigated by FTIR, DSC, XRD and SEM. The experimental results show that increasing SiO2 content in the glass leads to the increase of [SIO4] units, increases the continuity of glass network, and decreases the trend to crystallization of composites. The shrinkage of samples rises rapid around the glass softening temperature and the final shrinkage of samples decreases with increasing SiO2 content in the glass. Borosilicate glass/Al2O3 composites with 60wt% SiO2 sintered at 875 ℃ for 15 min show better properties： a bulk density of 3.10 g,cm-3, a porosity of 0.23 %, a er value of 7.55 and a tan 8 value of 0.00053 （measured at 10 MHz） and a well matching with Ag electrodes.     

外加Al2O3颗粒对Ti-Al-TiO2系合成产物微观结构的影响

Ti-Al-TiO2体系外加不同含量的Al2O3颗粒获得了Al2O3／TiAl基复合材料,研究了产物的相组成及微观组织。结果表明：Al2O3颗粒多分布在基体晶界处。随外加Al2O3含量的增大,晶粒变小,但增强相颗粒团聚严重。外加Al2O3量存在一个临界值。含量过高,易造成结构疏松,不致密,形成大的气孔,且由于TiO2的活化作用,会造成外加的Al2O3颗粒烧结呈板状联结分布;含量较低,颗粒与界面的结合不够紧凑,但颗粒的结晶度较好。     

Microstructure and microwave dielectric properties of lead borosilicate glass ceramics with Al2O3

The effects of Al₂O₃ addition on both the sintering behavior and microwave dielectric properties of PbO-B₂O₃-SiO₂ glass ceramics were investigated by Fourier transform infrared spectroscope (FTIR), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that with the increase of Al₂O₃ content the bands assigned to [SiO₄] nearly disappear. Aluminum replaces silicon in the glass network, which is helpful for the formation of boron-oxygen rings. The increase of the transition temperature T _g and softening temperature T _f of PbO-B₂O₃-SiO₂ glass ceramics leads to the increase of liquid phase precipitation temperature and promotes the structure stability in the glasses, and consequently contributes to the decreasing trend of crystallization. Densification and dielectric constants increase with the increase of Al₂O₃ content, but the dielectric loss is worsened. By contrast, the 3% (mass fraction) Al₂O₃-doped glass ceramics sintered at 725 °C have better properties of density ρ=2.72 g/cm³, dielectric constant ɛ _r =6.78, dielectric loss tan δ=2.6×10⁻³ (measured at 9.8 GHz), which suggest that the glass ceramics can be applied in multilayer microwave devices requiring low sintering temperatures.     

Microstructures and Mechanism of Al_2O_3/Al Composites Fabricated by the Reaction between SiO_2 and Molten Aluminum

1　IntroductionAmongtheavailablemethodsforfabricatingcompos ite ,thein situreactionsynthesispossessestechnicalandeconomicadvantages :simpleprocess ,lowfabricationcost .Throughthechemicalreactionbetweenliquidandsolid ,in situreinforcedceramicparticleswithfinedimen sionandgooddistributioncanbeformed .Theparticleshaveawellcombinedinterfacewiththematrixandhavenopollutionofimpurities .Thecompositeobtainedbyin situreactionhasexcellentproperties ,soithaswideap plications .Inthefabricationofthein sit…     

The effect of Sm2O3 on the chemical stability of borosilicate glass and glass ceramics

Sm2O3 containing zinc-borosilicate glass and glass ceramics were prepared by melt quenching method, and the effect of Sm2O3 and micro-crystallization on the chemical stability of borosilicate glass was explored. DTA analysis showed that the endothermic peak and exothermic peak of basic glass changed from 635 ℃ and 834 ℃ to 630 ℃ and 828 ℃ respectively as a result of the doping of Sm2O3. XRD analysis showed the promoting effect of Sm2O3 on crystallization ability of this glass. The cumulative mass loss of base glass, Sm2O3 containing glass, glass ceramic and Sm2O3 containing glass ceramic was 0.289, 0.253, 0.329, 0.269 mg/mm2 respectively after 26 days corrosion in alkali solution, and 1.293, 1.290, 0.999, 1.040 mg/mm2 respectively in acidic erosion medium. Micro-crystallization decreased and improved the alkali and acid resistance of borosilicate glass respectively, the addition of Sm2O3 increased the alkali resistance of base glass and glass ceramics, and the slight effect of Sm2O3 on the acid resistance of borosilicate glass was also observed.     

烧结Al2O3陶瓷在海水中的耐腐蚀性能研究

通过对SEM、孔径分布、孔隙率、弯曲强度等多项性能的测试,研究了由两性氧化物氧化铝烧结而成的陶瓷材料在海水中腐蚀的可能性. 研究结果表明,烧结氧化铝陶瓷在海水中浸泡一年后未发生腐蚀反应.     

原位合成Al_2O_3/FeAl复合材料的组织与性能

利用Fe-Al-Fe2O3体系的放热反应,原位热压合成了Al2O3/FeAl复合材料.借助XRD和SEM等研究了复合材料的物相组成和显微结构,以及Al2O3生成量对复合材料显微结构和力学性能的影响.结果表明:经1 250℃保温1.5h热压烧结的块体材料主要由FeAl及少量Al2O3相构成,FeAl基体为片层结构,增强相Al2O3分散在基体和晶界处.随着Al2O3含量的增加,基体晶粒尺寸明显减小,同时对材料起增强增韧作用.在Al2O3含量为1.2wt%时,试样的抗弯强度达到最大值1 329.22MPa;在Al2O3含量为0.8wt%时,试样的断裂韧性达到最大值29.95MPa·m1/2.此值正好处于金属与陶瓷材料性能链的断缺处.因此,本研究结果对于完善材料性能体系具有重要意义.     

Al2O3颗粒增强铝基复合材料储能焊接头微观组织及性能

对0.3 mm厚Al2O3颗粒增强铝基复合材料薄板进行了储能点焊连接研究试验。发现其微型点焊接头由熔核区、热影响区和熔核向热影响区过渡的熔合区（线）组成。由于储能焊极短的焊接时间,大的冷却速率达到106 K/s,使得熔核组织显著细化,具有快速凝固特征。熔核中增强相Al2O3颗粒发生偏聚现象,在熔核边缘区域出现了气孔缺陷。当焊接电容C=6600μF、电压U=80 V、电极压力F=18 N时,获得较高力学性能的焊接接头。     

CaO-Al_2O_3-SiO_2 系统微晶玻璃的成分、结构与性能

借助Ｘ射线衍射定性定量分析、扫描电镜、红外光谱等现代结构测试手段以及热膨胀系数、抗折强度等性能测试,讨论ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２系统微晶玻璃成分、结构与性能的关系,认为微晶玻璃成分通过对其中晶相含量、玻璃相结构以及两相结合状态的影响,而决定了试样的不同性能。     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

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Al2O3与LaF3薄膜在紫外波段的特性研究

用电子束蒸发方法制造了Al2O3、LaF3单层膜,对比研究了沉积速率和基板温度对薄膜紫外（193 nm）光学特性、微结构的影响.实验结果表明,LaF3在紫外波段的光学损耗明显小于Al2O3.AFM测试发现,在相同的工艺条件下,Al2O3表面粗糙度大于LaF3,且3薄膜表面粗糙度随基板温度增加而增加.Al2O3薄膜在紫外波段的光学特性严重依赖于沉积速率等制备条件,而沉积速率对3薄膜特性的影响不明显,即使是在5 nm/s的速率条件下,LaF3仍具有良好的光学特性.X射线衍射（XRD）测试发现,电子束蒸发制备的Al2O3薄膜为非晶态,LaF3薄膜有结晶现象.     

焙烧温度对S2O8^2-／Al2O3-Fe2O3固体酸催化性能的影响

制备S2O8^2-／Al2O3-Fe2O3型固体酸催化剂,用于催化乙酸和正丁醇合成乙酸正丁酯,采用TG／DSC、IR、SEM、XRD等对其结构和性能进行了表征,并研究了焙烧温度对其催化性能的影响。结果表明,不同焙烧温度对S2O8^2-／Al2O3-Fe2O3系列催化剂的结构和性能均产生一定的影响;随着焙烧温度的升高,酯化率呈先增加后降低的趋势,其中500℃焙烧的催化剂具有最佳的催化活性,其酯化率达到90．78％。     

铝热法合成NiAl／Al2O3复合材料

以铝粉和NiO粉为原料,采用铝热法合成了NiAl／Al2O3复合材料。通过X射线衍射分析仪（XRD）,扫描电子显微镜（SEM）并结合差示扫描量热仪（DSC）对其相组成、微结构和反应过程进行了分析。实验结果表明：850℃Al／NiO体系铝热反应被点燃,并自蔓延发生于整个反应系统;950℃保温40min,Al／Ni0体系铝热反应生成相互交织网状结构的NiAl／Al2O3复合材料。     

Teflon/Al2O3纳米复合膜的结构及微观摩擦学特性

为了提高聚四氟乙烯的耐磨损能力，用射频磁控溅射法交替溅射纯Teflon靶和Al2O3靶获得Teflon/Al2O3多层复合膜，通过PHI－5300ESCA型X射线光电子能谱及原子力显微镜（AFM）对其结构、力学性能和微观摩擦磨损特性研究表明：Teflon/Al2O3多层复合膜不但具有Al2O3膜的较高硬度和抗磨损性能，而且具有纯Teflon膜的减摩性和高承载能力。同Al2O3相比，复合膜的综合性能优于纯Al2O3膜和纯Teflon膜。Teflon/Al2O3多层复合膜的研制，解决了弹性金属塑料瓦耐磨损能力差的问题。     

Al2O3-C耐火材料的性能研究

为提高Ａｌ２Ｏ３－Ｃ耐火材料的性能，研究了烧成温度和石墨含量对Ａｌ２Ｏ３－Ｃ耐火材料气孔率、体积密度、常温耐压强度的影响，得出了适宜的烧成温度范围和最佳的石墨加入量，并对此进行了理论分析，同时，还研究了烧成温度对材料抗氧化性能的影响。     

制备条件对Fe/Al2O3选择性催化还原SO2的影响

不同负载量的Fe/Al2O3催化剂分别以浸渍法、共沉淀法和溶胶-凝胶法制得，对比评价了不同方法制备的催化剂样品以CO为还原剂，选择性催化还原SO2的活性。研究表明，铁催化剂有较高的去除SO2的活性，制备方法对催化剂活性具有显著影响。其中溶胶-凝胶法和共沉淀法最高活性分别可以达到95%和85%左右；而浸渍法样品的活性较差，最高转化率不到60%。3种不同组分催化剂的活性在低温时并不明显，在高温时明显地显示出高的负载量具有高的活性。     

Effect of sintering atmosphere on composition and properties of NiFe2O4 ceramic

Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.     

注射成型Al2O3陶瓷喂料的制备工艺

研究了Al2O3陶瓷注射成型喂料的制备工艺,探讨了加料顺序、混炼温度、混炼时间等参数对喂料性能的影响．结果表明：先对PP、PE混炼,再逐渐加入预先搅拌好的PL与Al2O3、DBP、SA的混合物,最后混炼0．5h,即得较均匀的注射喂料．