无压烧结Al2O3-SiC纳米复合材料

Al2O3＋5％SiC（体积比）复合陶瓷可以通过传统粉末加工工艺,用无压烧结来制备。工业用Al2O3SiC粉加水混碾成料浆,后凝固成颗粒状,经冷等静压制成生坯,在1750—1780℃氮气氛下无压烧结。1780℃可以接近全致密（〉99％）。加入少量MgO可以促进制品的低温烧成致密性。1780℃烧成后,维氏硬度和压痕断裂韧性分别为18GPa以及2．3MPa·m^1/2。透射电子显微镜显示,SiC粒子主要存在于基质颗粒的内部且在整个复合微结构分布良好。晶粒内的颗粒大小介于50～200nm之间,但晶粒间的颗粒较大,一般直径200～500nm。     

微波烧结Al2O3-TiC复合材料

用微波烧结制备Al2O3-TiC复合材料，并与常规烧结Al2O3-TiC复合材料对比，分析两种烧结方法对试样力学性能的影响，同时探讨添加剂对Al2O3-TiC复合材料烧结性能的影响。     

Al2O3对CaO烧结过程的作用

在较低温度下(≤1600℃)，将添加Al2O3的高纯石灰石在不同煅烧温度下制得了CaO烧结熟科。考察了煅烧温度、保温时间及不同的Al2O3添加量对CaO烧结的作用。试验结果表明，Al2O3的加入使CaO在煅烧过程中得到发育良好的晶粒和撮低的显气孔率。在高于1500℃煅烧的试样中，显气孔率与保温时间之间呈对数关系，这种烧结熟料良好的抗水化性能在于其级低的显气孔率和发育良好的CaO晶粒自身水化活性的降低。     

无压烧结制备Al2O3/SiC纳米复合陶瓷

用沉淀法包裹微米级SiC颗粒，通过常压、埋烧制备Al2O3／SiC纳米复合陶瓷。通过XRD、TG和SEM等分析了煅烧和烧结过程中相组成的变化、烧成收缩和显微结构。结果表明：利用SiC粉埋烧及碳粉制造还原气氛，含8wt％SiC(平均粒径为5mm)的复合粉末经800℃煅烧、成型，试样于1550℃，2h烧结，可制备Al2O3／SiC纳米复合陶瓷，其相对体积密度达95．2％，在烧结过程中由SiC氧化形成的无定形SiO2及与基质氧化铝反应形成的莫来石前躯体可大大促进烧结。     

微米级α-Al2O3陶瓷恒速无压主烧结曲线的建立

主烧结曲线对于预测陶瓷的烧结行为非常有用,以主烧结曲线理论为基础,对微米级α-Al2O3,的恒速无压烧结行为进行了研究.根据Hansen提出的全期烧结模型,结合低升温速率条件下热膨胀仪记录的烧结数据建立了α-Al2O3(平均粒径为2.5μm)的主烧结曲线,并由此得到其烧结过程中的表观激活能为1148kJ/mol.为验证所建主烧结曲线的正确性,对同批次坯体样品进行不同路径的烧结,用Archimedes法实测烧结体密度,所测结果与主烧结曲线预测的结果相一致,从而证明了所建主烧结曲线的正确性.因此微米级α-Al2O3主烧结曲线对烧结路径不敏感,烧结体的相对密度仅是时间和温度的函数,可以预测烧结收缩率和最终相对密度,反之,可以根据目标相对密度制定相应的烧结制度.     

Al2O3-TiCN的制备和性能

用气压烧结的方法制备了Al2O3-TiCN复相陶瓷。测量了其物理性能，用扫描电镜观察了其断口形貌，并分析了烧结温度对力学性能的影响，确定了最佳烧结温度。     

Al2O3含量对TiB2-Al2O3陶瓷性能的影响

本文以Y2O3-La2O3为烧结助剂,通过热压烧结制备了TiB2-A12O3复相陶瓷,研究了原料组成对材料的显薇结构和力学性能的影响。实验结果表明：随A12O3含量升高,混合原料的烧结性能提高,复相陶瓷中的晶粒尺寸逐渐减小;材料的抗弯强度随A12O3含量的增加出现先增大后减小的趋势,当A12O3含量为30wt%时,抗弯强度达最高值;A12O3含量的增加会导致材料的洛氏硬底（HRA）降低。     

Ti3SiC2/Al2O3复合材料的制备与性能研究

以TiC／TiO2/Si／Al／Ti等为主要原料，采用热压法原位合成Ti2SiC2／Al2O3复合材料，分别探讨了Al掺入量和工艺制度对Ti3SiC2/Al2O3复合材料物相、显微结构以及性能的影响。结果表明：原位合成制备的Ti3SiC2/Al2O3复合材料与传统方法合成制备的纯Ti3SiC2材料相比，材料的硬度和致密度均有很大的提高。     

B2O3-CuO掺杂CSLST微波介质陶瓷介电性能研究

选用B2O3-CuO(BC)低熔点复合氧化物作为烧结助剂,采用固相法制备(Ca0.9375Sr0.0625)0.25(Li0.5Sm0.5)0.75TiO3(CSLST)陶瓷,研究了不同含量的BC对CSLST陶瓷的晶相组成、烧结性能及微波介电性能的影响.研究结果表明:随BC添加量的增多,CSLST陶瓷的烧结温度降低,陶瓷的微波介电常数εr和谐振频率温度系数(Τ)f下降,品质因素Qf明显降低.当BC添加量为5wt％时,在1000℃保温5h可烧结,此时陶瓷具有较佳的微波介电性能:εr=80.4,Q×f=1380 GHz,(Τ)f=- 32.89×10-6/℃.     

微波烧结Al2O3-TiC复合材料的研究

以纳米级TiC、Al2 O3 为原料 ,用微波烧结制备Al2 O3 -TiC复合材料 ,并与常规烧结比较。分析了两种烧结方法对制备试样的力学性能的影响 ,并探讨了添加剂对Al2 O3 -TiC复合材料烧结性能的影响     

ZnO和Na2O对CaO-B2O3-SiO2介电陶瓷结构与性能的影响

研究了烧结助剂ZnO和Na2 O对CaO -B2 O3 -SiO2 (CBS)系微波介质陶瓷介电性能、相组成及结构特性的影响。烧结助剂ZnO在烧结过程中与B2 O3 及SiO2 生成低熔点玻璃相 ,有效地降低了材料的致密化温度 ,烧结机理为液相烧结。碱金属氧化物Na2 O虽然能够有效降低材料的烧结温度 ,但会破坏硅灰石晶体结构 ,引起材料微波性能显著降低。通过实验 ,制备出了具有优良微波介电性能的陶瓷材料 ,适用于LTCC基板及滤波器等高频微波器件的生产     

High Nonlinearity and High Voltage Gradient ZnO Varistor Ceramics Tailored by Combining Ga2O3, Al2O3, and Y2O3 Dopants

This paper deals with the electrical characteristics of rare‐earth‐doped ZnO varistor ceramics. Multiple donor dopants (Al³⁺, Ga³⁺, and Y³⁺) were employed to improve the comprehensive performance of ZnO varistor ceramics. The leakage current of rare‐earth‐doped ZnO varistor ceramics decreased noticeably with Ga₂O₃ dopants. The Ga³⁺ dopant occupies the defect sites of grain boundaries and increases the barrier potential of ZnO varistor ceramics, so the leakage current is effectively inhibited. Y₂O₃ is primarily located around the grains, which restrains ZnO grain growth, increasing the voltage gradient. The Al³⁺ goes into the lattices of ZnO grains, decreasing the grain resistance; thus, the residual voltage ratio can be controlled at low levels under a high impulse current. With the combined incorporation of Al³⁺, Ga³⁺, and Y³, excellent electrical properties of ZnO varistor ceramics can be acquired with a nonlinearity coefficient of 87, voltage gradient of 517 V/mm, leakage current of 0.96 μA/cm², and residual voltage ratio of 1.60. These rare multiple donor dopants can aid in engineering high‐quality ZnO varistors.     

Low Li2O content study in Li2O-Al2O3-SiO2 glass-ceramics

The price of lithium-containing minerals and other chemical materials continues to increase, resulting in an increase in the production cost of Li₂O-Al₂O₃-SiO₂ (LAS) system glass-ceramics. In the LAS glass-ceramics component, the reduction in the amount of Li₂O used can reduce the cost of the product. It is worthwhile to study whether it is possible to prepare glass-ceramics with low expansion properties under low Li₂O content. The effect of Li₂O content on the glass-ceramics of LAS system was studied. In this paper, spodumene was used as the main raw material, and TiO₂ and ZrO₂ were added as crystal nucleating agents to prepare transparent glass-ceramics with low expansion coefficient. The effects of the change of Li₂O content on the crystal phase and microstructure of glass-ceramics were investigated by XRD, DSC, FTIR and SEM. The results show that the main crystalline phase of the low expansion transparent glass-ceramics is β-quartz solid solution. When Li₂O content is in the range of 2.99 wt% to 4.13 wt%, low expansion glass ceramics can be prepared by an appropriate method. With the increase of Li₂O content, the average coefficient of thermal expansion (CTE) in the temperature range of 30 °C–300 °C shows a decreasing trend. When Li₂O content is in the range of 3.51 wt% to 4.13 wt%, the thermal expansion coefficient of the glass ceramics is extremely small, and even a negative expansion coefficient occurs.     

TiN改性Al2O3纳米复相陶瓷的研究进展

Al2O3陶瓷具有高硬度、耐高温、耐腐蚀和耐磨损等优点．是应用最广泛的陶瓷之一．但脆性大．难以加工．严重限制了它的应用范围。主要介绍了TiN改性Al2O3纳米陶瓷的研究进展．与SiC、ZrO2改性Al2O3纳米陶瓷相比,TiN—Al2O3纳米复相陶瓷不仅力学性能优异,而且具有导电能力,可用于电火花加工．扩大了Al2O3陶瓷的应用范围。最后对Al2O3纳米复相陶瓷的发展前景作了展望。     

Synthesis and microwave dielectric properties of BaO-Sm2O3-5TiO2 ceramics with NdAlO3 additions

BaO-Sm₂O₃-5TiO₂ (BST5) ceramics with NdAlO₃ additions of up to 15 wt% were produced with a solid state reaction method, and their structural and microwave dielectric properties were determined. Experimental results showed that NdAlO₃ neither merged nor altered the orthorhombic tungsten bronze structure of the main phase of the produced ceramics (except for a shrinkage in the crystal lattice), but it was segregated in distinct grains in the microstructure of the produced ceramics. However, the amount of NdAlO₃ strongly influenced the densification and the microstructure (i.e. grain shape and size) of the produced ceramics. Analysis of the experimental results suggests that the microstructural features can be correlated to the dielectric properties of these ceramics. Accordingly, the dielectric constant (ε_r) and the temperature coefficient of resonant frequency (τ_f) of the produced BLT5 ceramics can be tuned with the amount of NdAlO₃ additions and the sintering process parameters. The best dielectric properties were achieved for BaO-Sm₂O₃-5TiO₂ ceramics with 7.5% NdAlO₃ (ε_r=73.22, Q×f =10,300 GHz, and τ_f=−1.05 ppm/°C).     

Bi2O_3－Fe_2O_3系陶瓷材料的气－湿－温多功能特性

利用Ｘ射线衍射（ＸＲＤ）分析了烧结温度及Ｂｉ／Ｆｅ比对Ｂｉ２Ｏ３－Ｆｅ２Ｏ３系物相组成的影响。初步探讨了材料的导电类型、气敏性能及阻－湿特性，结果表明Ｂｉ２Ｏ３－Ｆｅ２Ｏ３系有可能作为一种气－湿－温多功能敏感材料体系     

Fabrication of 0.24Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 transparent ceramics by conventional sintering technique

0.24Pb(In_1/2Nb_1/2)O₃-0.42Pb(Mg_1/3Nb_2/3)O₃-0.34PbTiO₃ transparent ceramics were fabricated by a conventional sintering technique. Through optimization of sintering conditions of calcination and sintering temperatures and time, the obtained ceramics showed high optical transmittance of 53% and 71% at light wavelengths of 1300 and 2000 nm, respectively. The ceramics showed a rhombohedral to tetragonal phase transition at ~120°C and a tetragonal to cubic phase transition at 222°C. These transition temperatures were higher than those of 0.67Pb(Mg_1/3Nb_2/3)-0.33PbTiO₃ ceramics. In addition, the ceramics had a ferroelectric hysteresis loop, a large piezoelectric constant d₃₃ of 407 pC/N, and a planar electromechanical coupling factor k_p of 52%. These results suggest that the transparent ceramics may be used as a temperature-stable, linear electro-optic material.     

干摩擦及水润滑下氧化锆-氧化铝层状复合陶瓷的摩擦学行为

研究了氧化锆氧化铝三层结构层状复合陶瓷在干摩擦和水润滑下的摩擦学性能和磨损机制，并比较了氧化锆-氧化铝单层陶瓷在相同条件下的摩擦学性能。结果表明：相同条件下，层状陶瓷的摩擦系数和磨损率均低于单层陶瓷，根本原因在于层状陶瓷表面的压应力导致的韧性提高和磨损表面剪切应力的降低。水润滑可以有效地降低复合陶瓷的摩擦磨损，主要原因是由于水引起主导磨损机制发生变化，由干摩擦时的磨粒磨损和粘着磨损转变为摩擦化学磨损和疲劳磨损。     

Granular Y2O3 ceramics obtained by sintering and high-frequency fusion

Conclusions Fused yttrium oxide and apparently other highly refractory oxides and compounds can be used to produce, by the direct high-frequency heating method, highly pure fused materials which together with sinered materials may find application in the production of granular structured refractories. An investigation of the sintering of granular ceramics from fused and sintered Y₂O₃ in relation to the grain size composition, temperature, and time of firing show that the sintering of granular bodies from Y₂O₃ generally obeys the law for the sintering of coarsely grained powders.We characterize the basic thermomechanical properties of granular structured ceramics from Y₂O₃. We detected no essential difference in the properties of ceramics based on fused and sintered Y₂O₃. The resulting refractories of granular structured Y₂O₃ have a sufficient density and strength, a high refractoriness under load of 2 kg/cm², low creep rates and volatilization rates, excellent electric insulating properties in vacuum and in air, and can be used as highly refractory construction materials.Translated from Ogneupory, No. 4, pp. 45–50, April, 1973.     

Low-temperature sintering of Al2O3 ceramics doped with 4CuO-TiO2-2Nb2O5 composite oxide sintering aid

Dense alumina ceramics doped with 5 wt% 4CuO-TiO₂-2Nb₂O₅ composite sintering aids were obtained at low sintering temperatures of 950∼975 °C. The ceramic sintered at optimal condition shows good microwave dielectric properties (ε_r = 12.7, Q × f = 7400 GHz), high thermal conductivity (18.4 W/m K) and high bending strength (320 MPa). TEM and EDS analysis revealed that amorphous Cu-Ti-Nb-O interfacial films with nanometer thickness formed at the grain boundaries, which could provide paths of mass transportation for densification. Al³⁺ ions may be involved in mass transportation through substitution by Ti³⁺ and Ti⁴⁺ ions near the grain boundary during the sintering process. The accumulation of copper ions at the trigeminal grain boundary was observed. The migration and reaction of copper ions in grain boundaries may also play an important role in promoting mass transportation and low-temperature densification of alumina ceramics.