烧结法制MgO-SiO_2-Al_2O_3-B_2O_3-KF玻璃陶瓷成分设计优化及显微析晶研究

通过烧结与水淬相结合的方法制备并系统探讨了MgO-SiO2-Al2O3-B2O3-KF玻璃陶瓷的显微析晶.研究表明：MgO-SiO2-Al2O3-B2O3-KF玻璃陶瓷的烧结收缩率与玻璃化及组分的析晶程度相关;析晶程度愈高,烧结坯愈致密;试样中成分配比愈接近云母晶体成分的原子比,玻璃陶瓷的显微析晶程度愈高;在烧结温度为1 000℃时,即开始出现析晶,到1 050℃时,析晶程度达到最高,继续提高烧结温度,显微析晶又发生重熔.     

碱金属氧化物对CaO-MgO-Al_2O_3-SiO_2玻璃黏度和析晶性能的影响

用熔制法制备含不同碱金属氧化物的Ca O-Mg O-Al2O3-Si O2(CMAS)系微晶玻璃,通过旋转黏度仪测试该玻璃黏度,再结合差示扫描量热分析(DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)等分析方法,研究不同碱金属氧化物对微晶玻璃析晶性能的影响。结果表明:含不同碱金属氧化物的CMAS系微晶玻璃析出的主晶相均为辉石,但玻璃的高温黏度以及显微硬度存在差异。其中含6%Na2O(摩尔分数,下同)试样熔化温度为1 475℃,显微硬度为6.4 GPa。当3%K2O取代3%Na2O时,玻璃的高温黏度降低,熔化温度为1 460℃,析晶能力增强,显微硬度7.6 GPa。当3%Li2O取代3%Na2O时,玻璃高温黏度降低明显,试样熔化温度为1 385℃,析晶能力增强,显微硬度为7.1 GPa。     

低温高强SiO_2-B_2O_3-Al_2O_3-CaO-Na_2O陶瓷结合剂的结构与性能研究

陶瓷结合剂被广泛应用于金刚石磨料磨具的生产。制备了一组低温高强SiO2-B2O3-Al2O3-CaO-Na2O陶瓷结合剂。通过XRD、DSC、力学测试仪、热膨胀仪以及SEM等方法测试分析了陶瓷结合剂的结构与性能。结果表明,1#至3#组陶瓷结合剂的最佳烧结温度分别为720℃、700℃以及680℃,同时该组陶瓷结合剂平均抗折强度可达110MPa左右,热膨胀系数约为6.80×10-6~7.0×10-6℃-1等。同时分析讨论了SiO2与B2O3相对含量的变化对该陶瓷结合剂结构与性能的影响。     

Bi2O3-B2O3-TiO2系统玻璃的形成能力研究

采用传统的玻璃熔融方法,研究了Bi2O3-B2O3-TiO2-RmOn四元系统的玻璃形成区(RmOn分别为La2O3、Sb2O3、ZrO2、SiO2和Nb2O5氧化物),给出了上述四元系统的玻璃形成范围.研究发现Bi2O3-B2O3-TiO2-La2O3系统的玻璃形成范围最大,当TiO2的摩尔含量超过25%时,上述五个系统均不能形成玻璃.分别熔制了摩尔分数55Bi2O3-35B2O3-5TiO2-5RmOn的玻璃(RmOn分别为 La2O3、Sb2O3、ZrO2、SiO2和Nb2O5),测定了其红外吸收光谱、密度ρ、转变温度Tg、析晶开始温度Tx.初步研究结果表明Bi2O3-B2O3-TiO2-La2O3系统可作为具有性能优良非线性光学玻璃和光纤的理想基质材料.     

热处理制度对Li2O—Al2O3—SiO2系统玻璃析晶及热膨胀系数的影响

采用传统熔融冷却法获得了以P2O5为成核剂的Li2O-Al2O3-SiO2系统基础玻璃，通过差热分析确定了使该玻璃微晶化的热处理条件，并获得了不同热处理温度下Li2O-Al2O3-SiO2系统低膨胀微晶玻璃；利用X射线衍射分析和扫描电子显微镜对晶化试样的物相和微观结构进行了研究，讨论了热处理制度对玻璃的析晶及热膨胀系数的影响，研究结果表明：以P2O5为成核剂，采用不同热处理制度能获得Li2-Al2O3-SiO2系统低膨胀微晶玻璃；在析晶初始温度下进行热处理，析出β-石英晶体，但晶体生长缓慢，结晶程度低；提高晶化温度，析出β-锂辉石晶体且晶体生长迅速。     

TiO2掺杂的Li2ZnTi3O8-B2O3微波LTCC性能研究

采用传统固相反应法制备Li2 ZnTi3 O8-B2 O3低温共烧陶瓷(LTCC),研究了TiO2的添加对Li2 ZnTi3 O8-B2 O3微波LTCC的烧结性能及介电特性的影响.结果表明:B2 O3作为低熔点氧化物助烧剂,可有效降低Li2 ZnTi3 O8微波LTCC的烧结温度,并且保持较好的介电性能.同时,TiO...     

烧结温度和成分对Al_2O_3-TiC复合材料力学性能影响

以α-Al2O3粉、TiC粉为原料,采用热压烧结工艺制备了Al2O3-TiC复合材料,系统研究了烧结温度以及成分对Al2O3-TiC复合材料的组织结构和力学性能的影响规律.结果表明:α-Al2O3与TiC间没有发生化学反应,两相间具有很好的化学相容性.TiC的引入有利于提高Al2O3-TiC复合材料的力学性能.1 600℃热压烧结的Al2O3-20%TiC复合材料具有最佳的力学性能,其抗弯强度和断裂韧性分别达到509.45 MPa和5.27 MPa·m1/2,复合材料的断裂方式主要是沿晶断裂,同时伴有穿晶断裂.     

Na_2O对微晶玻璃装饰板烧结和析晶的影响

研究了Na_2O含量对CaO-Al_2O_3-SiO_2系统微晶玻璃装饰板析晶温度、析晶相,烧结收缩及表面气泡的影响。确定了合适的Na_2O含量及烧结温度范围。     

LiNbO3/Al2O3复合材料的制备及其力学性能

为了研究铁电相LiNbO3对Al2O3陶瓷材料结构及其力学性能的影响,以Al2O3 Nb2O5 和LiCO3为主要原料,分别通过高温固相法和热压烧结法,制备LiNbO3/Al2O3复合材料.对制备的复合材料进行物相分析,抗折强度的测试以及显微形貌观察.结果发现：LiNbO3的加入有利于促进Al2O3的烧结,降低了Al2O3陶瓷的烧结温度.当烧结温度超过1 200℃时,复合材料的主晶相仍然为LiNbO3和Al2O3,但由于少量Li元素挥发,生成物相LiNb3O8.在1 200℃保温3h,通过高温固相法烧结,5vol％ LiNbO3/95vol％ Al2O3复合材料的抗弯强度达到了最高,为162.34MPa.在1 300℃,150MPa（保温保压1h）热压烧结制备的15 vol％ LiNbO3/85 vol％ Al2O3复合材料致密度为92.82％,其抗弯强度和断裂韧性分别为393.94 MPa和2.38 MPa· m1/2.该复合材料中的LiNbO3晶粒出现了非180°畴结构,这种电畴结构有利于改善材料的力学性能.     

烧结温度对Al_2O_3-SiC复合陶瓷力学性能的影响

以Al2O3和SiC为原料,利用热压烧结法制备了Al2O3-SiC复合陶瓷.采用三点弯曲法、单边切口梁法等手段和SEM方法分别测定和分析了该复合陶瓷的抗弯强度、断裂韧性、致密度和断口形貌.结果表明,Al2O3-SiC10wt%复合陶瓷的致密度随热压烧结温度的提高而逐渐提高,最高可达98.42%;抗弯强度随烧结温度的升高而呈上升趋势,在1 800℃时抗弯强度最大为623MPa;断裂韧性明显是随温度的升高加强,特别是在1 850℃烧结时达到最高值7.9MPa·m1/2.材料的断裂方式主要为沿晶断裂,随着烧结温度升高,穿晶断裂所占的比例增大.     

Effect of nucleating agents on microstructure and mechanical properties of SiO2-Al2O3-ZrO2 glass-ceramics

SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength （120 MPa） than others.     

Preparation and crystallization action of SiO2 -Al2O3 -CaO-ZnO-R2O porous glass-ceramics

Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.     

Influence of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass-ceramics

ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase （β-wollastonite）. However, it promotes the crystallization at relatively low temperature.     

Effects of nucleating additives on crystallization and properties of CaO-B2O3-SiO2 glass-ceramics

ZrO₂, TiO₂ and P₂O₅ were doped in CaO-B₂O₃-SiO₂ glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO₂ as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO₂ containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 °C for 10 min, with low dielectric constant (5.87) and loss (3.21 × 10⁻⁴), which is desirable for LTCC application.     

Pressureless reactive sintering mechanism of nanocrystalline Bi2O3-Y2O3 solid electrolyte

The nanocrystalline Bi2O3-Y2O3 solid electrolyte material was synthesized by pressureless reactive sintering process with Bi2O3 and Y2O3 nano mixed powder as raw materials, which was prepared by a chemical coprecipitation process. The study on the behavior of nano δ-Bi2O3 formation and its grain growth showed that the solid solution reaction of Y2O3 and β-Bi2O3 to form δ-Bi2O3occurs mainly in the initial stage of sintering process, and nano δ-Bi2O3 crystal grains grow approximately following the rule of paracurve ((D-D0)2=K.t) during sintering process. After sintered at 600℃ for 2 h, the samples could reach above 96% in relative density and have dense microstructure with few remaining pores, the δ-Bi2O3 grains are less than 100 nm in size.     

BaO-MgO-Al2O3-SiO2系统微晶玻璃的研究

以MgO-Al2O3-SiO2系统为基础玻璃组成,TiO2为晶核剂,用少量的BaO取代MgO,制备出顽辉石/堇青石基微晶玻璃.采用差热分析、X射线衍射分析、扫描电镜等测试手段研究了BaO对玻璃析晶性能和显微结构等性能的影响,并探讨了不同量的BaO取代MgO对其电导率的影响.结果表明,在1 480℃通过熔融法制备玻璃试样...     

Structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass

Bi_2O_3-ZnO-B_2O_3 system glass is a kind of lead-free low melting sealing glasses. The structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass was investigated by DSC, FT-IR, XRD and SEM. The results show that with the increase of B_2O_3 content, the transition temperature Tg and softening temperature T_f of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glasses increase, which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass. With increasing the heat treatment temperature, a large number of liquid phases appear in samples and the sinter efficiency of the samples increases. The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi-O bond from [BO_3] pyramidal and [BiO_6] octahedral units and B-O from [BO_3] and [BO_4] units. With the decrease of B_2O_3 content, the crystallization tendency of the glass increases. In glass samples B_1 and B_2, crystallization starts at 460 ℃ and 540 ℃, respectively. Both of them precipitate Bi-(24)B_2O_(39) phases.     

CaO-Zr02-Ti02-A1203-B203-Si02玻璃陶瓷的制备及化学稳定性研究

玻璃陶瓷是固化处理中、高放废物和α废物较为理想的候选材料之一。研究了特定条件下制备的CaO-ZrO2-TiO2-A120,-B20,-SiOz体系玻璃陶瓷在水淬和空气中自然冷却的两种冷却制度对其结晶行为和显微结构的影响,用粉末浸泡实验方法测试了其化学稳定性。结果表明：自然冷却形成的玻璃陶瓷晶相主要是ZrSiO。和ZrTiOt;在25-70℃范围内,温度对玻璃陶瓷浸出率无明显影响,90℃下浸出率比25℃,40℃,70℃的浸出率高一个数量级;7d元素总的归一化浸出为1．87g／m^2。     

垃圾焚烧飞灰电弧炉熔渣微晶玻璃的晶化行为

将垃圾焚烧飞灰与适量废玻璃粉混合后用电弧炉熔融处理,产生的水冷熔渣进一步粉碎、压型并在750～1 050℃间热处理制取微晶玻璃,运用同步热分析仪、X射线衍射仪、扫描电镜等测试设备对微晶玻璃的晶化行为及性能进行分析测试.研究表明:微晶玻璃主晶相为硅灰石CaSiO3和少量透辉石Ca(Mg,Al)(Si,Al)2O6,其衍射峰随处理温度升高呈增加趋势,850℃热处理时所得微晶玻璃具有较佳的微观结构和物理、机械及化学性能,其密度为2.62 g/cm3、抗弯强度达90.44 MPa,耐酸碱性分别为2.7％、0.9％,重金属浸出浓度非常低.