无机膜陶瓷支撑体的制备与性能

采用固态粒子烧结法,通过添加成孔剂和高温粘结剂,制备气孔率和抗弯强度较高的氧化铝多孔陶瓷支撑体.通过L9(34)正交试验,优化支撑体的制备工艺,获得气孔率47.8%,抗弯强度32.9 MPa的陶瓷支撑体,其制备工艺条件为成孔剂添加量为15ω/%,高温粘结剂添加量2ω/%,烧成温度1300℃,恒温时间30 min.实验结果表明,烧成温度对陶瓷支撑体的气孔率和抗弯强度影响较显著,其次是成孔剂的添加量.     

生物玻璃增强多孔羟基磷灰石生物陶瓷的制备及其性能

研究多孔羟基磷灰石(HA)生物陶瓷的制备方法及性能.采用颗粒尺寸为500～600um的炭粉,以体系为SiO2-Na2O-CaO-MgO-Al2O3的生物玻璃为高温粘结剂,通过一定的混料、压制和烧结工艺,可制得孔隙率为30%～48%,抗弯强度达11.65MPa,大孔孔径约500～600 um、d小孔孔径1～20um并孔隙相互连通的多孔陶瓷.采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子万能实验机对样品的微观结构和抗弯强度进行分析,还通过分析天平,采用阿基米德原理对样品孔隙率进行测量.结果表明:随着烧结温度的升高,气孔率逐渐减小,抗弯强度逐渐增加.通过控制炭粉的含量,可以有效的控制多孔烧结体的孔隙率、大孔的分布及孔径.生物玻璃的加入可以促进材料的液相烧结,使多孔羟基磷灰石生物陶瓷敛密化,改善其力学性能,同时随着生物玻璃含量的增加孔隙率减少.     

凝胶注模成型制备微多孔氮化硅陶瓷

采用凝胶注模法,在无其它添加剂的条件下,通过提高单体含量,成功制备出高性能微多孔氮化硅陶瓷,陶瓷抗弯强度高达137 MPa以上,气孔率高达50%以上,孔中径小于1 μm.结果表明:随着有机单体含量的增加,氮化硅微多孔陶瓷气孔率单调增加;随着固含量的增大,氮化硅微多孔陶瓷气孔率单调下降,抗弯强度先上升然后又下降,固含量有一优化值,此时陶瓷体抗弯强度最大;随着烧结温度的增加,氮化硅陶瓷强度单调增加,而气孔率单调下降.     

造孔剂添加量对凝胶注模成型工艺制备8YSZ多孔陶瓷性能的影响

采用叔丁醇基凝胶注模成型工艺结合添加造孔剂法制备了高固相含量的YSZ多孔陶瓷。研究了固相含量为50%(体积分数)时,不同造孔剂添加量对烧结8YSZ多孔陶瓷的孔径及其分布、气孔率、抗弯强度以及热导率的影响。研究结果显示:8YSZ多孔陶瓷的气孔分布均匀,孔径在10μm左右,孔壁致密;气孔率在22.9%～39.8%之间,且随着造孔剂添加量的增加而增加;抗弯强度随着造孔剂添加量的增加而减小,最高可达(85.24±2.31)MPa;热导率在0.735～1.108W/m·K之间,且随着造孔剂添加量的增加而降低。上述结果表明,凝胶注模工艺中同时添加造孔剂不仅可以实现高固相含量多孔陶瓷的制备,而且可以同时实现孔结构可控,最终得到兼具有高强度、高气孔率和低热导率的8YSZ多孔陶瓷。     

高强度多孔氮化硅陶瓷的制备及性能研究

以氮化硅为原料,以叔丁醇为溶剂,采用凝胶注模成型工艺和无压烧结工艺,制备出具有高强度和高气孔率的多孔氮化硅陶瓷。在浆料中初始固相含量固定为10vol%的基础上,研究烧结温度和保温时间对多孔氮化硅陶瓷材料的气孔率、孔径尺寸分布、物相组成及显微结构的影响,分析抗弯强度与结构之间的关系。结果表明,通过改变烧结温度和保温时间,可制备气孔率63.3%~68.1%的多孔氮化硅陶瓷;气孔尺寸呈单峰分布,平均孔径为0.97~1.42μm;抗弯强度随烧结温度提高或保温时间延长单调增大,在1750℃保温1.5h下达到最大值(74.2±8.8)MPa。     

造孔剂含量对多孔BN/Si3N4复合陶瓷结构和性能的影响

以Si3N4为基体、BN为添加剂,采用添加PMMA造孔剂法制备出具有优良力学性能和介电性能的多孔BN/Si3N4复合陶瓷。通过对材料的物相组成、显微结构、气孔率、孔径分布、力学及介电性能的表征和测试,系统分析了造孔剂含量对材料结构和性能的影响。结果表明:随着造孔剂含量的增加,多孔BN/Si3N4复合陶瓷的气孔率增大,抗弯强度减小,介电常数减小,而介电损耗呈微弱的上升趋势。当造孔剂粒径为2μm,含量为5%(质量分数,下同)时,制备出气孔率达到40.8%,抗弯强度达到(114.67±10.73)MPa,介电常数为4.0,介电损耗为3.3×10-3的高性能多孔BN/Si3N4复合陶瓷透波材料。     

基于冰冻干燥法制备高气孔率氧化铝多孔陶瓷

利用冷冻干燥法制备多孔氧化铝陶瓷。系统讨论了影响多孔陶瓷微观结构的主要因素。结果表明:固体含量显著影响多孔陶瓷试样的强度和气孔率;粘结剂的添加对于多孔结构的保持很重要;烧结温度对最终的孔径分布和微观结构有较大影响。以水玻璃为粘结剂,可以显著提高多孔陶瓷的机械强度,但会对气孔率有一定的影响,少量添加可以提高气孔率,当加入量超过30%后,气孔率、孔径开始减小而对应的抗压强度会有一定的提高。     

TiCp/Ag-Cu-Ti复合钎料膜制备及其在SiC陶瓷连接上的应用

采用通用型流变仪研究分散剂种类及含量、粘结剂含量和浆料固含量对浆料流变性的影响;采用SEM、EDS研究SiC接头的微观结构和相组成,探讨影响抗弯强度的因素。结果表明,分散剂蓖麻油磷酸酯的质量分数为5%、粘结剂PVB的质量分数为2.6%及固含量的体积分数为26%时,浆料流变性良好,复合钎料膜韧性好,增强体分布均匀。以此膜连接SiC陶瓷接头的微观结构结果表明,连接界面致密无缺陷,界面反应层厚度为0.9～1.5 μm,增强体TiC均匀分散金属钎料基体中,与金属钎料无化学反应;TiC加入可提高连接部件的抗弯强度,而抗弯强度与反应层厚度关系密切,SiC连接部件最高抗弯强度为92 MPa,而此时的反应层厚度为1.5 μm。     

TiO_2对堇青石多孔陶瓷微观结构和性能的影响

以叔丁醇为成形介质和造孔剂,二氧化钛为烧结助剂,采用凝胶注模成形和无压烧结工艺制备堇青石多孔陶瓷.研究了添加5%(体积分数,下同)二氧化钛对堇青石多孔陶瓷的气孔率、微观结构、力学性能和气孔结构的影响,并对样品的断口形貌进行观察.结果表明,在1175 ℃烧结温度条件下,与不添加二氧化钛相比,当二氧化钛含量为5%时,所得堇青石多孔陶瓷的气孔率和开口气孔率分别由76.9%和96.4%下降为72.4%和95.1%,线性收缩率从20.7%提高到22.1%,而抗压强度则由3.23 MPa提高到5.83 MPa,气孔尺寸均呈单峰分布,中位孔径由2.29 μm下降到1.62 μm.二氧化钛的加入提高了堇青石粉末的低温烧结性能,在未明显降低堇青石多孔陶瓷气孔率以及未改变其气孔结构、孔径尺寸分布的前提下,材料的力学性能得到了显著改善.     

烧结助剂对高气孔率SiC陶瓷结构和性能的影响

由叔丁醇、丙烯酰胺和SiC粉及烧结助剂组成固相含量为10%(体积分数)的陶瓷浆料,采用凝胶注模成型和无压烧结工艺制备多孔SiC陶瓷,研究Al2O3和Al2O3+SiO2这两种烧结助剂体系对多孔SiC陶瓷的气孔率、显微结构和力学性能的影响。结果表明:Al2O3+SiO2复合烧结助剂明显改善SiC陶瓷的烧结性能,与采用单一的Al2O3烧结助剂相比,SiC样品的烧结温度和莫来石的生成温度均降低50℃左右;两种不同的烧结助剂制成的试样中的气孔均呈很窄的单峰分布,中位孔径为2μm左右;随烧结温度的升高压缩强度增大,而气孔率变化不大;以Al2O3+SiO2为烧结助剂、在1 400℃烧结的试样的气孔率和强度分别达到70.57%和17.74 MPa。     

铬-陶瓷复合结合剂的机械合金化制备工艺及性能研究

以金属铬粉和陶瓷结合剂粉体为初始原料,按照不同比例配混,采用机械合金化(MA)工艺对其进行处理。工艺参数为:球料比R=20∶1,转速n=350 r/min,球磨时间t=12 h;添加适量的无水乙醇为过程控制剂。将获得的复合粉体在660～740 ℃进行无压烧结,用SiC埋烧。采用三点弯曲法测试烧结后试样的抗弯强度,利用X射线衍射仪(XRD)测试试样的物相构成,用扫描电子显微镜(SEM)观察试样断口的微观形貌,采用阿基米德原理测试试样的密度和显气孔率。实验结果表明:利用MA处理工艺,可以获得金属相与陶瓷相均匀分布的复合结合剂;当金属铬粉的质量分数为30%,烧结工艺为700 ℃/30 min时,所得试样的抗弯强度达到最大值,为187 MPa。金属铬粉通过其颗粒表层的CrO与陶瓷形成良好的界面结合,从而提高复合结合剂的抗弯强度。      

Influence of submicron SiC particle addition on porosity and flexural strength of porous self-bonded silicon carbide

In the present study, porous self-bonded silicon carbide (SBSC) ceramics were fabricated at temperatures ranging from 1700 °C to 1800 °C using SiC powders, silicon and carbon as starting materials. The amount of (Si + C) powders is fixed and the influence of submicron SiC particle content (0 wt.% to 80 wt.%) on the porosity and strength of the ceramics was studied. The experimental results illustrate that the packing efficiency increased with the increase in submicron particle content to 40 wt.%, and thereafter decreased. The green porosity largely determines the final porosity of the sintered specimens, irrespective of the submicron SiC particle content. The flexural strength increased with the addition of submicron particle content and sintering temperature. Typically, SBSC ceramics prepared using 80 wt.% submicron SiC particle content possess 46% porosity and 42 MPa flexural strength when sintered at 1800 °C.     

Si粉粒径及其添加量对SiC陶瓷材料结构和性能的影响

将平均粒径为75 μm和48 μm、质量分数为0%~8%的Si粉分别添加到SiC陶瓷材料中,在1550℃下保温3 h烧成,研究Si粉粒径及其添加量对SiC陶瓷材料烧结性能、力学性能和显微结构的影响。结果表明:添加不同粒径及质量分数的Si粉可改善SiC陶瓷材料的显微结构,提高其烧结性能和力学性能;在一定范围内,较小粒径的Si粉更有利于形成均匀、致密的SiC烧结体,大幅提升SiC陶瓷材料的性能;当Si粉粒径为48 μm且添加的质量分数为4%时,SiC陶瓷材料的烧结性能和力学性能较优,其体积密度和显气孔率分别为2.58 g/cm3和13.5%,抗弯强度和洛氏硬度分别为25 MPa和115 HRB。      

Effect of initial α-phase content on microstructure and flexural strength of macroporous silicon carbide ceramics

The effects of the initial α-phase content on the microstructure and flexural strength of macroporous silicon carbide (SiC) ceramics were investigated. When β powder or a mixture of α/β powders containing small (≤3%) amounts of α powder were used, the grains showed a platelet-shape. In contrast, the grains had an equiaxed-shape when α powder or a mixture of α/β powders containing large (≥50%) amounts of α powder was used. The flexural strength increased with increasing α-SiC content in the starting composition, whereas the porosity decreased with increasing α-SiC content. The strength of the macroporous SiC ceramics was affected mostly by the porosity when the grain size was smaller than 10 μm, whereas the strength was controlled by pore size and grain size when the microstructure consisted of large (>10 μm) platelet grains.     

Characterization of porous Ti-bioglass composite produced by mechanical milling and space holder sintering

In this study, porous titanium-10 wt% bioglass(BG) composites were fabricated by the process of combining mechanical alloying with space holder sintering. The pore morphology and phase constituents of the milled powders and porous compacts were characterized by scanning electron microscopy(SEM), X-ray diffractometry(XRD), and Fourier transform infrared spectroscopy(FT-IR). The mechanical properties were determined by running compression test. The porosity of the sintered samples shows a downward trend with the increase of milling time. As the porosity increases, both the compressive strength and elastic modulus decrease. The results illustrate that the fabricated porous compacts with high porosity and suitable mechanical properties have the potential application in bone tissue engineering.     

热压B4C—C陶瓷复合材料的组织与性能

研究了添加游离碳含量对碳化物粉末的热压烧结行为及对Ｂ４Ｃ－Ｃ陶瓷的强度和断裂韧性的影响,用Ｘ射线衍射,扫描电镜对烧结的成分,显微结构和断裂行为进行了分析讨论,结果表明,在一定的热压条件下,添加７％Ｃ（质量分数）的碳化颗烧结体的相对密度可高达９８．５％,断裂韧性为７．６５ＭＰａ．ｍ＾１／２弯曲强度仍能达４６０ＭＰａ通过成分及断口形貌观察,由于晶界Ｃ对晶界的弱化及晶界的分层诱韧化作用使裂纹偏转,钝化可     

Effect of additives on mechanical properties of macroporous silicon carbide ceramics

Macroporous SiC ceramics were fabricated by carbothermal reduction of polysiloxane-derived SiOC containing hollow microspheres, followed by sintering and subsequent annealing. The effects of the additive composition and the annealing temperature on the porosity, microstructure, and mechanical strength of the resulting porous ceramics were investigated. Varying the additive composition was found to result in different porosities, microstructures, and mechanical properties. When the samples were sintered at 1750 °C and then annealed at 1900 °C for 4 h, the SiC prepared with 3% Al₂O₃ and 2% Y₂O₃ showed the highest strength (a flexural strength of 55 MPa and a compressive strength of 289 MPa, at a porosity of 45 %). The present results suggest that judicious selection of the sintering additive composition is very important for improving the mechanical properties of macroporous SiC ceramics.     

Effect of SiC particle size on flexural strength of porous self-bonded SiC ceramics

Porous self-bonded silicon carbide (SBSC) ceramics were fabricated from SiC powders with various particle sizes (0.7 μm, 25 μm, 50 μm, 65 μm), plus Si, C and boron (as a sintering additive). The effects of submicron (0.7 μm) SiC particle incorporation into the SBSC and the SiC particle size (25 μm, 50 μm, 65 μm) on the flexural strength and porosity of the ceramics were investigated as a function of sintering temperature. Incorporating 0.7 μm SiC particles into the ceramic material containing 25 μm SiC particles increased the flexural strength by 3 times, from 11.7 MPa up to 35.5 MPa after sintering at 1800 °C. Simultaneously, the porosity was reduced by ∼5 %. Furthermore, the flexural strength of ceramic with 25 μm SiC particles was superior to that with 65 μm SiC particles. Generally, the flexural strength of the SBSC increased as, both, a function of submicron SiC particle incorporation along with relatively small micron-sized particles (25 μm) in the microstructure of the ceramic plus increased sintering temperature.     

选择性激光烧结法制备SiC颗粒预制体

介绍了一种新的制备颗粒预制体的方法,即采用选择性激光烧结(SLS)法制备SiC颗粒预制体。结果表明,用表面已预处理的SiC与粘结剂混合粉料作为SLS用粉,在一定的激光烧结工艺条件下,可将其烧结成SiC颗粒均匀分散的预制体;并可通过控制烧结粉末的配比获得不同孔隙率的SiC颗粒预制体。