LCMAS微晶玻璃／Y—TZP复相材料

本工作对ＬＣＭＡＳ微晶玻璃／Ｙ－ＴＺＰ复相材料在不同的烧结温度下所出现的晶相进行了研究，发现材料在烧结温度下，Ｙ－ＴＺＰ中的ＺｒＯ２与微晶玻璃中的ＳｉＯ２发生化学反应生成锆英石（ＺｒＯ２·ＳｉＯ２），少量Ｙ－ＴＺＰ的加入起不到相变增韧作用。由于Ｙ－ＴＺＰ起到微晶玻璃晶核剂的作用，仍能使材料的抗折强度和断裂韧性得到大幅度的提高。当Ｙ－ＴＺＰ含量为９５ｗｔ％时，复相材料的抗折强度和断裂韧性分别为６３１     

添加Al_2O_3对SiC板粒／Y－TZP复合材料力学性能的影响

本文以ＳｉＣ板粒、ＺｒＯＣｌ２－８Ｈ２Ｏ、ＡｌＣｌ３和Ｙ（ＭＯ）３为原料，利用共沉淀和热压烧结工艺，制备ＳｉＣ板粒／Ｙ－ＴＺＰ和（含Ａｌ２Ｏ３）ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料．测试了材料的室温和高温力学性能．研究了添加Ａｌ２Ｏ３对ＳｉＣ板粒／Ｙ－ＴＺＯ复合材料的影响．结果表明，ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料与Ｙ－ＴＺＰ陶瓷相比，其室温强度和韧性出现明显下降，高温强度也没有改善；而在ＳｉＣ板粒与Ｙ－ＴＺＰ复合的基础上，添加Ａｌ２Ｏ３可明显提高材料的强度和断裂韧性，同时，材料的高温强度也获得显著改善．     

由SiO2/3Y-TZP包裹复合粉体制备ZrSiO4/3Y-TZP细晶陶瓷

对湿化学法制备的ＳｉＯ_２／３Ｙ－ＴＺＰ包裹复合粉体进行了热压烧结研究,并利用Ｘ射线衍射和透射电镜表征了烧结体的物相和显微结构．在低于１３００℃,复合粉体发生瞬时粘性烧结,材料密度迅速提高;随着烧结温度的升高,ＳＩＯ_２和ＺｒＯ_２发生反应生成ＺｒＳｉＯ_４．在１５００℃热压条件下,制备了平均晶粒尺寸为３５０ｎｍ的ＺｒＳｉＯ_４／３Ｙ－ＴＺＰ细晶复相材料．我们认为,在烧结过程中形成的第二相ＺｒＳｉＯ_４,特别是ＳｉＯ_２包裹层对抑制基体晶粒长大起主要作用．     

SiC－AlN－Y_2O_3复相陶瓷的制备与性能

通过热压烧结技术，ＳｉＣ、ＡｌＮ和Ｙ２Ｏ３粉末混合作在１９２０～２０５０℃、Ａｒ气氛下形成了致密的复相陶瓷．在室温下ＳｉＣ－ＡｌＮ－Ｙ２Ｏ３复相材料的抗弯强度和断裂韧性分别达到６００ＭＰａ和７ＭＰａ·ｍ１／２以上运用ＸＲＤ、ＳＥＭ和ＴＥＭ分析致密样品的断裂裂纹、形貌和组成．ＳｉＣ－ＡｌＮ－Ｙ２Ｏ３复相陶瓷在１３７０℃氧化试验３０ｈ，其氧化产物为莫来石．     

添加Al2O3对SiC板粒／Y—TZP复合材料力学性能的影响

本以ＳｉＣ板粒、ＺｒＯＣｌ２·８Ｈ２Ｏ、ＡｌＣｌ３和Ｙ（ＭＯ）３为原料，利用共沉淀和热压烧结工艺，制备ＳｉＣ板粒／Ｙ－ＴＺＰ和（含Ａｌ２Ｏ３）ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料。测试了材料的室温和高温力学性能。研究了添加Ａｌ２Ｏ３对ＳｉＣ板粒／Ｙ－ＴＺＯ复合材料的影响。结果表明，ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料与Ｙ－ＴＺＰ复合材料与Ｙ－ＴＺＰ陶瓷相比，其室温强度和韧性出现明显下降，高温强度也没有改善；     

SiC—AlN—Y2O3复相陶瓷的制备与性能

通过热压烧结技术，ＳｉＣ、ＡｌＮ和Ｙ２Ｏ３粉末混合体在１９２０￣２０５０℃、Ａｒ气氛下形成了致密的复相陶瓷。在室温下ＳｉＣ－ＡｌＮ－Ｙ２Ｏ３复相材料的抗弯强度和断裂韧性分别达到６００ＭＰａ和７ＭＰａ·ｍ＾１／２以上。运用ＸＲＤ、ＳＥＭ和ＴＥＭ分析致密样品的断裂裂纹、形貌和组成。ＳｉＣ－ＡｌＮ－Ｙ２Ｏ３复相陶瓷在１３７０℃氧化试验３０ｈ，其氧化产物为莫来石。     

纤维涂层对复合材料力学性能的影响

对于ＳｉＣ纤维／ＭＡＳ微晶玻璃复合系统，发现在烧结温度下，纤维和基体之间有较严重的化学反应发生，界面结合强，力学性能较差．通过对ＮｉｃａｌｏｎＳｉＣ纤维加涂层，发现Ｎｂ２Ｏ５和ｃ涂层对复合材料的界面结合改善不大，而ＬＣＡＳ晶玻璃涂层能使纤维和基体间的界面结合明显减弱，力学性能大幅度提高，室温抗折强度和断裂韧性分别达３２７ＭＰａ和１３．９ＭＰａ·ｍ１／２．     

碳化硅和氧化铝陶瓷的热等静压氮化

通过对无压烧结、热压烧结和热等静压烧结ＳＩＣ陶瓷以及热压烧结的ＳｉＣ粒子补强Ａｌ２Ｏ３基复相陶瓷（ＳｉＣｐ－Ａｌ２Ｏ３）和ＳｉＣ粒子与ＳｉＣ晶须共同增强的Ａｌ２Ｏ３基复合材料（ＳｉＣｐ－ＳｉＣｗ－Ａｌ２Ｏ３）在氮气氛中进行高温氮化处理，成功地实现了这些材料的开口气孔表面裂纹的愈合。研究表明：热等静压氯化工艺可以显著提高ＳｉＣ和Ａｌ２Ｏ３陶瓷的抗弯强度，对断裂韧性也有较大的改善作用。对于热等静压烧结ＳｉＣ陶瓷，在１８５０℃和２００ＭＰａ氮气压力下氯化处理１小时后，其抗弯强度和断裂韧性分别由５８２ＭＰａ和５．７ＭＰａ·ｍ１／２提高到９０７ＭＰａ和８．４ＭＰａ·ｍ１／２；对于热压烧结的ＳｉＣｐ－Ａｌ２Ｏ３复相陶瓷和ＳｉＣｐ－ＳｉＣｗ－Ａｌ２Ｏ３复合材料，在１７００℃和１５０ＭＰａ氮气压力下氮化处理１小时后，其室温抗弯强度分别由４６０和７０５ＭＰａ提高到８９５和１０３３ＭＰａ。     

ZrO2（Y—TZP）—Si3N4复合材料中抑制ZrN生成研究

研究了气氛加压烧成ＺｒＯ２（Ｙ－ＴＺＰ）－Ｓｉ３Ｎ４复合材料中抑制ＺｒＮ生成工艺问题，相组成分析表明：无论添加≤２０ｗｔ％工业ＺｒＯ２或者Ｙ－ＴＺＰ（３ｍｏｌ％Ｙ２Ｏ３）的氮化硅复合材料，在低于１８５０℃，３ＭＰａ氮气压力下烧成，表面无ＺｒＮ生成。     

低温烧结细晶Y-TZP

通过在Ｙ－ＴＺＰ中加入适量的硅酸盐玻璃添加剂,使其烧结温度明显降低,并且制备出具有细晶粒、高强度的四方相氧化锆增韧陶瓷材料．分析了添加剂含量及烧结温度与材料致密度、显微结构及力学性能的关系,发现在Ｙ－ＴＺＰ材料中加入１ｗｔ％的添加剂,可以使材料在１４００℃下烧结,氧化锆晶粒尺寸约为１００～２００ｎｍ;其抗折强度可达９５０ＭＰａ．     

SiC纤维／LCMAS微晶玻璃基复合材料的界面结合和力学性能

本工作通过在母体玻璃中引入ＭｇＯ后进行热处理得到一系列具有不同热膨胀系数的微晶玻璃．ＳｉＣ纤维／ＬＣＭＡＳ微晶玻璃基复合材料在烧结条件下，在纤维和基体间形成一厚度约为２μｍ的界面层．纤维、基体间的界面剪切应力通过单根纤维压出法测试，发现纤维、基体间的界面剪切强度对复合材料的力学性能有严重的影响，并且ＳｉＣ纤维／ＬＣＭＡＳ系微晶玻璃基复合材料具有较高的界面剪切强度，通过降低基体的热膨胀系数减弱界面剪切强度，可使复合材料的强度和断裂韧性都得到明显的改善．     

云母微晶玻璃/Y-TZP复相材料的制备和力学性能

本文用烧结法制备了云母微晶玻璃／－TZP复相材料,用X光衍射分析（XRD）法测定了材料断裂过程中氧化锆的相变体积分数,用拉曼微探针谱测定了相变区宽度,并对增韧机制进行了研究．结果表明：氧化锆的加入可以显著提高材料的力学性能．当加入40vol％ZrO₂时,云母微晶玻璃的强度和断裂韧性分别可达446MPa和4．8MPam^1／2氧化锆的相变分数随氧化锆含量的增加而减小,而相变区宽度随氧化锆含量的增加而增大;氧化锆主要通过应力诱导相交增韧机制来提高云母微晶玻璃的断裂韧性,但随着氧化锆含量的增加,裂纹在氧化锆颗粒附近的偏转会进一步提高材料的断裂韧性．     

3Y-TZP/LZAS微晶玻璃功能梯度涂层的微观结构与性能

为了提高钢基体微晶玻璃涂层的韧性, 在Q235钢基体上采用涂搪法制备了钇稳定四方相氧化锆/Li₂O- ZnO-Al₂O₃-SiO₂ (3Y-TZP/LZAS) 微晶玻璃功能梯度涂层。采用XRD、SEM分析了梯度涂层的物相组成和微观结构, 采用压痕法测试并计算了涂层的显微硬度和断裂韧性, 通过粘接-拉伸法测试了涂层的结合强度。结果表明, 3Y-TZP/LZAS微晶玻璃功能梯度涂层各层之间的界面结合紧密; 涂层与钢基体依靠玻璃中的SiO₂与铁的氧化物发生界面反应形成牢固的结合, 反应产物为Fe₂SiO₄和FeSiO₃; 涂层的显微硬度和断裂韧性沿涂层厚度方向逐渐增大, 涂层韧性提高是表面残余压应力增韧、3Y-TZP相变及3Y-TZP的颗粒增韧共同作用的结果; 梯度涂层与Q235的结合强度达16.3 MPa。热震实验表明, 梯度涂层在300℃下经历30余次热循环, 表现出较好的抗热震性能。     

The effect of multi-wall carbon nanotubes on electromagnetic interference shielding of ceramic composites

Multi-wall carbon nanotubes (MWCNTs)-3?mol% yttria-stabilized zirconia (3Y-TZP) (MWCNTs-3Y-TZP) composite was prepared by spark plasma sintering. The complex permittivities of the composite have been measured in the Ku-band range (12.4-18?GHz) and it is found that both the real and imaginary permittivities of the composite increase with the increasing content of MWCNTs. The effect of the content of MWCNTs on the electromagnetic interference (EMI) shielding effectiveness (SE) of the composite has been evaluated, and it is found that the EMI SE of the composite increases with the increasing content of MWCNTs. An EMI SE value as high as 25-30?dB has been achieved in the Ku-band range for the composite with 9?wt% content of MWCNTs, indicating that the MWCNTs-3Y-TZP composite can be used as an effective EMI shielding material.     

Microstructure and mechanical behaviour of 3Y-TZP/Mo nanocomposites possessing a novel interpenetrated intragranular microstructure

Yttria stabilized tetragonal zirconia polycrystal (Y-TZP)/0-100 vol % molybdenum (Mo) composites were fabricated by hot-pressing a mixture of Y-TZP powder containing 3 mol % yttria (Y₂O₃) and a fine Mo powder in vacuum. This composite system possessed a novel microstructural feature composed of an interpenetrated intragranular nanostructure, in which either nanometer sized Mo particles or equivalent sized zirconia (ZrO₂) particles located within the ZrO₂ grains or Mo grains, respectively. The strength and toughness were both greatly enhanced with increasing Mo content for the 3Y-TZP/Mo composites thus breaking through the strength-toughness tradeoff relation in transformation toughened ZrO₂ and its composite materials. They exhibited a maximum strength of 2100 MPa and a toughness of 11.4 MPa·m^1/2 for the composite containing 70 vol % Mo. These simultaneous improvements in strength and toughness were determined to be the result of a decrease in flaw size associated with the interpenetrated intragranular nanostructure, and a stress shielding effect created in the crack tip by the elongated Mo polycrystals bridging the crack tip in addition to the stress induced phase transformation.     

Apatite-forming ability of glass-ceramic apatite–wollastonite – polyethylene composites: effect of filler content

The bioactivity of a range of glass-ceramic apatite–wollastonite (A–W) – polyethylene composites (AWPEXs) with glass-ceramic A–W volume percentages ranging from 10 to 50, has been investigated in an acellular simulated body fluid (SBF) with ion concentrations similar to those of human blood plasma. The formation of a biologically active apatite layer on the composite surface after immersion in SBF was demonstrated by thin-film X-ray diffraction (TF-XRD) and field-emission scanning electron microscopy (FE-SEM). An apatite layer was formed on all the composites, with the rate of formation increasing with an increase in glass-ceramic A–W percentage. For composites with glass-ceramic A–W filler contents 30 vol %, the apatite layer was formed within 12 h of immersion, which is a comparable time for apatite formation on monolithic glass-ceramic A–W. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) demonstrated that the apatite formation on AWPEX samples with 50 vol % filler content occurred in a manner similar to that seen on pure glass-ceramic A–W, in that the calcium, silicon, and magnesium ion concentrations increased and, conversely, a decrease was observed in the phosphate ion concentration. These results indicate that a suitable in vitro response was achieved on a composite incorporating particulate glass-ceramic A–W with a particularly favorable response being observed on the AWPEX sample with 50 vol % filler content.     

HAP／Y－TZP复相生物陶瓷研究

羟基磷灰石，是一种具有优秀生物活性的生物材料，但作为承受负荷的骨组织替代物时，缺乏良好的力学性能．本文采用湿化学法制备ＨＡＰ及ＨＡＰ／Ｙ－ＴＺＰ复相粉体，通过热压工艺，以期改善ＨＡＰ的力学性能，分别进行上皮组织、成纤维细胞与膜片联合培养试验．结果表明：含４０ｗｔ％Ｙ－ＴＺＰ的ＨＡＰ复相陶瓷，其抗弯强度和断裂韧性均比同种工艺得到的ＨＡＰ提高７４％和９０％；上皮组织与膜片贴覆性好，不延缓细胞的生长，成纤维细胞与膜片接种良好．