拉伸强度与弯曲强度的关系及弯曲强度尺寸效应

本文研究了材料的破坏发生区、拉伸强度与弯曲强度的关系及弯曲强度的尺寸效应。拉伸及弯曲强度的关系为σ_t=σ_b(1-△/h),弯曲强度尺寸效应表现为σ_(bo)/σ_b=(1-△/h)/(1-△/h_0)。本文研究为精确测试材料拉伸强度提供了简便的方法,同时提供了破坏发生区的测试方法。     

谈Al2O3—MgO对氧化锆陶瓷强度的影响

近年来,氧化锆陶瓷作为高温结构陶瓷材料已越来越被人们所重视,其应用范围也日益扩大,且随着各个使用领域的不同,对其强度的要求也越来越高。从而对于如何完善或提高制备工艺,以保证材料或制品微观结构的均匀性,充分发挥各种材料潜在的优异特性已成为广大科技工作者研究的重要课题。     

结构陶瓷弯曲强度的Weibull统计实验研究

本文在强度统计方法的Weibull模数估计及试样数量优化研究基础上,对氧化铝陶瓷进行了弯曲强度统计的大子样模拟母体试验,同时也对碳化硅、氮化硅、氧化铅增韧氧化铝等典型结构陶瓷进行了实验研究。实验结果表明,利用无偏极大似然估计的理论结果及置信度和相对误差双参数可以明确材料强度及其强度统计数据的精度。     

高延性混凝土弯曲性能的尺寸效应

为了研究高延性混凝土尺寸变化对其弯曲性能的影响,测试了不同尺寸高延性混凝土试件的弯曲强度和弯曲韧性,采用统计学理论对试验结果进行了分析.结果表明:聚乙烯醇纤维增韧高延性混凝土极限弯曲强度及等效弯曲韧性指数都存在显著的尺寸效应,在相同龄期时,等效弯曲韧性指数的尺寸效应更为显著;随着养护龄期的增加,聚乙烯醇纤维增韧高延性混凝土极限弯曲强度和等效弯曲韧性指数的尺寸效应度增大.Ryan-Joiner正态性检验表明,聚乙烯醇纤维增韧高延性混凝土极限弯曲强度及等效弯曲韧性指数均服从正态分布,且随试件尺寸的增大,两者的变异系数均增大,说明聚乙烯醇纤维增韧高延性混凝土极限弯曲强度及等效弯曲韧性指数的尺寸效应符合Weibull尺寸效应统计理论的规律.     

氧化锆纤维布强度的研究

氧化锫纤维布的强度受到多种因素的影响,当氧化锆纤维布的晶相为四方晶相时,其力学性能最佳;优化布的织物结构可以大幅度提高其强度;PSU和S-PSU对氧化锆纤维布起到增强的作用,PSU也导致其吸碱率和吸碱速率下降,而采用S-PSU代替PSU则对吸碱率和吸碱速率下降会有所改善;通过细化氧化锆晶粒尺寸、提高晶体的完整性、保留气孔结构等方法可以获得高强度的氧化锆纤维布.     

玻璃弯曲强度的裂纹影响

玻璃弯曲强度的裂纹影响宋显辉，潘素瑛（武汉工业大学４３００７０）ＴｈｅＥｆｆｅｃｔｏｆＣｒａｃｋｓｏｎＢｅｎｄｉｎｇＳｔｒｅｎｇｔｈｏｆＧｌａｓｓ￥ＳｏｎｇＸｉａｎｈｕｉ；ＰａｎＳｕｙｉｎｇ（ＣｅｎｔｒｅｆｏｒＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈ＆Ａｎ...     

Al2O3/Al2O3-ZrO2(3Y)层状纳米陶瓷复合材料的显微结构及弯曲强度

在Al2O3-ZrO2(3Y,即含3%Y2O3,摩尔分数,下同)纳米陶瓷的基础上,以原位合成的Al2O3和Al2O3-ZrO2(3Y)纳米粉体为原料,采用干压成型及热压烧结的方法制备了Al2O3/Al2O3-ZrO2(3Y)层状纳米陶瓷复合材料,研究了ZrO2(3Y)含量对材料显微结构及力学性能的影响.结果表明:复合材...     

氧化锆陶瓷注凝成型研究

本文对ZrO2注凝成型工艺中分散剂、固相体积含量对浆料流变性的影响进行了研究.研究表明分散剂的加入可以使浆料的Zeta电位值提高近40mv,浆料粘度降低;随固相体积含量增加,浆料粘度增加,但使浆料粘度降至最低所需分散剂的量减少.     

Microstructure, Microchemistry, and Flexural Strength of Mullite Ceramics

The microstructure of mullite ceramics hot-pressed and sintered at different temperatures was studied using transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) with EDS, and electron probe microanalysis (EPMA). The specimens, consisting of stoichiometric mullite grains without glassy phase, are obtained by hot-pressing stoichiometric mullite powder at 1575°C for 1 h. Silica-rich glassy phases are observed using TEM at three-grain junctions of mullite grains in specimens heated at and above 1600°C. However, high-resolution transmission electron micrographs show no glassy phase at two-grain boundaries in all specimens. SEM with EDS analyses show that the average value of Al₂O₃ contents of mullite grains increases slightly with increasing temperature. These results are consistent with a published Al₂O₃–SiO₂ phase diagram. The flexural strength of mullite specimens at room temperature depends on their microstructure, such as the grain size and grain size distribution of mullite grains. The strength is high at room temperature and up to 1200°C, and it decreases at and above 1350°C, irrespective of the presence of the glassy phase.     

添加剂对钢渣微晶玻璃抗弯强度及颜色的影响

介绍了在微晶玻璃中引入添加剂后对其性能以及颜色的影响.实验结果表明:随着ZrO2引入量的增加,抗弯强度先是增大然后又有所下降,ZrO2的最佳引入量为1%.通过引入不同的着色剂可以制得不同颜色的微晶玻璃.     

Tensile Strength of Yttria-Stabilized Tetragonal Zirconia Polycrystals

Tensile strengths of 2.0 to 5.0 mol% Y₂O₃-stabilized ZrO₂ polycrystals were described using the newly developed tensile testing method. The tensile test was conducted by attaching three strain gauges on both sides of a rectangular bar that was 10 mm by 1 mm by 200 mm. The tensile strength of tetragonal ZrO₂ polycrystals (TZP) containing 2.0 mol% Y₂O₃ showed 745 MPa, whereas the bend strength of this material was 1630 MPa. Inelastic behavior of the stress-strain curve was observed at critical stresses and strains of 500 to 700 MPa and 0.25% to 0.35%, respectively. Although deviation from proportionality was observed to be small, it increased with the increase of temperature from −100° to 200°C.     

高强度钪铝共掺杂氧化锆电解质材料制备与性能

采用柠檬酸络合法制备了(Sc2O3)0.06(Al2O3)x(ZrO2)0.94–x(x=0,0.005,0.01,0.02)系列电解质材料。通过X射线衍射、扫描电子显微镜、电化学交流阻抗谱和力学性能测试等方法对试样进行了分析,并研究了Al2O3掺杂量对电解质材料性能的影响。结果表明:Al2O3掺杂能很好的促进电解质的烧结,有效的降低晶界电阻并提高其抗弯强度。当Sc2O3和Al2O3掺杂量分别为6%和1%摩尔分数时,800℃时氧离子电导率为0.050 S/cm,室温抗弯强度达912 MPa。采用厚度为120μm该电解质片做支撑的电池在800℃最高功率密度为0.43 W/cm2,且在0.625 A/cm2恒流放电200 h后该电池性能没有衰减。     

Strength and Toughness of Tape-Cast Yttria-Stabilized Zirconia

The biaxial flexural strength and fracture toughness of tape-cast yttria-stabilized zirconia, for application as the electrolyte in solid oxide fuel cells, have been measured at room temperature and at a typical operating temperature of 900°C. The flexural strength was measured in ring-on-ring loading and decreased from 416 MPa at room temperature to 265 MPa at 900°C. The fracture toughness was measured using two different techniques: indentation fracture and double-torsion loading. The latter was more reliable and gave a fracture toughness of 1.61 ± 0.12 MPa·m^1/2 at room temperature and 1.02 ± 0.05 MPa·m^1/2 at 900°C. The flexural strength and fracture toughness were quantitatively consistent with fracture being initiated at the observed surface defects. The lower fracture toughness at 900°C is partly due to a reduction in elastic modulus and partly due to a reduction in the work of fracture.     

SiC/莫来石复相多孔陶瓷气孔率和强度的影响因素

以煅烧高岭土、Al(OH)3粉末、SiC粉末为主要原料,以石墨为造孔剂制备了SiC/莫来石复相多孔陶瓷,研究了造孔剂含量、碳化硅颗粒粒径以及烧结温度对SiC/莫来石复相多孔陶瓷抗弯强度和气孔率的影响,并分别用XRD和SEM分析晶相组成和断面显微结构.结果表明:当SiC粒径为60 μm,造孔剂含量为15％时,在1400℃下保温3h制备的样品综合性能最佳,其孔隙率为30.3％,抗折强度达到58.0 MPa.     

Instrumented Micro-indentation of Zirconia Ceramics

Instrumented micro-indentation experiments are conducted with Vickers and spherical indenters in Y-TZP and two different Mg-PSZ ceramics. The load ( P )–depth of penetration ( h ) curves from Vickers indentation can be fitted to P = Ch ⁿ with n ∼ 1.8. It is shown that within the micro-indentation range, measurements of Young's modulus ( E ) can be conducted in zirconia ceramics using sharp indenters, and that the results are consistent with those from spherical indentation. Quantification of piling-up and sinking-in is accomplished from P – h curves. Results from finite element computations are used to assess pressure-sensitivity and plastic-hardening coefficient from indentation experiments.