Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning ele...Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning electron microscope（SEM）, energy dispersive spectroscopy（EDS） and other performance testing apparatus. Moreover, the effect of nano-TiN on the gradient cemented carbide was studied. It is found that gradient zone width increases slightly with nano-TiN introduction. Both cobalt and titanium concentrations reach the maximum near the gradient border. Tungsten concentration shows fluctuation from the surface to the bulk. （Ti ,W）C phase grains are refined for nitrogen introduction. Core-rim structure has been observed under the SEM back-scattered mode. The core appears as dark due to more titanium in it and the rim with more tungsten appears as grey. In addition, the hardness and transverse rupture strength of gradient cemented carbide are enhanced with nano-TiN introduced.展开更多
基金Funded by Research Funds for the Central Universities(No.2011SCU11038)Chengdu Science and Technology Project(Nos.10GGZD080GX-268 and 11DXYB096JH-027)
文摘Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning electron microscope（SEM）, energy dispersive spectroscopy（EDS） and other performance testing apparatus. Moreover, the effect of nano-TiN on the gradient cemented carbide was studied. It is found that gradient zone width increases slightly with nano-TiN introduction. Both cobalt and titanium concentrations reach the maximum near the gradient border. Tungsten concentration shows fluctuation from the surface to the bulk. （Ti ,W）C phase grains are refined for nitrogen introduction. Core-rim structure has been observed under the SEM back-scattered mode. The core appears as dark due to more titanium in it and the rim with more tungsten appears as grey. In addition, the hardness and transverse rupture strength of gradient cemented carbide are enhanced with nano-TiN introduced.
文摘西部大部分地区干旱少雨、昼夜温差明显,保温墙板处于恶劣环境地区就会产生局部应力集中导致出现裂纹从而缩短服役寿命.设计干湿循环加速试验,通过测试力学性能,微观观测内部结构演变,测定相对质量和相对动弹性模量进行雷达分析和数值回归,最后基于Wiener模型预测试样的可靠度,综合分析干湿循环加速作用下水泥基复合加芯墙板的性能退化规律.结果表明:随着干湿循环加速试验的持续进行,强度呈现增大的状态,抗压强度达到42.5 MPa,抗折强度9.5 MPa;微观结构内部反应产生较多的沉淀CaCO_(3)逐渐从较密实向松散发展;评价参数都从1开始增大又减小,但整体上呈降低趋势,质量损失率相对于动弹模量敏感度较低,关联度较高;经过回归模型分析,评价指标满足多项式函数的变化规律,可靠度分析质量损失、动弹性模量的工作寿命分别为4500、3500 d.
文摘目的比较四种不同粘结系统处理后不同纤维桩与根管各部的剪切粘结强度。方法45颗完整离体尖牙于釉牙骨质界冠方2 mm处截冠、根管治疗后随机分9组,使用两种纤维桩和四种粘结树脂及配套粘结剂修复:DTlight纤维桩,玻璃纤维桩,3MUnicem Rely XTM,DCcore Automix,Dual-link,Luxacore Z Automix。包埋后切不同根管段行剪切粘结实验并观察界面断裂类型,记录数据并统计分析。结果剪切粘结强度(MPa)为:D.T.light组:Luxacore Z Automix1(10.15±0.67)Mpa,DC coreAutomix(7.72±2.03)Mpa,Luxacore Z Automix2(7.25±0.71)Mpa,3MUnicem Rely XTM(6.61±1.82)Mpa,Dual-link(5.35±1.42)Mpa;玻璃纤维桩组:Luxacore Z Automix1(14.60±1.79)Mpa,3MUnicem Rely XTM(11.12±1.95)Mpa,DC core Automix(10.15±1.29)Mpa,Dual-link(8.55±1.40)Mpa。体视显微镜观察显示绝大部分样本的断裂方式都是粘结面型断裂。结论纤维桩修复的剪切粘结强度与纤维桩材料、粘结部位及粘结材料密切相关。
