Carbon‐content‐dependent phase composition,microstructural evolution,and mechanical properties of SiBCN monoliths

Three SiBCN monoliths: carbon‐lean, ‐moderate, and ‐rich monoliths with the same Si/B/N mole ratio have been prepared by mechanical alloying followed by reactive hot pressing. The role of carbon on phase composition, microstructural evolution, and mechanical properties were investigated. XRD and TEM investigations showed that the as‐sintered monoliths contain several components: Si metal, SiC, t‐BN, and BN(C), strongly correlated with the carbon content. TEM results also revealed that BN(C) enwraps SiC grain forming capsule‐like structure. Raman, NMR, and HRTEM studies suggested that the structural evolution within the BN(C) areas includes the graphitization of amorphous carbon and the lateral growth of BN(C), accompanied by an increase in the defect concentration. The defects form within BN (0002) basal planes resulting from the disordered carbon imbedded, which in turn determines the morphological evolution of BN(C). The ill‐developed microstructures for carbon‐lean monoliths and the excessive carbon in carbon‐rich ones both deteriorate their mechanical properties and densities.     

外援型自修复体系及其在环氧基复合材料中的应用

聚合物基自修复材料是近年来国内外的研究热点。根据自修复过程是否需要外加修复剂,聚合物基复合材料自修复方法主要分为外援型自修复和本征型自修复。外援型自修复体系主要包括双环戊二烯修复体系、环氧基修复体系、硫醇基修复体系、甲基丙烯酸缩水甘油酯修复体系、马来酰亚胺修复体系等。着重介绍了这几种自修复体系及其在环氧基复合材料中的应用,并展望了外援型自修复体系在聚合物基复合材料的应用前景及发展方向。     

低相对分子质量反式-1，4-聚异戊二烯蜡在橡胶配方中的应用

研究了低相对分子质量反式—1，4—聚异戊二烯蜡(LMTPIW)在橡胶配方中的应用。用LMTPIW替代芳烃油用于SBR或SSB／TPI配方中，可改善混练胶的加工性能；硫化胶的拉伸强度略有下降，回弹性、屈挠性能、热老化性能及抗湿滑性能都有所提高。当LMTPIW用量为20份时，胶料的综合性能最佳。     

内陆核电厂严重事故对水资源安全影响的评价方法研究

为研究内陆核电厂严重事故对水资源安全影响的评价方法,在分析内陆核电厂严重事故对水资源安全影响机理的基础上,从社会影响、经济影响、生态影响三个角度建立了适用于核电厂严重事故对水资源安全影响评价指标体系,提出了基于水资源使用功能和基于受影响的GDP的两种评价方法。以某内陆核电厂为典型案例,分析结果表明,该核电厂严重事故影响经济社会用水规模达6.1亿m~3,影响GDP规模达373亿元,对水资源安全的影响属于严重影响等级,两种方法评价结果基本一致。该方法对核电厂严重事故影响评估、应对重大水安全风险具有一定参考价值。     

线阵CMOS图像采集及编码传输的实现

为实现雨滴、雾滴等大气粒子的非接触测量,基于线阵CMOS图像传感器实现了粒子测量系统.充分利用FPGA的资源丰富、接口灵活、并行计算等特点,结合USB芯片实现稳定可靠的高速数据采集和传输.为解决线阵图像传感器数据高速采集和实时传输处理问题,基于Xilinx公司Spantan系列XC3S200为核心实现了高速数据的采集和...     

Effect of Thermal Cycling Treatment on Microstructure and Mechanical Properties of AlNp/2024Al Composite

The AlNp/2024 composite with a high volume fraction (50%) was fabricated by squeeze casting. Its mechanical properties were investigated by tensile tests at ambient temperature and the microstructure was observed by a transmission electron microscope (TEM). It was indicated that after six thermal cooling cycles treatment the AIN/2024Al composite exhibited higher elastic limit (σ0.01), tensile strength (UTS) and elastic modulus (E). TEM observation showed that there was higher dislocation density both in the matrix and the particle. δ′ phase is the mainly precipitate.     

Role of boron addition on phase composition,microstructural evolution and mechanical properties of nanocrystalline SiBCN monoliths

Nanocrystalline SiBCN monoliths with the same Si/C/N mole ratio and various boron additions ranged from 0 to 3.0 mol were prepared by mechanical alloying plus reactive hot pressing methods. Correction of boron content and microstructural/morphological evolution was investigated in detail by XRD, SEM, TEM and STEM-EDX structure characterization. Except for SiC and BN(C), boron addition contributes to B_xC formation. Besides, boron addition promotes the crystallization of SiC, leading to the formation of poor crystallinity of spherical structures in inner SiC. Furthermore, boron addition significantly promotes the grain growth of SiC and B_xC and therefore increases the relative volume ratios of B_xC/BN(C) and B_xC/SiC. Amorphous-like BN(C) changes to belt-like structures as boron addition increases. The new formed B_xC effectively contributes to the improvement of Vicker’s hardness while pull-out of BN(C) belt-like structures benefits the fracture toughness.     

数字化测绘技术在工程测量中的应用

主要介绍了工程测量实践中数字化测绘技术中的应用,并提出了一些看法供大家探讨.     

基于Procast的油缸支架铸件工艺分析及优化

铸造模拟软件作为一种有效的铸造工艺设计和优化工具，在全球铸造行业中日益得到广泛的应用。针对油缸支架在样品试制过程中发现的缩孔和缩松缺陷，利用Procast软件对其凝固过程进行数值模拟运算，并根据模拟结果对原有的工艺进行了优化。通过对铸件进行X射线探伤和解剖证实模拟结果是准确的。