微晶软磁合金制备技术的新进展

根据有关文献提供的研究结果,简述了传统软磁合金制备技术的研究现状,重点介绍了深过冷快速凝固技术的最新进展,阐明了深过冷快速凝固技术是制备大体积微晶软磁合金的有效方法.最后给出了采用深过冷快速凝固技术制备微晶软磁合金的研究内容.     

复合材料增强剂—陶瓷纤维(晶须)的制造工艺

本文评述了陶瓷纤维(晶须)的制造工艺及16种陶瓷纤维的性能。对今后陶瓷纤维的研究与开发提出了自己的见解。     

原位TiB_2/Al复合材料制备及凝固过程研究

利用原位法制备了TiB2/Al复合材料。根据X-射线衍射图探讨了增强相形成机制,测定了材料凝固动态曲线并分析了影响凝固的3个主要因素,采用扫描电镜研究了材料的拉伸性能。结果表明,当B2O3与TiO2的摩尔比为1.0时,反应式为:3TiO2+10Al+3B2O3→5Al2O3+3TiB2。影响材料凝固的3个主要因素是颗粒在母相中的分布,B2O3与TiO2的摩尔比以及反应温度。材料的强化主要是TiB2颗粒的弥散强化(即奥罗万机制)和TiB2为形核核心作用所导致的晶粒细化,材料的断裂属于TiB2颗粒被拔出而形成的微孔聚集型韧性断裂。     

大型离心式压缩机组的检验及分析

通过对大型离心式压缩机组的结构、标准、设计、制造、检验等的研究 ,介绍了大型离心式压缩机组的特点、检验、制造质量控制及其分析     

Dissipation in single crystal diamond micromechanical annular plate resonators

We report measurements of energy dissipation in single crystal diamond annular plate resonators for temperatures ranging from 4 to 300 K. An order of magnitude reduction in dissipation is observed as the temperature is lowered from room temperature (1/Q = 5 × 10⁻⁴) to 30 K (1/Q = 5 × 10⁻⁵).     

氮化硅及其微粉的制备

氮化硅陶瓷以其优异的性能被用来制作发动机元件、刀具、轴承等器件。本文主要介绍了氮化硅的性能、应用范围以及硅粉直接氮化法、SiO2还原氮化法、液相法、气相法等氮化硅微粉的制备方法。提出要批量生产Si3N4粉体，应从产品质量高、成本低和生产规模大等几个基本原则加以综合考虑。     

Low temperature fabrication of Cf/BNi/(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C-SiCm high entropy ceramic matrix composite by slurry coating and laminating combined with precursor infiltration and pyrolysis

In this study, the low temperature fabrication of a C_f/BN_i/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C-SiC_m high entropy ceramic (HEC) ceramic matrix composite (CMC) was achieved through slurry coating and laminating (SCL) combined with precursor infiltration and pyrolysis (PIP). Firstly, the (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C HEC powder was synthesized by pressureless sintering and ball milling. Then, a C_f/BN_i/HEC_m CMC preform was obtained by the SCL process. At last, the composite was densified by PIP of SiC at 1200 °C and a C_f/BN_i/HEC-SiC_m CMC was the final result. The density and open porosity of the HEC-CMC were 2.7 g/cm³ and 10%, respectively. The composite had a relatively high flexural strength (269 ± 25 MPa) and flexural modulus (53.3 ± 7.9 GPa). Fiber degradation was scarcely detected and fiber pullout was clearly observed. Most importantly, the fabrication method is simple and the fabrication temperature is rather low. This study opens a new insight for high entropy ceramic matrix composites fabrication.     

Shape Memory Alloy-Reinforced Metal-Matrix Composites:A Review

Metal-matrix composites reinforced with shape memory alloys(SMA, including long fiber, short fiber, and particle) are ‘‘intelligent materials' ' with many special physical and mechanical properties, such as high damping property,high tensile strength, and fatigue resistance. In this review article, the fabrication method, microstructure, interface reaction, modeling, and physical and mechanical properties of the composites are addressed. Particular emphasis has been given to(a) fabrication and microstructure of aluminum matrix composites reinforced with SMAs, and(b) shape memory effect on the physical and mechanical properties of the composites. While the bulk of the information is related to aluminum matrix composites, important results are now available for other metal-matrix composites.     

Cytotoxicity of Ti–6Al–4V–5Cu Alloy to MC3T3-E1 Cells

The aim of this work was to study the cytotoxicity of Ti–6 Al–4 V–5 Cu(TC4–Cu) alloy for dental applications and evaluate the cell viability of diff erent fabricated TC4–Cu alloys in contact with MC3 T3-E1 cells in vitro. Ti–6 Al–4 V(TC4) alloy was used as a negative control to evaluate the cytotoxicity level of TC4–Cu alloy so as to provide basic support for the dental clinical application. Control group TC4 and experimental group TC4–Cu with diff erent fabrications were incubated in the cell culture medium. The absorbance value of mouse osteoblast MC3 T3-E1 cells was detected by CCK-8 assay after 1, 3 and 7 days, respectively. The relative proliferation rate of cells was calculated, and then the toxicity level was valued for each group. Cell morphology on the surface was also studied by observing the cytoskeleton through F-actin filament staining. The experimental results showed that the absorbance values for the experimental and the negative control groups were not same at diff erent time points. Compared with diff erent fabricated TC4–Cu alloys, the annealing-TC4–Cu alloy showed much better biocompatibility. The mouse osteoblast MC3 T3-E1 cells cultured with annealing-TC4–Cu, rolling-TC4–Cu and solution + aging-TC4–Cu have no toxic eff ects, and these alloys could promote the proliferation of mouse osteoblasts.     

水平连铸直接复合成形铜包铝复合材料的组织与性能

研究了水平连铸直接复合成形铜包铝棒材的制备工艺和组织性能及退火处理对界面层塑性的影响。结果表明,采用水平连铸直接复合成形法在芯管长度L=210mm、铜铸造温度tCu=1230℃、铝铸造温度tAl=770～850℃、一次冷却水流量Q1=600L/h、二次冷却水流量Q2=600～800L/h、平均拉坯速度v=60～87mm/min的可行工艺窗口下能够制备出直径为30mm、铜包覆层厚度为3mm、质量良好的铜包铝复合棒材。在退火温度为530℃、保温时间为50min的工艺条件下,退火处理后可明显改善界面层的塑性。铜包铝复合棒材的抗拉强度和伸长率分别为80～94MPa和18%～31%。