聚氨酯软泡压陷性能的测试

介绍了软质聚氨酯泡沫塑料压陷性能的测试标准，不同厚度样品的压陷硬度测试值的差异，采用50%压缩负荷估计压陷硬度的简易测试方法，以及压陷性能测试的影响因素，并对测试聚氨酯软泡压陷性能的国家标准与国外标准的差别进行了比较。     

Hardness and Fracture Toughness of SiC-Particle-Reinforced MoSi2 Composites

The indentation technique has been used to evaluate the hardness and fracture toughness of SiC-reinforced MoSi₂ composites made by hot-pressing. It is seen that the toughness increases with increasing indentation crack length (under increasing load) and a probable mechanism responsible for this behavior is described. It is also observed that there is an optimum volume fraction of SiC particles for which the maximum fracture toughness of the composite can be achieved.     

压痕残余应力对氮化硅基复合材料阻力曲线行为的影响

通过压痕小裂纹直接量测法获得了ＴｉＣ，ＴｉＮ／Ｓｉ３Ｎ４复合材料的阻力曲线，采用更具合理性的指数经验公式拟合处理实验数据，初步探讨了Ｋ∞，Ｋ＾＊Ｒ，ΔＣ，等参数的物理意义。对压痕残余应力消除前 实验结果进行比较，发现压痕残余应力的消除，提高了材料的极限断裂韧性值Ｋ＾＊Ｒ，却大大减少了裂纹稳态生长的容限，使得材料的脆性行为更为突出。     

聚丙烯球形高效催化剂的工业应用研究

介绍了DQ-2型球形高效催化剂在间歇式液相本体法聚丙烯生产装置上进行工业应用的试验研究，试验证明，该催化剂具有节水、节电、反应平稳且操作时间短等聚合反应特性，催化剂活性平均为42kgPP／(gCat)，一级品率达90％，并与非球型高效催化剂进行了比较。     

Preparation and application of polybenzoxazine adsorption resin

The synthesis and application of polybenzoxazine adsorption resin was studied. First, the precursor was synthesized by the solventless method. And then a kind of spherical and granular polybenzoxazine resin was obtained using reverse‐phase suspension polymerization technique in the process of solidification. Besides, the influence of dispersion medium, the volume ratio of precursor to medium, the solidification temperature, and the agitation speed were studied in detail in the process of polymerization. Second, the spherical shape of the polybenzoxazine resin was identified by scanning electronic microscope and the thermal stability of resin was measured by thermogravimetric analysis. Finally, the adsorption capacity of the spherical resin on pyridine was studied in cyclohexane systems. The correlation coefficient of Langmuir adsorption constant temperature line was bigger than 0.99, which indicated that the equilibrium sorption date was coincident with the Langmuir isotherm equation. And the saturated adsorptive capacity of dried resin achieved 222.2 mg g^?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Coding scheme based on spherical polar coordinate for control over packet erasure channel

Like feedback strategy, coding scheme is an important part of networked control system design as well. On the basis of spherical polar coordinate, a novel coding scheme is proposed for stabilization problem of discrete linear time invariant system subject to packet erasure channel with feedback. The coding scheme uses encoder without access to control inputs. In the case that a decoder does not use control inputs, a definite relation between the quantized data and the corresponding quantization error is established, which helps to analyze the stability of system, and a selective quantization method is adopted, by which finite data rate is obtained. In the case that a decoder uses control inputs, instead of quantizing the system state at each time step as usual, the encoder quantizes the initial state all the time by updating quantizer. Sufficient conditions guaranteeing the system stable are presented for two cases, respectively, and the corresponding design methods for coding schemes are given. Copyright © 2012 John Wiley & Sons, Ltd.     

压力敏感性材料球形孔洞动态扩展问题

为进一步研究岩土材料爆炸场的特点,采用椭圆型屈服准则和自相似假设,并结合Hopkins三区模型,研究幂硬化材料球形孔洞动态扩展问题.通过对弹性区的研究得出弹性区应力的分布和弹塑性交界处的连续条件;然后在塑性区给出一个求解动态扩展问题的非线性微分方程组;最后通过打靶法数值求解该非线性微分方程组,给出满足边界条件的数值解,并讨论材料参数对场量的影响.结果表明,椭圆型屈服准则能很好地描述压力敏感性材料中孔洞的动态扩展.     

Mathematical models of grinding manufacture and tooth contact analysis of spherical gears

The spherical gear is a gear-driven mechanism with two degrees of freedom (DOF), which can transfer spatial motion and power. Grinding machining of the spherical gear is performed with a plate grinding wheel by using generating method, and based on mathematical model of the plate grinding wheel, the mathematical model of the spherical gear is set up. And then, the meshing model of a spherical gear pair is developed and the tooth contact analysis (TCA) of the spherical gear pairs is performed. After that, th...     

煤尘爆炸特征参数影响因素研究

采用20L球形爆炸装置研究了煤尘粒径、浓度、点火能量对煤尘爆炸最大压力、爆炸最大压力上升速率的影响。研究结果表明,在煤尘粒径一定的条件下,随着煤尘浓度的增大,爆炸最大压力及爆炸最大压力上升速率先增大后减小,煤尘浓度在400~480g/m3之间取得爆炸最大压力最大值0.94MPa、爆炸最大压力上升速率最大值28.79MPa/s;在煤尘浓度一定的条件下,爆炸最大压力不随煤尘粒径的减小而单调变化,爆炸最大压力上升速率随煤尘粒径的减小而逐渐增大;随着点火能量的增大,爆炸最大压力及爆炸最大压力上升速率明显增加。     

Electric field assisted solid-state interfacial joining of TaC-HfC ceramics without filler

The application of ultra-high-temperature ceramics (UHTCs) demands effective ways of joining in overcoming the problems associated with the fabrication of complex-shaped components. In this study, we choose to investigate a new method of rapidly joining pre-sintered TaC and HfC ceramics without any filler material using the spark plasma sintering (SPS) technique. A well-bonded TaC–HfC interface was observed with no apparent cracking and porosity at the joint. The joining mechanisms were predominantly driven by solid-state diffusion and localized plastic deformation. The nanomechanical properties of the TaC-HfC joint are better than the HfC while comparable to that of the TaC. High-load indentation (up to 200 N) results suggest that the TaC–HfC interface is stronger than the parent UHTCs with no crack propagating at the interface. Upon comparison with the parent UHTCs, the damaged area and the average crack length at the interface, reduced up to ~94% and ~56%, respectively. This study shows that the SPS technique can also apply to joining other UHTCs without any filler, resulting in the new field of developing complex components for the thermal protection system (TPS).