标准钢瓶标定试验及全变形值计算探讨

介绍了通过内测法测量标准瓶在不同压力下的进水量,运用回归分析法和“气瓶水压试验方法”(GB T9251—1997)标准中的全变形值计算公式,分析计算标准钢瓶在不同压力状态下的全变形值。

Effect of compression ratio on microstructure evolution of Mg−10%Al−1%Zn−1%Si alloy prepared by SIMA process

A new Mg−10%Al−1%Zn−1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation(SIMA)process.The effect of compression ratio on the evolution of semisolid microstructure of the experimental alloy was investigated.The results indicate that the average size ofα-Mg grains decreases and spheroidizing tendency becomes more obvious with the compression ratios increasing from 0 to 40%.In addition,the eutectic Mg2Si phase in the Mg−10%Al−1%Zn−1%Si alloy transforms completely from the initial fishbone shape to globular shape by SIMA process.With the increasing of compression ratio,the morphology and average size of Mg2Si phases do not change obviously.The morphology modification mechanism of Mg2Si phase in Mg−10%Al−1%Zn−1%Si alloy by SIMA process was also studied.

Influence of Cu content on microstructure and mechanical properties of thixoformed Al-Si-Cu-Mg alloys

The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and several of the samples were treated with the T6 heat treatment.The samples were then examined by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction(XRD) analysis,as well as hardness and tensile tests.The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting.The results also reveal that as the Cu content in the alloy increases,the hardness and tensile strength of the thixoformed alloys also increase.The ultimate tensile strength,yield strength and elongation to fracture of the thixoformed heat-treated Al-6Si-3Cu-0.3Mg alloy are 298 MPa,201 MPa and 4.5%,respectively,whereas the values of the thixoformed heat-treated alloy with high Cu content(6%) are 361 MPa,274 MPa and 1.1%,respectively.The fracture of the thixoformed Al-6Si-3Cu-0.3Mg alloy shows a dimple rupture,whereas in the alloy that contains the highest Cu content(6%),a cleavage fracture is observed.

Hawking Tunneling Radiation of Black Holes in Deformed Horava-Lifshitz Gravity

Tunneling of scalar particles and Dirac particles from a black hole in the deformed Horava-Lifshitz gravity is discussed in this paper. We consider the case that the dynamical coupling constant λ= 1, when it reduces to Einstein＇s General Relativity at large scales and the black hole behaves like the Reissner-Nordstr6m black hole. The result shows that though the black hole entropy bears logarithmic correction, the tunneling probability is still related to its differences for the scalar particles and Dirac particles.

The Influence of Market and Company Characteristics on Voluntary Disclosure

In this paper, the determinants of the voluntary disclosure level of firms have been investigated during a period of deep financial crisis. Two disclosure indexes used as dependent variables are proposed： a global index based on both quantitative and qualitative disclosure and a solely quantitative voluntary index. Firstly, the explanatory variables have been selected taking into account the main contributions of international literature. In addition, some specific variables have been introduced in order to take into account the peculiarities of Italian market system and the ongoing financial crisis. A positive relationship has been found among the global voluntary disclosure （GVD） and the number of employees, the dividend policy, and the presence of independent directors on the board. On the contrary, a negative correlation with respect to the percentage of the firm＇s outstanding shares held by directors （not independent） exists. With reference to the quantitative voluntary disclosure （QVD） index, there is a positive correlation with the number of employees, the dividend policy, the market floating, and the incidence of intangible assets. Moreover, such （quantitative） a disclosure is different depending on the industrial membership sector.

New method for analyzing recrystallization kinetics of deformed metal by differential scanning calorimeter

The drawn copper wires have been analyzed by differential scanning calorimeter(DSC) and a new method, which uses DSC measurements to determine the Johnson-Mehl-Avrami-Kolmogorov(JMAK) exponent via introducing Arrhenius behavior and modifying the baseline of DSC curves, has been proposed. The results show that JMAK exponent and recrystallization activation energy of the drawn copper wires with a strain of 2.77 are about 2.39 and 125 k J/mol, respectively. The line linking the tangency points of DSC curve hypotenuse can be used as the baseline when calculating recrystallization fraction. The JMAK exponent obtained by the DSC method is in a good agreement with that obtained by microhardness measurements. Compared to traditional methods to measure the exponent, the proposed method is faster and less labor intensive.