纳米技术在镁质耐火材料中应用的研究进展

利用纳米技术制备复相镁质耐火材料,不仅可以缓解高温工业对高性能镁质材料的需求,而且又能实现镁质耐火材料的轻质化和多功能化,进而达到提高产品附加值的目的.因此,利用纳米技术制备复相镁质耐火材料具有较高的研究意义.从镁质耐火材料损毁机制的角度,综述了近年来国内外纳米技术在低碳镁碳质、镁钙质、镁铝质耐火材料中的研究现状和进展,并且分析了纳米技术在镁质耐火材料中的作用机理,最后指出了纳米技术在镁质耐火材料中应用所面临的挑战和发展方向.

家具结构有限元分析研究综述

家具产品皆依据个人的经验设计而成,即使是经验老道的设计师在做设计时,也难做到面面俱到,利用有限元法可以对未生产的不同材料的家具产品进行可行性评估。只要方法得当,有限元的研究数据与实物验证的数据差别不大,有限元法可以作为一种有效的虚拟仿真验证的方法,替代传统的实物家具的验证。但该方法在国内还算作是一种较新的研究方法,并不完善,尚有许多未完成的研究方向。

陶瓷工业节能和清洁生产的研究应用

文章就目前广东陶瓷行业的能耗和物耗状况,从原料加工,成形过程,干燥工艺,烧成过程的节能降耗方面做了详尽的说明,并对陶瓷行业的废旧低质材料循环再利用进行了论述,提出了新的节能措施及技术。

标准成本体系下直接人工成本差异探析——以A公司为例

伴随着经济的发展,出现工业生产多样化和生产越来越复杂的现象,标准成本法能够实现与时俱进。通过对A公司进行案例设计和分析,将人工成本的实际指标进行归集,分别用传统的标准成本法和改良后的标准成本法进行处理,将案例中的直接人工差异按使用材料不同分解成常规材料、低质材料的人工效率差异和人工替代差异、工资率差异的价格差异,采用新的方式对直接人工进行差异的重新确定,得出改良后的方法更合理,适应性更强,适应当代工业企业成本核算和成本控制的需要。

A Model for Mechanical Property Evaluation of the Periodic Porous Low-k Materials by SAW

The influence of the distribution of nano-pores on the mechanical properties evaluation of porous low-k films by surface acoustic waves （SAW） is studied. A theoretical SAW propagation model is set up to characterize the periodic porous dielectrics by transversely isotropic symmetry. The theoretical deductions of SAW propagating in the low-k film/Si substrate layered structure are given in detail. The dispersive characteristics of SAW in differ- ent propagation directions and the effects of the Young＇s moduli E, E′ and shear modulus G′ of the films on these dispersive curves are found. Computational results show that E′ and G′ cannot be measured along the propagation direction that is perpendicular to the nano-pores＇ direction.

Hydration mechanism of low quality fly ash in cement-based materials

The hydration mechanism of low quality fly ash in cement-based materials was investigated. The hydration heat of the composite cementitious materials was determined by isothermal calorimetry, and the hydration products, quantity, pore structure and morphology were measured by X-ray diffraction(XRD), thermalgravity-differential thermal analysis(TG-DTA), mercury intrusion porosimetry(MIP) and scanning electron microscopy(SEM), respectively. The results indicate that grinding could not only improve the physical properties of the low quality fly ash on particle effect, but also improve hydration properties of the cementitious system from various aspects compared with raw low quality fly ash(RLFA). At the early stage of hydration, the low quanlity fly ash acts as almost inert material; but then at the later stage, high chemical activity, especially for ground low quality fly ash(GLFA), could be observed. It can accelerate the formation of hydration products containing more chemical bonded water, resulting in higher degree of cement hydration, thus denser microstructure and more reasonable pore size distribution, but the hydration heat in total is reduced. It can also delay the induction period, but the accelerating period is shortened and there is little influence on the second exothermic peak.

Tape casting of borosilicate glass/Al_2O_3 composites for LTCC substrate with various relative molecular masses of PVB

The dispersion, stabilization and rheological properties of the slurry with various relative molecular masses of PVB were studied. The sintering properties, microstructure and dielectric properties of borosilicate glass/Al203 composites were also investigated. The intensities of the typical vibrating bands decrease with the decrease of the relative molecular mass of PVB, which demonstrates that the content of butyral groups in PVB binders decreases correspondingly, leading to a rapid decrease in the viscosity of the mixed slurry. The solid content of samples increases with the decrease of the relative molecular mass of PVB, and this further leads to the increase of tape thickness, bulk density and dried-shrinkage coefficient of tapes. The bulk density, relative density, three-point strength and dielectric constant of sintered samples increase with the increase of the solid content, and the shrinkage and dielectric loss decrease. By contrast, samples for PVB-5s exhibit better properties of a bulk density of 3.10 g/cm3, a relative density of 98.1%, a three-point strength of 208 MPa, aεt value of 8.01, a tanδ value of 7.6× 10^-4 at 10 MHz and a well matching with Ag electrodes.

Identification of vibrational mode symmetry and phonon anharmonicity in SbCrSe_(3)single crystal using Raman spectroscopy

Developing an understanding of the physics underlying vibrational phonon modes,which are strongly related to thermal transport,has attracted significant research interest.Herein,we report the successful synthesis of bulk SbCrSe_(3)single crystal and its thermal transport property over the temperature range from 2 to 300 K.Using angle-resolved polarized Raman spectroscopy(ARPRS)and group theory calculation,the vibrational symmetry of each observed Raman mode in the cleaved(001)crystal plane of SbCrSe_(3)is identified for the first time,and then further verified through firstprinciples calculations.The ARPRS results of some Raman modes(e.g.,Ag2~64 cm-1 and Ag 7~185 cm-1)can be adopted to determine the crystalline orientation.More importantly,the temperature dependence of the lattice thermal conductivity(κL)is revealed to be more accurately depicted by the three-phonon scattering processes throughout the measured temperature range,substantiated by in-situ Raman spectroscopy analysis and the model-predictedκL.These results reveal the fundamental physics of thermal transport for SbCrSe_(3)from a completely new perspective and should thus ignite research interest in the thermal properties of other lowdimensional materials using the same strategy.