Utilizing Rare-Earth-Elements Luminescence and Vibrational-Spectroscopies to Follow High Pressure Densification of Soda–Lime Glass

A new series of soda–lime glass naturally doped with Nd and doped with 0.2 wt% of Eu2O3 was densified in a multi-anvil press up to 21 GPa. The densities of the millimetric samples were precisely measured using a floatation method in a heavy liquid made with sodium polytungstate. The obtained densification curve is significantly different from the calibration previously reported, reaching a maximum densification saturation of 3.55 ± 0.14%. This difference could be due to better hydrostatic conditions realized in this new study. The densified samples were characterized using Raman and Brillouin spectroscopy, as well as the emission of both Eu3+ and Nd3+. The evolution of the spectra was evaluated using integration methods to reduce error bars. The relative precision of the calibration curves is discussed. The evolution of Nd3+ transition was found to be the most sensitive calibration. Linear dependence with the density was found for all observables, with exception for Brillouin spectroscopy showing a divergent behavior. The Brillouin shift shows an unreported minimum for a densification ~0.4%.

NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

For a deeper understanding of the freeze-thaw weathering effects on the microstructure evolution and deterioration of dynamic mechanical properties of rock, the present paper conducted the nuclear magnetic resonance (NMR) tests and impact loading experiments on sandstone under different freeze-thaw cycles. The results of NMR test show that, with the increase of freeze-thaw cycles, the pores expand and pores size tends to be uniform. The experimental results show that the stress-strain curves all go through four stages, namely, densification, elasticity, yielding, and failure. The densification curve is shorter, and the slope of elasticity curve decreases as the freeze-thaw cycles increase. With increasing freeze-thaw cycles, the dynamic peak stress decreases and energy absorption of sandstone increases. The dynamic failure form is an axial splitting failure, and the fragments increase and the size diminishes with increasing freeze-thaw cycles. The higher the porosity is, the more severe the degradation of dynamic characteristics is. An increase model for the relationships between the porosity or energy absorption and freeze-thaw cycles number was built to reveal the increasing trend with the freeze-thaw cycles increase; meanwhile, a decay model was built to predict the dynamic compressive strength degradation of rock after repeated freeze-thaw cycles.

Different CA Compaction Property of the Asphalt Mixture on the Bailey Method

This paper evalates the compaction property of the asphalt mixture through the densification curve of the Superpave Gyratory Compactor, introduces four factors such as CEI、TDI、k1、k2 to reflect the compaction property of the asphalt mixture under construction and traffic load, and analyses the compaction extent of the asphalt mixture with different CA.Based on the performance demand and the construction techniques,this paper gives reasonable range of the Bailey parameters CA.

Interfacial reaction of LTCC/NiCuZn ferrites in multilayer composites

In this study, the cofiring behavior and interfacial interaction between a low dielectric constant LTCC material and NiCuZn ferrites at 900°C were studied using XRD, dilatometer, SEM, EPMA and TEM. It was observed that the delamination occurred at the interface between LTCC and NiCuZn ferrites added with Bi2O3. It may be due to the Bi enriched at the interface and diffused into LTCC, which shifted the densification curve of LTCC towards low temperature, and hence resulted in the shrinkage mismatch between LTCC and NiCuZn ferrites.

Analysis of Influence Rules of Material Composition on Compaction Characteristic of Asphalt Mixtures Using SGC Tests

Through analysis of densification curve characteristic of gyratory compaction, influence rules of the content of mineral aggregates of all sizes and asphalt on compaction characteristic of mixtures were studied. Test studies show that the mixture having more of asphalt has a faster density-increasing speed, that there is an optimal amount of fine aggregates for optimal compaction, and that an appropriate amount of mineral powder will improve workability of mixtures but overmuch mineral powder will make mixtures dry and hard. Conclusions from this research can provide basis for how to adjust material composition for improving compaction performance of mixtures.

Application of Master Sintering Curve Theory to Predict and Control the Sintering of Nanocrystalline TiO2 Ceramic

Master sintering curve (MSC), in which the sintered density is a unique function of the integral of a temperature function over time, is insensitive to the heating path. In this paper, the densification of rutile TiO2 was continuously recorded at heating rates of 2 °C/min and 5 °C/min, respectively, by dilatometer. The MSC for rutile TiO2 was constructed for pressureless sintering using constant heating rate date based on the combined-stage sintering model. The construction and application of the MSC were described in detail for different thermal histories. The MSC can be used to predict and control the densification, final density, and microstructure evolution during the whole sintering. The final density can be predicted for an arbitrary temperature–time path. A good consistence exists between the predicted and experimental densification curve, confirming that it is possible to accurately predict and control the sintering behavior of TiO2 from the initial to final stage of sintering using MSC.

Sintering densification curve: A practical approach for its construction from dilatometric shrinkage data

This article summarizes the usage of high-temperature dilatometry in ceramic processing and powder technology with special attention on the description of the sintering process. A practical method for transformation of dilatometric shrinkage data into densification curves (the dependence of the sample density on sintering temperature or time) is described in detail. A new automatic procedure to recalculate sintering shrinkage data allowing the plot of the densification curve has been developed, which is presented here.