Search

The paper studied the microcapsule particle size, size distribution and its influencing factors with melamine formaldehyde resin (MF-resin) as wall and CVL as core. The results indicated that the microcapsules mean particle size decreased, size distribution became narrow with the increase of emulsifying time and shear rate. Low pH value would make the microcapsules have rough surface morphology and large particle size.

The pressure drop at critical fluidization for two-dimensional vibrated fluidized bed(240 mm×80 mm) was studied, with large particle glass beads of average diameters dp of 1.8mm, 2.5mm and 3.2mm.The effect of the vibration strength, the static bed height and the particle diameter on the pressure drop was analyzed. The results of the study show that the pressure drop decreases with the increase of the vibration strength. It plays an even more prominent part with decreases of the static bed height and the particle diameter. The empirical correlation equations to predict the pressure drop was established, and the results of the prediction was compared with the experimental data, the error is in range of ±10%. The results can provide references for future design and research on the vibrated fluidized bed.

This research aimed to investigate the effects of pneumatic conveying drying conditions on damaged starch content and particle size of cassava starch using response surface methodology. Three parameters of interest, i.e. drying air temperature (120, 160, and 200oC), drying air velocity (20, 30, and 40 m/s), and feed moisture content (40, 50, and 60% d.b.), were varied. Experimental results showed that damaged starch content and average particle size of cassava starch before drying were approximately 0.45% and 21.47µm, respectively. However, after drying, the values were altered to approximately 0.69 to 6.84% and 15.40 to 31.67 µm, respectively. The drying air temperature, drying air velocity, and feed moisture content significantly affected the changes. The results indicated that cassava starch granules were damaged and then agglomerated into large particle during pneumatic conveying drying depending on operation conditions.

The influence of the accumulated structure formed by the aggregate particles on permeability and strength of permeable concrete was investigated by three-dimensional geometry method, which was proved by theoretical analysis and experimental study. In theoretical analysis, the accumulation structure of the aggregate was in a steady or quasi-steady state, particle size distribution was optimized to obtain the desired permeability coefficient and sufficient strength. The results showed that it is more appropriate that the ratio of the secondary particle size is 0.2d - 0.4d when the large particle size is d. To obtain good permeability in experimental study, the large voids have a large proportion in all kinds of voids statistics distribution of aggregate accumulation of structure in pervious concrete. The percentage of fine particles needs to be controlled to achieve the desired permeability and concrete strength.

A series of direct reduction roasting - magnetic separation tests were carried out with refractory limonite ore in two different particle size compositions. The effect of particle size in the grade and recovery of direct reduced iron (DRI) at different roasting time, temperature and reductant dosages was investigated, and the mineralogical transformations of DRI obtained at different roasting time were analyzed using scanning electron microscopy (SEM-EDS). The results demonstrate that direct reduction roasting with limonite ore in large particle size (100% －20mm) was feasible, and the reducibility of limonite ore in large particle size increased with increasing reductant dosage and roasting time. The optimum reduction roasting - magnetic separation parameters of 100%－20mm limonite ore were proposed as the following: roasting at 1200°C for 120min with 40% reductant, and milling 30min followed by low intensity magnetic separation, which resulted in the DRI with TFe grade of 90.2% and recovery of 89.3%.

Variations of decomposition rate and decomposition layer thickness of six spherical limestone particles with different sizes are calculated and compared with each other by the experiments and model of static decomposition of limestone under constant temperature. The results indicate that: the decomposition process of limestone can be explained by unreacted core model (UCM) when it is heated sharply; the decomposition rate of large particle is greater than that of small one; the smaller particle size, the larger decomposition layer thickness in unit time.

‘Trap’ effect of the newly developed semi-fixed abrasive tool (SFAT) plays key role in decreasing the surface damages of advanced ceramics caused by the undesirable large particles emerging in machining area. Influences of characteristics of the large particle, such as size, shape and concentration, on the ‘trap’ effect of SFAT are studied with Particle Flow Code (PFC) simulation and lapping experiments. A normalized normal force is defined to evaluate the ‘trap’ effect in PFC simulation, and surface roughness is taken as an indicator in lapping experiments. The results show that the change of surface roughness is according to the one of normalized normal force. Bigger normalized normal force is better for ‘trap’ effect and surface roughness. ‘Trap’ effect works well when the large particle is in small size, sharp shape, and low concentration. In this study, the followed characteristics of the large particle are good for ‘trap’ effect of SFAT made of 1000# SiC abrasive: size

Calciothermic reduction-diffusion (CRD) method was employed to prepare the Sm2Fe17 powder. By using CRD method, single-phase Sm2Fe17 powders were successfully made and no α-Fe phase detected. And Subsequent suitable nitrogenation treatment after CRD process enabled us to obtain Sm2Fe17Nx magnetic powders. However, the magnetic performance of the powders was below expectation due to their large particle size. Further study on effective milling process is needed.

This paper presents the study of rheological and mechanical properties of MR elastomers fabricated using small and large particle. Analysis indicated that MR elastomers fabricated with bimodal particles at a specific particle ratio ingredient show enhanced MR effect compared with those fabricated with monoparticles. MR elastomer samples were fabricated by using small and large particles with sizes of 5m and 50m respectively. Their rheological and mechanical properties were characterized with a MR rheometer. Experimental results agree well with the analysis.