Papers by Keyword: Fluidity

Abstract: Al-25%Si has excellent fluidity, which allows for the casting of heat sinks with thin and tall fins. During recycling, the content of impurities such as Fe, Cu, and Mg increases. The effect of these impurities on the fluidity of the alloy was investigated. The results show that the influence of impurity elements on fluidity is small. JIS ADC12 is a popular aluminum alloy that is more economical than Al-25%Si. Si was added to ADC12 to reach a 25% Si content, producing an economical Al-25%Si. The fluidity of Si-added ADC12 was almost the same as that of Al-25%Si. Heat sinks with fin heights of 50 mm, fin top thicknesses of 0.5 mm, and a draft angle of 0.5°, were cast using the Si-added ADC12. The molten metal filled the cavity, but solidification cracks occurred when the fin top thickness was 0.5 mm. When the fin top thickness was increased to 1 mm, solidification cracks did not occur.

Abstract: In high pressure water-rich formation, the grout is diluted by groundwater, could not develop early strength as quickly as possible for the dissipation of cementing material, failed to fill effectively the space between the segment and formation, which is unhelpful to control segment floating. In this study, by adding a variety of organic and inorganic materials to reduce grout setting time, meanwhile ensure the low loss of fluidity, high anti-aqueous dispersions, low shrinkage, finally, to achieved better effect than Two-component grouting.

Abstract: The effects Si and Mn addition on the fluidity length, mechanical properties, and casting cracks of a die-cast Al-4.5%Mg alloy were investigated. The Si content was 1, 2, or 3 mass% and the Mn content was 0.3, 0.6, or 0.9 mass%. Both Si and Mn did not affect fluidity. Si content of more than 1 mass% improved casting crack resistance. The effect of Mn on casting cracks was weaker than that of Si. When Si content was 2 mass%, both tensile stress and elongation were good. Mn did not affect the mechanical properties.

Abstract: Usage of mineral admixture and chemical admixture in concrete or mortar is a usual solution to reach full compaction, particularly where reinforcement blockage and lack of skilled labor happen. In this paper effect of mineral admixtures (Carbon-free fly ash, hereafter CfFA, and normal fly ash) on fresh properties and rheology of mortar have been investigated. As a result, it was confirmed that CfFA increased significantly the fluidity and air content of mortar in comparison to normal fly ash, both in 15% and 30% replacement; however, the flow loss and air stability within one hour were almost equal. In addition, the initial setting time has also been affected by variation of materials. The two mixing of 30% and 15% of CfFA had a shorter setting time in comparison to the mortar with normal fly ash. Furthermore, CfFA based mortar had a great influence on rheology of mortar. Compared to normal fly ash, CfFA Considerably decreased the plastic Viscosity and increased the productivity of the mortar, both in non-vibrated and vibrated condition, particularly those with 30% replacement.

Abstract: In this paper, to reduce the cost of production of parts by injection molding technology of metal powder mixtures (MIM technology), it is proposed to use metal powder mixtures (feedstock) with high fluidity for the manufacture of green parts. High fluidity is achieved by increasing the proportion of paraffin wax in the binder. This can significantly reduce the pressing pressure when pressing the feedstock into the mold cavity to values less than 1 bar, and eliminate the use of expensive injection molding machines with high compression pressure. High fluidity also allows the use of powders with large particle sizes, which significantly reduces the cost of feedstock. The absence of high pressure on the mold walls during the pressing of the feedstock allows the use of molds made of cheaper materials such as silicone, plastic, gypsum and others.

Abstract: A die to estimate the thickness of the thinnest fin of a heat sink made by die casting aluminum alloys is proposed. The die consists of a taper-off thin fin and a cooling area. It was shown that this die can be used to estimate the smallest fin thickness of different aluminum alloys.

Abstract: The paper experimentally proves the efficiency of electromagnetic effect on stimulated fluidity of magneto-hard powders. Fine Nd-Fe-B powder doesn’t have natural fluidity. To make it flow through hopper outlet we effected on the powder by constant and alternating gradient magnetic fields. Induction lines of constant magnetic field were horizontal, and alternating field lines were vertical. In order to form stimulated powder fluidity, higher induction gradient was situated below the powder receiver chamber. We experimentally found optimal magnetic fields parameters that form steady magneto fluidized bed from Nd-Fe-B powder, with an average particle size 1 μm. The study results of influence of magneto fluidized bed electromagnetic parameters on Ne-Fe-B powder efflux speed through outlets with diameters 1 and 2 mm are presented. Gradient field topology and parameters of electromagnetic effect providing minimal efflux time of 1000 mg of powder are defined.

Abstract: The domestic and foreign production polymers effects studies’ results on the cement-polymer test rheological indicators are analyzed, taking into account the composition of the functional groups of water-soluble polymers and the viscosity of their one-percent aqueous solution. The rheological studies’ results of the Yunis Granit bonding material for fixing the large-format slabs of natural stone and porcelain are presented. The Ostwald, Bingham and Barkley-Herschel equations are considered to describe the flow of pseudoplastic, viscoelastic and rheological complex bodies and their disadvantages. The formula for calculating the rheological parameters: the flowability and the dilution coefficient of nonlinear visco-plastic bodies is proposed and verified. It is shown that the proposed formula describes the structural-mechanical properties of nonlinear visco-plastic systems with a high correlation coefficient.

Abstract: Based on the particle size distribution test of 6 kinds of limestone powder, the fractal dimension of particle size distribution was calculated, and its influence on the surface area, median grain diameter and RR-B value was studied. In addition, 20% of the total mass of cement was replaced with limestone powder, and the effect of fractal dimension on fluidity of cement paste and 3, 7, 28d strength of mortar was investigated. The results showed that fractal dimension for limestone powder specific surface area has a good linear relationship with median grain diameter and RR-B value. The fractal dimension showed a quadratic function with the degree of the fluidity, and the maximum value was between 2.1-2.2. Mortar strength at the age of 3, 7, 28d value displayed a linear relationship with fractal dimension L4 had the greatest effect on strength. L1-L4 had more influence on the strength at the age of 3d and 7d than that of 28d. While the influence of L5-L7 on the strength at 3d, 7d and 28d was essentially similar to each other.

Abstract: The viability of casting heat sinks with thin fins using Al-25%Si was investigated, based on assessing cooling curves as well as fluidity tests and emissivity analyses of the resulting heat sinks. The fluidity, castability and emissivity of the semisolid die-cast Al-25%Si were excellent and superior to the results obtained using liquid die-cast A383, an aluminum alloy typically employed for casting. The cooling curves indicate that the significant latent heat of the Si in the alloy improves the fluidity and castability of the material. The addition of P did not greatly affect the refinement of primary Si in the alloy. These findings show that Al-25%Si is suitable for the die-casting of heat sinks with thin fins.