Papers by Keyword: Fluidity

Abstract: The thermal conductivities of quaternary Mg-Zn-Ca-MM alloys have been investigated by evaluating the effect of MM on Mg-4Zn-0.5Ca alloys, with an emphasis to develop a new Mg alloy without compromising thermal conductivity, process-ability and mechanical property. As a result, the thermal conductivity of 0.5 wt.% MM-added Mg-Zn-Ca alloy was almost same as that of MM-free Mg-Zn-Ca alloy. However, with further increasing MM contents, thermal conductivities of MM-added alloys decreased. The tensile yield strength was improved with increasing MM contents. In addition, the average spiral flow lengths of Mg-Zn-Ca-xMM alloys were almost same levels with Mg-Zn-Ca alloy.

Abstract: Effects of Si addition on the microstructure, fluidity and tensile property of Al-5/7mass%Mg alloys with Mg+Al₂Ca master alloy as Mg raw material were investigated in this study. With 7 mass%Si addition, the fluidity was remarkably improved in both Al-5Mg and Al-7Mg alloys. With increasing the Si content, the amount of the eutectic phases was increased in the microstructures. As a result of the tensile test, there was a drastic reduction in elongation with increasing Si content. Al-5Mg-7Si alloy showed a significant improvement of strength after solution heat treatment and artificial aging.

Abstract: To investigate the effect of Li₂O, K₂O and ZnO on SiO₂-Al₂O₃-B₂O₃-Na₂O vitrified bond for CBN grinding wheels, the refractoriness and fluidity of specimens with different additions were studied. The bending strength was measured by three-point bending tester and the microstructures were observed by super Depth-of-Field microscope. The results show that Li₂O, K₂O and ZnO can reduce the refractoriness and increase the high-temperature fluidity. Li₂O and K₂O make a contribution to improving the bending strength; however ZnO is harmful to specimens’ mechanical property. Additionally, the fluidity is important to control the number of gas bubbles in specimen according to the microstructure analysis.

Abstract: The apparent viscosities of the semi-solid SiCp/A357 composites with 0vol.%, 10vol.% and 20vol.% SiC particles manufactured by stir casting were investigated using a Couette type viscometer, and the composite fluidity was examined with a test casting. The results showed that, the viscosities of the semi-solid SiCp/A357 composites decreased with an increase in shear rate, but increased with the increasing of solid fraction, and apparent viscosity of 10vol.% SiCp/A357 composite was the lower than that of 20vol.% SiCp/A357 composite at the same solid fraction; and the composite fluidity results were in a good agreement with the viscosity ones.

Abstract: Phosphorus (P) is often added to wave-solder baths as an anti-oxidation agent for older generation eutectic Sn-37wt%Pb solders. For Pb-free solder alloys trace amounts of germanium (Ge) have been added successfully in Sn-0.7wt%Cu-0.05wt%Ni for anti-oxidation purposes during the wave soldering process. Despite this practice, there is little information on how P and Ge distribute in solder alloys and dross in this alloy system. In this paper, the effects of combinations of trace levels of Ge (< 100ppm) and P (< 100ppm) in Sn-Cu-Ni solder alloys and their dross has been investigated by XRD and SEM/EDS. It was found that the weight fraction of tin oxides in the dross is increased with an addition of less than 100ppm P. The dross consists on SnO oxide with Sn in samples containing Ge and no P, while SnO and SnO₂ oxide are both present when P and Ge additions are made. In samples containing P, (Cu,Ni)₆Sn₅ and Ni-P and/or Ni-Sn-P intermetallics particles were found.

Abstract: The authors investigated the mechanical mixing and compacting briquettes of nickel powder (particle size 30...75 μm) and nanopowder modifier SiC+Si₃N₄ (particle size 70...100 nanometers), obtained by the azide technology SHS. The mixtures containing 5%, 10%, 15%, 20% of the modifier were investigated. Mechanical mixing was carried out during 60 minutes in planetary mill «Pulverizette-5». Some physic-technological properties of the obtained powder mixtures, such as, particle size distribution, density, bulk weight and flowability, are determined. The powder compositions' pressing was carried out on hydraulic press PSU-50 with pressure 65...700 MPa. Nanopowder ligature briquettes of 18.2 mm diameter, height to 4.2 mm, weighing 5 grams, with relative density 70...89% and porosity 11...30%, intended for subsequent input in aluminum melt with the aim of modification are obtained.

Abstract: The slump loss of fresh concrete mixed with superplasticizers should be well controlled to ensure its transportation and pumping. In this paper, we describe a comprehensive overview of the mechanism of fluidity loss and then analyze the reason for the change. Researches show that the slump loss of fresh concrete is influenced by the mineral composition of cement clinker, the type and characteristics of aggregate, the species and dosage of admixture, the mix proportion and the construction environment, etc. Thus, a series of methods proven to be effective, such as adjustment of raw materials, adding methods of chemical admixture, synthesis of new types of superplasticizers, etc. have been proposed to solve the problems.

Abstract: In this study, influences of mixing procedure on the latex adsorption behavior, slurry fluidity and setting time of latex modified cement paste (LMCP) mixed with polycarboxylate (PC) as superplasticizer were analyzed. There were three kinds of mixing procedure: LMCP added latex later than PC (LMCP-L), LMCP added latex before PC (LMCP-B), LMCP added latex and PC simultaneously (LMCP-S). The results show that, the adsorption isotherm of SAE latex by cement grains fits the Langmiur type, and the presence of PC can affect the adsorption behavior. Regardless of the m_latex/m_cement (4% or10%), LMCP-B had the highest amount of adsorbed latex and slurry fluidity while LMCP-L had the lowest. And, the LMCP-B also had the longest initial and final setting times, while the setting times of LMCP-L and LMCP-S were comparable.

Abstract: This research paper deals with an investigation of the fluidity of plastic blends with a recycled filler. Five different blends with three filler concentrations were prepared. As a fillers were radiation crosslinked plastics used. Fluidity was determined by the spiral test where a cavity with the Archimedes spiral is used and a length of the resulting spiral is evaluated and compared. Results show that the more filler is used the worse fluidity there is; however lower concentrations have fluidity almost identical to the non-filled material and the difference is almost negligible. At higher concentrations is the difference more significant and thus it has to be taken into account. Particle size of the filler should be also taken into a consideration but its influence greatly depends on the matrix.

Abstract: This research was to determine the effect of rare earth metal (REM) on the fluidity of eutectic Al-11Si-Cu-Mg cast alloy. The rare earth metal used here is Lanthanum to produce Al-11Si-Cu-Mg-0.1La, Al-11Si-Cu-Mg-0.5La and Al-11Si-Cu-Mg-1.0La alloys. The fluidity was measured by permanent spiral mold, pre-heated at 450°C. The microstructure was characterized by optical microscope. The fluidity of complex Al-11Si-Cu-Mg eutectic alloy decreased with the increase of La addition. The 1.0 % of La addition led to refinement of silica particles, which reduced the fluidity length by 25%.