The heat transfer oil-based magnetorheological fluid(MRF) was prepared using oleic acid-modified micron carbonyl iron powder as a magnetic dispersed phase and strontium hexaferrite(SrFe_(12)O_(19))nanoparticles as an additive.The sedimentation stability of MRFs was studied.The results indicated that the stability of MRFs was improved remarkably by adding SrFe_(12)O_(19) nanoparticles and the sedimentation ratio was only 0.88 in 20 days when the content of nanoparticles reached 10 wt%.The Theological properties were characterized by a HAAKE rheometer without a magnetic field and a capillary rheometer with and without a magnetic field.The effects of SrFe_(12)O_(19) nanoparticles,the temperature,and magnetic field strength were investigated.In addition,the rheological properties could be predicted well using the improved Herschel-Bulkley model,even under a magnetic field.A theoretical model was also proposed to predict the yield stress based on the microstructure of the MRF under an applied magnetic field.
A series of triethylammonium-based chlorogallate(Ⅲ) ionic liquids with varied Lewis acidity was synthesized, characterized, and firstly applied to isobutane alkylation. The [Et3NHCl]-GaCl3 with χGaCl3 = 0.65 displayed a potential catalytic activity for the alkylation. The addition of copper halide into the chlorogallate(Ⅲ) ionic liquids dramatically enhanced the alkylation reaction. Up to 70.1% C8 selectivity and 91.3 RON were achieved with the [Et3NHCl]-GaCl3-CuCl (χGaCl3 = 0.65, CuCl = 5% mol) under 0.5 MPa, 900 r/min, 15 min, 288 K using the industrial C4 cut (isobutane/butene = 10). These results indicate that the chlorogallate(Ⅲ) system may be used as a promising catalyst for the C4 alkylation.
A chemical model,based on Pitzer activity coefficient model,is developed with a speciation approach to describe the solubility and chemistry of nesquehonite in concentrated chloride solutions.The chemical equilibrium constants for nesquehonite and aqueous species,i.e.0 3 MgCO,3 MgHCO,and MgOH +,are precisely calculated as a function of temperature according to the Van't Hoff equation by use of standard Gibbs free energy,standard formation enthalpy and heat capacity.The most recent solubility data are regressed to obtain new Pitzer parameters with good agreement.The predictive ability of the new model is improved significantly in comparison with previous models.The behavior of speciation chemistry for nesquehonite in various chloride media is explained through this modeling work on the basis of the 2 3 Mg /CO bearing species distribution,activity coefficient and pH changes.
