Effects of Ultrasonic Treatment during the Solidification Process on the Structure Formation of Low Carbon Steel
This paper studied effects of ultrasonic treatment during the solidification process on structure formation of low carbon steel. Results showed that with ultrasonic treatment grains were refined and the steel ingot avoided the cast widmanstatten structure. When ultrasonic treatment was employed, pearlite was broken and the average length of pearlite was decreased from 550 mm to 140 mm. The corresponding aspect ratio was reduced from 12 to 1. At high magnification the treated pearlite was cloud-like, rather than plate-like, as normal. Ultrasonic treatment also can remove the gas from low carbon steel. These phenomena of low carbon steel generated by ultrasonic treatment were explained. [doi:10.2320/matertrans.M2011091]
Effect of Ultrasonic Treatment on the Solidification Microstructure of Die-Cast 35 CrMo Steel
The effects of ultrasonic treatment (UST) on the solidification microstructure of a 35CrMo steel cast ingot were investigated. To avoid the erosion of a high-temperature melt, a T-shaped ultrasonic waveguide unit was used to introduce ultrasonic vibrations into a 35CrMo steel die casting melt. The experimental results show that the microstructure of the ingot was refined by ultrasonic treatment. While the microstructure of untreated 35CrMo steel is coarse dendritic grains, after the introduction of ultrasonic treatment, the solidification microstructure transforms from coarse dendritic to equiaxed grains, and the dendrites are also refined. Samples from different positions of the ingots were subjected to different ultrasonic effects, and the effects on grain refinement also varied due to the severe attenuation of the ultrasound in the melt. The mechanisms of grain refinement using ultrasonic treatment for 35CrMo steel melt are presented.
Characterization of Aqueous Dispersions and Gels Made of Sodium Caseinate and Basil Seed Gum: Phase Behavior, Rheology, and Microstructure
The interactions between sodium caseinate (NaCas) and basil seed gum (BSG) in the presence of calcium chloride (CaCl 2 ) were investigated. The phase behavior of the mixed aqueous dispersions and their gels revealed a homogeneous mixture, obtained at the higher concentrations of both CaCl 2 and BSG. The Herschel-Bulkley model sufficiently fitted the flow behavior of the mixture solution data. Apparent viscosity increased significantly ( p  < 0.05) by increasing the concentration of BSG, where the addition of CaCl 2 had no significant effect on the viscosity of the samples ( p  > 0.05). Furthermore, there was an increase in thixotropy due to the higher concentrations of BSG and CaCl 2 . Based on the frequency sweep test, at the low frequencies, a more gel-like behavior was observed in the case of the higher concentrations of either BSG or CaCl 2 . The rheological and SEM data suggested that the stronger structure of NaCas-BSG gel in the presence of the higher concentrations of CaCl 2 was related to the induction of complex formation between the two biopolymers.