Papers by Keyword: Salt Solution

Abstract: Cobalt-based alloys have recently gained so much attention in the medical field due to their improved mechanical properties such as wear resistance and high thermal stability. However, limitations in the area of corrosion has posed a great challenge, leading to further studies being carried out on the corrosion resistance of these alloys. In this study, an investigation on the corrosion resistance of Co-Cr-Mo based alloys in 0.9 % NaCl solution was carried at 37 oC and pH of 7.4 using potentiodynamic polarization and chronopotentiometry electrochemical techniques. The surface analysis of the alloys before and after corrosion test was done using scanning electron microscope (SEM). The results obtained from the electrochemical tests showed sample without titanium (Ti) addition to be more resistance to corrosion in the salt solution compared to those containing Ti. It was observed that a decrease in Cr content in the alloys resulted in an increase in corrosion rate from 0.7868 to 1.3805 mpy. The SEM images confirmed the presence of Cr, Co and Mo in the alloys.

Abstract: This study was aimed to develop conductive packaging for ohmic heating. Polypropylene (PP) was mixed with conductive material (CM) in the ratios of 70:30 (CM30), 75:25 (CM25), and 80:20 (CM20) (w/w), then the conductive bottles were developed using extrusion blow molding process. The bottles were suspended in different sodium sulfate (Na₂SO₄) solutions (0.2, 0.3, and 0.5% w/w) as a transmitting current medium for ohmic heating and heated for 8 min. The CM30 and CM 25 had the highest electrical conductivity compared to the CM20, however the CM20 exhibited best processability, hence it was selected to be used for ohmic heating of orange juice. Different concentrations of Na₂SO₄ solutions had the effects on ohmic heating. The CM20 bottle suspended in 0.2% Na₂SO₄ solution resulted in the most uniform heating and suitable for ohmic processing of orange juice. The new conductive bottles developed could potentially be used for beverage processing by ohmic heating.

Abstract: Rising weight and cost requirements in the automotive industry have led to an increasing substitution of metals by short-or endless-fiber reinforced thermoplastics. The use of thermoplastic matrices is necessary to meet the cycle time challenges which arise from large production quantities. The substituted components are often applied in the chassis or motor compartment, which means an exposition to environmental influences, e.g. moisture or thawing salts, during the entire operating lifetime. The degradation of the material properties of PA6GF30 due to a longtime exposition in DI (deionized) water, sodium-and calcium-chloride solutions is investigated and the fracture behavior examined by scanning electron microscopy analysis. Also, the fatigue properties were determined on a special test rig, which allows the spraying of the specimen with the different fluids during the mechanical cyclic testing.

Abstract: The solubility of CO₂ in water and aqueous solutions of NaCl, KCl, CaCl₂, NaCl+KCl (weight ratio= 1:1), NaCl+CaCl₂ (weight ratio= 1:1), KCl+CaCl₂ (weight ratio= 1:1) and NaCl+KCl+CaCl₂ (weight ratio= 1:1:1) was determined experimentally at 35, 45 and 55°C up to 16 MPa and the concentration of the salt was up to 14.3 wt% while in simulation the salt ions of Na⁺, K⁺, Ca²⁺, and Cl^- was determined at wide temperature-pressure-ionic strength range (273 to 533 K, from 0 to 2000 bar, and from 0 to 4.5 molality of salts). Based on experiment data, the solubility increased with increase in pressure but decreased with increasing the temperature and salt concentration. Meanwhile, the model also predicted the CO₂ solubility in seawater at two phase coexistence (vapour-liquid or liquid-vapor) and at three-phase coexistence (CO₂ hydrate-liquid water-vapor CO₂).

Abstract: Capillary absorption effect is very important to the research of concrete durability. Initial surface absorption test (ISAT) method has been employed to investigate the effect of W/C, age, aggregate volume percent and concentration of NaCl solution as a transmission medium of the capillary absorption of the cement-based materials. Experiment results indicate that, the capillary absorption coefficient increases with the increasing of W/C, but decreases with the increasing of age and aggregate volume percent. Within a certain range of low concentration, the capillary absorption coefficient increases with the increasing of the concentration of NaCl solution, however when the concentration is too high, the transmission rate will be lower than pure water. This investigation provides an experimental foundation for the durability design and service life assessment of concrete structures.

Abstract: The electrochemical performance of polyaniline (PANI)/stainless steel electrodes prepared in H₂SO₄ and p-toluene sulfonic acid (p-TSA) using potentiodynamic method were investigated in corresponding acids and three kinds of sodium salts, respectively, by cyclic voltammetry, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy (EIS). It is concluded that the counter anion of acid employed in the electropolymerization plays a key role in the free volume of PANI. The kinetic parameters of PANI are strongly influenced by the free volume both in acid and in salt solutions. In addition, the utilizing of salt solution is beneficial to the kinetic analysis of the energy-storage process of PANI, although the capacitance of PANI in salt solution decays on cycling due to the lack of protons.

Abstract: Salt solution ingress into concrete will result in serious deterioration of concrete materials, and then bring concrete structure in danger. So researchers pay more attention to the transportation of salt solution in concrete. In this paper, the ingress of 5% NaCl, 5%Na2SO4 and H2O into concrete under capillary siphon effect were investigated, and the influence factors such as water to binder ratio, mineral admixture, porosity and pore structure were also analyzed by methods of capillary solution-absorption experiment and evaporated water test. Results show that in capillary siphon effect, first the salt solution ingress into concrete increase quickly in very short time and then with the increase of time the solution absorption mass keep stable gradually. The types of salt solution are not the decisive factors controlling the solution ingress. Addition proper mineral admixture such as compound of fly ash (FA) and silica fume (SF) can decrease solution absorption mass under capillary siphon effect efficiently. In capillary effect, pores with aperture above 30 nm have close relativity with solution absorption mass. The decrease of porosity and improvement of pore structure can reduce the ingress of solution into concrete.

Abstract: The frost resistance of concrete subjected to 3.5% NaCl solution, 5%, 7%, and 10% Na2SO4 solution and seawater were investigated by quick freeze-thaw test. There were two criteria, the relative dynamic modulus of elasticity (RDME) and the mass of scaling, for evaluating the frost resistance of concrete. The results showed that scaling was the main characteristic of deterioration when concrete subjected to freeze-thaw cycles in 3.5% NaCl solution and seawater, whereas RDME had little change. When freezing and thawing in Na2SO4 solution, concrete failed because of internal damage and surfaces of lower strength concrete specimens appeared local swelling and scaling before failure. Concentration of Na2SO4 solution had influence on frost resistance of concrete: deterioration of concrete in 5% or 7% Na2SO4 solution was severe but slower when the concentration reached to 10%. Entraining air into concrete was the best method to improve the durability of concrete subjected to freeze-thaw cycles in all solutions.

Abstract: After some biographical notes, Fick’s 1855 seminal paper is analysed and the contributions of Stefan and Roberts-Austen are briefly mentioned.