Narrow Results

Gelcasting process as a promising method for fabrication of reliable ceramics has been utilized to develop alumina-zirconia nanocomposites from nanosized powders. Sedimentation and viscosity measurement were performed to find the accurate dispersing condition for production of alumina-zirconia nanocomposite slurry with high solid loading and low viscosity. The gelcasting was accomplished by in situ polymerization of an acrylamide base monomer. The effects of solid loading, viscosity and deairing were also studied. Finally, crack and flaw free samples with relative densities of 99%, were achieved from the optimal slurry with 35vol. % solid loading, by performing sintering at 1600°C for 2 hours. SEM micrographs showed dense microstructure with fine and homogenous dispersion of zirconia phase in the alumina matrix.

To further clarify the effect of the polishing slurry dispersant on the chemical mechanical polishing (CMP) performance of 304 stainless steel, a series of tests were carried out. The correlation between the material removal rate (MRR), surface roughness of 304 stainless steel, dispersant composition, and their content was investigated under two kinds of polishing slurry (hydrogen peroxide oxidant and ferric chloride oxidant) conditions. The experimental results indicated that the MRR and surface roughness of 304 stainless steel arrived at the maximum when the content of sodium hexametaphosphate dispersant was 1.2% (wt) under the hydrogen peroxide–oxalic acid polishing slurry condition. The values of MRR and surface roughness were 146 nm/min and 10 nm, respectively. The MRR and surface roughness of 304 stainless also reached the maximum value as the content of the propanetriol dispersant was 1.2% (wt) under the ferric chloride–oxalic acid polishing slurry condition. However, the values of MRR and surface roughness were 457 nm/min and 22 nm, respectively. Therefore, sodium hexametaphosphate was recommended as the dispersant of hydrogen peroxide–oxalic acid polishing, and propanetriol was recommended as the dispersant of ferric chloride–oxalic acid polishing slurry condition, according to the above analysis. This study lays a theoretical foundation for the improvement of 304 stainless steel CMP performance.

To determine the optimal dispersion conditions of graphene flakes for ink, its heat dissipation properties were investigated by changing the particle size, dispersant, and binder types. In the case of particle size, the smaller the size of the graphene flakes, the better the dispersion, and regardless of the amount of dispersant and the type of binder, the greatest dispersion effect was exhibited by the mixed dispersant. Under these conditions, internal cohesion did not occur as in Newtonian flow over time, and for this reason, heat was released quickly, with a rapid cooling rate. It is clear that this process of determining the optimal dispersion conditions considering multiple factors will provide a good reference for determining dispersion conditions for various variables in the future.

Four different dispersants, sodium dodecyl benzene sulfonate (SDBS), cetyl trimethyl ammonium bromide (CTAB), polyvinylpyrrolidone (PVP) and polyacrylic acid (PA) were used to disperse carbon nanotubes(CNTs) composite plating solution. Dispersion effect was compared by the absorbance value of the bath. The analysis indicated that dispersants had variation of different dispersants on CNTs suspension, under the same technology condition, the dispersion effect of PA was better than PVP, CTAB and SDBS. When the optimum amount of PA was added, it had the good dispersion stability, the narrow particle size distribution and small average particle diameter. Surface quality of the slide bearings were significantly improved as well.