Nano-sized Alumina Particles Research Articles

CHIPPAC TO DOUBLE CHINESE MANUFACTURING CAPACITY

This chapter addresses the occurrence, behavior, and treatment of nanosized (<100 nm) alumina, ceria, and amorphous silica particles in the wastewater generated from chemical mechanical planarization (CMP) processes during the manufacture of semiconductor wafers. The chapter is primarily directed to engineers who may need to design and/or operate wastewater treatment processes in semiconductor manufacturing facilities (fabs). The composition of CMP slurry wastewaters is described, along with the principal physical and chemical processes that influence the behavior of alumina, ceria, and silica particles in an aqueous system. Key unit operations that may be applicable to the removal of nanosized particles from wastewaters are described, including coagulation, flocculation, sedimentation, filtration, flotation, electrocoagulation, and biological wastewater treatment. The engineered application of these unit operations to the removal of nanosized particles is currently gated by the limited availability of information on actual performance and operational experience. Key research needs are described, including the need for validated analytical methods for measuring nanoparticle fate and behavior in complex waste streams, as well as for evaluating the long-term stability of nanoparticles in the solid concentrates that are produced by wastewater treatment.

Preparation of Nanosized Drug Particles by the Coating of Inorganic Cores: Naproxen and Ketoprofen on Alumina

Nanosized alumina particles with modal diameters of 8 and 13 nm, respectively, were successfully coated by the adsorption of naproxen [(+)-6-methoxy-α-methyl-2-naphthalene acetic acid] and ketoprofen [α-methyl-3-(4-methylbenzoil) benzene acetic acid] in aqueous and ethanol solutions. The presence of the drugs at the alumina surface was confirmed by attenuated total reflection infrared spectroscopy and electrokinetic measurements, while their bound amounts were assessed by thermogravimetric analysis.

Thermal conductivity enhancement of suspensions containing nanosized alumina particles

Various suspensions containing Al2O3 nanoparticles with specific surface areas in a range of 5–124 m2 g−1 have been prepared and their thermal conductivities have been investigated using a transient hot-wire method. Nanoparticle suspensions, containing a small amount of Al2O3, have substantially higher thermal conductivity than the base fluid, with the enhancement increasing with the volume fraction of Al2O3. The enhanced thermal conductivity increases with an increase in the difference between the pH value of aqueous suspension and the isoelectric point of Al2O3 particle. For the suspensions using the same base fluid, the thermal conductivity enhancements are highly dependent on specific surface area (SSA) of nanoparticle, with an optimal SSA for the highest thermal conductivity. For the suspensions containing the same nanoparticles, the enhanced thermal conductivity ratio is reduced with the increasing thermal conductivity of the base fluid. The crystalline phase of the nanoparticles appears to have no obvious effect on the thermal conductivity of the suspensions. Comparison between the experiments and the theoretical model shows that the measured thermal conductivity is much higher than the values calculated using theoretical correlation, indicating new heat transport mechanisms included in nanoparticle suspensions.

Graft polymerization of vinyl monomers onto nanosized alumina particles

To enhance the interfacial interaction in alumina nanoparticles filled polymer composites, an effective surface modification method was developed by grafting polystyrene and polyacrylamide onto the particles. That is, the alumina surface was firstly treated with silane, followed by radical grafting polymerization in aqueous or non-aqueous systems. Results of infrared spectroscopy and dispersiveness in solvents demonstrated that the desired polymer chains have been covalently bonded to the surface of the alumina particles. They also greatly changed their surface characteristics. In addition, effects of polymerization conditions, including ways of monomer feeding, concentrations of monomer and initiator, and reaction time, on the grafting reaction were presented. It was found that the growing polymer radicals and/or the grafted polymer chains had a blocking effect on the diffusion of radicals or monomers towards the surface of nanoalumina. This was due to the fact that the interaction between the solvent and the grafted polymers was weaker than that between the grafted polymers and the nanoparticles. 2002 Elsevier Science Ltd. All rights reserved.

Grain stabilisation of copper with nanoscaled Al 2O 3-powder

Copper powders with a median particle diameter of 60 μm were mixed with different amounts of nanosized alumina powder with a median particle diameter of 14 nm in an asymmetric moved mixer followed by hot extrusion. Investigations of the microstructure reveal considerable less recrystallization and grain growth up to temperatures near to the melting point of copper, compared to hot extruded samples made of copper powder without additives and composites with microsized alumina powder content. It was shown by EDX measurements, that the nanosized alumina particles are located exclusively at the grain boundaries of the copper grains. Due to the nanopowder additions an increase in hardness and yield stress is observed, which can be attributed to inhibited recrystallization and grain growth.

Electrodeposition of particle-strengthened nickel films

Dispersion-strengthened nickel films were obtained by co-deposition of Al 2O 3 particles with a mean particle diameter of 14 nm followed by heat treatment at 850 °C. The co-deposition was achieved by addition of Al 2O 3 powders in a typical Watts bath before electroplating of nickel on copper substrates. The Ni films are analyzed by light and transmission electron microscopy and by measurement of the coercivity and the microhardness. The particle-strengthened Ni films show a remarkable improvement of hardness due to grain stabilization and dispersion hardening of the nickel grains by alumina nanoparticles as observed by structural investigations of the samples. Reinforcement of electrodeposited nickel films by nanosized alumina particles is a simple process producing wear-resistant coatings.

Effect of powder granulometry and pre-treatment on sintering behavior of submicron-grained α-alumina

Two kinds of commercial, submicron-grained, nondoped α-alumina powders were cold-isostatically pressed and then sintered at a constant heating rate. Before the sintering, pre-treatments were executed at 820 or 920 ° C for 50 h. The effects of the pretreatments on the densification behavior and the microstructural development are discussed. The powders contained some nano-sized alumina particles about 10 nm in diameter as well as sub-micron-sized primary particles about 0.1 μm in diameter, which agglomerated in packs of 0·2–0·4 μm diameter. The densification rate curves showed a low temperature shoulder during sintering attributed to these nano-sized particles. After pretreatments, the nano-particles disappeared, resulting in disappearance of the shoulder in the subsequent densification rate curves. These treatments, however, caused little change in the apparent activation energy in the intermediate stage sintering. For the weakly agglomerated powders, the bodies sintered with pre-treatments had coarser final microstructures.