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INTRODUCTION
MTI-50-CSO 0.05 micron colloidal silica (SiO2) slurry is a very unique polishing suspension because it provides a chemical mechanical polishing (CMP) action for materials such as crystals, ceramics, composites and soft metals. It is stabilized at alkaline pH values (typically >9.5). At higher pH values colloidal silica is held in nearly perfect suspension by the electrochemical repulsive forces of the fine particles themselves. This chemical balance electrochemcially attacks the surface of a crystal, a ceramic or mineral surface to form a thin reacted layer on the specimen surface. This reacted layer can then be removed via the mechanical action of the polishing cloth or another abrasive (e.g. alumina or diamond). Polishing rates and surface finishes are significantly better for crystals, ceramics, and minerals as compared with straight mechanical abrasives such as diamond. Thus the highest removal rates and the most reliable action for removing both surface and subsurface damage on crystals, ceramics, and minerals is via chemical mechanical polishing with colloidal silica slurry.
APPLICATION
As with other exothermic chemical reactions the chemical contribution can be enhanced by increasing the temperature of the polishing action. This can be accomplished by increasing the polishing pressure which increases the friction between the polishing cloth, colloidal silica and the specimen. Cleaning of the surface is best accomplished by running water on the surface for the final 10-15 seconds of the polishing cycle and then immediately rinsing the specimen surface with water. This allows the cloth to mechanically remove the reacted layer and any residual colloidal silica. The most efficient application is to initially wet the polishing cloth with MTI-50-CSO Colloidal Silica Slurry and then to slowly drip or spray the suspension onto the polishing cloth. It is recommended that water be applied continuously to the polishing cloth for 10-15 seconds prior to completion of the polishing step. This aids in removing the fine particles which may be electrostatically attracted to the specimen surface.
SPECIFICATIONMaterials: SiO2Particle size: 0.05 micronpH: 9.5Volum: 16 Oz / bottleStorage: 40-1000 F
Trouble Shooting Guide for Colloidal Silica Slurry
Symptom
Cause
Action
Crystallized residue on specimens
Improper cleaning of specimen
Repolish specimens and apply rinse water to pad and specimen for last 10-15 seconds
Etching of specimen
Too high a polishing pH
Use an alternative polishing suspension
Excessive scratching on specimen
Crystallization of silica
Keep bottle closed when not in use and filter colloidal silica through a filtering cloth
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