Colloidal Silica & Alumina Polishing Suspensions

Kemet Colloidal Silica and Alumina Suspensions use a combination of chemical-mechanical polishing actions, providing specimens with a deformation-free surface. This is produced by having a mixture of abrasive particles dispersed throughout a chemically aggressive liquid carrier. Usually having a particle size of between 0.05µm and 1 µm with a stabilised alkaline of pH of 9.5 or acidic pH of 3-3.5.

It is also used for the final polishing of many materials such as, ceramics, composites and soft metals.

Kemet Colloidal Alumina

Colloidal Silica and Alumina Polishing

This is an acidic disperation Colloidal Alumina with a pH between 3 to 3.5. It can be used to provide a chemical mechanical polishing action, on materials such as germanium, silicon, sapphire and silicon carbide. Also used on pure metals providing low scatter finishes on nickel, tungsten copper, steel and aluminium. It can be used on most common laps and pads, but polyurethane and short nap cloths are recommended. Use either full strength or diluted 1:1 or higher with deionised water.

Alumina Suspensions for special applications

Micron Use Size Code
0-1 Steel & Hard metals 1 litre 600711
0-0.7 Semi-hard metals 1 litre 600712
0-0.3 Soft metals 1 litre 600713

Alumina Powder for polishing most materials

Micron Use Size Code
Gamma 0.04 Superfinishing of soft metals such as copper, lead, aluminium 1kg 600251
Alpha 0.3 Final polishing of copper alloys, nickel, brass, bronze, aluminium 1kg 600252
Alpha 1.0 Fine pre-polishing of all metals 1kg 600253

Kemet Colloidal Silica

On ceramics and minerals the Colloidal Silica electrochemically attacks the surface to form a thin reactive layer on the specimen surface. This reacted layer can then be removed via the mechanical action of the cloth or abrasive. Compared with straight mechanical abrasives polishing, finishes are far better with Colloidal Silica. The chemical reaction is exothermic, so this action can be increased by raising the temperature. This can be achieved by increasing the polishing pressure. It can be used on polyurethane, short nap cloths and dense low-napped silk. Either full strength or diluted 1:1 or higher with deionised water.

In application, wet the polishing cloth with distilled water, then slowly drip or spray the Suspension onto the polishing cloth. Then finally, for about 10 seconds before you finish polishing, apply water continuously to remove fine particles, which are electro-statically attracted to the specimen.

Colloidal Silica

Micron Use Size Code
0.06 Final Polishing Stage 1 litres 600261
0.06 Final Polishing Stage 5 litres 600199
0.06 Final Polishing Stage 20 litres 600202