Starting from the core requirements of polishing powder – namely, high hardness, chemical stability, controllable particle size and morphology – in this article, I will screen out several particularly suitable oxides for you and analyze their respective characteristics, as well as how to select the appropriate oxide based on the application scenario.
First, let’s take a look at what features an excellent polishing powder should have?
- High hardness: It must be harder than the material to be polished to achieve effective micro-cutting.
2 Chemical stability: It does not undergo unnecessary chemical reactions with the workpiece or liquid during the polishing process.
- Controllable particle size and morphology: A narrow particle size distribution is necessary to achieve uniform cutting force and a smooth surface; morphology (such as spherical or polyhedral) affects polishing efficiency and scratch control.
How to choose oxides for your polishing compound ?
We believe that the following oxides are the most suitable for use as polishing powder:
- Alumina poweder, which is α-phase alumina, has extremely high hardness (Mohs hardness 9) and stable chemical properties. It meets the requirements of high hardness and low cost. However, during use, attention should be paid to the selection of particle size to avoid overly sharp morphology that may cause scratches. It is advisable to choose spherical or processed α-phase alumina.
Suitable for application on stainless steel, hard alloy, sapphire substrate and advanced ceramics.
2. Zirconia powder , with its high hardness and unique high toughness, is resistant to impact and wear. It effectively balances toughness and hardness. It is suitable for polishing advanced ceramics, gemstones, and metals, and is also used as an enhancing material for alumina polishing balls.
- Silica dioxide, although not as hard as the previous ones, is extremely important in its colloidal form for polishing. Colloidal silica dioxide has a negatively charged surface in alkaline conditions, generating repulsive forces between particles, which can form a very stable and uniform suspension, making it the preferred choice for scratch-free fine polishing. It is suitable for the final fine polishing of conductor wafers (Cu, SiO₂ dielectric layers), computer hard disk substrates, and precision metal components.
- Iron oxide powder, also known as red iron oxide, is a traditional polishing powder for optical glass. However, due to its environmental pollution and potential damage to workpieces, its current usage is decreasing.
In addition to choosing the appropriate oxide based on the suitable application scenarios, we need to pay close attention to the particle size, distribution, morphology, and purity, as these directly affect the polishing effect.
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