White corundum micropowder (mainly composed of α-Al₂O₃) has significant advantages in the field of stone polishing due to its unique physical and chemical properties, as follows:
1. High hardness and wear resistance
– Mohs hardness reaches 9: second only to diamond, it can efficiently polish medium and high hardness stones such as marble and granite, quickly remove scratches and improve gloss.
– Strong self-sharpening: Micropowder particles maintain sharp edges during wear, rough grinding to remove scratches in the initial stage, and passivation to fine polishing in the later stage, reducing the need for process switching.
– High durability: Compared with abrasives such as silicon carbide, white corundum has a low wear rate, long service life, and reduces overall costs.
2. Uniform particle size and fine polishing effect
– Concentrated particle size distribution (such as W10-W40 micropowder grade) ensures uniform grinding and avoids irregular scratches, especially suitable for high-precision mirror polishing.
– High surface finish: Micropowder particles are fine and can fill the tiny pores of stone, form a smooth reflective surface, and enhance the texture of stone.
| ITEM | D0（um） | D3(um) | D50(um) | D94(um) |
| #240 | ＜127 | ＜103 | 57.0±3.0 | ＞40 |
| #280 | ＜112 | ＜87 | 48.0±3.0 | ＞33 |
| #320 | ＜98 | ＜74 | 40.0±2.5 | ＞27 |
| #360 | ＜86 | ＜66 | 35.0±2.0 | ＞23 |
| #400 | ＜75 | ＜58 | 30.0±2.0 | ＞20 |
| #500 | ＜63 | ＜50 | 25.0±2.0 | ＞16 |
| #600 | ＜53 | ＜41 | 20.0±1.5 | ＞13 |
| #700 | ＜45 | ＜37 | 17.0±1.5 | ＞11 |
| #800 | ＜38 | ＜31 | 14.0±1.0 | ＞9.0 |
| #1000 | ＜32 | ＜27 | 11.5.±1.0 | ＞7.0 |
| #1200 | ＜27 | ＜23 | 9.5±0.8 | ＞5.5 |
| #1500 | ＜23 | ＜20 | 8.0±0.6 | ＞4.5 |
| #2000 | ＜19 | ＜17 | 6.7±0.6 | ＞4.0 |
| #2500 | ＜16 | ＜14 | 5.5±0.5 | ＞3.0 |
| #3000 | ＜13 | ＜11 | 4.0±0.5 | ＞2.0 |
| #4000 | ＜11 | ＜8.0 | 3.0±0.4 | ＞1.8 |
| #6000 | ＜8.0 | ＜5.0 | 2.0±0.4 | ＞0.8 |
| #8000 | ＜6.0 | 3.5 | 1.2±0.3 | ＞0.6 |
3. Excellent chemical and thermal stability
– Acid and alkali resistance: It does not react with acids and alkalis at room temperature, and is suitable for wet polishing (such as water cooling process) to avoid contaminating the stone.
– High temperature resistance (melting point 2050℃): It is not easy to sinter or deform during high-speed polishing, maintains stable grinding performance, and is suitable for long-term operation.
| Typical Chemical composition | |
| AL2O3 | 99.3%min |
| SiO2 | 0.06% |
| Na2O | 0.3%max |
| Fe2O3 | 0.05%max |
| CaO | 0.04%max |
| MgO | 0.01%max |
| K2O | 0.02#max |
| Typical physical properties | |
| Hardness: | Mohs:9.0 |
| Maximum service temperature: | 1900 ℃ |
| Melting Point: | 2250 ℃ |
| Specific Gravity: | 3.95g/cm3 |
| Volume density | 3.6g/cm3 |
| Bulk density(LPD): | 1.75-1.95 g/cm3 |
| Color: | White |
| Particle shape: | Angular |
4. Wide applicability
– Compatible with a variety of stones: including marble (low hardness), granite (medium and high hardness), artificial quartz stone, etc.
– Adapt to different processes: It is applicable throughout the process from rough polishing (quick trace removal) to fine polishing (high gloss), and supports matte or mirror effects.
5. Environmental protection and economy
– Non-toxic and harmless: It does not contain heavy metals, complies with environmental protection standards such as RoHS, and protects the health of workers and environmental safety.
– Recyclable: Micro powder can be recycled (such as sedimentation recovery), reducing resource waste and waste treatment costs.
6. Increase the added value of stone
– High gloss and durability: After polishing, the surface has enhanced stain resistance, easy to clean and maintain, and extends the beauty cycle of stone.
– Good color reproduction: Neutral properties prevent stone oxidation and discoloration, especially suitable for light-colored or complex-textured stones (such as Carrara white marble).
Advantages compared with other abrasives
– vs silicon carbide: higher hardness, stronger chemical stability, suitable for high-precision polishing; but the cost is slightly higher.
– vs diamond powder: better cost-effectiveness, suitable for large-scale processing of non-superhard stones.
– vs cerium oxide: stronger grinding force, suitable for repairing deep scratches, not just surface treatment.
Application scenario suggestions
– Mirror polishing: marble floors in high-end hotels and shopping malls.
– Repair and renovation: repair of scratches on old granite countertops.
– Special-shaped carving: detail polishing of complex stone sculptures.
In summary, white corundum powder has become an efficient and reliable choice for stone polishing due to its hardness, stability and environmental protection characteristics. It is especially suitable for scenes with high requirements on surface quality and processing efficiency.
