5mm-6mm Pressureless Sintered Silicon Carbide Grinding Balls
Price:
Negotiable
MOQ:
Negotiable
Delivery Time:
Negotiable
Brand:
KEGU
Product Description
5mm-6mm Pressureless Sintered Silicon Carbide Grinding Balls
Silicon Carbide (SiC), a typical covalently bonded compound, offers exceptionally high hardness, superior wear resistance, excellent high-temperature mechanical properties, and outstanding chemical stability, making it a key member of advanced structural ceramic materials. SiC grinding balls are produced from high-purity SiC powders through forming, high-temperature sintering, and precision finishing. They are widely used in crushing, ultra-fine grinding, and dispersion of high-hardness materials.
Manufacturing Processes
Forming Methods
- Roll forming - Ceramic feedstock is directly rolled into green balls of the required size. Simple, suitable for small to medium batches.
- Isostatic pressing - Includes wet-bag and dry-bag cold isostatic pressing. Dry-bag pressing offers high automation, uniform green density, and good sphericity, but demands good powder flowability and granulation quality.
- Extrusion + post-treatment - SiC powder, high-char-yield resin, and short fibers are mixed, extruded into balls, cured, and pyrolyzed to obtain carbon-ceramic preforms, which are then densified by silicon infiltration (reaction bonding), followed by grinding/polishing to achieve high dimensional accuracy.
Sintering Processes
SiC has >90% covalent bonding and extremely low self-diffusion coefficients, making sintering challenging. The main sintering techniques for 5-6 mm grinding balls are:
- Pressureless sintering (atmospheric sintering) - Performed in non-oxidizing atmosphere at 2000-2150 °C, achieving >98% theoretical density. Includes solid-state and liquid-phase sintering. No shape/size limitations, low cost, mature for mass production of 5-6 mm balls.
- Reaction sintering - Porous preforms (carbon + SiC) are infiltrated with molten silicon above 1500 °C, forming β-SiC. Low temperature, low shrinkage, near-net shape; suitable for complex precision shapes.
- Hot pressing - Mechanical pressure applied during heating enables fine-grained, high-density (≥99%) products at lower temperatures and shorter times. Limited die life, low batch output, high cost; used for small-batch high-performance products.
- Hot isostatic pressing (HIP) - Provides very high density and excellent sphericity, but high equipment investment and cost; not for large-scale production.
Sintering Process Comparison
| Process | Sintering temp. (°C) | Density (%) | Advantages | Application scope |
|---|---|---|---|---|
| Pressureless sintering | 2000-2150 | ≥98 | Low cost, mass production | High volume, 5-6 mm general purpose |
| Reaction sintering | 1500-1700 | Near full | Near-net shape, low shrinkage | Complex, precision shapes |
| Hot pressing | 1800-2200 | ≥99 | Fine grains, high density | Small batches, high performance |
| Hot isostatic pressing | 1800-2000 | ≥99 | Uniform density, superior sphericity | Premium bearing-grade products |
Physicochemical Properties
Mechanical Properties
- Hardness - Mohs hardness 9.5, second only to diamond (10). Knoop hardness ~3000 kg/mm². Vickers hardness HV10 ≥22 GPa; premium grades reach HV0.5 ≥2600.
- Density - Bulk density 3.07-3.20 g/cm³, >60% lower than steel balls (~7.8 g/cm³), reducing equipment load and energy consumption.
- Elastic modulus - Young's modulus 380-430 GPa (~1.5× that of steel), ensuring excellent dimensional stability under heavy loads.
- Fracture toughness - ~3-4 MPa*m¹/², typical for brittle ceramics.
Thermal Properties
- Thermal conductivity - High: 120-200 W/(m*K) at 20 °C, exceeding that of many metals and ~3× that of silicon.
- Coefficient of thermal expansion (CTE) - Low: 3.6-4.1×10⁻⁶/K (20-400 °C).
- Maximum service temperature - SSiC (pressureless sintered) up to 1800 °C in inert atmosphere; 1600 °C in air.
Chemical & Electrical Properties
Excellent corrosion resistance - resists almost all known reagents at room temperature. A dense SiO₂ layer forms upon oxidation, providing further protection. Suitable for strong acids, strong alkalis, and aggressive environments. SiC is a wide-bandgap semiconductor with high resistivity. It is non-magnetic and non-conductive, safe for magnetic field environments and applications requiring electrical insulation.
Key Physicochemical Indicators
| Property | Typical value / range |
|---|---|
| Main composition (SiC content) | ≥95% (black SiC), ≥97% (green SiC), up to ≥99% |
| Bulk density | 3.07 - 3.20 g/cm³ |
| Mohs hardness | 9.5 |
| Vickers hardness (HV10) | ≥22 GPa (≥2600 HV0.5) |
| Elastic modulus | 380 - 430 GPa |
| Thermal conductivity (20 °C) | 120 - 200 W/(m*K) |
| CTE (20-400 °C) | 3.6 - 4.1×10⁻⁶/K |
| Flexural strength | ≥400 MPa |
| Compressive strength | ≥2200 MPa |
| Apparent porosity | <0.2% |
Application Scenarios
Powder Processing
Due to low specific gravity and extreme hardness, 5-6 mm SiC balls are ideal grinding media for stirred mills (attritors). They are particularly suited for ultra-fine grinding of superhard ceramics such as SiC, Si₃N₄, B₄C, and TiC, achieving particle sizes from micron to sub-micron or even nano-scale. Homogeneous (SiC balls grinding SiC powder) or highly compatible media minimize contamination and preserve product purity.
New Energy Materials Processing
In ultra-fine grinding of Li-ion battery cathode materials (e.g., LiFePO₄, NMC), 5-6 mm SiC balls replace steel or ZrO₂ balls to avoid metallic contamination, improving battery cycle life and safety. In PV industry ultra-fine powder grinding, SiC balls offer comparable performance to expensive ZrO₂ balls at significantly lower cost.
High-Temperature & Corrosive Environments
SiC balls operate continuously at 1600 °C, exhibit low CTE, and resist thermal shock. They are used in drive systems of high-temperature calcining equipment, load-bearing parts in heat treatment furnaces, etc. Their excellent acid/alkali resistance makes them suitable for chemical reactors and electroplating sludge treatment.
Optical Glass & Hard-Brittle Materials
5-6 mm SiC balls are used for high-precision free grinding and polishing of optical glass, ceramics, sapphire, and silicon wafers. Green SiC balls (SiC >97%) are particularly effective for cemented carbide and glass, achieving surface roughness Ra <0.1 μm.
Pharmaceutical & Food Industries
SiC is non-toxic and poses no health risks. As grinding media, it avoids heavy metal leaching associated with metallic balls and complies with GMP and other hygiene standards.
Bearings & Valve Components
5-6 mm precision SiC balls are also used as corrosion-resistant bearing elements, suitable for deep-well drilling bearings, chemical reactor seals, and other applications demanding high wear and corrosion resistance.
Performance Advantages Over Other Grinding Media
Material Comparison
| Property | SiC | Al₂O₃ | ZrO₂ | Si₃N₄ | Bearing steel |
|---|---|---|---|---|---|
| Density (g/cm³) | 3.07-3.20 | 3.75-3.95 | 5.6-6.0 | ~3.2 | ~7.8 |
| Mohs hardness | 9.5 | 9 | 8.5 | ~9 | 5-6 |
| Vickers hardness (HV10, GPa) | ≥22 | ~15 | ~12 | ~15-18 | ~6-8 |
| Elastic modulus (GPa) | 380-430 | ~300-350 | ~200-210 | ~300-320 | ~210 |
| Thermal conductivity (W/(m*K)) | 120-200 | 20-30 | 2-3 | 15-30 | ~45 |
| Fracture toughness (MPa*m¹/²) | 3-4 | 3-4 | 10-15 | 5-7 | ~50 |
| Max. service temperature (°C) | 1600+ | 1500-1600 | ≤600 | 1200 | ≤500 |
| Corrosion resistance | Excellent | Good | Good | Excellent | Poor (rust) |
| Conductivity / magnetism | Non-conductive, non-magnetic | Insulating | Insulating | Insulating | Magnetic & conductive |
Key Advantages of SiC Grinding Balls
- Highest hardness, best wear resistance - Mohs 9.5, wear life 2-5× that of Al₂O₃ balls.
- Highest thermal conductivity, superior heat dissipation - 120-200 W/(m*K), far exceeding Al₂O₃ and ZrO₂, rapidly removing grinding heat and preventing thermal degradation of sensitive materials.
- Best thermal stability - Operates above 1600 °C; ZrO₂ degrades above 600 °C, bearing steel above 500 °C.
- Outstanding corrosion resistance - Resists strong acids, alkalis, and aggressive media, unlike metallic balls that rust and introduce contaminants.
- Chemical inertness & low contamination - Minimal impurity pickup, ideal for high-purity applications (electronic materials, pharmaceutical ingredients, semiconductor powders).
- Light weight, energy saving - Density ~40% of steel, significantly reducing mill motor load and energy consumption.
- Excellent dimensional stability - Low CTE combined with high elastic modulus ensures precision under thermal variations.
- Cost-effective - Combines no contamination, no breakage, high grinding efficiency, and low wear; overall cost in superhard material grinding lower than ZrO₂ balls.
Compared with other ceramic grinding media, SiC offers irreplaceable advantages in extreme hardness, wear resistance, thermal conductivity, and high-temperature stability, especially for applications demanding high grinding efficiency, product purity, and elevated temperature operation. Its fracture toughness is lower than that of ZrO₂; thus, in coarse crushing dominated by high impact loads, careful selection is required. However, for fine and medium grinding in stirred mills (5-6 mm size), the brittleness limitation can be mitigated by proper ball-to-material ratio and process control.
For further information or to discuss your specific needs, please contact us directly.
Similar Products
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.
Company
Shaanxi KeGu New Material Technology Co., Ltd
Location
No. 2 Workshop, Zone B, Dongyuan Ceramic Industrial Park, Wangyi District, Tongchuan, Shaanxi 727000, China
Contact Person
Scarlett.S