Cemented carbide bearing balls are spherical parts made by sintering high-hardness refractory metal carbide (such as WC, TiC) micron-sized powder as the main component, and cobalt (Co), nickel (Ni), or molybdenum (Mo) as a binder, using powder metallurgy processes in a vacuum furnace or hydrogen reduction furnace. Their specific physicochemical properties are as follows:
I. Physical Properties of Cemented Carbide Bearing Balls
1. High Hardness
Hardness range: HRA 90-92 (equivalent to HRC 69-81), far exceeding that of ordinary steel balls (HRC 60-65).
Performance: Under dry friction conditions, tungsten carbide (WC) has a low coefficient of friction, and the binder phase cobalt (Co) acts as a solid lubricant, further reducing friction.
Advantages: Wear resistance is tens to hundreds of times that of steel balls, significantly extending bearing life.
2. High Density
Density: Approximately 14.9 g/cm3, nearly twice that of steel balls (approximately 7.8 g/cm3).
Impact: High density gives the ball bearing higher inertia, suitable for high-speed rotation scenarios, while also enhancing impact resistance (but note that cemented carbide itself is relatively brittle).
3. Strong Thermal Stability
High-Temperature Performance: Maintains high hardness at 900-1000℃, exhibiting excellent red hardness.
Applications: Suitable for high-temperature environments (such as oilfield equipment, spraying machines), avoiding the performance degradation caused by thermal expansion of traditional steel balls.
4. High Dimensional Accuracy
Manufacturing Process: Through precision grinding and polishing, the surface roughness Ra value can be below 0.012μm, and the diameter tolerance is controlled within ±0.001mm.
Advantages: Reduces vibration and noise during bearing operation, improving rotational accuracy and stability.
II. Chemical Properties of Cemented Carbide Bearing Balls
1. Excellent Corrosion Resistance
Corrosion Resistance: Resistant to corrosive media such as air, acids, and alkalis; not easily oxidized.
Applications: Suitable for corrosive environments such as hydrochloric acid laboratories and chemical equipment, replacing easily corroded steel balls.
2. High Chemical Stability
Oxidation Resistance: Does not readily react with oxygen at high temperatures, forming a dense oxide film on the surface, preventing further corrosion.
Performance: Maintains surface smoothness even after long-term use, reducing wear caused by corrosion.
III. Mechanical Properties of Cemented Carbide Bearing Balls
1. High Compressive Strength
Compressive Strength: Up to 6000 MPa, far exceeding that of high-speed steel (approximately 2000 MPa).
Performance: Can withstand high loads without plastic deformation, suitable for heavy-duty bearing applications.
2. Lower Bending Strength
Bending Strength: Generally 1000-3000 MPa, lower than compressive strength.
Impact: Strong impacts or bending loads on cemented carbide bearing balls should be avoided, otherwise brittle fracture may occur.
3. High Elastic Modulus
Elastic modulus value: (4-7)×10? MPa, higher than high-speed steel.
Advantages: Small deformation under stress, helping to maintain bearing geometric accuracy.
IV. Application Scenarios and Advantages of Cemented Carbide Bearing Balls
Cemented carbide bearing balls, due to their physicochemical properties, are widely used in the following fields:
1. High-end manufacturing: Precision bearings, instruments, aerospace (requiring high precision and long life).
2. Harsh environments: Oilfield equipment, spraying machines, hydrochloric acid laboratories (high temperature resistance, corrosion resistance).
3. Special needs: Fishing gear, counterweights, decoration (high density, wear resistance).
