BryCoat coatings are used to manufacture TiC-Coated Bearing Balls (TiC Balls) for high value precision instrument bearings.
These bearings are used in niche applications where performance is critical and conditions are difficult. Many space mechanisms and missile systems require bearings to perform in changing temperatures, space, bombardment by ionized gases, and other difficult environments. In these specialized applications, pseudo-hybrid bearings utilizing TiC-Coated Steel bearing balls have provided the needed performance and reliability.
Performance in Extreme Situations
- Reduced wear of balls and races.
- Can run in fully lubricated, boundary lubrication, loss of lubricant, and, in some cases, unlubricated situations.
- TiC layer resists material transfer (microwelding) that causes adhesive wear.
- Thermal expansion match of balls to races maintains preload in changing environments.
- Strong inhibition of lubricant breakdown—extends lubricant lifetime.
- Lower stress levels than ceramic balls.
- Increased fatigue resistance.
- Conductive material prevents electric charge buildup.
- High temperature, low temperature and changing temperature tolerance.
- Elasticity, density, thermal expansion and bulk hardness match steel properties.
- Decreases tribochemical reactions
Physical Properties of TiC-Coated 440C Bearing Balls
|Density||–||7.8||3.3||4.92||7.8||Bulk properties of steel|
|Surface Hardness||Gpa||7||20||30||30||Surface properties of TiC|
|Surface Roughness||Ra nm||10||5 – 7||3 – 5||3 – 5|
|Friction Coefficient vs Steel||0.7||0.6||0.25||0.25|
About TiC Coated Bearing Balls:
- Steel balls – typically 440C
- Coated with thin film of TiC (Titanium Carbide) ceramic
- Hard and inert surface layer
- Low friction surface
- Tolerant to wet or corrosive environments
- Lower stress levels in race than with solid ceramic balls
- Higher surface hardness than Si3N4
- Uniform hardness distribution-less variation than Si3N4 and Steel
- Outstanding adhesion to core material through specialized CVD process
- Maintains the bulk properties of steel balls
- Provides surface properties of TiC
Instrument Bearing Approaches
- Conventional Bearings – Steel Balls/Steel Races
- Hybrid Bearings – Ceramic (Si3N4) Balls/Steel Races
- Improve inertness & reduce adhesion
- Fatigue life worse
- Can lose preload
- Pseudo-hybrid bearings – TiC-coated steel balls/steel races.
- Best of Both Worlds!
Properties of TiC Coated Balls
- Extremely hard thin film surface layer of 3,500 HK
- Inert surface does not interact with fluids or races
- Low friction
- Smooth surface
- Fine monophased microstructure, 0.1µm (4 µin.) grain size
- Coating thickness of >2 µm after lapping
- Core ball of 440C, Rex20, Carbide, or other materials.
- Balls typically produced to Grade 3 specifications.
- Check out these helpful resources:
- PVD Process Description
- Guide to Substrate Preparation for thin film coatings
- Thickness Conversion Chart
- Temperature Conversion Chart
TiC Coated Bearing Balls Applications
- Space Mechanisms
- Inertial guidance systems
- Momentum wheels
- Reaction wheels
- Space components and instrumentation
- Mirror scanners
- Medical instruments
- Bearings that must move smoothly after long idle periods
- High value, demanding environment applications