TiC Coated Bearing Balls

Titanium Carbide (TiC) applied by CVD Vacuum Deposition Process on Precision Bearing Balls.

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

Property	Units	Steel	Si3N4	TiC	TiC-Coated Steel
Density	-	7.8	3.3	4.92	7.8	Bulk properties of steel
Elastic Modulus	GPa	210	320	450	210
Bending Strength	Mpa	450	1200	900	450
Bulk Hardness	GPa	7	20	30	7
Thermal Expansion	10-6/K	12	3	7	12
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.

TiC Coated Bearing Balls Applications

Space Mechanisms
Inertial guidance systems
Gyroscopes
Accelerometers
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