Wholesale Tungsten Carbide Seal Ring/tc Ring

Applicable Industries	Building Material Shops, Energy & Mining
Type	Sleeve
Material	Tungsten carbide

Other Attributes

Place of Origin	Zhejiang, China
Brand Name	CF
Model Number	TC bush
Standard or Nonstandard	Standard or Nonstandard
density	4.5
Temperature	1500
light band	within 2
Hardness	115
Purity	90%
HRA	92

Supply Ability

Supply Ability

10000 Piece/Pieces per Month

Product Details

Product Parameters

Grade	Tungsten Carbide Seal Rings , Mechanical Seal, Sealing rings YG6/YG8/YG8C/YG11/YG11C
Heat resistance	900°C
Density	14.5 g/m3
Certificate	ISO9001
Application	Mechanical seals, pumps, valve
Size	OEM
Feature	Superior wear,Corrosion resistance
Customized	Available
Standard or Nonstandard	Nonstandard

Tungsten Carbide Sealing Rings' Regular Properties table

Grade	Main chemical component					Bending strength (≥N/mm2)	Hardness (≥HRA)	Desity (g/cm³)	Linear Bulge Modulus	Suitable Medium
	WC	CO	Ni	Tic	Other
YWN6	94	\	6	\	\	1500	89	14.5-14.9	5.2	Oil,Sewerage,  Acid, Alkli, Fat, Fluidify Hydrocarbon, Strong Alkali With Grain
YWN8	92	\	8	\	\	1650	88	14.4-14.8	5.3
YWN10	90	\	10	\	\	2100	87	14.5-14.9	5.3
YG6	94	6	\	\	\	1550	89.5	14.5-14.9	5	Oil,Sewerage,  Soft Acid or Alkli, Fat, Fluidify Hydrocarbon, Medium With Grain
YG8	92	8	\	\	\	1700	89	14.6-14.9	5.1
YG13	87	13	\	\	\	2400	88	13.9-14.2	6	Gas seal of compressors
YG15	85	15	\	\	\	2500	87	13.9-14.2	6.3
YT10	80	10	8	8	2	1700	89	13	6	Oil,Sewerage,  Soft Acid or Alkli, Fat, Fluidify Hydrocarbon, Medium With Grain
TN80	20	\	20	50	10	1450	89	7	7.8

Why Choose Us

Tungsten carbide seal ring is a composite material made of tungsten carbide hard particles (mainly WC) and metal binder (usually cobalt Co, sometimes nickel Ni or nickel-chromium alloy NiCr) through powder metallurgy process, which belongs to cemented carbide. With its excellent hardness, wear resistance, compressive strength, thermal conductivity and good chemical corrosion resistance (especially when using cobalt-based binder), it has become one of the most common and reliable material combinations in the dynamic and static ring pairs of mechanical seals (often paired with graphite, SiC or itself).

1. Material basis: composition and structure

·Main component:

oTungsten carbide particles (WC): Constituents of the body and skeleton of the material, providing extremely high hardness and wear resistance. The grain size ranges from submicron to several microns. The finer the grain, the higher the hardness, strength and wear resistance.

·Binder:

oCobalt (Co): Most commonly used (accounting for 5% - 20% of the total volume). It has a relatively low melting point, good fluidity, and can well infiltrate WC particles, providing excellent toughness, impact resistance and thermal conductivity. It is the first choice for most standard working conditions. However, it is prone to corrosion in acidic, highly oxidizing or high-temperature oxidizing environments.

o Nickel (Ni) / Nickel-chromium alloy (NiCr): Used to replace cobalt, providing better corrosion resistance (especially acid and oxidizing environments), and is used in food, pharmaceutical, strong acid and other working conditions. Its thermal conductivity is usually slightly lower than that of cobalt-based WC, and its toughness is also slightly worse (higher sensitivity to gaps and particles).

· Structure and performance regulation:

o By changing the WC grain size, binder type and content, additives (such as Cr3C2, VC used to inhibit grain growth) and production process, the hardness, toughness (bending strength), wear resistance, corrosion resistance and thermal conductivity of the material can be precisely controlled.

oPorosity: The ideal high-quality seal ring requires Class A or very low Class B porosity (ASTM B276 / ISO 4499) to ensure complete tightness, prevent fluid leakage, improve polishability and reduce local stress concentration sources.

2. Key physical and mechanical properties

·Extreme hardness:

o Typically 87 - 94 HRA (Rockwell A scale), or 1350 - 1900 HV (Vickers hardness). This gives it extremely strong resistance to abrasive wear, adhesive wear and galling, and is the basis of wear resistance. Hardness depends mainly on WC content and grain fineness.

·High flexural strength (TRS):

o Typically ranges from 1400 MPa to more than 3000 MPa (depending on grade and binder type/content). This represents the material's ability to resist bending fracture, reflecting its toughness. It is essential to resist impact loads and seal surface deformation. Cobalt-based WC generally has a higher TRS than nickel-based.

·High elastic modulus:

o About 500 - 700 GPa. This means that the material is very "rigid" and has minimal deformation under load. This helps maintain the flatness and parallelism of the sealing surface and reduces leakage.

·Extremely high compressive strength:

o Much higher than the bending strength (usually >3500 MPa). This enables it to withstand the high closing forces (end surface specific pressure) when the mechanical seal is in operation without crushing.

·Good thermal conductivity:

o (Cobalt-based WC) is about 80 - 100 W/(m·K). Significantly higher than steel and ordinary ceramics. This helps to quickly conduct the heat generated by friction away from the sealing end face, effectively reducing the end face temperature and reducing the risk of liquid film vaporization, material thermal cracking, coking and sealing surface deformation. Nickel-based WC has a slightly lower thermal conductivity (about 20 - 50 W/(m·K)) and slightly inferior heat dissipation.

· Low coefficient of thermal expansion (CTE):

o About 5.0 - 6.5 × 10^-6 /K (cobalt-based), 4.5 - 6.0 × 10^-6 /K (nickel-based). It is at a lower level among commonly used engineering materials. Low CTE means that the size changes less when heated, which helps to maintain the stability of the sealing gap and reduce deformation and leakage caused by thermal stress.

· High density:

o Typically in the range of 13.5 - 15.0 g/cm³, reflecting its dense structure, which contributes to overall rigidity and wear resistance.

3. Chemical and tribological properties

· Chemical corrosion resistance:

o Cobalt-based WC: Very stable and corrosion-resistant in neutral or weakly alkaline environments, oils, and most hydrocarbons. However, in strong acid (sulfuric acid, hydrochloric acid, nitric acid, etc.), strong alkali, oxidizing media (such as salt water, nitrate solution, hot water) and sulfur-containing media, the cobalt binder phase is easily dissolved and corroded, causing the WC particles to lose support and fall off (selective corrosion). The corrosion resistance of the cobalt phase can be improved by adding chromium.

o Nickel-based/nickel-chromium-based WC: Significantly better than cobalt-based, it has good tolerance in strong acid, alkaline media, salt solutions, oxidizing environments, high-temperature water vapor, etc. It is the first choice for corrosive working conditions. However, it may still be corroded in hot concentrated alkali (such as >100°C, >40% NaOH).

·Friction and wear properties (wear resistance):

oSuperior resistance to abrasive wear: Its high hardness is the key to resisting plowing and grooving wear of hard particles (such as solid particles in the medium).

o Good resistance to adhesive wear: When combined with a suitable soft counterface (such as graphite, carbon graphite), the risk of "adhesion-tear" is low, and the friction coefficient is moderate (about 0.05 - 0.15 for carbon graphite).

o Strong abrasion resistance: High hardness and thermal conductivity make it resistant to local material welding (abrasion) caused by friction heat.

o Important matching principles:

▪ The hardness of the matching pair should be different (hard-soft matching): WC is usually paired with graphite/carbon graphite or siliconized graphite/pyrolytic graphite impregnated with metal or resin.

▪ WC-WC hard-to-hard matching is not recommended: Although it is used in extreme high-pressure and high-speed conditions (such as some API 682 configurations), the friction coefficient is high (>0.4), the heat load is huge, and the requirements for surface cleanliness, cooling, and centering are extremely demanding, which can easily lead to severe friction thermal cracking, severe wear and even seal failure.

▪ Recommended pairing: WC vs. graphite/carbon graphite, WC vs. reaction sintered SiC, WC vs. pressureless sintered SiC. WC-SiC is usually more resistant to pressure and temperature than WC-graphite.

4. Manufacturing process

1. Powder preparation: WC powder, binder powder (Co/Ni, etc.), and possible grain growth inhibitors are mixed evenly.

2. Molding: Molding and isostatic pressing are commonly used. The density of the pressed green sheet is required to be uniform to reduce sintering deformation.

3. Sintering:

o Critical process!

It is carried out in a protective atmosphere (vacuum or hydrogen).

o Temperature:

Temperature close to or higher than the melting point of the binder metal (cobalt-based: ~1400°C; nickel-based: ~1500°C).

o Process:

The binder melts and infiltrates the WC particles, sintering occurs between the particles, and the material is densified.

oHIP (Hot Isostatic Pressing): Usually used as a subsequent process, it is carried out under high temperature and high pressure argon gas, which can effectively eliminate residual porosity (down to Class A or lower), greatly improve material strength and reliability, and is a standard requirement for modern high-quality sealing rings.

4.Post-processing:

oFinishing: Grinding, polishing, and grinding to achieve strict dimensional tolerances and surface finish (Ra < 0.025 µm or even mirror finish). Flatness and verticality are key to ensuring sealing.

oGrooving: For sealing rings that require fluid dynamic grooves, laser processing, EDM processing or fine grinding are performed.

oCoating (optional): Under special working conditions (such as strong corrosion), PVD/CVD coatings (such as DLC, CrN) can be deposited to protect the binder phase.

5. Typical application scenarios

Tungsten carbide sealing rings have a wide range of applications due to their excellent balanced performance:

·Petrochemical (Oil & Gas, Petrochemical): Shaft seals for pumps, compressors, and agitators. Widely used in crude oil transportation, refineries (atmospheric and vacuum, catalytic cracking, hydrocracking), ethylene units, synthetic ammonia, methanol, PTA, etc., to handle hydrocarbons, oils, solvents, acids (requires nickel base), alkalis (requires nickel base), and high-temperature liquids.

·Chemical Processing: Pumps and reactor stirring shaft seals involving various highly corrosive media (acids, alkalis, salts, solvents). Nickel-based WC is the standard for highly corrosive environments.

·Pulp & Paper: Pump seals for handling pulp, black liquor, bleach, etc.

·Pharmaceutical & Food/Beverage: Nickel-based WC that meets hygiene standards (such as FDA) is used for clean pumps (CIP/SIP systems), agitators, etc., to handle liquid medicines, water, syrups, dairy products, etc.

·Water & Wastewater: Pump seals for municipal water supply and sewage treatment plants.

·Energy and Power (Power Generation): Boiler feed water pumps, cooling water pumps, turbine shaft seal auxiliary systems.

·Marine & Offshore: Marine pumps, ballast pumps and other seawater environment seals.

·General Industrial Pumps: All kinds of water pumps, chemical process pumps for various media such as clean water, coolants, hydraulic oils, etc.

·High temperature and high pressure conditions: WC is often used in high temperature (>150°C) or high pressure (>20 bar) sealing occasions (need to cooperate with suitable mating surfaces and good cooling) due to its excellent thermal conductivity and mechanical strength.

·Medium containing particles: Excellent resistance to abrasive wear makes it suitable for handling media containing a small amount of solid particles (but avoid a large amount of hard particles).

6. Design and selection considerations

·Matching pair selection: Absolutely critical! Hard-soft pairing is the mainstream (WC vs. graphite). WC vs. SiC is suitable for more demanding high pressure and high speed conditions. Avoid WC vs. WC.

·Binder selection: Determined by the corrosiveness of the medium. Cobalt-based is used for non-corrosive and nickel-based is used for strong corrosion. The medium composition, concentration, temperature, pH value, and oxidizability must be clarified.

·Cooling and flushing: The high thermal conductivity of WC is very important, butgood cooling (API flushing plan Plan 11, 13, 21, 31, 32, 41, etc.)is still required to control the end face temperature rise, especially under high PV values. Avoid dry friction. Sealing chamber insulation/heating also affects the end face temperature stability.

·Structural design: Usually designed as a flat annular structure (to avoid thermal deformation due to excessive thickness), combined with elastic elements (such as bellows, springs). Consider the influence of thermal deformation and use an asymmetric structure when necessary.

·Tolerance and surface quality: The requirements for flatness, parallelism, and surface roughness are extremely strict (the light band is continuous, uniform, and tight).

·PV value (Pressure x Velocity): WC sealing rings can withstand higher PV values, but the specific limit depends on cooling, matching materials, and design. High PV value means high heat load.

7. Advantages summary

1. Excellent wear resistance: Resistant to abrasive, adhesion, and abrasion wear.

2. Extremely high hardness: Ensure the geometric stability of the sealing surface.

3. Both strength and toughness: High compressive and bending strength, resistance to impact and deformation.

4. Excellent thermal conductivity: (especially cobalt-based) effectively conducts friction heat and reduces end surface temperature rise.

5. Low thermal expansion coefficient: Good dimensional stability and reduced thermal deformation.

6. Chemical stability: (especially nickel-based) performs well in a wide range of media.

7. Mature, reliable, and widely used: Decades of successful application history and mature technology.

8. Disadvantages and Challenges

1. Limited corrosion resistance of cobalt-based materials: susceptible to corrosion in acidic and oxidizing media. Wrong material selection is a common cause of failure.

2. Relatively high cost: more expensive than ordinary metals and ceramics, but extremely cost-effective.

3. Sensitive to scratches: the surface is hard but brittle, and the surface should be protected from scratches by hard objects after precision machining. Assembly requires extreme care.

4. High friction coefficient (improper pairing): if improperly paired with hard surfaces such as SiC, the friction coefficient and heat generation will increase dramatically.

5. Nickel-based WC has slightly lower thermal conductivity and toughness: a trade-off is required when heat dissipation requirements are extremely high or impact resistance requirements are strong.

6. Possible thermal cracking: under extreme thermal shock or insufficient cooling, especially when hard pairing or high PV values.

7. High density: may increase the risk of imbalance of high-speed rotating parts (but usually within a controllable range).

9. Analysis of common failure modes

·Binder corrosion (mainly cobalt-based): In a corrosive environment, the binder dissolves and the WC particles fall off, resulting in excessive wear and leakage.

·Thermal cracking: The local temperature gradient of the end face is too large, resulting in excessive thermal stress and forming a network of cracks (mostly seen in insufficient cooling, dry friction, frequent startup, hard-to-hard matching, and high PV value).

·Coking/carbon deposition: The medium carbonizes on the end face at high temperature, hindering contact and causing leakage or dry grinding.

·Severe adhesion/scratching: Improper matching, insufficient lubrication, and large startup impact lead to large-area adhesion welding.

·Abrasive wear: Hard particles in the medium cause excessive wear and groove marks on the end face (although wear-resistant, it cannot withstand continuous erosion by a large number of hard particles).

·Deformation of the sealing ring: High pressure, thermal deformation or uneven load leads to flatness damage.

·Scratches/breakage: Installation, disassembly or hard objects in the medium cause damage to the precision end face.

·Oxidation/Rust: In high temperature oxidizing environment (such as hot water, steam), cobalt base is easily oxidized into powdery oxide.

10. Comparison with other sealing ring materials

·VS Alumina Ceramic (Al2O3):

oWC:Higher hardness and strength, better toughness, excellent thermal conductivity. More impact resistant, better heat dissipation.

oAl2O3:More brittle, poor thermal conductivity, extremely sensitive to thermal shock, low cost. Used in low pressure, clean water and other mild working conditions.

·VS Silicon Carbide (SiC - including reaction sintering/pressureless sintering):

oWC:Better toughness (Co-based), thermal conductivity is equivalent to or slightly better than RS SiC (Co-based). More resistant to impact loads,usuallyless corrosion resistance than high-purity SSiC/NSSiC.

oSiC:Highest hardness, best wear resistance, best chemical inertness (especially SSiC/NSSiC),more resistant to high-temperature oxidation. Slightly inferior toughness (much better than Al2O3), high-purity SiC costsmuchmorethanWC.

·VS Impregnated Metal Graphite/Carbon Graphite:

oWC: Extremely high strength and hardness, high rigidity, butusually used as a hard ring.

oCarbon Graphite: Used as a soft ring (matching material), with good self-lubrication.

·VS Engineering Plastics/PTFE: Mainly used as a soft ring or non-contact sealing surface. Cannot be directly compared with the performance of hard surfaces.

·VS Stainless Steel: Stainless steel has low hardness and poor wear resistance. It is mainly used as a base or sleeve, and rarely used as a sealing surface (unless specially coated).

Summary and comparison: WC is one of the materials with the most balanced performance: while maintaining extremely high hardness and good wear resistance, it has high strength and excellent toughness (thanks to the binder metal phase), especially cobalt-based WC has very good thermal conductivity. This makes it extremely reliable and long life when dealing with high pressure, high speed, and medium temperature range conditions (especially oils, hydrocarbons, and non-strongly corrosive water-based media). Nickel-based WC provides high-performance solutions in the corrosive field. While SiC may be superior in terms of hardness and corrosion/high temperature resistance, WC’s toughness and impact resistance make it advantageous in applications prone to vibration, shock, or where misalignment may be a problem.

Conclusion

Tungsten carbide seal rings are a cornerstone material in the mechanical seal space, representing an exceptional combination of performance, reliability, and relatively broad adaptability. Understanding the interdependencies of its composition (WC + binder), excellent physical and mechanical properties (hardness, strength, thermal conductivity, low CTE), chemical resistance (especially considering the binder), key manufacturing processes (especially HIP densification), and mating surface design is critical to properly selecting and optimizing a sealing system for a specific application. Whether handling common hydrocarbon, water-based fluids, or in more aggressive chemical environments (nickel-based WC is an option), tungsten carbide seal rings play an integral role in ensuring efficient, long-life, low-leakage operation of rotating equipment. Continued material improvements and processing technology advancements (e.g., finer grains, nanostructures, improved binders, advanced HIP processes) will further solidify its dominance in this critical application space. Ultimately, successful sealing applications require combining high-performance materials (such as WC) with sound design, precise manufacturing, correct installation and maintenance.