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What is Cemented Tungsten Carbide?

“Carbide” is often used as a generic term for the composite material containing hard particles composed of tungsten carbide, along with softer, metallic binder used to hold or “cement” the particles in place.

The creation of this material starts with Tungsten ore that is refined into Tungsten powder (W).  The Tungsten powder is combined with Carbon (C) and heated to high temperature causing the Carbon and Tungsten to chemically bond forming Tungsten Carbide (WC). After cooling, the material is crushed and screened into a powder, with specific grade sizes.

Making the Grade:

When the WC powder is then blended with powdered binders, typically Cobalt or Nickle, as well as other additives, you create a “graded powder”. Each grade has different amounts of WC and binders added, as well as varying grain size of the WC powder.  Centrifuge wear parts are typically 6-10% binder, with balance made of WC, and grain sizes of under 1 micron to 3 microns in size, and with corrosion resistant additives.

Shaping the Powder:

Pressing the graded powder in a die with a hydraulic press is the most economical method for smaller parts that are mass produced. Our centrifuge tiles are made using this method.

Manufacturing large or complex parts like feed and discharge nozzles, require the graded powder to be compacted into “billets” by hydrostatic pressure. By whichever of the two methods the carbide has been compacted, it is still very soft, chalk like material and is referred to as “green’’. If required, the green compact can be shaped by conventional methods of turning, drilling, milling, or grinding to create a “preform”. We are also able to produce carbide preforms using Additive Manufacturing.

Sintering:

The carbide “preform’’ is then placed on a tray that is loaded into a sintering furnace and heated to the melting point of the binder, generally 2,500°F to 2,800°F. Sintering causes the part to shrink by about 20% in linear measurement and approximately 50% by volume. After cooling, you are left with a hard carbide blank. 

Finishing:

The carbide can be used “as-sintered” and brazed to steel, as with our tiles, epoxied and mounted with steel for certain discharge nozzles, or even finished to exact tolerances for components with critical fit.

 

What is Cemented Tungsten Carbide?

We offer a wide variety of carbide grades including submicron, fine, medium, and coarse-grained tungsten carbides with a mixture of binders and additives to create the right balance of hardness, toughness, abrasion and corrosion resistance for the application. 

Finishing:

The carbide can be used “as-sintered” and brazed to steel, as with our tiles, epoxied and mounted with steel for certain discharge nozzles, or even finished to exact tolerances for components with critical fit.

Wear Resistance

Generally, grades with more binder or coarser grains, (lower hardness), the wear or abrasion resistance will be less. However, there will be an increase in strength. It is always necessary to balance high hardness/ high wear resistance with lower hardness/high strength. To test the abrasion or wear resistance of our carbide grades, we typically conduct a dry sand (G65) or slurry test (B611). 

Strength

The amount of binder and the variation in grain size will also affect the impact strength (a shock load) and the fracture toughness (a measure of crack initiation and crack propagation). More binder and/or coarser grains will generally increase the impact strength and the fracture toughness. With submicron grained grades, impact strength and the fracture toughness decrease when compared to coarser grained grades of equal cobalt content; however, hardness increases.

Grade Name

Binder

Binder

(wt %)

Hardness

Grain Family

HRA

HV30

KFS33

Co

6

93.0

1800

Submicron

KFS64

Co

10

91.8

1590

Submicron

KFM65

Co

11

89.7

1310

Medium

HARC

Co-Cr

6.9

93.3

1850

Fine

K701*

Co-Cr

10

92.4

1680

Fine

CNC68

Co-Ni-Cr

6.5

93.4

2000

Submicron

CNC10

Co-Ni-Cr

8.5

90.5

1410

Fine

KR855

Co-Ni-Cr

10

91.8

1580

Submicron

KR466

Co-Ni-Cr

12

90.0

1355

Fine-Medium

CN13S

Co-Ni-Cr

12.5

88.7

1220

Coarse

KR887

Co-Ni-Cr

15

90.2

1370

Submicron

HAN6

Ni

6

90.5

1410

Medium

GTD

Ni-Cr

9.2

91.6

1550

Fine

HAN10

Ni

10

90.0

1340

Fine

 

*K701 is not able to be brazed

Additional Cemented Tungsten carbide materials available, as well as ROCTEC and Stellite options