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Tungsten carbide is used in many different applications, from wedding rings to drill bits. As an integral part of the coating world, tungsten carbide coatings help many heavy industrial companies stay up and running longer. However, not all tungsten carbide coatings are the same. There are many different chemical compositions of tungsten carbide thermal spray coatings with varying percentages of tungsten carbide and various metals to tailor the coating for different environments.

Tungsten carbide itself is a ceramic and, therefore, very hard but brittle. With the addition of metals, like cobalt and nickel, users can increase the ductility of the overall coating and improve its performance. There are countless different formulas and compositions, but the ones briefly explored in this article are tungsten carbide cobalt, tungsten carbide nickel, and tungsten carbide cobalt chrome.

Tungsten Carbide Cobalt

Tungsten carbide cobalt (88WC 12Co) is a wear coating that helps with sliding wear, abrasion, and fretting resistance. As a rule, thermal spray coatings don’t typically handle impact or point loads well, but tungsten carbide cobalt does offer some impact wear resistance. Tungsten carbide cobalt is not very corrosion resistant; therefore, it is best in dry environments.. One great application for this material is feed rolls, whether for paper, sheet metal, or other products.

Tungsten Carbide Nickel

Tungsten carbide nickel (90WC 10Ni) is also a wear coating but offers more corrosion resistance at a lower hardness. It also resists sliding wear, abrasion, and fretting. Since this tungsten carbide does not contain cobalt, it will not degrade in a radioactive environment. It works great for ball and gate valves among other applications — Fig. 1.

Tungsten Carbide Cobalt Chrome

Tungsten carbide cobalt chrome (86WC 10Co 4Cr) is a wear and corrosion-resistant coating often used as a hard chrome plating alternative. It is harder than both tungsten carbide cobalt and tungsten carbide nickel, reaching up to the 70 HRC range, and excels in abrasion wear resistance and erosion fretting resistance. Tungsten carbide cobalt chrome is the one our shop uses most of the three and can also be applied via the high-velocity air fuel (HVAF) process creating a much more ductile and harder coating with superior corrosion resistance than high-velocity oxygen fuel applied tungsten carbide cobalt chrome — Fig. 2.

Different Tungsten Carbide Coatings for Different Applications

Each of the previously mentioned tungsten carbide coatings will provide wear resistance and extend the service life of parts. The key to finding the best solution for your piece is matching the right chemical composition to the right operating environment. For instance, some coatings will do better than others in wet or corrosive environments. Temperature limitations are also another factor to watch for in coating selection. It is often best to work with a reliable thermal spray company to determine which one is right for your project.