Wear, corrosion and hardfacing applications product supplier Weartech began distributing a new portfolio of wear-resistant surface treatments, called UltraFlex, last month. The prod- uct is manufactured by Kenna-metal, a global supplier of tooling and industrial materials, and increases the wear performance of components with complex geometries.

UltraFlex provides metallurgical-bonded, void-free cladding that provides longer and more predictable service life for critical components in demanding environments, combining Kennametal’s use of tungsten carbide-based materials with superalloy-based technologies from Kennametal Stellite.

Weartech technical director Adam Wintle states that Kennametal’s UltraFlex portfolio provides a range of material solutions to protect against abrasive, erosive, corrosive, and galling wear needs for base materials, including carbon and alloy steels, stainless steels and cobalt and nickel alloys.

“With the ability to customise thickness and treat complex geometries, the proprietary UltraFlex technology facilitates dramatically extended com- ponent life, more predictable wear and maintenance, higher productivity and reduced operating costs,” he says, adding that UltraFlex protects the geometries in ways that welding cannot.

“Parts with complex geometries, inner diameters and other non-line-of-sight features may experience inconsistent protection when using traditional thermal spray or weld overlay. By comparison, UltraFlex conforms to intricate shapes and small internal diameters and reaches remote locations that traditional hardfacing technologies cannot,” Wintle points out.

The UltraFlex surface treatment can be applied in a range of thicknesses, from about 0.254 mm to 2.03 mm and, depending on the application, the smooth UltraFlex surface can be used as applied or machined to the desired finish.

“Surface treatments with mechanical bonding may not endure harsh environments, owing to porosity and cracking. The proprietary UltraFlex process metallurgically bonds the wear system directly to the substrate, providing a surface with consistent thickness and minimal dilution,” he states.

Wintle further points out that Kennametal’s expertise regarding metallurgical and materials science enables the company to formulate, design and deliver superior protection across the entire spectrum of corrosive and abrasive wear.

“UltraFlex product formulations draw from Kennametal’s depth and breadth of materials science understanding and experience – from cobalt-based alloys addressing corrosion resistance to carbide composites for slowing abrasive and/or erosive wear,” he states.

For components such as severe service valves, Wintle notes that the Stellite alloy-based grade of UltraFlex ensures that there is no cracking or delamination of the surface to protect the substrate.

For components such as the pump bottoms in fluid catalytic cracking units, harsh abrasion and erosion can destroy components within a matter of months, he explains.

“Kennametal’s tungsten carbide-based solution – applied to the wetted surface of the component – has been proven to improve component life by up to four times.”

Pump Impellers
The oil pumps at a US-based Gulf Coast oil refinery recently showed accelerated internal wear, which often results in the entire case having to be replaced. Compared with typical industry pump performance, run lengths were about a month shorter and maintenance-related costs were higher, says Wintle, noting that the application requires pumps capable of withstanding significant catalyst fines.

“The refinery investigated several wear-resistant products for their pumps and found all were limited, owing to the nature of the technologies. Thermal spray coatings and weld overlays could be used in line-of-sight applications, but not for small interior surfaces.

“The refinery found that thermal sprays also registered mechanical bond failures, while preferential erosion of the soft matrix between the hard particles in weld overlays was recorded. Hard diffusion coatings are enough to be punctured by large abrasive particles,” he notes.

Working with Kennametal, the refinery used infiltration-brazed tungsten carbide cladding and UltraFlex to coat the inside of closed impellers that are unreachable by any other means.

The metallurgical bond and a dense, uniform distribution of tungsten carbide particles throughout the coating created good erosion resistance and toughness in complex geometries, he points out.

“Therefore, after 13 months in service, a treated oil pump showed no significant signs of internal erosion. “This technology has also been applied to fluidised catalytic cracking unit fractionator bottoms and debutaniser reboiler services, with no signs to date of increased vibration or loss of hyd- raulic performance,” says Wintle.

Severe Service Valves

Modern valves control the flow of all types, including thin gases, highly corrosive chemicals, super- heated steam, abrasive slurries, toxic gases and radioactive materials.

“There are valves that can also handle temperatures ranging from subfreezing to that of molten metal and the pressure of a high vacuum; up to thousands of pounds per square centimetre,” states Wintle.

He explains that severe-service metal-seated ball valves used in harsh environments are made of exotic metal alloys and, as a result, require coatings to protect the surfaces against a combination of corrosion and wear.

“Thermal spray and Stellite weld overlay coatings are widely used to protect balls and seats. But, as customers require improved performance for longer component life, new material solutions are needed. Kennametal has developed surface treatment technologies that metallurgically fuse advanced metal compositions onto balls and seats, resulting in good wear and corrosion resistance in environments where chemicals are transported, often in very high temperatures,” notes Wintle.

UltraFlex technology enables Kennametal to select the most suitable coating material that will resist specific conditions and offer customers engineered materials beyond standard coatings.