Craig FitzGerald of ISO-Reliability Partners introduces Graphalloy®, a self-lubricating composite graphite-metal material that can operate without conventional lubrication, even in high-temperature, chemically aggressive or inaccessible environments.
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In industrial operations where traditional bearings are prone to failure, a unique material has steadily built a reputation for reliability under extreme conditions. That material is Graphalloy®, a graphite-metal alloy renowned for its ability to operate without conventional lubrication, even in high-temperature, chemically aggressive, or inaccessible environments.
Developed by the Graphite Metallizing Corporation, Graphalloy® has become a preferred solution for engineers seeking long-lasting, maintenance-free performance in sectors ranging from power generation to chemical processing. Its distinct structure combines the inherent lubricity of graphite with the mechanical strength of metals such as nickel, bronze, copper or silver. The result is a material that not only withstands harsh conditions but excels in them.
A true composite
Graphalloy® is not a simple mixture or coating but a true composite. The manufacturing process involves machining high-purity graphite into the required shape, then impregnating it with molten metal under vacuum or pressure. This infusion permeates the graphite’s porous matrix, enhancing its strength while preserving its natural self-lubricating characteristics. The outcome is a solid, homogenous material that offers a rare combination of dimensional stability, wear resistance and thermal resilience.
One of the standout qualities of Graphalloy® is its thermal capability. Unlike conventional lubricated bearings, which often fail as lubricants evaporate, degrade or ignite, Graphalloy® maintains performance at temperatures up to 538°C in oxidising environments, and up to 400°C in steam. This makes it particularly valuable in applications such as ovens, kilns, and turbines, where high heat is a constant factor.
Impressive mechanical properties
The mechanical properties of Graphalloy® are equally impressive. It exhibits a low coefficient of friction, even under dry-running conditions. It does not seize or gall, making it ideal for oscillating or rotating motion. The material also offers high resistance to wear and maintains its dimensional integrity across a wide temperature range, thanks to its low thermal expansion.
Crucially, Graphalloy® resists attack from a broad range of chemicals, including acids, alkalis and solvents. This makes it suitable for use in some of the most aggressive industrial environments, where corrosion and contamination are persistent concerns.
Available in over 100 grades
Graphalloy® is available in various grades, each tailored to specific conditions. For example, nickel-based grades are often used in food processing or pharmaceutical settings due to their corrosion resistance and compliance with hygiene standards. Other grades are designed to handle dry start-up conditions in pumps or continuous operation in high-temperature conveyors.
The applications of Graphalloy® are wide-ranging. In the pump industry, it is frequently used for sleeve bearings in vertical or submersible pumps, where conventional materials often fail during dry start-up or intermittent flow. In valves, particularly those handling steam or corrosive gases, Graphalloy® bushings provide consistent performance without lubrication, even after extended periods of inactivity.
Temperature and chemical resistance
In high-temperature environments such as industrial ovens or conveyor systems, Graphalloy® eliminates the need for lubrication, preventing dripping or smoke, a significant advantage in industries such as food production or textiles. The material’s chemical resistance also makes it ideal for components in mixers, agitators and pumps operating in corrosive environments, including those containing acids, ammonia or chlorine gas. Even in the nuclear sector, Graphalloy® is used in valve stems and bushings where radiation, pressure and heat demand exceptional material performance.
In addition to these benefits, Graphalloy® offers important operational advantages. It requires no maintenance or lubrication systems, significantly reducing downtime and associated costs. It can operate continuously or intermittently without the need for supervision, making it suitable for remote or hazardous locations. Graphalloy® does not contaminate products, making it environmentally friendly, and contributes to safer operations by eliminating the risks associated with lubricant leakage or failure.
Application-specific conditions
Despite these advantages, Graphalloy® is not without limitations. It typically carries a higher initial cost than traditional bearing materials such as bronze or PTFE. It also has a lower load capacity compared to hardened steel and can be brittle under impact. Furthermore, it is sensitive to thermal shock, which can, if not effectively managed, cause cracking in certain grades. These factors mean that engineers must consider application-specific conditions such as load, speed, temperature and environment when selecting Graphalloy®.
When compared to other common bearing materials, as shown in Table 1, the advantages of Graphalloy® become particularly evident.
Real-world applications
In real-world applications, the advantages of Graphalloy® translate into tangible operational gains. For instance:
In a steel mill’s hot rolling line, Graphalloy® bearings replaced lubricated roller chain bearings that had been failing weekly due to lubricant breakdown.
Following the switch, maintenance intervals were extended to over a year, with no unexpected downtime.
In a chemical processing facility, Graphalloy® components were installed in a sodium hydroxide mixing tank. They operated continuously
for five years without showing signs of wear or corrosion, a remarkable improvement over the previous sealed bearing system.
A nuclear power station using Graphalloy® in its steam valve assemblies reported reduced maintenance schedules and improved
system responsiveness under high-pressure and temperature
conditions.
Dependable, low-maintenance solutions
Graphalloy®’s success is rooted in its ability to solve complex problems in environments where other materials simply cannot cope. Its blend of mechanical strength, chemical stability and self-lubrication makes it an ideal candidate for engineers seeking dependable, low-maintenance solutions. While the upfront cost may be higher, the lifecycle cost benefits, including reduced downtime, lower maintenance and improved safety, are substantial.
As industries move toward more resilient, efficient and sustainable operations, materials such as Graphalloy® are becoming increasingly important. In an age where performance under pressure is not just desirable but essential, Graphalloy® stands out as a material that delivers quietly, consistently, and under the most punishing of conditions.
A range of graphite-metal/alloy bushings and bearings is available from ISO-Reliability Partners. “Graphalloy® is an ideal solution for any bearing or bushing application where lubricants fail due to the surrounding environment,” says Craig FitzGerald.
ISO-Reliability Partners is an original equipment manufacturer (OEM) of class-leading micro-fine oil filtration solutions. ISO owns the iconic Filter Focus brand of vacuum dehydration systems, automated water removal for compressed air, and high-efficiency industrial air scrubbing. “Our high production standards ensure customer satisfaction and unrivalled protection of their critical production equipment,” concludes FitzGerald.