In this project, Argonne National Laboratory (Argonne) and John Crane Inc. will jointly develop an industrial-scale process for forming superlubric coatings based on a graphene-nanodiamond solution. This process will be applied to the dry gas seals of gas compressors and similar equipment, thereby reducing friction in the seals and reducing the leakage of toxic and greenhouse gases through worn seals. By improving the reliability of sealing systems, there is considerable opportunity to reduce emission associated with seal failures, to reduce maintenance costs, and to improve productivity.
Argonne National Laboratory, Lemont, IL 60439
John Crane Inc, Morton Grove, IL 60053
Minimizing friction and wear-related mechanical failures remains one of the greatest challenges in contemporary mechanical systems; the search for new materials, coatings, and lubricants that can reduce such failures continues worldwide. Mechanical shaft seals used in pumps, turbines and centrifugal compressors are critically important components of these systems, which are used in many industries, from paper, pulp, and chemicals to petroleum, oil exploration, and power generating plants. These shaft seals prevent leakage of products from rotating equipment. In many instances the concerned products are toxic gases or hazardous chemicals. The Environment Protection Agency (EPA) has estimated that industrial pumps contribute 12% of total hazardous emissions to the atmosphere. Per the 2014 annual inventory of United States Green House Gas Emissions and Sinks (GHG Inventory), methane emissions reported from compressors for the natural gas production segment was 86,259 metric tons (MT) and for gas process segment was 724,295 MT, and for transmission and storage segment was 1,261,080 MT, for a total of 2,071,633 MT of methane released into the atmosphere.
One method of reducing these leaks is to make seals that is coated with diamond and graphene material that exhibits superlubricity. Superlubricity is the state in which the friction between two sliding surfaces is reduced to nearly zero (coefficient of friction, CoF < 0.005). Superlubricity is highly desirable in order to minimize friction in real-world engineering applications. In a major breakthrough the Argonne team demonstrated for the first time that superlubricity can be achieved at true macroscale in a dry environment by the addition of nanodiamonds and graphene flakes between two surfaces, one made of silicon and one made of diamond-like carbon. In this system, the coefficient of friction was just 0.004, significantly reducing friction losses. The tribological conditions, such as contact pressure, environment, velocity and tribo-pair, used in these tribological tests are compatible with required conditions for John Crane’s gas seal applications; it is therefore appropriate to further develop Argonne’s technology for John Crane’s gas seal applications.
The benefits of graphene coating make an excellent value proposition for John Crane clients in all industries. Project team estimate that this technology, once fully developed and qualified, can be successfully commercialized in 1-2 years. John Crane’s position as a market leader known for its technology developments could successfully introduce graphene coatings into the market based on the company’s extensive manufacturing, distribution, qualification capabilities, and customer base. In addition to the key critical advantages mentioned above, the proposed technology can offer the following benefits consistent with DOE’s ongoing efforts:
John Crane tested the performance of various solid lubricants developed for the DoD tests and down-selected one solid lubricant, which performed well in both dry nitrogen and air atmospheres. More optimization of the solid lubricant is necessary to extend its performance life and is underway. Argonne characterized the tested DoD parts received form John Crane in December 2018. Based on the analysis: