Atmosphere Carburizing Using Electric Discharge-Activated Nitrogen-Natural Gas Mixtures

The service life of stainless steel wire mesh belts in sintering furnaces is limited, because material deterioration results in wire fracture. A newly developed humidification system establishes a furnace atmosphere that maintains a protective oxide scale on the belt surface throughout the sintering process and at the same time creates an environment that is reducing to the sintered metal compact. This work includes thermodynamic calculations of the furnace atmosphere dew points that satisfy these oxidation / reduction criteria. Scanning Electron Microscopy, combined with Energy-dispersive X-ray Analysis, and mechanical testing methods have been used to compare belts that have undergone the same length of service in a nitrogen-hydrogen atmosphere and in an atmosphere that was modified using the newly developed humidification method. The material examinations have revealed that the new humidification system significantly extends the service life of stainless steel belts.

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A new, cryogenic nitrogen gas (-195oC) cooling system has been developed which limits the thermal expansion and substrate softening problems, and enables a non-stop, gun-on-target spraying. Fully automated, the operation of the new AP LIN-Cooling System is based on thermal imaging of the entire substrate and multi-zone cooling with novel, cryofluidic nozzles. Thermal logs and images of components processed are saved by the system for quality auditing purposes. This paper presents results of industrial tests of the system during WC-10Co4Cr coating of Boeing 737 landing gear, demonstrating a 50% reduction in spraying time, corresponding reductions in the consumption of powder and HVOF gases, and additional labor savings due to the use of flexible masking, unfeasible with the traditional cooling methods. Analysis of residual stresses, structures and properties of the coating and AISI 4340 steel substrate shows that the cryogenic nitrogen cooling results in high-quality products.

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A cryptocurrency mining operation is expanding a multi MegaWatt facility. They needed an air cooled cooling solution for their single phase liquid immersion cooling tanks. They have multiple tanks each requiring over 1500 gallons per minute of BitCool immersion fluid to be pumped to the fluid-to-air heat exchangers. Dry Coolers provided modular pump solution with steel base, valving, electrical isolation, and pressure and temperature transmitters.

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