To achieve high deposition rate and efficiency, electric arc spraying has been routinely used to deposit carbon steel coatings. Although retention of carbon in these coatings is poor due to the use of compressed air during spraying, the coatings are sufficiently hardened by brittle iron oxide inclusions to be suitable for hardfacing mechanical components used in mild adhesive and abrasive wear environments. However, carbon steel coatings can be employed for hardfacing mechanical components used in more aggressive wear environments, provided they are hardened by the carbon retention rather than by iron oxide inclusions. Therefore, to increase retention of carbon, reduce inclusion of iron oxides, and improve hardness and wear properties of carbon steel coatings, deposition experiments were carried out using an inexpensive nitrogen, which is produced on-site by a pressure swing adsorption or a membrane separation system, instead of compressed air during spraying.

Carbon steel coatings can be employed for hardfacing mechanical components used in moderately aggressive wear environments, provided they are sufficiently hardened by retained carbon. However, when thermal spraying using compressed air as the atomising gas, properties of carbon steel coatings are degraded by carbon loss through oxidation and oxide inclusions. It is shown that the physical and mechanical properties of these coatings can be greatly improved by spraying with inexpensive nitrogen produced on site by pressure swing adsorption or membrane separation, without the cost penalties incurred when using pure nitrogen. In some circumstances, such coatings can be used to replace more expensive alloy hardfacing layers.

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Proper specification, measurement, and control of annealing furnace atmospheres are critical to reduce sooting, oxidation, sticking, and distortion. This article describes how to effectively design and utilize a nitrogen-hydrogen annealing atmosphere.

Heat-treating industry is adopting more and more industry 4.0 techniques and solution packages, to improve production process and product quality. Proper specification, measurement, and control of heat-treating atmospheres are always critical to achieving the desired metallurgical and microstructural results. The combination of atmosphere measurements and other furnace operating parameters (e.g., furnace temperature and pressure) can provide a better view of the whole production. Thermodynamic calculations and field experiences can be integrated into the smart solution to provide process engineers more capabilities to manage and optimize production. In this article, our recent research and development work on smart solutions for the heat-treating industry will be presented and discussed.