A Linde paper suggests using hydrogen or fuel gas with nitrogen in the arc spray coating process “significantly improves productivity and safety”.

The paper is due to be presented at tomorrow‚s International Thermal Spray Conference and Exposition, held at the Hilton Americas Hotel in Houston, Texas.

Arc spaying is a coating process in which materials, such as zinc wire, are heated to form minute (atomized) particles that are sprayed onto a surface to render it corrosion resistant.

The makeup of the process gas can have a significant impact on the thickness of the coating.

The Linde paper, entitled “New Developments Using Arc Spraying to Produced Tailored Coatings”, authored by Werner Kroemmer and Peter Heinrich, project managers for Thermal Spraying at Linde Gases Division‚s application development laboratories in Munich, Germany, provides details on the production enhancement gained from adding a small amount of a fuel gas, such as hydrogen, ethylene or acetylene, to nitrogen as the process gas.

Using a series of tables and charts, the authors demonstrate how the coating thickness increased using a gas mixture versus conventional single process gas such as nitrogen or compressed air.

As coating thickness increases, fewer passes over the targeted surface are required, which results in increased productivity.

“Based on the data ascertained, it can be established that when using compressed air as the atomizing gas, the deposited coating is thinner than with gas mixtures which provide more energy for the fusing process”,

Kroemmer points out in the paper.

“Based on the fuel gas concentration, it can be determined that for a concentration of 3% to 4% hydrogen in nitrogen, a maximum was registered. The same can be determined for the gas mixture nitrogen/ethylene.”

The Linde researchers also investigate the impact of the fuel gas mixtures on dust particle size which were substantially reduced using hydrogen or fuel gas, compared with compressed air in the process gas. This leads to a commensurate improvement in workplace environment and safety.

The Texas conference began today (Monday) and finishes on Thursday 24th of May.