This paper informs about the potential dangers associated with the gases used in thermal spraying. These include fuel gases, oxygen, inert gases, and carbon dioxide. The paper addresses the following: flammability, explosion, oxygen enrichment and tolerance, asphyxiation, and low-temperature technology. It presents regulations and leaflets relating to the safe storage, handling, and use of gases with various supply options. Safe working techniques are recommended along with a brief description of the relevant safety equipment. Paper includes a German-language abstract.

Reactive plasma spraying (RPS) with hydrocarbon (HC) gas has been studied as a way to improve the mechanical properties of Ni-Cr alloys and reduce the oxygen content of MCrAlY coatings. A conventional dc plasma torch has been modified by attaching a conical graphite tube (reactor) onto the end of the gun and spraying parameters were adjusted accordingly. Significant improvements have been achieved in terms of both objectives. As test results indicate, the hardness of Ni-Cr alloys has been doubled and the oxygen content in MCrAlY coatings has been reduced by an order of magnitude.

Chromium oxide coatings are currently produced predominantly by the plasma spray process utilizing the high process temperatures required to fully soften the high melting point chromium oxide powder. The development of the HVOF process, combining the relatively high flame temperatures of hydrogen, propylene or propane fuel gases with the notably high particle velocities generated by the process, is known to produces dense, low porosity coatings. By utilizing acetylene, the highest flame temperature fuel gas commercially available, and acetylene based mixtures, the HVOF process can be used to successfully spray chromium oxide powder previously impractical for HVOF systems. This paper describes the results of a programme of work carried out to study the effect of gas related parameters on the properties of Cr 2 O 3 , coatings deposited by HVOF using acetylene and acetylene based mixtures as fuel gases. It further describes the engineering of gas supply systems to overcome the working limitations of acetylene pressures and flowrates to achieve acceptable gas pressures and flow rates and subsequent particle temperature and velocity.