The HVAF process provides a slightly different (to HVOF and other thermal spray processes) and unique combination of thermal and kinetic energy, which presents a technical challenge to material manufacturers who have over the past years optimized their material offerings to the demands and characteristics of plasma, combustion and more recently the various HVOF processes. The recent development of HVAF ID torches, capable of applying the highest quality coatings into dimensions of less than 100mm (4”), has provided a further need to optimize spray materials for the best possible interaction between the spray device and the feedstock in order to meet developing coating specifications from various industries. This paper will discuss the methodologies utilized from the points of view of torch design, material manufacture, spray parameter and procedure optimization, as a means of producing the highest performing coatings to meet specific industry aspirations.

In Solid Oxide Fuel Cells (SOFC), thermal spraying has become a preferred process in order to create functional and protective coatings. After a long period of research, SOFC is on the way to become a fully developed technology starting into mass production. Cost aspects of coating generation are becoming decisive. For this reason, thermal spraying has become the preferred process to apply e.g. Manganese Cobalt Iron Oxide (MCF) coatings which prevent the formation of volatile Cr oxides in the SOFC air supply and off-gas. Also Lanthanum Strontium Manganese Oxide (LSM) is now preferentially applied via thermal spraying. The presentation highlights the properties of commercially available spray powders for SOFC, their processing via different spray processes, and the properties of coatings achieved.

The present study describes the development of agglomerated and sintered WC and Cr 3 C 2 based cermet powders with complex and highly corrosion resistant Fe and Ni matrix alloys. In addition a Fe-Cr-C with a Ni matrix was tested as a potential low cost alternative to standard Cr 3 C 2 -NiCr powders. The powders were sprayed by HVOF using liquid and gaseous fuel. Microstructure and phase composition of the coatings were analyzed by microscopy and X-ray diffraction. The technical properties of the coatings were examined by hardness measurements, abrasive wear and cavitation tests as well as corrosion tests. The results were compared with state-of-the-art coatings of WC-Co-Cr 86/10/4 and Cr 3 C 2 -NiCr 75/25.

Cobalt containing carbide powders such as WC-Co and WC-Co-Cr for thermal spraying exist in numerous modifications varying in chemistry, carbide size, and production method. They are widely used for wear, erosion and corrosion protection in many industrial fields. However, for decades it has been well-known from the hard metal industry that WC and Co containing hard metals in breathable dust form can provoke severe lung diseases if inhaled. Recent examinations have proven that this toxicity can be significantly reduced if the Co is pre-alloyed by Fe. In thermal spraying employees are also dealing with Co containing carbides, for example in powder and coating production. Therefore, in order to reduce the hazards for health and the environment, a new class of agglomerated and sintered carbide powders using Fe based binder materials have been developed and investigated. In the present study the powders were HVOF sprayed in order to examine the influence of their different composition and morphology on the microstructure and the properties of the coatings in comparison to standard materials. The experiments comprise microstructural examinations, wear and corrosion tests.