Microstructural and Mechanical Properties of Ni-Base Thermal Spray Coatings Deposited by Flame Spraying
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coatings is one of the most effective strategies to protect materials against corrosion and to increase the wear resistance of materials. This allows for developing components with optimized surface behavior using cheaper or more processable materials, like mild carbon steel. Different coating alternatives of carbon steel can be found in the literature: stainless steel,[1,2] 100Cr6 steel,[3,4] Mo,[5,6] organic coatings,[7,8] ceramic coatings,[9,10] and WC-Co.[11,12] Thermal spray is a technique that produces a wide range of these coatings BRADAI MOHAND AMOKRANE and SADEDDINE ABDELHAMID, Assistant Professors, are with the Laboratory of Technology of Materials and Engineering of the Processes, Faculty of Technology, University of Bejaia, 06000 Bejaia, Algeria. Contact e-mail: [email protected] MOUADJI YOUCEF, Assistant Professor, is with the Laboratory of Mechanic, Faculty of Science Engineering, University of Constantine, 25000 Constantine, Algeria. BENABBAS ABDERRAHIM, Professor, and BOUNAR NEDJEMEDDINE, Assistant Professor, are with the Laboratory of Interaction Materials and Environment, University of Jijel, 18000 Jijel, Algeria. MAMMERI AHMED, Assistant Professor, is with the E.T.S. Industrial Engineering, University of Oviedo, Campus, 33203 Gijon, Spain. Manuscript submitted February 14, 2011. Article published online July 28, 2011. 932—VOLUME 42B, OCTOBER 2011
for diverse applications. The principle of thermal spray is to melt material feedstock (wire or powder) to accelerate the melt to impact on a substrate where rapid solidification and deposit build-up occurs.[13] Thermal spraying uses two principal energy sources, chemical energy of the combusting gases that power the flame spray torches (e.g., high velocity oxygen fuel (HVOF) spraying) and electric currents providing energy for the plasmatons (e.g., atmospheric plasma spraying (APS)). All these techniques allow for the deposition of coating on materials generally ductile to improve their corrosion and wear resistance. Nevertheless, more traditional electric arc wire spray and combustion flame spray are still widely used.[14–17] The flame spray deposition technique has several disadvantages compared with the HVOF or APS methods, including a bigger grain size microstructure, pore size, and crack length, but it also has certain advantages, such as its being more economical, easier to handle, and more adaptable to the manufacturing process with a short series or recovery of pieces. Flame spray was the first thermal spray process developed. Modern torches have changed, and the high particle velocities are in the range of 200– 300 m/s. Oxyacetylene torches are using acetylene as the main fuel in combination with oxygen to generate high combustion temperatures and particle temperatures around 2873 K (2600 C).[13] In recent years, thermally sprayed nickel-based alloys are used in a variety of applications, e.g., as bond coats for thermal barrier coatings on turbine components, as restorative layers for machine parts, as bond coats in internal combustion engine cylinder
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