Coatings of Metal-Matrix-Composite (MMC) with enhanced wear resistance were created by thermal spraying. The used powders composed of iron and nickel aluminides reinforced with alumina, Cr- and Ti-carbides were produced before by self-propagating high temperature synthesis (SHS). The fused and crushed composite powders were sprayed by atmosphere plasma spraying (APS) and gas detonation spraying (D-Gun). Spray powder and coating properties like morphology, structure, microhardness, porosity, bond strength, wear and corrosion resistance are examined using optical and scanning electron microscopy, XRD analysis, pin-on-disc (wear resistance). The produced MMC coatings are compared to commercially used wear resistant coatings, e.g. high velocity oxyfuel flame sprayed Cr 3 C 2 -NiCr. The properties of a special coating type depend on the used spraying method. Plasma sprayed MMCs show a slightly higher porosity than D-Gun sprayed coatings. The chemical composition of used powders has a big influence on the coating properties. Fe- and Ni-aluminide matrix coatings reinforced additionally with carbides, especially Cr 3 C 2 , show a better wear resistance compared to coatings containing just oxides as hard material.

Iron aluminides show great potential for use in high-temperature oxygen and sulfur environments, but the intermetallic phases of the Fe-Al system tend to be brittle. This paper describes a powder making process in which FeAl phases are reinforced with inclusions from other intermetallic phases that arrest cracks and prevent them from spreading. Thermally sprayed coatings produced from these SHS powders are analyzed with regard to their composition and structure. Paper includes a German-language abstract.

In this paper, metal matrix composite layers are produced by thermal spraying using cored aluminum wire. Two types of wire were produced, one containing mechanically alloyed Al and Cr 2 O 3 powders, the other, Al and AI 2 O 3 . The powders undergo self-propagating high temperature synthesis during the spraying process, which has a positive effect on coating properties such as bonding, cohesion, and wear resistance. Different spraying methods were used in the experiments, but satisfactory results were only achieved via atmospheric plasma spraying. Paper text in German.

Aluminum coatings reinforced with either Al 2 O 3 or SiC particles were deposited onto aluminum substrates and subjected to various tests. The coatings were made with mechanically alloyed powders via atmospheric plasma spraying (APS). Both types of coatings had uniformly distributed hard particles, porosities in the range of 4 to 5%, and bond strengths of around 20 MPa. The wear resistance of the SiC-reinforced coatings, however, was almost 35% higher than the coatings containing Al 2 O 3 . X-ray examination (XRD) showed that the Al 2 O 3 particles undergo partial phase transformation during spraying, making them more prone to wear.