Mechanical and Corrosion Properties of ZrB2–SiC Composite Ceramics with Oxide Additions

Powder Metallurgy and Metal Ceramics - Hot pressing was used to produce compact ceramic samples with the following composition (wt.%): 60 ZrB2 + 20 SiC + 20 (Al2O3 + 32 t-ZrO2). The tetragonal...     

Formation of electric-spark coatings from composite materials based on titanium-chromium carbide and diboride

Electrode composite materials of the TiCrB₂-(Fe-Cr) and TiCrC-(Fe-Cr) systems are discussed. The composition, structure, mechanical and tribotechnical properties of the materials have been studied. Coatings from the materials developed have been applied to the 30KHGSA steel and VT3-1 titanium alloy. The effect of the length of electric-spark alloying and electrode and substrate materials on the mass-transfer kinetics has been analyzed. It has been shown that the materials developed can be successfully deposited onto steels and titanium alloys by the electric-spark method.     

Formation of a Corrosion-Resistant Layer on Steel by Reaction with a Si3N 4 ― Al2O3 Composite under the Conditions of Light-Thermal Treatment

The formation of a surface layer on low-alloyed steel during light-thermal treatment with a composite material based on Si₃N₄ Al₂O₃ was investigated. The working surfaces were studied using metallographic, x-ray diffraction, and electron-probe microanalysis. It was found that the corrosion-resistant phases Al₂SiO₅, (Fe, Cr)₂O₃, (Cr, Al) ₂O₃, and NiCrO₄ formed in the alloyed layer, increasing its microhardness by 2-5 times and its corrosion resistance in sea water by more than two orders of magnitude.     

Protective Coatings on Heat-Resistant Nickel Alloys (Review)

The literature on materials for protective coatings on heat-resistant nickel alloys and methods for their production is reviewed in order to generalize the results and determine the principal directions for solution of the problem under consideration. It is shown that a promising approach is the development of layered composite ceramic coatings which, thanks to a graded variation of properties, are able to provide an optimal combination of adherence, mechanical strength, and corrosion and heat resistance. The methods of physical vapor deposition, plasma spraying, and electron-beam deposition remain the principal industrial processes for coating deposition.     

Plasma coatings of (TiCrC)-(FeCr) composite powder alloys: Structure and properties

The coatings of the (TiCrC)-(FeCr) composite are deposited on steel and titanium alloy by plasma method. The composition, structure, and tribotechnical properties of these coatings are studied in comparison with traditional materials based on the Ni-Cr alloy. The effect of preliminary surface treatment methods, i.e., sandblasting treatment and electrospark alloying, on coating properties is examined. The fretting corrosion of coatings is investigated. It is established that coatings based on double titanium-chromium carbide have considerably greater wear resistance than that of Ni-Cr alloys at almost equal friction coefficients. It is established that electrospark alloying is competitive with traditional sandblasting treatment in environmental effect and coating-to-based adhesion. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 37–45, 2007.     

Microstructure of fracture of a laser–electric spark coating on titanium after abrasive wear

We present results of a study of the microstructure of a ZrB₂-containing combined laser–electric spark coating deposited on a titanium alloy and subjected to wear with a nonrigidly fastened abrasive performed by scanning electron microscopy in combination with an electron-probe microanalysis. It is established that the coating is characterized by a gradient microstructure over the thickness, and its subsurface layer is modified by Zr, O, Si, and C additives. We put forward the assumption that an increase in the hardness of the coating after abrasive treatment is due to its plastic deformation with the fragmentation of the structural elements and alloying with the indicated additives.