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2453 |
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Properties of nanostructured composite titanium coating on aluminium surface |
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Yuriy Tyurin / E.O.Paton Electric Welding Institute, NASU , Ukraine Oleg Kolisnichenko/ E.O.Paton Electric Welding Institute, NASU, Ukraine Oleg Ivanov/ Belgorod State University, Joint Research Center , Russia Marina Kovaleva/ Belgorod State University, Joint Research Center , Russia |
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The cumulative-detonation technology is created for deposition of nanocomposite titanium powder coatings on the aluminium alloys samples. The gas mixture consumption (propane-oxygen-air) is 5 <3 per 1 kg of powder. The coating (130 µm thickness) is uniform, dense, with a good adhesion to the substrate. A thickness of lamellas in the coating is 100 - 1000 nanometers. Hardness of thin lamellas in the coating is 1590±120 HV0,01. The particles of deformed titanium has hardness 244±21 HV0,01.. And hardness of the substrate under the coating varies to a depth of 100 mm from 190 HV0.01 to an average hardness of the sample material equal to 160 HV0.01. Lamellas consist of the dislocation-free titanium nanocrystalline grains 30 nm in size, separated by interlayers of the amorphous phase (C, Al), and nanocrystallites of titanium oxide and titanium carbide with a cubic lattice. The main phase in the coating layer is Ti with face-centred close-packed structure (a = 2.965 Å) There are also following phases in the coating: TiC with cubic lattice (a = 4.349 Å), and TiO with cubic lattice (a = 4.027 Å). The deforming of coating by a spherical diamond indenter of the Rockwell C has shown that indenter monotonously penetrates into the coating within a load range of 0.9 to 200 N. The loss of the coating to substrate adhesion strength was fixed from a dramatic increase in the indenter penetration depth (~ 160 mm), a small jump of the acoustic emission signals and elemental analysis of traces of deformation by the diamond indenter under a load of 184.3 N. Therefore, the loss of the cohesion strength of the coating at a load on the indenter equal to 93.N, and the loss of the coating to substrate adhesion strength at a load of 184.3 N were fixed. |