Properties of Nickel Powder Alloys Hardened with Titanium Carbide
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PROPERTIES OF NICKEL POWDER ALLOYS HARDENED WITH TITANIUM CARBIDE T. S. Cherepova,1, 2 H. P. Dmytrieva,1 О. І. Dukhota,3 and М. V. Kindrachuk3
UDC 669. 018. 25:669.24
We determine the melting point, hardness, and porosity of nickel powder alloys obtained by the method of hot pressing. A titanium content of 30–60 vol.% guarantees the wear resistance of alloys under the conditions of fretting corrosion. The heat resistance of these alloys was determined at a temperature of 1100°С and their wear resistance was found at temperatures of 20, 850, 950, and 1050°С. It is shown that, as the porosity increases, the heat resistance of the alloys decreases, and the characteristics of mean linear wear increase with temperature. We managed to obtain an alloy of the optimal composition with a melting point higher than 1300°С, which can be used in the aircraft industry. Keywords: nickel powder alloys, titanium carbide, heat resistance, wear resistance, melting point.
The service life of the aircraft engines is determined by the durability of various components of its hot gas pass, including working blades whose serviceability depends on the wear and corrosion-erosion resistance of their contacting surfaces, i.e., of the shroud platforms. The faces of shroud platforms can be protected by applying coatings formed by materials whose wear resistance is higher than the wear resistance of the blade material. This increases their service life and simplifies repairs, which is reduced, in this case, to the replacement of the coatings but not of the blades themselves. At present, the KhTN-61 and KhTN-62 cast eutectic-type alloys created at the Institute for Metal Physics of the Ukrainian National Academy of Sciences are successfully used for this purpose [1, 2]. As a result of the development of gas-turbine engines of new generation and upgrading of the existing engines in the case where, parallel with the prolongation in the life, it is necessary to increase the power per unit mass of the engine, which inevitably leads to the increase in working temperatures and acting loads, it is necessary to develop new wear-resistant materials capable to meet the elevated requirements [3]. The commercial KhTN-type cast alloys contain insufficient amounts of the carbide phase determined by the composition of the eutectic and, hence, cannot provide the required high level of wear resistance. To increase the carbide content of alloys, the development of new materials was based on the application of the methods of powder metallurgy and taking into account the following design-basis requirements: the specific contact loads > 20 МРа, the range of working temperatures 20–1100°С, the heat resistance on the level of the heat resistance of alloys used for these purposes within the entire range of working temperatures, the wear resistance must be higher than for the KhTNtype alloys, and the melting point of the alloy must satisfy the technological conditions of manufacturing of the blades (degassing and soldering at 1270°С), i.e., must be higher than 1300°С. To
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