Laves phase NbCr2-based high-temperature oxidation-resistant coating on alloy surface

Abstract

The invention discloses a Laves phase NbCr2-based high-temperature oxidation-resistant coating on an alloy surface, which is characterized in that a preparation method of the coating comprises the following steps: (1) preparing a penetrating agent from 8-20 percent by weight of Si, 6-15 percent by weight of Al, 1-7 percent by weight of NaF and 65-85 percent by weight of Al2O3; (2) ball milling and refining the penetrating agent after being mixed; (3) burying a sample to be penetrated in a corundum crucible filled with the penetrating agent, covering the corundum crucible by using a cover, sealing by using a high-temperature adhesive and drying at 100DEG C for 2h; and (4) placing the sample to be penetrated into a high-temperature electric resistance furnace, preserving the heat at the temperature of 800-1,200DEG C under the condition that the temperature-rise speed is 16DEG C / min for 2h, cooling the sample to the room temperature along the furnace after finishing the heat preservation, taking out and cleaning the surface to obtain an Si-Al cementation sample. The invention has the advantages that: (1) the interface is smooth; (2) an oxidation film seriously falls off at the beginning phrase of the oxidation at 1,200DEG C and the disaster oxidation is generated; and (3) the high-temperature oxidation-resistant property of a Cr-50Nb alloy can be improved.

Description

technical field [0001] The invention relates to an anti-oxidation coating on the surface, in particular to an anti-oxidation coating on the surface of a Laves phase NbCr2-based superalloy. Background technique [0002] Laves Phase NbCr Formed by Alloying Element Cr and Refractory Metal Nb 2 It is an important class of intermetallic compounds, which not only has an appropriate specific gravity and a high melting point, but also has a yield strength as high as 600MPa at 1200°C. These properties make Laves phase NbCr 2 It has become a new type of high-temperature structural material with great application potential in advanced aero-engine hot-end components. Therefore, it has aroused great interest of domestic and foreign research scholars. [0003] However, the Laves phase NbCr 2 It has a topological close-packed structure and a complex crystal structure, which makes this kind of compound very brittle at room temperature, which seriously hinders its practical application a...

AI Technical Summary

Problems solved by technology

However, the problem of Nb-based alloy high-temperature oxidation-resistant coatings is that the bonding force between the coating and the substrate is not strong enough, and the expansion coefficient does not match, which will make the coating prone to peeling or cracking when subjected to thermal fatigue or thermal shock, thereby significantly reducing The service life of Nb-based alloys and the reliability of the coating, so it is necessary to add a certain amount of modifying elements to the silicide coating to improve its toughness and high temperature oxidation resistance

But for the Laves phase NbCr rich in soft second phase Nb 2 The coating preparation of the base alloy has not been reported yet, which is good for fully utilizing Nb to toughen the Laves phase NbCr 2 The effect is unfavorable

Although He et al. used the embedding infiltration method in NbCr rich in soft second phase Cr 2 The coating prepared on the surface of the base alloy can greatly improve the high temperature oxidation resistance of the alloy at 1100°C, but the oxidation resistance of the coating at 1200°C is still unknown; and the coating preparation process is embedded and infiltrated at a high temperature of 1000°C for 12 hours , which inevitably causes the grain growth of the matrix alloy, resulting in a decrease in ductility and toughness at room temperature

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