Niobium-silicide alloys having a surface region of enhanced environmental-resistance, and related articles and processes
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
Problems solved by technology
Method used
Image
Examples
example 1
[0063]A niobium-silicide sample was prepared by dry-mixing a composition with the following nominal constituents: 38.7 atom % Nb, 2.0 atom % Hf. 18.4 atom % Ti, 0.9 atom % Al, 2.7 atom % Cr, 12.2 atom % Si, and 1.9 atom % Sn. The sample also contained 23.2 atom % Ge. The composition was arc-melted, to prepare an alloy sample in the shape of a disc. A test coupon was cut from the sample, and had approximate dimensions of 1 cm×1 cm×1 cm. A surface of the coupon was polished to remove any dirt and impurities. The coupon was then placed in a conventional box furnace, and heated in an air atmosphere for 100 hours, at a temperature of 1150° C.
[0064]FIG. 1 is a cross-sectional representation of the test coupon (obtained by SEM (scanning electron microscope) after removal from the box furnace. As depicted in the figure, article 10 includes a bulk alloy portion 12, i.e., the main portion of the alloy body. The bulk alloy portion, both before and after the heat treatment, was primarily made u...
example 2
[0069]Niobium-silicide test samples were prepared by arc-melting, according to the general procedure described in Example 1. The specific composition of each sample is indicated in FIG. 4. Each of the samples was subjected to oxidation testing at temperatures of 1150° C. and 1000° C., for 100 hours. Sample 1 was based on embodiments of the present invention. The sample contained 23.2 atom % germanium, which migrated to the surface to form the enriched layer during the oxidizing heat treatment. Samples 2 and 3 were comparative alloys. They contained relatively low levels of germanium, and were outside of the scope of this invention.
[0070]The chart in FIG. 4 depicts the weight-change in the sample, after the particular heat-treatment tests. As those familiar with these tests understand, weight loss is often an indication of oxide spallation. (Weight loss can also occur due to the evaporation of gaseous oxides). Oxide spallation is usually initiated by the penetration of oxygen and / or ...
example 3
[0074]In this example, the germanium-enriched layer was formed by way of the diffusion technique described previously. A germanium (Ge) slurry was created by mixing Ge metal with an organic binder and carrier. The binder for this example was a Remet® product called Ethyl Silicate 40. The carrier was ethyl alcohol, which also functioned as an agent to adjust the viscosity of the slurry. Ge metal powder (purchased from Alfa Aesar), sieved to a −325 mesh, was combined with the binder and carrier in the following concentration:
[0075]50.0 g Ge
[0076]27.5 g Remet® Ethyl Silicate 40
[0077]27.5 g Ethyl alcohol
[0078]The mixture was sealed in a container and mixed via a paint shaker for 30 minutes, prior to being loaded into a gravity-fed spray gun. The mixture was air-sprayed on a niobium-silicide substrate surface, using a conventional DeVilbiss spray gun. The slurry was allowed to air-dry on the coupon, and then a second layer was sprayed over the first. The second layer of slurry was allowe...
PUM
| Property | Measurement | Unit |
|---|---|---|
| Temperature | aaaaa | aaaaa |
| Temperature | aaaaa | aaaaa |
| Fraction | aaaaa | aaaaa |
Abstract
Description
Claims
Application Information
Login to View More