摘要:
A gamma titanium aluminide substrate is hardfaced by providing a hardfacing material with a titanium-aluminum, gamma-titanium aluminide alloy component having a composition of titanium and about 42 to about 49 atomic percent aluminum, and a nonmetallic powder, such as titanium diboride. This hardfacing material is preferably furnished as a hardfacing alloy source in the form of a hollow tube of metallic titanium tube material, and a filler powder within the hollow tube. The filler powder is a filler mixture of an aluminum-containing alloy powder comprising more than about 50 atomic percent aluminum, and the nonmetallic powder. The relative proportions of the titanium tube material and the aluminum-containing alloy powder are such that their net composition is a gamma phase titanium aluminide composition. The hardfacing material is applied to the substrate, as by a welding process.
摘要:
The inside surface of the mold used to cast gamma titanium aluminide articles is pretreated with a facecoating of an inoculant such as titanium diboride or titanium carbide. When the molten metal of the composition that produces the gamma titanium aluminide is cast into the mold, the facecoating nucleates grains at the surface of the casting, which inhibits the formation of surface-connected porosity in the casting. Subsequent hot isostatic pressing of the article produces a sounder article than otherwise could be achieved.
摘要:
Nickel base superalloys which contain niobium (columbium) to promote gamma double prime strengthening are improved by replacing the niobium with tantalum on an atom-for-atom basis and then heat treating the new alloy at temperatures in excess of those conventionally used for superalloys which include niobium. The resultant tantalum-bearing alloys are found to exhibit increased strength and greater phase stability than corresponding niobium-bearing alloys.
摘要:
A method for East/West stationkeeping of a geostationary satellite maintains the osculating value of longitude from exceeding a specified deadband for a specified drift period between maneuvers. In the planning, the mean longitude, the mean drift rate and the mean eccentricity vector are calculated and then maneuvers are executed to maintain the values below a magnitude such that the osculating longitude will be within the specified deadband over a specified drift period. The target conditions are achieved through a plurality of maneuvers which initiate a period of free drift which lasts for a specified number of days. During the free-drift period, longitude remains within its deadband, and no additional maneuvers are needed or are performed. The method has the advantage that it can take into account limitations on thruster on-time by allowing for a generalized number of stationkeeping maneuvers.
摘要:
A weldable oxide dispersion strengthened alloy which provides improved welds and welded structures of oxide dispersion strengthened materials is characterized by good retention of dispersoid distribution in the fusion weld zone.
摘要:
Chlorinated organic compounds from the aqueous waste streams from a process for manufacturing and isomerizing dichlorobutenes and dehydrochorinating 3,4-dichlorobutene-1 to chloroprene, which is the principal monomer in the manufacture of neoprene rubber, are removed by means of a process, wherein the aqueous waste from the dichlorobutene-isomerization step and brine formed in the dehydrochlorination step are combined to produce an aqueous solution containing about 1-5% sodium chloride and the solution, while maintained at a pH of less than about 6, is extracted with a small amount of a liquid hydrocarbon. The liquid hydrocarbon extract is then incinerated, while the extracted aqueous solution is discharged into a natural body of water. In this way, the level of 1,4-dichlorobutene-2, which is toxic to fish, in the natural body of water can be maintained at a safe level.
摘要:
Provided is a method for heat treating a precipitation-hardened article having a thick section and a thin section so that the thin section can be solution annealed while the metallurgical structure of the thick section is substantially unaffected by the solution-annealing process. The method restores the microstructure of the thin section uniformly by solution annealing the thin section to achieve a preselected microstructure but without affecting the microstructure of the thick section.
摘要:
A process for refurbishing a worn surface of a shroud support component of a turbomachine, as well as a shroud support component refurbished with the process. The process generally entails removing a surface region of the worn surface so as to define a repair surface on the component. A braze tape formed from a slurry to comprise a braze material and a wear-resistant alloy is then applied to the repair surface, followed by a heat treatment to cause the braze tape to diffusion bond to the repair surface so as to define a built-up surface. The built-up surface is then machined to define a wear-resistant coating on the component.
摘要:
A gamma titanium aluminide alloy article, is prepared using a piece of a gamma titanium aluminide alloy having a composition capable of forming alpha, alpha-2, and gamma phases. The alpha transus temperature of the gamma titanium aluminide alloy piece is determined. The gamma titanium aluminide alloy piece is consolidated by hot isostatic pressing at a temperature of from about 50 F. to about 250 F. below the alpha transus temperature and at a pressure of from about 10,000 to about 30,000 pounds per square inch, for a duration of from about 1 to about 20 hours. The piece is heat treated at a temperature of from about 5 F. to about 300 F. below the alpha transus temperature for a time sufficient to refine the microstructure and generate a microstructure comprising from about 10 to about 90 volume percent gamma phase. The step of heat treating is conducted at a temperature of from about 45 F. to about 200 F. above the temperature of the step of hot isostatic pressing.