Ta-10W alloy is a kind of high density, high melting point, high strength alloy material, with high high temperature strength, good ductility and excellent corrosion resistance. At the same time, the tensile strength of Ta-10W can still reach 100 MPa at high temperature of 2 000 ℃, and its high temperature creep resistance and high temperature durability are also very superior. Therefore, Ta10W alloy has a very important application in the aerospace field due to its excellent properties. The high temperature oxidation resistance of the alloy is relatively poor, Ta-10W alloy will be oxidized at 300 ℃, the higher the temperature, the more severe the oxidation, until the complete "pulverization" damage, this shortcoming limits the application range of Ta-10W alloy. In order to solve the poor oxidation resistance of Ta-10W alloy and improve its service life at high temperature, the most effective method is to prepare protective coating on the surface of the alloy.
Common high temperature oxidation resistance coatings of tantalum tungsten alloy include heat resistant alloy coating, aluminide coating, silicide coating and noble metal coating, among which iridium metal has a high melting point (2 443 ℃) and excellent oxidation resistance at 2 100 ℃. Research shows that the iridium oxide resistant coating on the nozzle used in the liquid rocket engine of space vehicle orbit introduction and attitude control does not require the cooling of the fuel liquid film on the inner wall of the nozzle, improves the specific impulse and life of the engine, and increases the payload of the satellite, which has a great application prospect. Therefore, the preparation of iridium oxide-resistant coating on tantalum tungsten alloy has scientific significance and application value.
For preparation of iridium coating, widely used methods include chemical vapor deposition (MOCVD) to prepare iridium coating, decomposition deposition of iridium triacetylacetone (Ir (ACAC) 3) as precursor, and electroplating of iridium coating with sodium chloroiridium (Na3IrCl6) as main salt. At present, the iridium coating prepared by the above methods in China is not dense enough or defective.
An iridium coating was deposited on Ta-10W alloy by vacuum arc ion deposition. The size of the specimen is φ 3mm×100 mm. Before the coating is deposited, the sample is first pickled to remove the oxide on the surface of the test rod, then cleaned with acetone to remove the oil on the surface, and dried in the air. The cleaned test was placed in an arc ion deposition vacuum chamber, and then vacuumized and deposited an iridium coating with a thickness of (100±10) μm.
