Nb - w alloys are usually prepared by powder metallurgy and smelting. The powder metallurgy method is to prepare the billet by mixing, pressing and sintering niobium, tungsten and other element powder into prealloy bars, and then use two or more vacuum electron beam smelting or vacuum arc smelting or the two smelting methods. The aim of electron beam smelting is to remove impurities (such as interstitial elements, low melting point metals and non-metallic impurities) in the prealloy bars, to control the alloy composition and to prepare a certain size billet. The aim of vacuum arc melting is to prepare the billet with more uniform composition, smaller grain size and larger diameter. Ingot billet machining after squeezing breakdown and forging temperature above 1200 ℃, and then under 500 ℃ temperature rolling, drawing, to the preparation of bar, sheet, strip, wire, etc.
Generally, the nb-w alloy adopts the inert gas tungsten electrode welding and electron beam welding process to carry out self-welding, and the brazing method can be used to weld with titanium and titanium alloys. Before welding, the metal must be cleaned of oil and other stains with organic solvents such as CCl4. During welding, it must be in high vacuum (vacuum degree below 1). 333 x 10Pa) or high purity inert gas chamber. The welding operation of niobium tungsten alloy must be very careful, otherwise it is difficult to get good plastic joints. Niobium tungsten alloy has high strength at high temperature and good plasticity at room temperature. It is mainly used for the skin of the space shuttle, nuclear reactor engineering, jet engine parts, as well as the thermal radiation screen and catheter of the space power generation system.
The related facilities of chang 'e-3 are partly made of niobium tungsten alloy and coating materials. Niobium tungsten alloy and coating materials are mainly used to protect the rear wing of the transmission shield to protect the impact of high temperature, but the specific amount is very small.
Tag: Niobium, Titanium
