Stellite alloy background
At the beginning of the 20th century, the American Elwood invented the Stellite alloy. Stellite alloy is a type of cemented carbide, which has good corrosion resistance, wear resistance, and high resistance to high-temperature oxidation, Stellite alloy is a cobalt-based alloy.
A basic introduction to Stellite alloys
Stellite alloys mainly contain cobalt, nickel, tungsten, chromium, and a small amount of metal elements such as tantalum, titanium, molybdenum, niobium, lanthanum, etc., and iron in special cases. Stellite alloys are often used in powder form, mostly as welding rods, and to a lesser extent as castings. Stellite alloy powder is mainly used in thermal spraying, hard surfacing welding, spray welding and other processes. Stellite alloys have good high temperature resistance as well as good wear and corrosion resistance. It has a wide range of applications in the field of wood cutting, machinery, military industry, metallurgy, automobile, paper and food processing. As a high-hardness material, Stellite alloy is difficult to process and the cost of material cutting is high.
Corrosion of Stellite alloys
As a corrosion-resistant material for surfacing welding, there are also scholars who study it. Stellite alloy has good corrosion resistance in acetic acid, nitric acid and hydrochloric acid solutions. Due to the presence of a large number of Cl ions in the salt solution, it is one of the factors that cause damage to the passivation film, when the potential is too high, the passivation film in the weak part of the surface of the material will break down and form pits. The critical value of pitting corrosion of Stellite alloy is generally higher than that of the matrix, even if the current density in the corrosion solution increases, the corrosion current density of Stellite alloy will still be at a low level, and the corrosion resistance is greatly improved. In addition to acid etching resistance, Stellite alloys also have the advantage of water erosion resistance. Because the isolation of water vapor cannot be completely guaranteed in the actual industry, in the low temperature and low pressure environment, the formation of water droplets flow, will cause damage to the surface of the material, and at the same time, because the working environment contains CL ions, it is very easy to cause corrosion, and Stellite alloy can effectively resist this corrosion, excellent corrosion resistance.
The main application of Stellite alloys:
With the development of China's economic situation, machining occupies an increasingly important position, among which cutting processing is the most widely used. Valve body and valve seat are widely used in various fields of engineering, but in harsh environments, such as natural gas pipelines, valve bodies and valve seats are easily worn. The alloy needs to be overlaid on the surface of the valve body to prevent wear, and the commonly used surfacing material is Stellite alloy.