Materials with the highest melting point: Carbides, nitrides, metal tungsten?
Tungsten is a chemical element, the chemical symbol is W, the atomic number is 74, is a very hard, steel gray to white transition metal. The minerals containing tungsten are wolframite and scheelite. The physical characteristics of tungsten are very strong, especially the melting point is very high, which is the highest of all non-alloy metals. Pure tungsten is mainly used in electrical and electronic equipment, and many of its compounds and alloys are also used in many other applications (the most common filament with light bulbs, tungsten in X-ray tubes and superalloys). Tungsten is a rare and high melting point metal, which belongs to the sixth cycle (the second long period) of the periodic table. Steel tungsten is not only a non-ferrous metal, but also an important strategic metal. Tungsten ore was called "heavy stone" in ancient times. Scheelite was discovered by Swedish chemist Carl William Sheyer in 1781, and a new elemental acid-tungstate was extracted, and tungstate was also extracted from wolframite discovered by Spanish de Puer in 1783. In the same year, tungsten powder was obtained by reducing tungsten trioxide with carbon for the first time and named this element. The content of tungsten in the crust is 0.001%. Twenty kinds of tungsten-bearing minerals have been found. Tungsten deposits are generally formed with the activity of granitic magma. After smelting tungsten is silver-white glossy metal, melting point is very high, hardness is very high. The minerals containing tungsten are wolframite and scheelite. The physical characteristics of tungsten are very strong, especially the melting point is very high, which is the highest of all non-alloy metals. Pure tungsten is mainly used in electrical and electronic equipment, and many of its compounds and alloys are also used in many other applications (the most common filament with light bulbs, tungsten in X-ray tubes and superalloys). All three of the most stable isotopes recently developed have micro-radioactivity. Isotopes: there are five tungsten isotopes in nature. Their half-lives are very long, so they can be regarded as stable isotopes. All of these isotopes can be transformed into hafnium through α decay. So far, the half-life of 180 W can be measured, and its half-life is 1.8 × 1018 years. No natural decay has been observed. The half-life of forced degradation is 182 W, T 1 ≤ 2 > 8.3 years, 184 W, T 1 ≥ 2 > 29 years, 185 W, T 1 ≥ 2 > 13 years, 186 W, T 1 ≥ 2 > 27 years. So far, their half-lives are only theoretical values. On average, α decay occurs twice a year in a gram of 180 W. At present, there are 27 kinds of artificial radioisotopes of tungsten, the most stable of which is 181W, the half-life of 185W is 121.2 days, the half-life of 185W is 75.1 days, the half-life of 188W is 69.4 days, and the half-life of 178 W is 21.6 days. The half-lives of other radioisotopes are less than 24 hours, most of which are less than 8 minutes.
