The 2.1 physical properties of molybdenum
Molybdenum is an element of group VIB of the periodic table of elements, atomic number 42, atomic weight 95.94. High melting point and high boiling point is one of the distinctive features of molybdenum, its melting point is 2620 ℃, second only to carbon, tungsten, tantalum and rhenium, osmium, boiling point is 5560 ℃.When the temperature is 20 ℃, molybdenum density is 10.22 g/cm3, only abouttungsten 1/2. Coefficient of expansion of molybdenum wire (5.8 ～ 6.2) × 10-6 ,only general steel 1/3 ~ 1/2, and silica are similar, low coefficient of linear expansion makes the size of molybdenum materials stability at high temperature,reducing the risk of rupture. Molybdenum thermal conductivity several times inmany high temperature alloy, copper is about 1/2. High conductivity coppermolybdenum, is about 1/3, and decreases with the increase of temperature.Molybdenum has a high modulus of elasticity modulus of elasticity, is one of theindustry in the highest, and affected little by temperature, even at 800 ℃ remain higher than ordinary steel at room temperature. One of the important properties of thermal neutron capture surface is small and molybdenum, the molybdenumcan be used in structural material in nuclear power center. Extended properties of molybdenum tungsten than good, can be processed into a foil is very thin and very thin wire. Table 1 is the main physical properties of molybdenum.
The physical properties of molybdenum in Table 1
The 2.2 chemical properties of molybdenum
Molybdenum has 2 outer shell is not electronic filled, N layer and O layerstructure, the free electron layer is 1s22s2p63s2p6d104s2p6d55s1, so the structure of the molybdenum with a variety of chemical valence, can form a large variety of compounds. Very stable chemical properties at room temperature of molybdenum in the air, can not be corroded, hydrochloric acid, hydrofluoric acid,lye, but soluble in concentrated sulfuric acid, nitric acid and aqua regia; when the temperature reaches 400 ℃, will have mild oxidation, higher than 600 ℃ rapidlyoxidized molybdenum trioxide; higher than 700 ℃, water vapor will Mo strongoxidation of two molybdenum oxide. Table 2 mo and some molten metal,nonmetal elements under different conditions of action.
Table 2 the effect of molybdenum and some molten metal, nonmetal elements
