Application Of Molybdenum And Molybdenum Materials In Petrochemical Industry

Jan 13, 2020

The density of molybdenum is 10.2 g / cm3. Melting point is 2610 ° C. The boiling point is 5560 ° C. The molybdenum powder is pressed into a green body by isostatic pressing, sintered at about 2100 ° C, and hot-processed in the range of 870-1260 ° C. Molybdenum alloy plates, strips, foils, pipes, rods, wires and profiles can be produced through plastic processing. After adding different raw materials, their strength and low-temperature plasticity can be improved.

The chemical nature of molybdenum is also very stable, it will not be corroded by hydrochloric acid, hydrofluoric acid and lye, but it will be corroded in nitric acid, aqua regia or hot concentrated sulfuric acid. Molybdenum is also an important additive element. At high temperatures, molybdenum can effectively accelerate solid strengthening, prevent chloride pitting, and improve anticorrosive performance in the reducing solution.

The large demand for oil has forced people to accelerate the exploitation of deep oil layers on land and in the ocean. Deep oil layers are often contaminated by corrosive hydrogen disulfide, carbon dioxide and highly chlorinated brines, and thus contain 0.15% to 0.25% of molybdenum. AISI 4100 series Cr-Mo steel is widely used. The improved 4140 series of molybdenum-containing 0.4% to 0.6% is a low-alloy steel with the most resistance to sulfide stress cracking (SCC), which can be used in sulfur-containing wells.

With the deepening of the drilling depth and the continuous deterioration of the use conditions, the application of stainless steel and nickel-based alloys containing higher molybdenum, such as alloy C-22 (13% Mo) and alloy C-276 (16% Mo) will continue to increase. Because chromium can naturally form a thin protective passivation film on the surface of steel, stainless steel has corrosion resistance. In fact, molybdenum can make this passivation film stronger, and it can be quickly regenerated when the passivation film is destroyed by chloride. The increase of molybdenum content can improve the corrosion resistance of pits and cracks on stainless steel. Type 316 (2% to 3% Mo) is the most widely used molybdenum-containing stainless steel. It is designated as a tank, pipe and heat exchanger material for food processing and processing and pharmaceutical production. Increasing the content of molybdenum can enhance the resistance to chlorides in the air, so Type 316 can also be used as the material of choice for a large number of uses at sea and around the coast.

Volatile oxides are easily formed when molybdenum reaches a temperature above about 600 ° C. Therefore, the high temperature application of molybdenum is best in an inert gas protection or vacuum environment.