Molybdenum copper alloy
Molybdenum-copper alloy is used as a heat sink material because of its high thermal conductivity. The properties of the two alloys are similar, but the density of the molybdenum-copper alloy is less than that of the tungsten-copper alloy. The preparation of molybdenum copper alloy is mainly using the melt dip method, using high-quality molybdenum powder and oxygen-free copper powder, using isostatic pressing (high temperature sintering - copper infiltration), fine structure, good arc breaking performance, good electrical conductivity, good thermal conductivity, small thermal expansion.
Liquid phase sintering method: tungsten copper or molybdenum copper mixed powder after pressing molding, liquid phase sintering at 1300-1500°. The material prepared by this method has poor uniformity and many closed pores, and the density is usually less than 98%. However, the sintering activity can be improved by adding a small amount of nickel to the activated sintering method, mechanical alloying method or oxide supply reduction method to prepare ultrafine and nano-powder, so as to improve the density of W-Cu and MO-Cu alloys. However, the electrical and thermal conductivity of the material will be significantly reduced by the activation sintering of nickel, and the conductivity of the material will also be reduced by the introduction of impurities in mechanical alloying. The process of preparing powder by oxide co-reduction method is complicated, and the production efficiency is low.
Tungsten and molybdenum skeleton melting method: tungsten powder or molybdenum powder is first pressed into shape, and burned into a certain porosity of tungsten and molybdenum skeleton, and then molten copper. This method is suitable for tungsten copper and molybdenum copper products with low copper content. Compared with molybdenum copper, tungsten copper has the advantages of small mass, easy processing, linear expansion coefficient, thermal conductivity and some main mechanical properties comparable to tungsten copper. Although the heat resistance is not as good as tungsten and copper, but better than some heat resistant materials, so the application prospect is good. Because the wettability of molybdenum-copper is worse than that of tungsten and copper, especially in the preparation of molybdenum-copper with low copper content, the density of the material after melting and infiltration is low, resulting in the material's air tightness, electrical conductivity, thermal conductivity can not meet the requirements, and its application is limited.
This specification is applicable to the manufacture of molybdenum-copper alloy rods used as heat sink sealing materials and alumina ceramic sealing and structural materials for military high-power microelectronic devices, as well as the manufacture of molybdenum-copper alloy rods used for high thermal conductivity expansion sealing and heat sink for civil high-power microelectronic devices.
Molybdenum copper alloy combines the advantages of copper and molybdenum, high strength, high specific gravity, high temperature resistance, arc ablation resistance, electric conductivity and good processing performance. Using high quality molybdenum powder and oxygen-free copper powder, using isostatic pressing molding (high temperature sintering - copper infiltration), to ensure product purity and accurate ratio, fine structure, excellent performance. Good arc breaking performance, good electrical conductivity, good thermal conductivity, small thermal expansion.
Molybdenum is an essential nutrient for all nitrogen-fixing plants. Molybdenum is associated with the maintenance of ascorbic acid balance in plants. Molybdenum participates in the metabolism of some enzymes in the human body.
Molybdenum participates in the synthesis of xanthine oxidase, aldehyde oxidase and sulfite oxidase. Xanthine oxidase is an important metabolic enzyme. In addition to participating in intracellular electron transport, protein plays a catalytic role in purine metabolism. They are related to the release and utilization of ferritin, aldehydes can relieve the toxic effects of toxic aldehydes in the human body, remove free radicals in the human body, so it has anti-aging and anti-cancer effects.
Molybdenum deficiency has been reported in the serum of patients with arrhythmia and unexplained angina pectoris. Molybdenum supplementation may protect the myocardium. Besides selenium deficiency and copper deficiency, molybdenum deficiency is also one of the possible causes of disease in China. The content of molybdenum in the heart and aorta of people in molybdenum-deficient areas was significantly lower than that of people in non-molybdenum-deficient areas. Autopsy also found that the content of molybdenum in the myocardium was significantly reduced in those who died of myocardial infarction. In addition, molybdenum can enhance the therapeutic efficacy of drugs. For example, molybdenum fertilizer can increase the content of strong and drug activity of Foxglove.
Molybdenum is a component of nitrite reductase in the body, which can reduce nitrite to become ammonia and lose carcinogenicity. Molybdenum deficiency can increase the content of nitrous acid in the environment and crops, thus affecting the intake and storage of nitrous acid in animals and people, and increasing the carcinogenic factors. For example, Yanting County in Sichuan Province, Linxian County in Henan Province, Taihang Mountain in Shanxi Province and some places in South Africa are short of molybdenum, and the incidence of esophageal cancer is high. The treatment of grain with molybdate acid or ammonium molybdate fertilizer not only increases the crop yield, but also significantly reduces the incidence of esophageal cancer in this area.
