Molybdenum addition

Cast irons are iron with high levels of carbon. Heat treatments and alloying element additions produce gray cast iron, malleable iron, ductile iron, spheroidal cast iron and other grades. The mechanical properties vary significantly. Nickel-containing cast irons have improved hardness and corrosion resistance. Copper or molybdenum additions improve strength. 

Table 1.21 Effect of molybdenum additions to Fe-15Cr-13Ni stainless steel on the critical pitting potential J S.H.E.)...

Raney nickel catalysts, unpromoted or doped with molybdenum or chromium, were prepared from the precursor alloys of the type Ni A13. The structure and phase composition of the catalysts have been deternfmetl. Hydrogenation of valeronitri le at 90°C and 1.6 MPa in cyclohexane was performed to evaluate catalyst activities and the relative amounts of amines formed. Doping catalysts by chromium improved reaction rates and yields of primary amine, whereas molybdenum addition was ineffective. 

The table 2 shows moreover that the effects of chromium (x = 0.11) and of molybdenum additives were beneficial for the intrinsic activity V q. 

Molybdenum additives By using data from Table 5.15, determine a protective tribofilm formation from the degradation of molybdenum dialkyldithiocarbamate (MoDTC), molybdenum dialkyldithiophosphate (MoDDP) directly and in combination with ZDDPs or sulfur compounds. 

The various types of compound and their mechanisms of action have been reviewed by Mitchell . He concluded that the question of the extent to which the molybdenum additives decompose to produce molybdenum disulphide, if at all, was not yet resolved and certainly depended on the type of compound and the operating conditions. There was little doubt that molybdenum dithiocarbamates form molybdenum disulphide, probably by decomposition at hot spots caused by asperity interactions. It was less certain that molybdenum dithiophosphates form molybdenum disulphide, although mixtures of zinc dialkyidithiophosphate and molybdenum complexes had been shown to do so . 

According to the latest estimates of Skinner [18], elements potentially recoverable from seawater are sodium, potassium, magnesium, calcium, strontium, chlorine, bromine, boron, and phosphorus because of their practically unlimited presence in the ocean. After improving respective technologies, recovery of the following elements is expected to become profitable as well lithium, rubidium, uranium, vanadium, and molybdenum. Additional profit can be gained since desalinated water will probably be obtained as a by-product. This could be important for countries with a very limited number of freshwater sources (e.g., Israel, Saudi Arabia). 

Hydrazo compounds are reported as intermediates in nitrogen fixation by molybdenum-containing nitrogenase. Tungsten chemistry has been reported for comparison with molybdenum. Addition of methyl lithium to [W(NPh)Me3Cl] followed by 1 equiv. of hydrazine afforded [ W(NPh)Me3 2(//-r/1,r/1-NH2NH2)(/u- 72, 7 -NHNH)] in good yield.82... 

Alloying steels for improved corrosion resistance in chemical and hydrocarbon plants is based on chromium and molybdenum additions. The lowest of these alloys, lCr-l/2Mo and l-l/4Cr-l/2Mo, are often used above 800°F (425°C). Low-aUoy Cr-Mo steels (with 5% or greater Cr) are resistant to high-temperature sulfidic corrosion. However, the Cr-Mo alloys find their most critical use in high-temperature, high-pressure hydrogen service. The most commonly used alloys are the... 

K. Sugimoto and Y. Sawada, The Role of Molybdenum Additions to Austenitic Stainless Steels in the Inhibition of Pitting in Acid Chloride Solutions, Corros. Sci., Vol 17, 1977, p 425-445... 

Nonlegumes respond to added Mo because of the requirements for Mo by their nitrate reductase enzymes. Molybdenum additions in the presence of high amounts of N in the soil have prevented depressed crop yields due to excess N. Grains such as com, wheat, and rice have shown improved utilization of N following Mo application, but again, not all cultivars have the same Mo requirements. Many crops in the Brassica family respond to added Mo. Some of the early studies describing whiptail in cauliflower also found that different Brassica crops required different amounts of Mo. 

Crevice corrosion resistance improves with molybdenum additions, and a chloride crevice corrosion test (5% NaCl at 90 °C, pH adjusted to 0.5 and 1.0) indicated a chloride crevice corrosion threshold between pH 0.5 and 1.0. 

Corrosion resistance. Excellent resistance to atmospheric corrosion and scaling at elevated temperatures. Corrosion resistance in acids and chloride solution is increased by addition of molybdenum. Addition of titanium and niobium increases resistance to intergranular attack. Scaling resistance is increased by addition of chromium and silicon. 

All these steels have good combinations of strength, ductility, and toughness at low and high temperature, along with good formability, weldability, and corrosion properties. The molybdenum addition in 316 series increases the corrosion resistance and enhances the mechanical resistance through matrix reinforcement. The stabilization with... 

In all conditions, the organo molybdenum additive (MoDTP) gave optimum friction and wear performance. 

McK] McKamey, C.G., Horton, J.A., The Effect of Molybdenum Addition on Properties of Iron Aluminides , Metall. Trans. A., 20A, 751-757 (1989) (Experimental, Phase Relations, Meehan. Prop., 16)... 

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