Addition Of Molybdenum Research Articles

The Effects of Molybdenum Additions on the Sintering and Mechanical Behavior of Ultrafine-Grained Tungsten

Tungsten (W) is a brittle material at room temperature. Although the lack of ductility remains a difficult challenge, solid solution alloying of tungsten with rhenium offers an effective approach to improve tungsten’s room temperature brittleness. There are strong motivations to seek a substitute element for rhenium, because it is prohibitively expensive, for manufacturing solid solution tungsten alloys with improved mechanical behavior. As one of the potential substitute elements, the effects of molybdenum were studied in terms of its effects on densification and the grain growth of samples produced with nano-tungsten powder by pressureless sintering. A study on the mechanical properties of sintered tungsten-molybdenum alloy, including hardness, indentation toughness and bending stress–strain relationships, is also reported. It was found that alloying tungsten with molybdenum clearly reduced tungsten grain size, significantly increased hardness and indentation toughness, and also resulted in an appreciable improvement in tungsten’s tensile behavior during bending.

Influence of Small Content Elements Additions on the Glass Forming Ability of Zr-based Bulk Metallic Glasses Alloys

The present work reports investigation on the Glass Forming Ability (GFA) of Zr-based Bulk Metallic Glasses (BMG’s) by microalloying with early transition metals. GFA was measured as the amorphous fraction formed in samples with different diameters using optical microscopy (OM) and image analysis techniques. Samples with the highest GFA had their oxygen content measured in a Leco RO-400. This study shows that additions of Molybdenum or Iron in a Zr48Cu(48-x)Al4Mx (M = Mo or Fe) alloys resulted in a minor GFA improvement, but far from the results reported in the literature with Nb additions in this system. Niobium microalloying to a Zr62Cu15.5Al10Ni(12.5-x)Nbx and (Zr55Cu30Al10)100-xNbx alloys have a deleterious effect on the GFA. Oxygen measurements of (Zr55Cu30Al10)99Nb1 and Zr62Cu15.5Al10Ni12.4Nb0.1 alloys have shown similar oxygen content, indicating that oxygen was not a limiting factor on this study. The amorphous fraction quantification from OM image analysis maintains the same fraction ratio from the heat released at the crystallization event from heating DSC analysis.

Effect of molybdenum addition in nickel-based catalyst on hydrogenation reaction of 2-ethyl-2-hexenal hydrogenation to 2-ethyl-hexanol

The 2-ethyl-hexanol compound is much needed in the plasticizer industry as a precursor for the synthesis of bis diesters (2-ethyl hexyl) phthalate (DEHP). This compound can be synthesized by oxo reaction. One of the steps in the oxo reaction is consecutive hydrogenation reaction of the 2-ethyl-2-hexenal to 2-ethyl-hexanol. This reaction requires nickel-based catalyst as an effective step for obtaining higher and purer 2-ethyl-hexanol yields. This research aims to develop the formula and procedure of catalyst synthesized in Laboratory of Catalysis and Reaction Engineering Institut Teknologi Bandung and get a rate of the reaction. The catalysts were synthesized by co-impregnation with a nickel content of 20%-w and varied with molybdenum loading (5-20%). The support that used for these metals is alumina-phosphate (AlP2). The synthesized catalysts were tested for their activity against the 2-ethyl-2-hexenal conversion at 120°C, 30 bar in the fixed bed reactor and compared its performance with a commercial catalyst. The results showed the addition of molybdenum loading increases selectivity of 2-ethyl-hexanol but decrease the conversion of 2-ethyl-2-hexenal. The highest selectivity was achieved by Ni5-Mo20/AlP2 (X=31%, S=85%), but the highest conversion was achieved by Ni20/AlP2 (X=88%, S=32%). Nickel tend to play a part of breaking the C=C bond. Meanwhile, molybdenum tends to break the C=O bond. This shows that the hydrogenation of C = C bonds and the C = O bond is very depending on nickel and molybdenum metal loading.

The Effects of Mo and Nb on the Microstructures and Properties of CrFeCoNi(Nb,Mo) Alloys.

The effects of niobium and molybdenum additions on the microstructures, hardness and corrosion behaviors of CrFeCoNi(Nb,Mo) alloys were investigated. All of the CrFeCoNi(Nb,Mo) alloys displayed dendritic microstructures. The dendrites of CrFeCoNiNb and CrFeCoNiNb0.5Mo0.5 alloys were a hexagonal close packing (HCP) phase and the interdendrites were a eutectic structure of HCP and face-centered cubic (FCC) phases. Additionally, the dendrites of CrFeCoNiMo alloys were a simple cubic (SC) phase and the interdendrites were a eutectic structure of SC and FCC phases. The volume fraction of dendrites and interdendrites in these alloys were calculated. The influences of the volume fraction of dendrite in the alloys on the overall hardness were also discussed. The CrFeCoNiNb alloy had the larger volume fraction of dendrite and thus had the highest hardness among these alloys. The CrFeCoNi(Nb,Mo) alloys also showed better corrosion resistances in 1 M H2SO4 and 1 M NaCl solutions by comparing with commercial 304 stainless steel. The CrFeCoNiNb0.5Mo0.5 alloy possessed the best corrosion resistances in these solutions among the CrFeCoNi(Nb,Mo) alloys.

Cladding of Tribaloy T400 on steel substrates using a high power Nd:YAG laser

Tribaloy T-400 is a cobalt based alloy with molybdenum additions, which has been developed for improved resistance to high temperature wear, galling and corrosion. Its hardness is provided by a hard intermetallic Laves phase, dispersed in a tough matrix of cobalt rich eutectic or solid solution. However, cracking limits its applications such as hard facing using laser surface cladding/coating. The primary aim of this work is accomplished by cladding crack free Tribaloy T-400 layer using a high power Nd:YAG laser. The optimal process conditions of cladding crack free Tribaloy T-400 coating on different steel substrates were obtained. The effects of iron dilution on the hardness of cladded Tribaloy T-400 coating are investigated. Dilution determined from clad geometry is verified from dilution calculated from an analysis of the composition of the clad. Microstructures of clad layers produced using optimal process parameters with and without preheating the substrate were analysed by Scanning Electron Microscopy (SEM). The chemical compositions of different phases present in the clad were analysed by Energy Dispersive X-ray Spectroscopy (EDS). Presence of phases with FCC and BCC structures and Laves phase (Co3.6Mo2Si0.4) in the clad were identified and analysed by X-ray Diffraction (XRD). The residual stresses in the clads were evaluated using hole drilling technique. The correlation between the process conditions and the resulting microstructures are discussed. Based on the results of this research, further scaling up to industrial application of laser cladding of Tribaloy T-400 is promising.

Influence of Cobalt and Molybdenum Additives on the Structure and Shape Memory Parameters of Reaction-Sintered Porous Nickel Titanium Alloys

We have studied the structure and properties of porous nickel titanium (TiNi) alloys obtained upon reaction sintering of Ti and Ni powders with Co and Mo additives. It is established that Co and Mo doping additives retain the compaction of Ni powder achieved at the initial stage of sintering. The maximum deformation of porous samples loaded in the austenite state was observed upon adding Co, while the addition of Mo resulted in minimum deformation. The addition of Co leads to single-stage martensitic transformation in TiNi phase, while the addition of Mo leads to the two-stage transformation that is more homogeneous over the volume. Both Co and Mo additives lead to increase in the maximum accumulated strain due to the formation of favorably oriented stress-induced martensite and reoriented quench-induced martensite.

Effect of Molybdenum Additions on the Structure of TiB2–(Fe–Mo) Composite Materials

To examine the effect of molybdenum additions on the structurization of TiB2–(Fe–Mo) composite materials, differential thermal analysis of the samples with 8, 13, and 20 wt.% Mo in the metallic phase was carried out and their structure was examined after sintering. It is shown that molybdenum is an active component in the systems with 8 and 13 wt.% Mo and promotes the formation of complex Mo2FeB2 borides, which additionally strengthen the material. When the molybdenum content of the metallic phase increases to 20 wt.%, boride compounds intensively form in the system, making the composite material brittle.

Molybdenum Influence on the Mixed-Alkali Effect of Lithium–Sodium Phosphate Glasses

In this work, we investigated the mixed-alkali effect (MAE) in molybdophosphate glasses of general composition xNa2O–(40 – x)Li2O–yMoO3–(60 – y)P2O5, where 0 ≤ x ≤ 40 and 20 ≤ y ≤ 40. MAE was assessed in terms of the glass-transition temperature (Tg) and electrical conductivity of the prepared samples. New insights concerning the influence of molybdenum on MAE are provided herein. In particular, it was observed by differential scanning calorimetry that the addition of molybdenum decreased MAE magnitude for Tg. This behavior seems to be related to the formation of better connected and stronger networks when molybdenum oxide (MoO3) was incorporated into the phosphate glasses. Moreover, it was demonstrated that the addition of MoO3 increases the overall electrical conductivity of the glasses, mainly due to the increase of the density of mobile atoms, with no clear influence on MAE. This work provides a deeper understanding regarding the structure of molybdophosphate glasses in terms of both the formation of ...

Role of molybdenum in Ni-MoO2 catalysts supported on reduced graphene oxide for temperature dependent hydrogen evolution reaction

Non Platinum group metal (PGM) catalyst received huge attention for the electrochemical water splitting to produce hydrogen. Among different non PGM groups nickel (Ni), nickel oxide (NiO), nickel molybdenum oxide (Ni-MoOx) show very good activity towards hydrogen evolution reaction (HER). In this work, Ni and Ni-MoO2 nanostructured particles were impregnated on the reduced graphene oxide (RGO) sheets and utilized for hydrogen evolution reaction (HER) in highly alkaline medium (1 M KOH). Electrochemical studies have been done by linear sweep voltammetry (LSV) which concludes that there is decrease in overpotential of about 124 mV at 10 mA cm−2 as we switch from Ni/RGO to Ni-MoO2/RGO. To understand reaction mechanism, temperature dependent HER have also performed within the temperature range of 293–333 K respectively. Electrochemical impedance spectroscopy (EIS), Arrhenius activation energy calculations concluded enhanced catalytic activity of Ni-MoO2/RGO. Temperature-controlled experimental data clearly confirm that addition of molybdenum leads to reduction in energy barrier for hydrogen evolution in Ni-MoO2/RGO.

Hydrotreatment of 2‐Methoxyphenol over High Ni‐Loaded Sol‐Gel Catalysts: The Influence of Mo on Catalyst Activity and Reaction Pathways

AbstractMo (content ranging from 0 to 18.8 wt%) is used as an additive in Ni‐containing sol‐gel derived catalysts NiCuMo/SiO2 for the hydrotreatment of guaiacol as a model compound in biomass derived pyrolysis liquids. The catalysts had a high Ni loading, from 39 to 51 wt%, promoted by copper with an atomic ratio Cu/Ni close to 0.12. The experiments were done in autoclave at 320 °C, at a hydrogen pressure of 9 MPa. Addition of molybdenum results in an increase in activity of the catalyst, accompanied with an increase in selectivity towards the deoxygenation reactions. This is attributed to the formation of solid solutions NiMo(Cu) and 4+ and 5+ charge states of Mo on the catalyst surface. Moreover, an increased mean metal particles size is observed at higher Mo loading, due to the weakening of the interaction between the active component (Ni) and the stabilizer (SiO2) in the presence of Mo.

Phase transformations in the reaction cell of TiNi-based sintered systems

The present work addresses the structural-phase state changes of porous TiNi-based compounds fabricated by reaction sintering (RS) of Ti and Ni powders with Co, Mo, and no additives introduced. The study also emphasizes the features of a reaction cell (RC) during the transition from the solid- to liquid-phase sintering. Mechanisms of phase transformations occurring in the solid phase, involving the low-melting Ti2Ni phase within the RC, have been highlighted. Also, the intermediate Ti2Ni phase had a crucial role to provide both the required RS behavior and modified phase composition of RS samples, and besides, it is found to be responsible for the near-equiatomic TiNi saturation of the melt. Both cobalt and molybdenum additives are shown to cause additional structuring of the transition zone (TZ) at the Ti2Ni−TiNi interface and broadening of this zone. The impact of Co and Mo on the Ti2Ni phase is evident through fissuring of this phase layer, which is referred to solidified stresses increased in the layer due to post-alloying defects in the structure.

Analyze the effect of Molybdenum on Heat Resistance Stainless Steel Casting SCH 22

There was SCH 22 component named hanger that is produced by casting, where it is one of the components applied at 1100°C work temperature. Problems on the product is the occurrence of scaling, causing the the function failure and shortening its lifetime. Generally, this scaling occurs when the material is exposed to high temperature, then kinds of iron oxide layers are arisen such as FeO, Fe3O4, and others. Based on the literature, Molybdenum can be added to the SCH 22 with maximum limit of 0.5%. The purpose of this study is to know the influence of Molybdenum to the mechanical properties and analyze the phenomenon of scaling on Heat Resistant Stainless steel Casting (SCH 22). It is expected that molybdenum could increase the scaling resistance in the high temperature. The method is making specimens through metal casting process where the molybdenum content are made to 0.3%, 0.7%, 1.1%. Each specimen should be heated at 1150°C and held for 4 hours. Then the mechanical strength and micro structure are observed to see the effect such molybdenum addition. The result is obtained that the 0.7% addition of molybdenum element can reduce the degradation due to scaling on Heat Resistance Stainless Steel Casting SCH 22.

Corrosion Characterization in Nickel Plated 110 ksi Low Alloy Steel and Incoloy 925: An Experimental Case Study

Incoloy 925 is an age hardenable Nickel-Iron-Chromium alloy with the addition of Molybdenum, Copper, Titanium and Aluminium used in many applications in oil and gas industry. Nickel alloys are preferred mostly in corrosive environments where there is high concentration of H2S, CO2, chlorides and free Sulphur as sufficient nickel content provides protection against chloride-ion stress-corrosion cracking. But unfortunately, Nickel alloys are very expensive. Plating an alloy steel part with nickel would cost much lesser than a part make of nickel alloy for large quantities. A brief study will be carried out to compare the performance of nickel plated alloy steel with that of an Incoloy 925 part by conducting corrosion tests. Tests will be carried out using different coating thicknesses of Nickel on low alloy steel in 0.1 M NaCl solution and results will be verified. From the test results we can confirm that Nickel plated low alloy steel is found to exhibit fairly good corrosion in comparison with Incoloy 925 and thus can be an excellent candidate to replace Incoloy materials.

A study on mechanical behavior and wear performance of a metal–metal Co–30Cr biomedical alloy with different molybdenum addition and optimized using Taguchi experimental design

Molybdenum-added biomedical alloy has been prepared using a high-temperature vertical vacuum casting technique with five (0, 1, 2, 3, and 4 wt%) diverse weight percentages. The density, microhardness, and sliding wear behavior of the fabricated alloys were studied, showing that the addition of molybdenum content in the metal–metal alloy (i.e., Co–30Cr) increases the density from 7.2 to 8.7 g/cc for 0–4 wt% of Mo, respectively. Similarly, the hardness of prepared biomedical alloy also increases from 653 to 720 HV on addition of 0–4 wt% Mo particulate, respectively. The hardness is investigated by the microhardness tester. The aim of this current research work is to optimized the sliding wear behavior of molybdenum-added Co–30Cr alloy for implant material by Taguchi experimental design technique at five different normal loads (5–25 N), sliding velocities (0.26–1.3 m/s), sliding distance (500–2500 m), and reinforcement, i.e., Mo (0–4 wt%) respectively. To obtain the optimum wear response of prepared biomedical alloy added with Mo contents, the Taguchi L25 orthogonal array was implemented. The wear test is performed on a pin-on-disc tribometer against a hardened alloy steel (EN-31) disc under different operating conditions at room temperature. Afterwards, field-emission scanning electron microscopy and atomic force microscopy were utilized to analyze the microstructure, contour of wear mechanism, and 3D surface topography of samples after test run.

Effects of Molybdenum Addition on Hydrogen Desorption of TiC Precipitation-Hardened Steel

The hydrogen-trap states in TiC and MoC that have coherent interfaces with ferrite were investigated using first-principles calculation. The trapping sites of TiC were the interfaces and interstitial sites of ferrite. On the other hand, the trapping sites of MoC were ferrite interstitial sites; the interface had a negative binding energy with H. Thermal desorption analysis confirms that the amounts of diffusible hydrogen were significantly reduced by addition of Mo in Ti-bearing steel.

Modification of M2 hardfacing: Effect of molybdenum alloying and laser surface melting on microstructure and wear performance

The influence of alloying (10 wt% Molybdenum) and post deposition treatment (Laser Surface Melting) on the structural characteristics and wear performance of Plasma Transfer Arc deposited M2 hardfacings have been investigated. The nature of matrix and carbides of M2 hardfacing had changed upon Molybdenum addition while the Laser Surface Melting caused structural refinement and a decrease in carbide volume fraction. Despite an increase in hardness, Laser Surface Melting has resulted in reduction in sliding wear resistance against alumina counterface, while the Molybdenum enhanced the wear resistance even with decrease in hardness. This counter intuitive behaviour is attributed to Magnelli oxide containing tribo-oxide layer formation on the worn surface of Molybdenum alloyed hardfacings.

The effects of goutweed (Aegopodium podagraria L.) tincture on the background of toxic doses of allopurinol with the excessive intake of purine derivatives and proteins

There is an increasing interest in the use of herbal preparations as part of the combined therapy, including cases of hyperuricemia and gout. Preparations of goutweed (Aegopodium podagraria L.) aerial part are characterized by organoprotective and favorable metabolic effects, including the effect on the uric acid metabolism largely related to hydroxycinnamic acids. Allopurinol continues to be the most widely used hypouricemic drug.Aim. To characterize the renal, metabolic, and psychotropic effects of goutweed tincture combined with allopurinol in rats under the conditions of the excessive intake of purine derivatives and proteins.Materials and methods. The experiments were performed on the background of the excessive intake of purine derivatives and proteins in rats (10-day administration of the yeast extract in the dose of 10 g/kg with addition of molybdenum in the amount of 0.3 mg per animal and i/p injection of inosine in the dose of 50 mg/150 g). Goutweed tincture (1 ml/kg), allopurinol (50 mg/kg) and their combination were administered intragastrically during the whole period of the studies. The state of the excretory renal function, biochemical parameters of the blood plasma, the activity of xanthine oxidase (CSR) and the content of uric acid in the liver and kidneys, as well as the state of the CNS in the combined open field and an elevated plus maze tests were studied. Results. The renal injury on the background of excessive purine derivatives and proteins was verified by the criteria of hyperfiltration with increased water reabsorption and reduced ability of the kidney to excrete water load, a decrease in urea clearance and an increase of proteinuria. The level of urea and nitrogen of amino groups of the low-molecular compounds in the blood plasma increased in the absence of changes in creatininemia and uricemia (with a marked increase of renal excretion of uric acid on the background of the liver xanthine oxidase increased activity). Under the conditions of the excessive intake of purine derivatives and proteins goutweed tincture provided effective excretion of potassium, normalized the total protein content in the blood, as well as urea clearance without affecting other parameters and not leading to toxic effects. It also did not change the uric acid content and the xanthine oxidase activity of the liver and kidneys. On the background of allopurinol, the severity of the kidney damage increased with the threefold increase in the relative kidney weight, hyperazotemia, an abrupt decrease in GFR and urea clearance, reabsorption decrease, a tendency to increase in natriemia and, especially kalemia, a significant increase of proteinuria, as well as an increase in the total protein content in the blood. Goutweed tincture did not enhance the toxicity of allopurinol and did not prevent xanthine oxidase inhibition. It exerted the marked antiproteinuric effect, maintained sodium reabsorption, leading to the decrease in its excretion, reduced natriemia on the background of normokalemia. The tincture reduced the anxiety of animals in the elevated plus maze test, this effect was evident when the tincture was combined with allopurinol; in this case the intensity of vegetative and emotional signs in the open field test was also reduced. Conclusions. Goutweed tincture does not enhance the toxicity of allopurinol under the conditions of the excessive intake of purine derivatives and proteins.

Effect of Cooling and Isothermal Holding on the Amount of Martensite/Austenite (M/A) Constituents, Microstructure and Mechanical Properties of Microalloyed Pipeline Steel

Constant increase of energy consumption in modern industry requires construction of heavily loaded pipelines with high throughput capacity. Therefore, high-strength steels should be used for the cost reasons. Additionally, the pipelines are also often used in the areas with cold climate and high seismicity. Therefore, strength and plasticity reduction is unacceptable. Bainitic steels with retained austenite (RA) or martensite/austenite (M/A) constituents meet these requirements. The purpose of this investigation is to determine thermo-mechanical treatment parameters with further accelerated cooling and additional isothermal holding for M/A-phase and mechanical properties formation. Experimental modeling of the production process was carried out using Gleeble HDS-V40 thermo-mechanical simulator. All investigations were realized with two high-strength micro-alloyed steels with different molybdenum and carbon content. Results showed that decrease of temperature and duration of isothermal holding as well as addition of molybdenum promote bainitic microstructure nucleation and reduce grain size and M/A-constituents. All these factors lead to a slight improvement in mechanical properties.

Effect of molybdenum additions on the microstructures and corrosion behaviours of 316L stainless steel-based alloys

ABSTRACTAlloys were made by alloying 5, 10, 15, 17.5 and 20 wt-% Mo with Type 316L stainless steel. Sigma phases containing 21–29 wt-% Mo formed along the austenite grain boundaries with the addition of 5 wt-% Mo and increased with additions up to 15 wt-% Mo, but they decreased with further additions. Laves phases containing 33–40 wt-% Mo co-precipitated at additions of 10 wt-% Mo which increased with further Mo increases. The corrosion resistance, assessed by potentiodynamic polarisation in a 10 mM NaCl solution adjusted to pH 4, increased relative to Type 316L for alloys made with 5 and 10 wt-% added Mo, but decreased with further additions due to preferential corrosion of the Laves phase. The alloy made with 10 wt-% added Mo had the highest corrosion resistance due primarily to the high Mo content of the austenite.

PYRODUR 4923

Abstract Pyrodur 4923 is a high-temperature resistant stainless steel with molybdenum addition. Special properties include resistant to scaling up to around 600 C (1110 F), and maximum hardness approximately 590 Hv. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1277. Producer or source: Deutsche Edelstahlwerke.