Applications In Metallurgy Research Articles

Research in spray forming technology and its applications in metallurgy

The processing, materials characterization, and applications of spray formed Cu–15Ni–8Sn, Cr12MoV steel, and GCr15 steel are reported in this paper. Spinodal decomposed phase, metastable γ′ pre-precipitates, and discontinuous precipitates exist during aging treatment of spray formed Cu–15Ni–8Sn alloy. The as-sprayed Cr12MoV steel shows the depressed martensite start temperature Ms and the reduced hardenability in comparison with the conventionally processed one. TEM micrographs of the spray formed GCr15 steel reveal the fine pearlite with interlamellar spacing of 85 nm and the martensite of the width of 0.35 μm.

Computational thermodynamics applied to steel elaboration

The CEQCSI software (Chemical EQuilibrium Calculation for the Steel Industry) was developed at IRSID under the guidance of Jean Morlet. This paper discusses the place of CEQCSI in the fast expanding field of Computational Thermodynamics packages, analyzes the major impact experimentation at Imphy had on its evolution, presents a few examples of industrial applications in ladle metallurgy and inclusions control, and finally evokes trends in the association of thermodynamic codes with CFD (computational fluid dynamics) codes and kinetic models.

Production of pure tungsten oxide from scheelite concentrates

Scheelite concentrates, obtained from Uludag, Bursa (Turkey), containing roughly 50% W, are treated by the chelate‐added acidic leaching route. Dissolved tungsten ions are then selectively precipitated by the addition of ‘ammonia ion‐containing’ reagents – either organic or inorganic – and thus are purified from other ions present in the solution. Selective precipitation of pure (> 99%) tungstate salt was realized from the polytungstate solution at 25°C by adding a ‘chelate‐breaking agent’ at a NH4+/WO3 weight ratio of ≥ 1/4. The formula of the complex salt is indicated by (NH4)3PW12O40·9H2O. The optimum precipitation conditions are investigated with the aim of making pure tungsten oxide via a thermal breakdown process. Tri‐ammonium‐dodeka‐tungstate‐phosphate salt can be easily converted to nanometer‐sized WO3 particles by a simple calcination operation carried out above 650°C. Weight loss ratios of the samples vary between 8.7 and 9.6% at the end of this 2‐h thermal breakdown process. Tungsten trioxide obtained can be suitably employed in tungsten‐related powder metallurgy applications with its extremely low impurity content of 0.04% Mo, 0.15% SiO2, 0.06% Fe and 0.03% Al.

Radiation effects in high-disperse metal media and their application in powder metallurgy

Experimental and theoretical results showing up effects of metal powder radiation processing, such as powder grinding, chemical refinement, and changes in powder particle surface state, are discussed. It is shown that preliminary irradiation of metal powders leads to profound structural alterations at all further stages of their processing by conventional methods of powder metallurgy and eventually effects the properties of the resulting product.

Monte Carlo simulation of particle behaviour

Abstract Already well established in solid state physics and microscopic materials science, modelling using randomized Monte Carlo techniques can provide a powerful method to simulate the flow and packing behaviour of powders. Lyndon Smith of the University of the West of England in Bristol discusses the advantages of this approach and demonstrates its potential in powder metallurgy applications.

Separating Rare Earth Elements

Rare earth elements find a wide range of applications in metallurgy, fuel cells, the coloring of glass and ceramics, and the production of magnets, but their separation is difficult, leading to high prices. In his Perspective, Fray discusses the separation process reported by Uda et al., which greatly reduces the number of separation steps required. If this process is adopted commercially, the price of rare earth elements may be reduced substantially.

THE PLASMA SPOUTED BED REACTOR FOR APPLICATIONS IN METALLURGY AND MATERIAL SYNTHESIS

THE PLASMA SPOUTED BED REACTOR FOR APPLICATIONS IN METALLURGY AND MATERIAL SYNTHESIS

Die Entwicklung der Chemie in Peru von den Anfängen bis zur Gegenwart

The evolution of chemistry in Peru begins in the high stages of civilizacion of the preincaic epoche. They is described for the incaic time by the chronicler Garcilaso de la Vega. After conquest of the country through Spanish colonizers follow the evolution of the chemistry under Spanish influence. She refers especially to applications in metallurgy and pharmacy. Additional impulses give the foundations of universities. Expedition travels of European scientists into the new continent increase the importance of chemistry in Peru. The south American natural world is made known in Europe simultaneously. In the 18/19th century influenced positively Jose Hipolito Unanue y Pavon, Mariano Eduardo de Rivera y Ustariz and Antonio Raimondi de Acqua the chemistry and mineralogy in Peru. Into the 20th century, the Sociedad Quimica del Peru together with the Departments of Chemistry of the universities have a coordinating and acting role. A first overall view of the history of chemistry in Peru was published by the Peruvian chemist Juan de Dios Guevara in 1993. The survey is completed by an analisis of fields of research, the chemistry training in the universities and considerations for chemical industry in Peru.

99/02980 Lignite coke manufacturing according to quality standards under consideration of applications in metallurgy and environmental protection

The relationship between the equilibrium concentrations of the carbon-hydrogen species in polycyclic aromatic hydrocarbons (PAH) found in coke oven emissions by Kirton et al and those which they measured has been investigated. A thermodynamic database for the species involved for use with the MTDATA computational package has been constructed and used to predict concentrations for local equilibrium between the group of PAH species at varied temperature. The temperature at which the concentration of each species observed would be in equilibrium with representative methane and hydrogen concentrations in coke oven gases has also been calculated. In each case the most satisfactory agreement between equilibrium and observed concentrations occurs above 1100K. In the group calculation, the higher PAH are over-predicted and this is consistent with the known kinetic restriction on soot formation. Some substituted benzenes and the biphenyl series are seriously under-predicted within the PAH group, and in the calculations for the model coke oven gas, do not equilibrate with methane and hydrogen at temperatures representative of coke ovens: this is consistent with their formation by reaction during quenching. The predicted equilibrium concentrations of the majority of species are within an order of magnitude of group equilibrium concentration at 1150K.

A review of advances in powder metallurgy applications : J.Hebeisen, F.H.Froes. (University of Idaho, Moscow, Idaho, USA.)

A review of advances in powder metallurgy applications : J.Hebeisen, F.H.Froes. (University of Idaho, Moscow, Idaho, USA.)

Principles and characteristics of a new generation plasma immersion ion implanter

A new generation multipurpose plasma immersion ion implanter (PIII) was custom designed, constructed, and installed in the City University of Hong Kong. The system is designed for general R&D applications in metallurgy, tribology, surface modification, and fabrication of novel materials. Using the new rf ion source in conjunction with the internal antenna system, the plasma density achieves excellent uniformity both laterally and axially. The system also incorporates two metal sources, including four metal arc sources and a sputtering electrode, so that multiple metal deposition and implantation steps can be performed in succession in the same equipment without exposing the samples to air. This capability can be critical to the study of surface properties and corrosion resistance. This article describes the design objectives, the novel features, and the characteristics of this new generation PIII equipment.

Quantitative δ' Phase Analysis in Al–Li Alloys using the Rietveld Method

Powder X-ray diffraction and the Rietveld method have been exploited to determine quantitatively the mass fraction and the mean size evolution with aging time of the δ′ precipitates in an Al–Li alloy at 453 K. Although obtaining good refinements is not straightforward, the principal difficulties being the texture of the sample, the small intensities of the δ′ peaks, the coincidence of the most intensive δ′ peaks with α peaks, and the determination of several parameters (crystallographic structure, linear absorption, texture, temperature factors) before Rietveld application in order to avoid too many free parameters, this technique has proved to be a very powerful tool in applications in physical metallurgy.

Enhancement of pulsed laser removal of metal oxides by electrochemical control

Pulsed laser irradiation of oxidized metallic surfaces in an electrolytic cell under proper voltage conditions is demonstrated to be a promising new approach for effective removal of oxide films. Systematic measurements on simulated corrosion-product films by optical reflectance profile and energy dispersive X-ray spectroscopy are used to study the physical mechanisms of this novel phenomenon, the physical conditions for its observation and its possible generality. It was observed that the utilization of a basic electrolyte solution and the imposition of a certain cathodic potential prior to laser irradiation is an essential requirement for a high removal efficiency. This new technique has potential applications in metallurgy, semiconductor fabrication technology and decontamination of nuclear power plans and is suitable for maskless patterning of oxidized surfaces.

Hydride-dehydride conversion of solid Ti6Al4V to powder form

An investigation is described in which the aim was to produce through the hydride-dehydride process a titanium alloy powder from Ti6Al4V alloy in a compact form (cast rods or electrode chips) and from oxidized Ti6Al4V REP powder. The possibilities and efficiency of obtaining Ti6Al4V powders for use in powder metallurgy applications were examined. The conditions of a reversible hydride-dehydride process were determined by X-ray and scanning electron microscope characterization of the powders.

The tomographic atom probe: New dimensions in materials analysis

The tomographic atom prob (TAP) is the most advanced of the three‐dimemsional atom probes currently in use. Atom probes are unique in that both the lateral and the depth resolution are high. The genera; development of atom probes and the principle of operation ot the TAP, in which the sample is field evaporated atomic loayer by atomic layer, are outlined. The analysis of a nickel base superalloy is given as an example of an application in metallurgy.

Principles of soldering and brazing

Improve your current joining processes Examine new techniques for unique applications Accurately troubleshoot joining problems Select the best joining method for specific needs Includes separate bibliography. This detailed, yet easy-to-understand ASM book critically examines the key physical principles of soldering and brazing, and explains their relevance to making jointsuproviding you with new insights. The relationships between processing conditions, filler materials, base materials, joint geometry and their influence on integrity are thoroughly explained and illustrated. By understanding these principles, you will know what materials and processing conditions to use and how to achieve the best joints. In addition, a special chapter is devoted to case studies of problem solving and process development. You will see prime examples of how to develop effective soldering and brazing solutions and identify failure modes. Equilibrium phase diagrams illustrate the metallurgical reactions and chances in physical properties that take place during joining. When not available, a methodology for determining an alloy systemAs critical characteristics enables you to specify the best filler for a particular application. In addition, the book covers the latest developments in joining, including composite solders, diffusion soldering and brazing, and advances in techniques for joining non-metals. Contents: Filler Alloys and Their Metallurgy Applications of Phase Diagrams to Soldering and Brazing The Role of Materials in Defining Process Constraints The Joining Environment Assessment of Joining Quality Characterization and Process Development in Soldering and Brazing: Selected Case Studies.

Plasma Technology in Extractive and Process Metallurgy

Thermal plasma technology may be useful for a broad range of applications in extractive and process metallurgy. Plasma technology is being used in the melting/remelting and refining of metals/alloys and scrap. Plasma technology may also be potentially useful in the benericiation of complex ores, treatment of wastes, reduction of oxides, the generation of value added products, and the recovery of precious metals from waste products. This paper gives an overview of thermal plasma applications in the field of extractive and process metallurgy.

Formation of monodisperse refractory metal particles by impulse discharge

A new method of forming monodisperse metal particles has been developed, in which the tip of a consumable wire electrode is fused and then formed into a separating droplet by an impulse discharge. The properties of the particles make them suitable for application in calibrating devices for particle size analysis, specialized applications in powder metallurgy and creating new tools. An experimental study has been carried out to test optimum conditions for dispersion. The physical processes occurring during impulse discharge when a droplet of molten metal forms and detaches have been examined to obtain conditions for producing monodisperse particles. It has been shown that initiation of the impulse discharge under conditions required for production of monodisperse droplets is possible when a non-equilibrium system containing ‘hot’ electron and ‘cool’ molecular subsystems is formed in the interelectrode space. The interaction between electrons obtaining their energy from the electric field and the surface of the consumable electrode provides the heat and force required to form and separate the metal droplets. The high energy concentration on the melting electrode gives rise to monodisperse metal powders with unique properties.

The HLM method: a simple way to get the solid–liquid phase diagrams and enthalpies of transition of pure components and mixtures

A simple method of thermal analysis is described which gives the same information as differential scanning calorimetry. The method is based on the Heat-Leak-Modulus, HLM, of a sample cell placed in a constant temperature reservoir. In the present study, the HLM method is used for the investigation of pure components and mixtures from −190 to 50 °C. The method allows the determination of glass-transition, crystallizations, solid–solid transition, eutectic, and melting temperatures with a reproducibility better than ±0.1 °C. The enthalpy of a transition can be determined with a reproducibility of ±5%. The simplicity, the low cost, and the precision of the HLM method fills the gap between standard cooling curves and sophisticated differential scanning calorimetry experiments. The HLM method has numerous applications in physical chemistry, polymer science, metallurgy, and chemical engineering.

SHS technology

The impact of controlled exothermic reactions on the sphere of materials processing is discussed. Although self‐propagating high‐temperature synthesis (SHS) has applications in sintering, densification, metallurgy, welding, coatings, and powder synthesis it is estimated that only 3–5% of its possible uses have been realized. Present applications are reviewed.