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Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2009.6.1.1 | Award Amount: 18.20M | Year: 2011

The intelligent and cost effective use of CCS technologies requires new strategies to increase the net efficiency of coal fired power plants. Among them, the most promising are summarised as below: - Increase working steam temperature and pressure in new USC power plants (350-370 bar, 700/720C minimum), and hence increase the severity of fireside operating conditions, - Promote clean coal technologies based (for example) on oxy-combustion \ co-firing technologies (by a continuous increase of biomass % in mixture with coal), in order to reduce CO2 capture losses and the amount of CO2 to be captured and stored. The project aims to increase the net efficiency of coal fired plants by increasing the performance and reliability of some critical components identified as follows: - refractory materials of the combustion chamber (especially for oxy-combustion application), up to 1800 C - headers and pipework (avoidance of weld Type IV cracking phenomena, working temperature increase), up to 650-660 C - super heaters (optimised performance in high temperature oxidation/hot corrosion environments), up to 720 C - coated pipes and boiler components able to withstand co-combustion conditions (high temperature oxidation/hot corrosion, erosion-adhesion and wear), - HP and IP steam turbine rotor components and turbine casing up to 750-780 C For each critical component, a full-scale prototype will be realised and installed into an industrial plant and/or in test loop(s) at known temperature, pressure and atmosphere conditions


Rovatti L.,Polytechnic of Milan | Casati R.,Polytechnic of Milan | Emami A.,Polytechnic of Milan | Lecis N.,Polytechnic of Milan | And 3 more authors.
International Journal of Cast Metals Research | Year: 2015

To investigate the influence of chemical compositions of different hardfacing alloys on wear performance experimental high vanadium Fe–C–B–Ni alloys in the form of blended powders have been cast in a laboratory furnace and analysed in three configurations: hypereutectic, neareutectic and hypoeutectic. The solidification behaviour was defined by differential scanning calorimetry while the main microstructural features were characterised by microscopy, X-ray diffraction and microhardness as well as pin-on-disc wear tests. Fe–V rich powders to an originally hypereutectic Fe–C–B–Ni alloy induced the shift to hypoeutectic solidification and promoted the presence of larger quantities of hard V-rich carbides. The new V-bearing alloys showed higher wear performance and higher bulk hardness than the reference alloy. The improved wear properties were mainly due to the precipitation of fine V-rich carbides that effectively reinforced the structure without any evidence of pull-out and cracking of the smaller particles. © 2015 W. S. Maney & Son Ltd.


Lussana D.,University of Turin | Massazza M.,Cogne Acciai Speciali Spa | Baldissin D.,University of Turin | Baldissin D.,Compumat Srl | And 12 more authors.
7th European Stainless Steel Conference: Science and Market, Proceedings | Year: 2011

The production process of austenitic stainless steels involves several steps at high temperature leading to the formation of an oxide layer at the surface. The removal of this layer, both during intermediate steps of the production process and in the final acid pickling treatment, represents an important cost for the process. The high temperature oxidation is a complex phenomenon [1,2], influenced by many parameters at the same time, and it is sensible even to little variations of them. A better understanding of the role of these parameters on the growth of different oxides could drive the optimization of the production process and hence to a reduction of production costs. In this study, samples of a 304L stainless steel were obtained directly from the industrial production process in order to characterize the oxide layers formed after hot rolling and after heat treatment and quenching. Thickness, microstructures, adherence and composition of the samples surface were analysed by means of SEM/EDS technique, revealing different morphologies of the oxide phase. X-Ray diffraction analysis showed the presence of mixed Cr/Fe oxides, with corundum or spinel structure, together with Fe oxides with halite structure. According to thermodynamic modelling at 1050 °C and with a partial pressure of O2 of 0.087 atm, only corundum and spinel phases should be present, with an expected weight ratio of 55/45 respectively. Quantitative estimation of phase fraction obtained by Rietveld analysis gave different results on different samples. In all cases spinel was the main phase. The obtained data suggests a non homogeneous degree of oxidation on different zone of the same sample. Several breakaway oxidations [3] were observed on all samples. They give rise to the formation of new oxide layers superimposed to the main one, possibly accounting for the observed non homogeneous morphologies and structures.


Marano E.F.,University of Turin | Lussana D.,Cogne Acciai Speciali Spa | Castellero A.,University of Turin | Baricco M.,University of Turin
Metals and Materials International | Year: 2016

Nanoporous microtubes of a nickel-copper alloy were obtained from a Cu-44Ni-1Mn (wt%) commercial wire (200 μm diameter). A new synthesis method was established through three steps: 1) partial oxidation of the wire at 1173 K in air, 2) removal of the inner unoxidized core by chemical etching, 3) reduction in 10 bar hydrogen atmosphere. During oxidation, the segregation of Cu and Ni occurred because of their different diffusion coefficients in the corresponding oxides. As a consequence, pores were formed by Kirkendall effect and due to selective chemical etching of the different oxides. Additional porosity formed because of volume contraction during reduction with hydrogen. After reduction, the microtube shows a composition gradient from the inner wall (almost pure nickel) to the outer wall (almost pure copper). The process allowed to obtain microtubes with tuneable wall thickness and inner pores around 180 ± 80 nm. The morphological features developed suggest improved capillarity properties for applications in MEMS. © 2016 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht


Lussana D.,University of Turin | Baldissin D.,University of Turin | Baldissin D.,Compumat Srl | Massazza M.,Cogne Acciai Speciali Spa | Baricco M.,University of Turin
Oxidation of Metals | Year: 2014

An AISI 304L stainless steel was oxidised in a TGA instrument at temperatures ranging from 800 to 1,200°C and for up to 3 h. The measured weight gains were fitted starting from the Wagner model, taking into account both a linear and a parabolic behaviour. Rate constants and activation energies were calculated. The fraction of oxides as a function of annealing time at 1,050°C were estimated by Rietveld refinement of XRD patterns of oxidised samples. These data were compared with the theoretical equilibrium conditions calculated with the Calphad approach. A simplified model able to describe the main kinetic features of the oxidation of an AISI 304L steel in industrial conditions (1,050°C and 0.087 atm of oxygen partial pressure) was developed. © 2013 Springer Science+Business Media New York.


Lussana D.,University of Turin | Miranti L.,University of Turin | Castellero A.,University of Turin | Rizzi P.,University of Turin | And 4 more authors.
Metallurgia Italiana | Year: 2013

In this study, high temperature oxidation treatments were performed on an AISI 304L steel under controlled conditions, in order to investigate the breakaway oxidation phenomenon. It consists on the local fracture of the oxide layer due to thermal or mechanical shocks, and the consequent exposition of non-oxidized metal to the oxidizing atmosphere. Due to its nature, it is a phenomenon difficult to foresee and monitor. Thermal analysis and electronic microscopy techniques were optimized in order to characterize the breakaway oxidation. The influence of temperature, oxidizing atmosphere and moisture were evaluated, especially from the point of view of the industrial production process of stainless steels. The possibility of accurately predicting the times at which the breakaway oxidation appears, turned out to be limited.


Andrianopoli C.,Cogne Acciai Speciali S.p.A | Gebert A.,CeWOTec GmbH | Bouaifi B.,AM Technology
Proceedings of the World Powder Metallurgy Congress and Exhibition, World PM 2010 | Year: 2010

Severe stresses, higher process temperatures, increased operating speeds, use of harder and more aggressive materials are making the manufacture of structural components, by using conventional materials, inadequate to satisfy the demand of new productions. In this study FeCrVC based powder alloys for plasma powder welding coating (PTA process) have been investigated and developed taking into consideration both the industrial application and the economic aspects. Prototype components have been produced using the optimised powder alloys. Several tests have been carried out and their results were evaluated and correlated to the alloy compositions. A comparison between conventional hard alloys and the FeCrVC alloys demonstrated their increased abrasive wear resistance and the longer component life that give cost advantages to the tools coated using these new FeCrVC based powders.


Patent
CB Trafilati Acciai S.p.A. and Cogne Acciai Speciali S.p.A. | Date: 2011-07-13

The present patent application relates to a method for preparing a two-phase austeno-ferritic stainless steel wire, rope and/or strand, said method being characterized by the fact it comprises a stabilization step wherein said wire, rope and/or strand is subjected to a thermal or thermo-mechanical treatment at a temperature between 480C and 700C. This method allows the realization of a two-phase austeno-ferritic stainless steel wire, rope and/or strand having good elongation and necking properties thus ensuring good properties in terms of elasticity and resistance to fragility, still also maintaining at the same time good properties in terms of toughness due to rather good yield snervamento rupture and relaxation features.


Scalerandi M.,Polytechnic University of Turin | Gliozzi A.S.,Polytechnic University of Turin | Olivero D.,CogneAcciai Speciali SpA
Journal of Nondestructive Evaluation | Year: 2014

One major problem in ultrasonic NDT for steel products and welding inspection is that standard linear methods are often unable to distinguish the nature of signals. Partially recrystallized grains, voids, small cracks or inclusions in the piece under investigation could produce indications very similar in terms of acoustic energy reflected and ultrasonic peaks envelope. Here, we analyze the nonlinear response to ultrasonic excitations of steel bars with both kind of imperfections purposefully generated. Using the Scaling Subtraction Method as a tool for the analysis, we show differences in the nonlinear signature, which can be used to distinguish nondestructively a crack/delamination from a region with imperfect grains formation, with possible applications of this technique in the production cycle. © 2014 Springer Science+Business Media New York.


Rollet S.,Cogne Acciai Speciali Spa | Franciscono A.,Cogne Acciai Speciali Spa
Yejin Fenxi/Metallurgical Analysis | Year: 2012

When elements of high concentration in high-alloyed steel are determined by OES-Spark, X-ray fluorescence spectrometry (XRF) and inductively coupled plasma optical emission spectrometry (ICP-OES), absorption enhancements, grain size effects, differences in metallurgical phases composition, inter-elemental interferences (OES-Spark and XRF) and poor precision (ICP-OES) affect the accuracy of the response. The preparation of samples as borate beads would lead to many advantages, i.e. elimination of phase composition and metallurgical grain-size effects, high homogeneity and dissolution of inclusions (oxides, nitrides, carbides) and treatment of any shape and amount of sample. In this work, a new method of preparation has been developed. The experimental trials have been conducted in determination of high-alloyed steel international certified materials by XRF.

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