scholarly journals Critical Raw Materials Saving by Protective Coatings under Extreme Conditions: A Review of Last Trends in Alloys and Coatings for Aerospace Engine Applications

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1656
Author(s):  
Maria Luisa Grilli ◽  
Daniele Valerini ◽  
Anca Elena Slobozeanu ◽  
Bogdan O. Postolnyi ◽  
Sebastian Balos ◽  
...  
Keyword(s):  
Raw Materials ◽  
Protective Coatings ◽  
Mitigation Measures ◽  
High Tech ◽  
Extreme Conditions ◽  
Critical Elements ◽  
High Temperature Alloys ◽  
Recent Trends ◽  
Operating Lifetime ◽  
Critical Raw Materials

Several applications where extreme conditions occur require the use of alloys often containing many critical elements. Due to the ever increasing prices of critical raw materials (CRMs) linked to their high supply risk, and because of their fundamental and large utilization in high tech products and applications, it is extremely important to find viable solutions to save CRMs usage. Apart from increasing processes’ efficiency, substitution, and recycling, one of the alternatives to preserve an alloy and increase its operating lifetime, thus saving the CRMs needed for its manufacturing, is to protect it by a suitable coating or a surface treatment. This review presents the most recent trends in coatings for application in high temperature alloys for aerospace engines. CRMs’ current and future saving scenarios in the alloys and coatings for the aerospace engine are also discussed. The overarching aim of this paper is to raise awareness on the CRMs issue related to the alloys and coating for aerospace, suggesting some mitigation measures without having the ambition nor to give a complete overview of the topic nor a turnkey solution.

scholarly journals Complex Concentrated Alloys for Substitution of Critical Raw Materials in Applications for Extreme Conditions

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1197
Author(s):  
Dumitru Mitrica ◽  
Ioana Cristina Badea ◽  
Beatrice Adriana Serban ◽  
Mihai Tudor Olaru ◽  
Denisa Vonica ◽  
...  
Keyword(s):  
Raw Materials ◽  
Extreme Environment ◽  
Extreme Conditions ◽  
The European Union ◽  
Critical Metals ◽  
Research Directions ◽  
Level Of Involvement ◽  
General Evaluation ◽  
Critical Metal ◽  
Critical Raw Materials

The paper is proposing a mini-review on the capability of the new complex concentrated alloys (CCAs) to substitute or reduce the use of critical raw materials in applications for extreme conditions. Aspects regarding the regulations and expectations formulated by the European Union in the most recent reports on the critical raw materials were presented concisely. A general evaluation was performed on the CCAs concept and the research directions. The advantages of using critical metals for particular applications were presented to acknowledge the difficulty in the substitution of such elements with other materials. In order to establish the level of involvement of CCAs in the reduction of critical metal in extreme environment applications, a presentation was made of the previous achievements in the field and the potential for the reduction of critical metal content through the use of multi-component compositions.

scholarly journals The Critical Raw Materials in Cutting Tools for Machining Applications: A Review

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1377 ◽  
Author(s):  
Antonella Rizzo ◽  
Saurav Goel ◽  
Maria Luisa Grilli ◽  
Roberto Iglesias ◽  
Lucyna Jaworska ◽  
...  
Keyword(s):  
Cutting Tool ◽  
Raw Materials ◽  
Single Point ◽  
Cutting Tools ◽  
Mitigation Measures ◽  
Mechanical Processing ◽  
Machining Processes ◽  
Contact Mode ◽  
Mechanical Machining ◽  
Critical Raw Materials

A variety of cutting tool materials are used for the contact mode mechanical machining of components under extreme conditions of stress, temperature and/or corrosion, including operations such as drilling, milling turning and so on. These demanding conditions impose a seriously high strain rate (an order of magnitude higher than forming), and this limits the useful life of cutting tools, especially single-point cutting tools. Tungsten carbide is the most popularly used cutting tool material, and unfortunately its main ingredients of W and Co are at high risk in terms of material supply and are listed among critical raw materials (CRMs) for EU, for which sustainable use should be addressed. This paper highlights the evolution and the trend of use of CRMs) in cutting tools for mechanical machining through a timely review. The focus of this review and its motivation was driven by the four following themes: (i) the discussion of newly emerging hybrid machining processes offering performance enhancements and longevity in terms of tool life (laser and cryogenic incorporation); (ii) the development and synthesis of new CRM substitutes to minimise the use of tungsten; (iii) the improvement of the recycling of worn tools; and (iv) the accelerated use of modelling and simulation to design long-lasting tools in the Industry-4.0 framework, circular economy and cyber secure manufacturing. It may be noted that the scope of this paper is not to represent a completely exhaustive document concerning cutting tools for mechanical processing, but to raise awareness and pave the way for innovative thinking on the use of critical materials in mechanical processing tools with the aim of developing smart, timely control strategies and mitigation measures to suppress the use of CRMs.

scholarly journals The Potential for REE and Associated Critical Metals in Karstic Bauxites and Bauxite Residue of Montenegro

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 975
Author(s):  
Slobodan Radusinović ◽  
Argyrios Papadopoulos
Keyword(s):  
Raw Materials ◽  
Bauxite Residue ◽  
Raw Material ◽  
Late Triassic ◽  
Critical Metals ◽  
Critical Elements ◽  
Secondary Raw Material ◽  
Increasing Demand ◽  
First Time ◽  
Critical Raw Materials

Research for critical raw materials is of special interest, due to their increasing demand, opulence of applications and shortage of supply. Bauxites, or bauxite residue after alumina extraction can be sources of critical raw materials (CRMs) due to their content of rare earth elements and other critical elements. Montenegrin bauxites and bauxite residue (red mud) are investigated for their mineralogy and geochemistry. The study of the CRM’s potential of the Montenegrin bauxite residue after the application of Bayer process, is performed for the first time. Montenegrin bauxites, (Jurassic bauxites from the Vojnik-Maganik and Prekornica ore regions from the Early Jurassic, Middle Jurassic-Oxfordian and Late Triassic paleorelief) are promising for their REE’s content (around 1000 ppm of ΣREE’s). More specifically, they are especially enriched in LREEs compared to HREEs. Regarding other CRMs and other elements, Ti, V, Zr, Nb, Sr and Ga could also be promising. In bauxite residue, the contents of Zr, Sr, V, Sc, La, Ce, Y, Ti and Nb are higher than those in bauxites. However, raw bauxites and bauxite residue as a secondary raw material can be considered as possible sources of CRMs.

scholarly journals Solutions of Critical Raw Materials Issues Regarding Iron-Based Alloys

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 899
Author(s):  
Pavel Novák ◽  
Tiziano Belezze ◽  
Marcello Cabibbo ◽  
Ernst Gamsjäger ◽  
Manfred Wiessner ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Review Paper ◽  
Raw Materials ◽  
Ductile Cast Iron ◽  
Economic Importance ◽  
Supply Risk ◽  
High Temperature Alloys ◽  
Sintered Diamond ◽  
Iron Based ◽  
Critical Raw Materials

The Critical Raw Materials (CRMs) list has been defined based on economic importance and supply risk by the European Commission. This review paper describes two issues regarding critical raw materials: the possibilities of their substitution in iron-based alloys and the use of iron-based alloys instead of other materials in order to save CRMs. This review covers strategies for saving chromium in stainless steel, substitution or lowering the amounts of carbide-forming elements (especially tungsten and vanadium) in tool steel and alternative iron-based CRM-free and low-CRM materials: austempered ductile cast iron, high-temperature alloys based on intermetallics of iron and sintered diamond tools with an iron-containing low-cobalt binder.

scholarly journals Solutions for Critical Raw Materials under Extreme Conditions: A Review

Materials ◽  
2017 ◽  
Vol 10 (3) ◽  
pp. 285 ◽  
Author(s):  
Maria Grilli ◽  
Tiziano Bellezze ◽  
Ernst Gamsjäger ◽  
Antonio Rinaldi ◽  
Pavel Novak ◽  
...  
Keyword(s):  
Raw Materials ◽  
Extreme Conditions ◽  
Critical Raw Materials

scholarly journals Iron Metallurgy Slags as a Potential Source of Critical Elements - Nb, Ta and REE

Mineralogia ◽  
2016 ◽  
Vol 47 (1-4) ◽  
pp. 15-28 ◽  
Author(s):  
Monika Kasina ◽  
Marek Michalik
Keyword(s):  
Blast Furnace ◽  
Ad Hoc ◽  
Technology Development ◽  
Raw Materials ◽  
Critical Elements ◽  
Potential Source ◽  
Steelmaking Slags ◽  
Valuable Metals ◽  
Metallurgical Processes ◽  
Critical Raw Materials

Abstract The recovery of valuable metals from metallurgical slag disposals is a promising option to protect natural resources, limited due to technology development and increased consumption. The Ad-hoc Working Group on Defining Critical Raw Materials within the Raw Materials Supply Group has proposed a list of critical elements which have the greatest economic importance and meet the requirements of sustainable development in Europe. The goal of this study was to examine steelmaking- and blast-furnace slags from metallurgical processes to determine concentrations of elements of the greatest criticality for Poland, e.g. Nb, Ta and REE, and to discuss the viability of their recovery. Slag analyses indicate enrichment of REE relative to UCC, NASC and average chondrite compositions in blast-furnace slags and Nb and Ta in steelmaking slags. To make recovery of these critical elements reasonable and profitable, it is recommended that they be recovered together with other useful raw materials.

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