Materials Science and Engineering Overview
What are the principal goals of Materials Science and Engineering?
Materials Science is the scientific field that studies the interrelationship between the structure and the properties of materials. In engineering terms, the goal of this discipline is to design or project the structure of a determined material to get some determined properties basing it on the materials science knowledge.
Why development of new catalysts is mentioned in the area of surface engineering?
Surface engineering is the sub-discipline of materials science which deals with the surface of solid matter. Like the catalysts must be present when and where the chemical reactions take place, as they usually occur over the surface of the reactors, that’s the big relationship between both subjects and that is the reason catalysts have a great importance in the area of surface engineering.
What is a catalyst?
It’s a substance that when is present in some chemical reaction, facilitates the progression of it. The catalyst doesn’t participate directly as a reactant in the chemical reaction, but its presence affects the performance of the reaction.
Give examples of functional surface technologies.
Hardening of the surface, different chemical properties, optical properties change (for photovoltaic devices), combustion fuels.
What methods are used to obtain nanostructures/nanomaterials?
Various techniques of nanolithography such as optical lithography, X-ray lithography dip pen nanolithography, electron beam lithography or nanoimprint lithography were also developed.
Self-Propagating Synthesis and Which Materials Can Be Produced in This Way?
This paper considers the technique of obtaining boride-containing nanostructured composite materials by the method of self-propagating high-temperature synthesis (SHS). It is shown that the selection of regimes and conditions of reactions allows receiving materials on the basis of titanium and chromium borides as well as aluminum oxide with finely dispersed structure and high mechanical properties.
What is the main goal of severe plastic deformation and which technologies belong to this category?
Severe plastic deformation (SPD) is a generic term describing a group of metalworking techniques involving very large strains typically involving a complex stress state or high shear, resulting in a high defect density and equiaxed ‘ultrafine’ grain (UFG) or nanocrystalline (NC) structure. Methods: Equal channel angular extrusion, High pressure torsion, Accumulative roll bonding, Repetitive corrugation and straightening, Asymmetric rolling, Mechanical alloying, Surface treatments
Give some examples of powder technologies.
Powder metallurgy is used to make unique materials impossible to melt or form in other ways. A product of this type is tungsten carbide (WC). WC is used to cut and form other metals. It is very widely used in industry for tools of many types. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts and diamond tools.
What are the most common applications of nanostructured materials?
Employment of nanostructures gives advantage to development of such fields as energy storage and quantum computing.
Give examples of advanced materials in the group of metals, ceramics, polymers.
Metals: TiAl, Porous Ti / Ceramics: Si3N4, Al2O3, ZrO2
Why titanium aluminide alloys are considered as prospective structural materials?
Because this IMC has the following properties: high melting point, low density, high strength at high temperature, low corrosion at high temperature.
What are differences between conventional alloys and intermetallic alloys?
Alloys generally are homogeneous mixture or solid solution of two or more components with one of the major components being a metal. In an ideal case, it is assumed that there is no interaction between the solute and solvent. In some cases, the solute and solvent attract each other.
Indicate principal advantages and disadvantages of titanium aluminides.
Adv: Lighter, higher strength at higher temperature, high ratio strength/density. Dis: Poor castability, expensive production costs.
What technologies are used in the manufacturing of titanium aluminides?
Powder Bed Fusion, direct Energy Deposition, electrode Induction melting inert Gas Atomization, shaped Hot Isostatic Pressed, metal Injection Molding, thermal Spray, vacuum Induction melting inert Gas Atomization.
What functions can be imparted to the surface of materials? Give some examples.
Surface engineering techniques can be used to develop a wide range of functional properties, including physical, chemical, electrical, electronic, magnetic, mechanical, wear-resistant and corrosion-resistant properties at the required substrate surfaces. Almost all types of materials, including metals, ceramics, polymers, and composites can be coated on similar or dissimilar materials.
What are the main functions of thermoelectric materials?
The main function of these materials is the production of thermo-couples currently.
Indicate materials properties included in the thermoelectric figure of merit.
The efficiency of a thermoelectric device for electricity generation is given by (h), defined as: (energy provide to the load)/(heat energy absorbed at hot junction). The ability of a given material to efficiently produce thermoelectric power is related to its dimensionless figure of merit given by: ZT=(
/
How the thermoelectric figure of merit can be optimized?
For good efficiency, it can be made using materials with high electrical conductivity, low thermal conductivity and high Seebeck coefficient.
Give a few examples of thermoelectric materials.
Bismuth chalcogenides and their nanostructures, lead telluride, inorganic clathrates, magnesium group IV compounds, silicides.
What are the challenges associated with multi materials joining?
Friction stir welding and other solid-state joining processes, proactive weld residual stress control, weld microstructure/property engineering, more reliable prediction the performance of welded structures.
What is understood by sustainable manufacturing?
It is the creation of manufactured products through economically-sound processes that minimize negative environmental impacts while conserving energy and natural resources
What are the unique properties of: Mollusc shell, Lotus leaf, Gecko’s foot and Shark skin?
Ms: biodegradable, LL: super-hydrophobic material, GF: adhesion, SS: anti-bacterial.
What is the principle of freeze casting and what materials can be produced by this method?
Freeze-casting is a technique that exploits the highly anisotropic solidification behavior of a solvent (generally water) in a well-dispersed slurry to template controllably a directionally porous ceramic.
Tissue scaffolds, photonics, metal-matrix composites, dentistry, materials science and even food science.
Explain the term ‘brick-and-mortar structure’ and characterize its exceptional properties
Nacre is a brick-and-mortar structure of CaCO3 mineral platelets (aragonite), which provide strength, and proteins, which allow for ductility and toughness. Comparison of the strength and toughness of natural nacre and nacre-like alumina/PMMA ceramics made using freeze casting. Toughening is associated with brick pull-out and frictional sliding in the compliant polymeric layer.
What is the definition of MAX phases? Explain relations between composition, structure and properties.
The MAX phases are a new and exciting class of carbides and nitrides that bridge the gap between properties typical of metals and ceramics, while offering fundamentally new directions in tuning the structure and properties of ceramics for emerging applications.
Indicate potential applications of MAX phases.
High temperature applications mainly (Ti2AlC), for gas burner nozzles and industrial die inserts. Foil bearings, glove and condom molds, tooling for dry drilling concrete and non-stick cookware. Sputtering targets for electrical contact deposition, electrode production.