Metal and Non-Metal Materials: Properties and Treatments

Posted on Jan 21, 2025 in Electromechanical Engineering

Metal and Non-Metal Materials

Metals

Corrosion, especially in metals like iron exposed to seawater, is a significant challenge. Different types of corrosion include:

Intergranular corrosion: Occurs at the grain boundaries of the metal, leading to a loss of cohesion and internal destruction.

Ceramics

Crystalline Ceramics

Derived from fused silica, these ceramics possess high mechanical strength and temperature resistance. They are used in motors, infrared radiators, and bearings.

Non-Crystalline Ceramics

Amorphous in nature, these ceramics have lower mechanical and thermal resistance compared to crystalline ceramics. They are used in glass-ceramic production.

Glass-Ceramics: Made from aluminum silicate, lithium, and magnesium, these materials offer increased mechanical strength and low thermal expansion. They are used in furnaces and electrical resistance applications.

Metal Materials: Alloys

An alloy is a homogeneous mixture or solid solution of a metal with other elements (metallic or non-metallic), retaining the metal’s appearance and properties.

Solidification Diagrams

These diagrams are graphical tools used to identify changes during the cooling process of alloys, based on their composition.

Alloy Steel

Chromium Steel

Highly corrosion-resistant due to a compact chromium oxide layer.

Nickel-Chromium Steels (Stainless Steel)

These steels possess excellent mechanical properties, including high elasticity and elongation at room temperature. They are used in various applications, from surgical instruments to cooking appliances.

Refractory Steel

Characterized by hardness, wear resistance, and ductility. Used in missile components and gears.

Fast Cutting Steel

Allows high cutting speeds without softening. Used in tools for turning, milling, drilling, and planing.

Treatments

Thermal Treatments

Annealing: Heating, maintaining temperature, and slow cooling for homogenization, regeneration, and stabilization.
Normalizing: Heating, maintaining temperature, and air cooling.
Quenching: Heating and rapid cooling (martensitic, precipitation, and surface hardening).
Tempering: Heating below the hardening temperature and cooling.

Thermochemical Treatments

Carburizing: Incorporating carbon into the surface layer.
Nitriding: Incorporating nitrogen into the surface layer.
Cyaniding: Incorporating carbon and nitrogen into the surface layer.
Sulfinizing: Incorporating sulfur into the surface layer.

Mechanical Treatments

Cold Working: Rolling, cold stamping, drawing.
Hot Working: Forging, hot stamping, extrusion.

Surface Treatments

Metallization: Spraying molten metal onto a surface.
Hard Chrome Plating: Applying an electrolytic chromium layer.

Protection Against Corrosion

Chemical Modification of the Surface

Chromate Conversion Coating: Forming a chromium oxide layer.
Phosphating: Forming a metal phosphate layer.
Anodizing: Forming an oxide layer of the metal itself.

Non-Metallic Coatings

Paints and Varnishes: Applying paints and varnishes.
Plastics: Coating metals and electrical components.
Ceramic Glazes: Fusing materials onto the metal surface.

Metallic Coatings

Electrodeposition: Plating from metal salts.
Electrophoresis: Electrolytic coating by electrostatic attraction.
Hot-Dip Galvanizing: Coating by immersion in a molten metal bath.
Diffusion Coating: Forming a surface alloy.

Cathodic Protection

Connecting the metal to an anode with a lower oxidation potential.

Corrosion Inhibitors

Reducing corrosion rate by adding high molecular weight polyamides, long chains, and phenolic materials.