Nanoscience: Mechanical Properties

Presentation Transcript

Nanoscience: Mechanical Properties Olivier Nguon CHEM *7530/750 Feb 21st 2006

Outline I. Great Mechanical Properties II. Nanostructured Materials III. Conclusions and Applications

Tensile test Determination of mechanical properties Stress: σ = F/S Strain: ε = Δ l/l 0

Stress, σ (Mpa) Max stress : rigidity Necking Max flexibility: Yield quality Fracture Strain, ε (%) Elastic twisting Plastic disfigurement Tensile Test bend Typical Tensile Test bend or Strain Stress bend

Modulus = slant Strain Elastic Deformation Hooke's law: σ = E ε E = Young modulus (Pa) Stiffness of material Non direct models exist (visco-versatile conduct) Stress, σ

Mechanical properties Yield quality: greatest worry before lasting strain Tensile quality: most extreme anxiety Ductility: measure of misshapening (L f – L o )/L o Toughness: capacity to absorbe vitality: territory under bend

Hardness Resistance to plastic distortion Measure of profundity or size of space

II. Nanostructured materials

Nanoparticles Conventional materials: Grain estimate micron to mm Nanoparticles increment grain limits Influence on mechanical properties: Increased hardness, yield quality, flexible modulus, strength

Comparison ductile bends Comparison: Al Mg cryomilled (20 nm) Al Mg ultra fine grain (80 nm) Al Mg coarse (2 mm) Cryomilling: Milling in fluid N 2 Ultrafine grain: electrodeposition B. Han, Red.Adv.Mater.Sci ; 9 (2005) 1-16

Mechanical properties of nanomaterials contrasted with coarse grain materials Higher Young modulus and elasticity (to 4 times higher) Lower plastic misshapening More weak

Strength and Hardness with grain measure Strength and Hardness of nanostructured material increments with diminishing size Grain limits distortion

Comparison of Young modulus

Elongation nanostructured materials Elongation diminished Lower thickness of versatile disengagements Short separation of disengagement development

III. Conclusions

Mechanical properties Mechanical properties: Strength, sturdiness, hardness expanded Materials more weak Due to expanded grain limits thickness and less separations thickness

Important elements on mechanical properties History of the material: Temperature, strain : impact on measure of disengagements, grain estimate Impurities : isolate at high temperature and influence mechanical properties

Applications Biomedical: bones, inserts, and so forth. High quality, solid, enduring materials: automotives, gadgets, aviation, and so on. Composites materials