Nanomaterials and Nanocomposites - Production Methods PDF

UNIT 3: Nanomaterials and nanocomposites- Part A Nanomaterials and Nanocomposites: Introduction to Nanomaterials, Classification, Approaches of synthesis (Top Down and Bottom up approach) Introduction to nanocomposites, fabrication, Carbon-metal nanocomposites,...

UNIT 3: Nanomaterials and nanocomposites- Part A Nanomaterials and Nanocomposites: Introduction to Nanomaterials, Classification, Approaches of synthesis (Top Down and Bottom up approach) Introduction to nanocomposites, fabrication, Carbon-metal nanocomposites, Bio-inspired nanocomposites. Application of Nanocomposites in Aerospace, Coating, Mechanical, Electrical & Electronics, Fuel cell, thermoelectric device, thermal interface materials  Nanomaterials ntroduction  Nanomaterials ntroduction  Nanomaterials Introduction The concept of nanotechnology was first given by renowned physicist Richard Feynman in 1959 and earned Nobel Prize. The term “nano” means dwarf and nanotechnology can be understood as the multidisciplinary science of developing, characterizing, and synthesizing materials by controlling their sizes and shapes at the scale of nanometers. This class of material has the characteristic that at least one of the dimensions lie between 1 to 100 nm. Such materials are noted for high surface-to-volume ratios, which enhances the properties of these materials substantially when compared to those of bulk materials. lassification Based on the degree of spatial confinement, nanomaterials can be subdivided into four major types: 0-D: Zero dimensional 1-D: One dimensional 2-D: Two dimensional 3-D: Three dimensional Production of Nanomaterials by Top-Down Method In this method, solid and state processing of the materials are mostly used and this method involves breaking of the bulk material into smaller particles using physical processes such as crushing, milling, and grinding methods. Generally, this method is not appropriate for formulating evenly shaped nanomaterials, and it is very difficult to get very small size nanoparticles even with high energy usages. The major difficulty of this method is the shortage of the surface structure as it has significant impact on physical properties and surface chemistry of nanomaterials. In addition, this method also causes substantial crystallographic loss to the processed shapes. Production of Nanomaterials by Bottom-Up Method In this method, materials are prepared by atom-by-atom or molecule- bymolecule to make large amount of materials. This method is more frequently used for producing most of the nanomaterials. This method has an ability to produce a uniform size, shape, and well- distributed nanomaterials. It basically control the chemical synthesis process in a precisely manner to prevent undesirable particle growth. This method plays an important role in the production and processing of nanomaterials with better particle size distribution and better morphology. Another important feature is that its an environment friendly and economical processes for the nanoparticle production. There are many approaches for synthesizing nanomaterials like hydrothermal, combustion synthesis, gas-phase methods, microwave synthesis, and sol-gel processing. Top-Down Method Top-Down Method https://www.youtube.com/watch? v=6pSkixSwIZY&t=134s Top-Down Method  Bottom-Up Method Sol Gel method The sol-gel process is a synthesis route consisting of the preparation of a sol and successive gelation and solvent removal. The sol-gel process consists of chemical transformation of a liquid (the sol) into a gel and with subsequent post-treatment and transition into a solid oxide material. The main benefits of sol-gel processing are the high purity and the uniform nanostructure achievable at low temperatures. The sol-gel process allows to synthesis ceramic materials of high purity and homogeneity by preparation techniques that are different from the traditional process of fusion of oxides.  Bottom-Up Method Sol-Gel Fabrication-Sol Gel https://www.youtube.com/watch?v=Farnv1Cs