Materials Composition and Structure
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Questions and Answers

The compositions of materials include ______ compositions and mineral compositions.

chemical

The ______ composition refers to the chemical constituents.

chemical

With the increase of ______ content, the strength, hardness and toughness of carbon steel will change.

carbon

Stainless steel comes into being by adding ______, nickel and other chemical components into steel.

<p>chromium</p> Signup and view all the answers

Many inorganic materials consist of a variety of ______ compositions.

<p>mineral</p> Signup and view all the answers

The ______ compositions are the key factors for the properties of some building materials.

<p>mineral</p> Signup and view all the answers

Cement reveals different characteristics because of different ______.

<p>clinkers</p> Signup and view all the answers

The structures of materials can be divided into ______-structure, meso-structure and micro-structure.

<p>macro</p> Signup and view all the answers

The thick structure above ______ that can be identified with magnifying glass or naked eyes is called as macro-structure.

<p>millimeter</p> Signup and view all the answers

The ______ level refers to the macro-structure.

<p>engineering</p> Signup and view all the answers

Atoms, the building block of ______, consist of a nucleus surrounded by a cloud of orbiting electrons.

<p>elements</p> Signup and view all the answers

At the ______ level, the total material is considered as continuous and homogeneous and average properties are assumed throughout the whole volume of the material body.

<p>engineering</p> Signup and view all the answers

The nucleus consists of positively charged ______ and neutral neutrons, and so has a net positive charge.

<p>protons</p> Signup and view all the answers

The minimum scale that must be considered is governed by the size of the ______ cell, which is the minimum volume of the material that represents the entire material system.

<p>representative</p> Signup and view all the answers

Atoms tend to arrange themselves in the most stable patterns possible, which means that they have a tendency to complete or fill their outermost ______ orbits.

<p>electron</p> Signup and view all the answers

Ionic bonding involves a transfer of an ______, so one atom gains an electron while one atom loses an electron.

<p>electron</p> Signup and view all the answers

If the properties are the same in all directions, then the material is ______ and the representative cell is a cube.

<p>isotropic</p> Signup and view all the answers

A covalent bond involves the sharing of ______ between two atoms.

<p>electrons</p> Signup and view all the answers

The micro-level structure that can be observed by optical microscope is called ______ or sub-microstructure.

<p>meso-structure</p> Signup and view all the answers

What is mainly studied in this structure are the size, shape and interface of ______ and particles, and the size, shape and distribution of pores and micro-cracks.

<p>grains</p> Signup and view all the answers

The simplest model of metallic bonding is the ______ of electrons model.

<p>sea</p> Signup and view all the answers

The material consists of ______ such as aggregates distributed in a matrix such as hydrated cement or bitumen.

<p>particles</p> Signup and view all the answers

Metal ions have free ______, the metal materials such as iron, steel, aluminum, copper and their alloys have good thermal conductivity and electrical conductivity.

<p>ions</p> Signup and view all the answers

The strength, hardness, and melting point of atomic crystal are high, such as ______, quartz and silicon carbide.

<p>diamond</p> Signup and view all the answers

The dimensions of the ______ differ considerably, from the wall thickness of a wood cell at 5 × 10 -6 m to the length of a brick at 0.225 m.

<p>particles</p> Signup and view all the answers

The bonding force in covalent bond is ______.

<p>strong</p> Signup and view all the answers

The atomic and molecular structures of materials that can be studied by electron microscopy, X- ray diffractometer and other means are called ______.

<p>microstructure</p> Signup and view all the answers

An obvious limitation of the ionic bond is that it can only occur between atoms of different ______.

<p>elements</p> Signup and view all the answers

The material is considered as a composite of different ______, which interact to realize the behavior of the total material.

<p>phases</p> Signup and view all the answers

If the properties can only be described with reference to ______, the material is anisotropic.

<p>orientation</p> Signup and view all the answers

Study Notes

Materials Composition and Structure

  • Materials composition includes chemical composition and mineral composition, which are key factors for the properties of materials.
  • Chemical composition refers to the chemical constituents, and varying chemical compositions result in different properties.
  • For example, increasing carbon content in carbon steel changes its strength, hardness, and toughness, making it prone to rust, which can be addressed by adding chromium, nickel, and other chemical components to create stainless steel.

Mineral Composition

  • Many inorganic materials consist of various mineral compositions, which are key factors for the properties of some building materials (e.g., natural stone, inorganic gel, and other materials).
  • Cement exhibits different characteristics due to different clinkers.

Structure of Materials

  • The structures of materials can be divided into macro-structure, meso-structure, and micro-structure, which are key factors related to the properties of materials.

Macro-structure

  • Macro-structure refers to the thick structure above millimeter that can be identified with a magnifying glass or naked eyes.
  • At the engineering level, the total material is considered, and it is normally taken as continuous and homogeneous, with average properties assumed throughout the whole volume of the material body.
  • The minimum scale that must be considered is governed by the size of the representative cell, which varies from 10^(-3) m for metals to 0.1 m for concrete and 1 m for masonry.

Meso-structure

  • Meso-structure refers to the micro-level structure that can be observed by optical microscope.
  • It includes the size, shape, and interface of grains and particles, and the size, shape, and distribution of pores and micro-cracks.
  • The material is considered as a composite of different phases, which interact to realize the behavior of the total material.

Microstructure

  • Microstructure refers to the atomic and molecular structures of materials that can be studied by electron microscopy, X-ray diffractometer, and other means.
  • Atoms consist of a nucleus surrounded by a cloud of orbiting electrons, and the nucleus consists of positively charged protons and neutral neutrons.

Bonding of Atoms

  • Atoms tend to arrange themselves in the most stable patterns possible, which means they have a tendency to complete or fill their outermost electron orbits.
  • Ionic bonding involves a transfer of an electron, resulting in high strength, hardness, and melting point, but also volatility and medium density.
  • Covalent bonding involves the sharing of electrons between two atoms, resulting in strong bonding force, high strength, hardness, melting point, and density.
  • Metallic bonding involves sharing electrons, resulting in volatile strength and hardness, high density, and good thermal and electrical conductivity.

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Learn about the chemical and mineral composition of materials and how they affect their properties. Understand how varying compositions result in different properties and characteristics.

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