8 What are the three classes of matrix materials in composit

8. What are the three classes of matrix materials in composites? 9. 9a. Spheroidite steel is a good example of Metal Matrix Composite material. What are the matrix material and the dispersed phase acting as a reinforcing agent? 9b. Name one material that is commonly used as the fibers in fiber reinforced composites. 10. 10a. In metals increasing \"imperfections\" e.g. grain boundaries, dislocations, vacancies in the material will increase or decrease the resistivity of that material? Briefly explain why. 10b. Does the resistivity of a copper increase or decrease when it is heated to a higher temperature? Briefly states why

Solution

(8) Answer:- Three classes:-

(i) Ceramic matrix

(ii) Metal matrix

(iii) Polymer matrix

9(a) Answer:- In concrete reinforced with steel the matrix phase is concrete and the reinforcing phase is steel.

9(b) Answer:- Graphite/epoxy composites the graphite fibers are the reinforcing phase and epoxy resin is the matrix phase.

10(a) Answer:- Material are often stronger when they have defects. A vacancy is a lattice position that is vacant because the atom is missing, due to this resistance property increase.

10 (b) Answer:- At higher temperature , copper increases resistivity properties. An electron to interact with an atom and lose some of its energy , there needs to be an appropriate energy level change.

When temperature increases the distribution of energy levels in the atoms widens and there are more possibilities of interaction between an electron and an atom. Hence the energy is lost quicker which is same thing as increasing the resistance.