Degradation and Protection What is affecting the materials?

Definitions Degradation occurs when a material looses its properties – All materials degrade at the surface (to varying degrees) when they enter into contact with … UV Liquids Oxygen

Protection methods attempt to slow down the degradation

1. Degradation and protection of Wood A) Properties of wood: – Hardness, elasticity, resilience – Low thermal and electric conductivity – Easily shaped and assembled – Light weight

1. Degradation and protection of Wood B) Degradation – It can rot, be subject to disease – fungus, insects and micro-organisms can infest the wood. C) Protection: – By varnishing, heating, painting or treating the wood, we can extend its lifetime.

2. Degradation and Protection of Ceramics Ceramic is a solid non-metallic material obtained by heating inorganic matter containing various compounds A) Properties – Low thermal and electrical conductivity – Hardness – Resist corrosion – Durable B) By giving a heat treatment, we can reduce its weakness to thermal shock

3. Degradation and Protection of Metals A) Properties (varies with the metal) – Usually shiny – Good conductors (heat and electricity) – Ductility and Malleability depend on the materials B) Degradation – Corrosion and Oxidation C) Protection: – Coat the metal with a less corrosive metal (Zn, Au, Ag, Ni) – Coat the metal with paint, enamel, grease, resin

Chemical Changes

Chemical Review 1. Chemical vs. Physical Changes – Gas formation – Release or absorption of energy (light or heat) – Precipitation – Color change

Chemical Review 2. Types of chemical changes – A) Synthesis vs. Decomposition – B) Photosynthesis vs. Cellular Respiration – C) Oxidation – D) Combustion

Chemical Review 2. Types of chemical changes – A) Synthesis vs. Decomposition Synthesis – When 2 or more molecules or elements become one molecule Decomposition – When 1 molecules is broken down into 2 or more molecules or elements

Chemical Review 2. Types of chemical changes – B) Photosynthesis vs. Cellular Respiration Cellular Respiration – What we do – Take in Oxygen Photosynthesis – Plants (during the day) – Take in Carbon dioxide

Chemical Review 2. Types of chemical changes – C) Oxidation Requires Oxygen E.g. corrosion

Chemical Review with the Particle model 2. Types of chemical changes – C) Oxidation E.g. corrosion

Chemical Review 2. Types of chemical changes – D) Combustion Requires Oxygen (O 2 ) Gives off energy

Combustion side note: – Types of combustion: Slow Rapid – Requires outside energy input – gives off heat and light that is observable Spontaneous

Combustion Triumvirate (Fire Triangle)