Pendahuluan pengetahuan materiallll.pptx

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1. Pengenalan Material

2. Klasifikasi material Logam Keramik Komposit polymer © 2011 Cengage Learning Engineering. All Rights Reserved. 1 -

3. logam Material yang tersusun atas satu atau berbagai jenis material logam Logam murni= tersusun atas satu jenis logam, bisa dilihat langsung di tabel periodik ( besi=Fe, Tembaga=Cu, Seng=Zn ) Logam alloy/paduan= logam yang tersusun atas minimal dua jenis logam ( tidak bereaksi kimia, hanya larut, tidak bisa dilihat unsur penyusunnya secara makro ), ( Baja=Fe+C, stainless steel=Fe+Cr, Kuningan=Cu+Zn )

4. keramik Material yang tersusun atas minimal 2 jenis unsur (antara logam dengan non-logam), dimana terjadi reaksi kimia dan tidak bisa dilihat unsur penyusunnya secara makro , ( Fe 2 O 3 =Fe+O 2 , Al 2 O 3 =Al+O 2 , SiC=Si+C ) Keramik tradisional (dari alam komposisi bermacam-macam) Keramik teknik (buatan, komposisi tertentu) © 2011 Cengage Learning Engineering. All Rights Reserved. 1 -

5. komposit Material yang tersusun atas minimal dua jenis material ( tidak bereaksi kimia, hanya menempel, bisa dilihat material penyusunnya secara makro ) Body kapal=fiber+resin Ban kendaraan= kawat+karet Beton=pasir © 2011 Cengage Learning Engineering. All Rights Reserved. 1 -

6. polymer Material yang memiliki rantai ikatan kimia yang sangat panjang Thermoplastik (bisa dibentuk ulang), PP, HDPE, PET Thermoset (tidak bisa dibentuk ulang), resin epoxy © 2011 Cengage Learning Engineering. All Rights Reserved. 1 -

7. © 2011 Cengage Learning Engineering. All Rights Reserved. 1 -

8. © 2011 Cengage Learning Engineering. All Rights Reserved. 1 - Functional Classification of Materials

9. Material properties 1. Physical properties 2. Mechanical properties 3. Chemical properties

10. Physical properties Colour –light wave length Specific heat – t he heat required to raise the temperature of one gram of a substance by one degree centigrade (J/kg K) Density – mass per unit volume expressed in such units as kg/cm 3 Thermal conductivity –rate at which heat flows through a given material (W/m K) Melting point – a temperature at which a solid begins to liquify Electrical conductivity – a m easure of how strongly a material opposes the flow of electric current ( Ω⋅ m ) Coefficient of thermal expansion – degree of expansion divided by the change in temperature (m/°C)

11. Mechanical properties Tensile strength – m easures the force required to pull something such as rope,wire or a structural beam to the point where it breaks Ductility – a measure of how much strain a material can take before rupturing M alleability – the p roperty of a material that can be worked or hammered or shaped without breaking Brittleness – break ing or shatter ing of a material when subjected to stress (when force is applied to it )

12. Elasticity – the property of a material that returns to its original shape after stress (e.g. external forces ) that made it deform or distort is removed Plasticity - the deformation of a material undergoing non-reversible changes of shape in response to applied forces Toughness – the ability of a material to absorb energy and plastically deform without fracturing Hardness – the property of being rigid and resistant to pressure; not easily scratched Machinability – the property of a material that can be shaped by hammering, pressing, rolling

13. Chemical properties Corrosion resistance - a material's ability to resist deterioration caused by exposure to an environment Flammability - How easily something will burn or ignite Heat of Combustion - This chemical property is the amount of energy that is released as heat when a substance is burned with oxygen. Toxicity - How much a substance can damage an animal, plant, cell, organ, or other organism Radioactivity - The emission of radiation from an atom with an unstable nucleus