8.1 Alloy and Its Importances im(2).pptx

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1. 8 : Manufactured Substances in Industry

2. What will you learn? Alloy and Its Importance Compositon of Glass and Its Uses Compositon of Ceramics and Its Uses Composite Materials and Its Importance 8.1 8.2 8.4 8.3

3. 8.1 Alloy and Its Importance

4. Learning Standard Describe briefly alloy with examples Justify the usage of alloys based on their composition and properties 8.1.1 8.1.2 8.1.3 Compare the properties of an alloy with its pure metal through experiment

5. 8.1 Alloy and Its Importance

6. 8.1 Alloy and Its Importance

7. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

8. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

9. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

10. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

11. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

12. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals Conclusion: Is the hypothesis acceptable? What is the conclusion of this experiment ? Discussion : 1. Why must the stainless steel plate and iron plate be cleaned with a sandpaper ? 2. Compare the rate of corrosion of the stainless steel and iron plates . 3. Which block formed a dent with a larger diameter ? 4. State the relationship between the diameter of the dent and the hardness of the substance . The rate of corrosion of stainless steel is lower compared to iron . To remove the oxide layer from the surface of the metal . Copper block The smaller the diameter of the dent, the harder the substance.

13. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals The alloying process helps to prevent the corrosion of metal and alter the properties of a pure metal to make it harder and stronger.

14. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

15. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

16. 8.1 Alloy and Its Importance Comparison of Properties of Alloys and Pure Metals

17. 8.1 Alloy and Its Importance Justify the Uses of Alloys based on Their Composition and Properties The uses of alloys is based on the composition and properties of the alloy produced. Alloys are made for specific purposes. Scientists change the elemental composition to produce alloys with different properties. For example, steel and stainless steel originate from the same pure metal, which is iron. However, both alloys have different properties and are used for different purposes.

18. 8.1 Alloy and Its Importance Justify the Uses of Alloys based on Their Composition and Properties

19. 8.1 Alloy and Its Importance Justify the Uses of Alloys based on Their Composition and Properties A superconductor is an example of an alloy used in electrical transportation such as the Maglev train. Superconductors do not have electrical resistance at very low temperatures. Tis alloy is used to make a magnet that can levitate the train and move it at a very high speed.

20. Quiz time!!!

21. W hat did you learn today?

22. Test Yourself 8.1 (page 259)

23. PREPARED BY: PUAN NOR SURAIYA AFIZA BINTI SALIM SMKPBP(1) THANKS Please keep this slide for attribution

24. Test Yourself 8.1

25. Test Yourself 8.1 1. Atoms in pure iron are arranged in an orderly manner and in layers. (a) What is the effect of atom arrangement in pure iron on the ductility and malleability of the metal ? (b) Iron alloy can be made by mixing some carbon into molten iron. How does the arrangement of atoms in the iron alloy affect the hardness of the alloy? Foreign atoms (carbon atom) disturb the orderly arrangement of atoms in pure iron. The layers of atoms are harder to move or slide over each other. Thus the addition of carbon strengthens the structure of iron and makes iron stronger and harder . When a force is applied, the layers of atoms slide over each other. Pure metal is soft, that is ductile and malleable .

26. Test Yourself 8.1 2. The purity of gold is measured in carats (K). 24 carat gold is pure gold without the addition of any other metal whereas 18 K gold is a mixture comprising of 18 units by mass of gold with 6 units by mass of other metal such as copper. (a) What is the role of copper in 18 K gold? (b) Calculate the composition percentage by mass in 24 g of 18 K gold. To make gold harder and stronger

27. Test Yourself 8.1 3. Justify the following statements: (a) Stainless steel is used to make washing machines (b) High voltage electric cables are made from aluminium alloy (c) 18 K gold is used to make rings Washing machines are in contact with water. Water and oxygen cause metals to rust. Stainless steel is resistant to corrosion . Electrical cables are hung on tall poles. Aluminium alloy has low density . Pure gold is soft. Gold alloy is harder and stronger.